import { useEffect, useMemo, useState, useCallback } from 'react'
import { Link, useLocation, useNavigate, useParams } from 'react-router-dom'
import type { SiteContent, StudyProgram, StudySection } from './content'
import { DEFAULT_COLOSSIANS_STUDY_SECTIONS } from './colossiansStudyData'

type Props = { content: SiteContent }

type StudyAuthState = {
  checked: boolean
  authenticated: boolean
  username: string
  enrolledStudySlugs?: string[]
  displayName?: string
  subscribeNewsletter?: boolean
}

type StudyAuthStatusResponse = {
  authenticated: boolean
  username: string
  enrolledStudySlugs?: string[]
  displayName?: string
  subscribeNewsletter?: boolean
}

type StudyAccountOverview = {
  profile: {
    username: string
    displayName: string
    subscribeNewsletter: boolean
  }
  stats: {
    noteCount: number
    memberSince: string
    lastLoginAt: string | null
  }
  studies: Array<{
    slug: string
    title: string
    status: 'active' | 'planned'
    enrolled: boolean
    totalLessons: number
    completedLessons: number
    noteCount: number
  }>
}

type StudyNotesMap = Record<string, string>

function getLegacyColossiansStudy(content: SiteContent): StudyProgram {
  const legacySections = content.colossiansStudySections?.length ? content.colossiansStudySections : DEFAULT_COLOSSIANS_STUDY_SECTIONS
  return {
    id: 'study-colossians',
    slug: 'colossians',
    title: 'Colossians: Rooted in Christ',
    description: 'Walk through Colossians in guided lessons with commentary, Greek notes, and discussion prompts.',
    status: 'active',
    difficulty: 'intermediate',
    estimatedHours: 12,
    completionBadge: 'Colossians Completion',
    numberOfChapters: 4,
    sections: legacySections,
  }
}

function getStudies(content: SiteContent): StudyProgram[] {
  if (Array.isArray(content.studies) && content.studies.length > 0) return content.studies
  return [getLegacyColossiansStudy(content)]
}

function getStudyBySlug(studies: StudyProgram[], slug: string | undefined) {
  const safeSlug = (slug ?? 'colossians').trim().toLowerCase()
  return studies.find(study => study.slug === safeSlug)
}

function getSectionById(sections: StudySection[], sectionId: string | undefined) {
  if (!sectionId) return undefined
  return sections.find(section => section.id === sectionId)
}

function getLessonNumber(sections: StudySection[], sectionId: string | undefined) {
  const index = sections.findIndex(item => item.id === sectionId)
  return index >= 0 ? index + 1 : 0
}

function getPrimaryQuestion(section: StudySection) {
  if (section.focusQuestion?.trim()) return section.focusQuestion.trim()
  return section.studyQuestions.length > 0 ? section.studyQuestions[0] : 'How does this passage shape the way we follow Christ this week?'
}

function getChapterSummaries(study: StudyProgram) {
  const highestSectionChapter = study.sections.reduce((max, section) => Math.max(max, section.chapter), 0)
  const totalChapters = Math.max(study.numberOfChapters, highestSectionChapter)
  return Array.from({ length: totalChapters }, (_, index) => {
    const chapter = index + 1
    const lessonCount = study.sections.filter(section => section.chapter === chapter).length
    return { chapter, lessonCount }
  })
}

function isNewLesson(section: StudySection): boolean {
  if (!section.releasedAt) return false
  const releaseDate = new Date(section.releasedAt)
  const now = new Date()
  const daysSinceRelease = (now.getTime() - releaseDate.getTime()) / (1000 * 60 * 60 * 24)
  return daysSinceRelease >= 0 && daysSinceRelease <= 14
}

function isComingSoon(section: StudySection): boolean {
  if (!section.releasedAt) return false
  const releaseDate = new Date(section.releasedAt)
  const now = new Date()
  return releaseDate > now
}

function isSectionReleased(section: StudySection): boolean {
  if (!section.releasedAt) return false
  const releaseDate = new Date(section.releasedAt)
  if (Number.isNaN(releaseDate.getTime())) return false
  return releaseDate <= new Date()
}

function getReleaseDateDisplay(section: StudySection): string {
  if (!section.releasedAt) return ''
  const date = new Date(section.releasedAt)
  return date.toLocaleDateString('en-US', { month: 'short', day: 'numeric', year: 'numeric' })
}

function getNoteId(studySlug: string, sectionId: string) {
  return `${studySlug}--${sectionId}`
}

async function readJson<T>(url: string, init?: RequestInit): Promise<T> {
  const response = await fetch(url, init)
  const data = await response.json().catch(() => ({})) as T & { message?: string }
  if (!response.ok) {
    throw new Error((data as { message?: string }).message ?? 'Request failed')
  }
  return data as T
}

function normalizeEnrolledStudySlugs(value: unknown): string[] {
  if (!Array.isArray(value)) return []
  return value.filter(item => typeof item === 'string' && item.trim()).map(item => item.trim().toLowerCase())
}

function isEnrolledInStudy(auth: StudyAuthState, studySlug: string | undefined): boolean {
  if (!auth.authenticated || !studySlug) return false
  const normalized = studySlug.trim().toLowerCase()
  if (!normalized) return false
  return normalizeEnrolledStudySlugs(auth.enrolledStudySlugs).includes(normalized)
}

export function StudyLandingPage({ content }: Props) {
  const studies = getStudies(content)
  const activeStudies = studies.filter(study => study.status !== 'planned')
  const plannedStudies = studies.filter(study => study.status === 'planned')
  const firstActiveStudy = activeStudies[0]
  const firstActiveStudyFirstReleasedSection = firstActiveStudy?.sections.find(isSectionReleased)

  return (
    <main className="study-index-page" aria-label="Study hub">
      <section className="section-study-course-hero">
        <div className="section-inner study-course-hero-inner">
          <p className="eyebrow">Self-Paced Bible Academy</p>
          <h1>Study at Your Own Pace</h1>
          <p className="study-course-hero-copy">Pick a study track, move lesson by lesson on your own schedule, and keep personal notes as you grow through each passage.</p>
          <div className="study-course-meta">
            <span>{studies.length} study tracks</span>
            <span>Self-paced flow</span>
            <span>Personal notes</span>
            <span>Audio + commentary</span>
          </div>
          <div className="study-course-hero-actions">
            {firstActiveStudyFirstReleasedSection && <Link to={`/study/${firstActiveStudy.slug}/${firstActiveStudyFirstReleasedSection.id}`} className="btn-primary">Start Learning</Link>}
            <Link to="#study-tracks" className="btn-secondary">Browse Tracks</Link>
            <Link to="/study/signup" className="btn-primary">Create Account or Login</Link>
            <Link to="/study/account" className="btn-secondary">My Account</Link>
          </div>
        </div>
      </section>

      <section className="section-study-hub-flow" aria-label="How self-paced study works">
        <div className="section-inner">
          <div className="study-module-header">
            <p>How It Works</p>
            <h2>A Simple Self-Paced Rhythm</h2>
          </div>
          <div className="study-hub-flow-grid">
            <article className="study-hub-flow-card">
              <p className="study-module-lesson">Step 1</p>
              <h3>Choose Your Track</h3>
              <p>Start with any active study and begin at lesson one, or jump back in where you left off.</p>
            </article>
            <article className="study-hub-flow-card">
              <p className="study-module-lesson">Step 2</p>
              <h3>Work Each Lesson</h3>
              <p>Read the text, listen to audio, review commentary, and process key Greek word notes.</p>
            </article>
            <article className="study-hub-flow-card">
              <p className="study-module-lesson">Step 3</p>
              <h3>Save Notes and Continue</h3>
              <p>Keep personal notes per lesson and build your own study archive over time.</p>
            </article>
          </div>
        </div>
      </section>

      <section id="study-tracks" className="section-study-module" aria-label="Available studies">
        <div className="section-inner">
          <div className="study-module-header">
            <p>Available Now</p>
            <h2>Current Study Tracks</h2>
          </div>
          <div className="study-module-list">
            {activeStudies.map(study => (
                (() => {
                  const releasedCount = study.sections.filter(isSectionReleased).length
                  return (
              <Link key={study.id} to={`/study/${study.slug}`} className="study-module-row">
                <div className="study-module-row-left">
                  <div style={{ display: 'flex', alignItems: 'center', gap: '0.75rem', marginBottom: '0.5rem', flexWrap: 'wrap' }}>
                    <p className="study-module-lesson">Start Anytime</p>
                    {study.difficulty && <span style={{ backgroundColor: study.difficulty === 'advanced' ? '#d32f2f' : (study.difficulty === 'intermediate' ? '#f57c00' : '#388e3c'), color: '#fff', padding: '0.25rem 0.75rem', borderRadius: '16px', fontSize: '0.75rem', fontWeight: '600', textTransform: 'capitalize' }}>{study.difficulty}</span>}
                  </div>
                  <h3>{study.title}</h3>
                  <p>{study.description}</p>
                  {study.estimatedHours && <p style={{ fontSize: '0.875rem', color: '#666', marginTop: '0.5rem' }}>⏱ {study.estimatedHours} hours</p>}
                </div>
                <div className="study-module-row-right">
                  <p className="study-module-focus">Track Snapshot</p>
                      <p>{releasedCount > 0 ? `${releasedCount} lessons available now` : 'Lessons will be published soon.'}</p>
                      <p>{study.sections.length > 0 ? 'Estimated pace: every other Monday' : 'Pacing details coming with first lesson release.'}</p>
                </div>
              </Link>
                  )
                })()
              ))}
          </div>
        </div>
      </section>

      {plannedStudies.length > 0 && (
        <section className="section-study-module" aria-label="Upcoming studies">
          <div className="section-inner">
            <div className="study-module-header">
              <p>Coming Soon</p>
              <h2>Next Study Tracks</h2>
            </div>
            <div className="study-module-list">
              {plannedStudies.map(study => (
                <article key={study.id} className="study-module-row study-module-row--disabled" aria-disabled="true">
                  <div className="study-module-row-left">
                    <p className="study-module-lesson">Planned</p>
                    <h3>{study.title}</h3>
                    <p>{study.description}</p>
                  </div>
                  <div className="study-module-row-right">
                    <p className="study-module-focus">Status</p>
                    <p>Preparing lesson structure and media.</p>
                  </div>
                </article>
              ))}
            </div>
          </div>
        </section>
      )}


    </main>
  )
}

export function StudySignupPage() {
  const navigate = useNavigate()
  const [mode, setMode] = useState<'signup' | 'login'>('signup')
  const [email, setEmail] = useState('')
  const [password, setPassword] = useState('')
  const [subscribeNewsletter, setSubscribeNewsletter] = useState(true)
  const [busy, setBusy] = useState(false)
  const [message, setMessage] = useState('')
  const [done, setDone] = useState(false)
  const [loggedInAs, setLoggedInAs] = useState('')

  useEffect(() => {
    readJson<StudyAuthStatusResponse>('/api/study-auth/status')
      .then(data => {
        if (data.authenticated) {
          setDone(true)
          setLoggedInAs(data.username ?? '')
        }
      })
      .catch(() => {})
  }, [])

  const submit = useCallback(async () => {
    if (!email.trim() || !password.trim()) {
      setMessage('Please enter your email and password.')
      return
    }
    setBusy(true)
    setMessage('')
    try {
      const data = await readJson<{ username: string; enrolledStudySlugs?: string[] }>(`/api/study-auth/${mode}`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ username: email, password, ...(mode === 'signup' ? { subscribe: subscribeNewsletter } : {}) }),
      })
      setDone(true)
      setLoggedInAs(data.username ?? email.trim().toLowerCase())
    } catch (err) {
      setMessage(err instanceof Error ? err.message : 'Something went wrong. Please try again.')
    } finally {
      setBusy(false)
    }
  }, [mode, email, password, subscribeNewsletter])

  return (
    <main className="thanks-page" aria-label={mode === 'signup' ? 'Create account' : 'Sign in'}>
      <div className="thanks-card study-signup-page-card">
        <p className="eyebrow">Free Student Account</p>
        <h1>{mode === 'signup' ? 'Create Your Account' : 'Welcome Back'}</h1>

        {done ? (
          <>
            <p className="study-signup-success">You're signed in as <strong>{loggedInAs}</strong>. Your notes are ready on every lesson.</p>
            <div className="study-signup-actions">
              <button type="button" className="btn-primary" onClick={() => navigate('/study')}>Go to Study Hub</button>
              <Link to="/study/account" className="btn-secondary">My Account</Link>
              <Link to="/study" className="btn-secondary">Browse Tracks</Link>
            </div>
          </>
        ) : (
          <>
            <div className="study-signup-form">
              <label htmlFor="signup-email">Email</label>
              <input
                id="signup-email"
                type="email"
                value={email}
                onChange={e => setEmail(e.target.value)}
                placeholder="your@email.com"
                autoComplete="email"
                autoFocus
              />
              <label htmlFor="signup-password">Password</label>
              <input
                id="signup-password"
                type="password"
                value={password}
                onChange={e => setPassword(e.target.value)}
                placeholder="At least 8 characters"
                autoComplete={mode === 'signup' ? 'new-password' : 'current-password'}
                onKeyDown={e => e.key === 'Enter' && submit()}
              />
              {mode === 'signup' && (
                <label className="contact-consent" style={{ marginTop: '0.75rem' }}>
                  <input
                    type="checkbox"
                    checked={subscribeNewsletter}
                    onChange={e => setSubscribeNewsletter(e.target.checked)}
                  />
                  <span>Send me updates from Verse by Verse with Nate. I can unsubscribe anytime.</span>
                </label>
              )}
              {message && <p className="study-signup-error">{message}</p>}
              <div className="study-signup-actions">
                <button type="button" className="btn-primary" disabled={busy} onClick={submit}>
                  {busy ? (mode === 'signup' ? 'Creating...' : 'Signing in...') : (mode === 'signup' ? 'Create Account' : 'Sign In')}
                </button>
              </div>
              <p className="study-signup-switch">
                {mode === 'signup'
                  ? <><span>Already have an account? </span><button type="button" className="study-signup-toggle" onClick={() => { setMode('login'); setMessage('') }}>Sign in instead</button></>  
                  : <><span>New here? </span><button type="button" className="study-signup-toggle" onClick={() => { setMode('signup'); setMessage('') }}>Create a free account</button></>  
                }
              </p>
            </div>

            <div className="study-signup-why-grid" style={{ marginTop: '2rem' }}>
              <article className="study-signup-why-card">
                <p className="study-signup-why-icon" aria-hidden="true">📝</p>
                <h3>Notes on Every Lesson</h3>
                <p>Save your own notes per lesson — up to 500 notes across all tracks.</p>
              </article>
              <article className="study-signup-why-card">
                <p className="study-signup-why-icon" aria-hidden="true">📖</p>
                <h3>Space to Go Deep</h3>
                <p>Each note holds ~2,000 words so you can write as much as you need.</p>
              </article>
              <article className="study-signup-why-card">
                <p className="study-signup-why-icon" aria-hidden="true">🔒</p>
                <h3>Private to You</h3>
                <p>Your notes are tied to your account. Nobody else can read them.</p>
              </article>
              <article className="study-signup-why-card">
                <p className="study-signup-why-icon" aria-hidden="true">⚡</p>
                <h3>Free Forever</h3>
                <p>Just an email and password. No charge, no ads. Stay signed in 30 days.</p>
              </article>
            </div>
          </>
        )}

        <div className="study-signup-actions" style={{ marginTop: '1.5rem' }}>
          <Link to="/study/account" className="btn-secondary">My Account</Link>
          <Link to="/study" className="btn-secondary">Back to Studies</Link>
        </div>
      </div>
    </main>
  )
}

export function ColossiansStudyIndexPage({ content }: Props) {
  const { studySlug } = useParams<{ studySlug?: string }>()
  const studies = getStudies(content)
  const study = getStudyBySlug(studies, studySlug)
  const [auth, setAuth] = useState<StudyAuthState>({ checked: false, authenticated: false, username: '', enrolledStudySlugs: [] })
  const [enrolling, setEnrolling] = useState(false)
  const [enrollMessage, setEnrollMessage] = useState('')

  useEffect(() => {
    let cancelled = false
    readJson<StudyAuthStatusResponse>('/api/study-auth/status')
      .then(data => {
        if (cancelled) return
        setAuth({
          checked: true,
          authenticated: Boolean(data.authenticated),
          username: data.username ?? '',
          enrolledStudySlugs: normalizeEnrolledStudySlugs(data.enrolledStudySlugs),
        })
      })
      .catch(() => {
        if (cancelled) return
        setAuth({ checked: true, authenticated: false, username: '', enrolledStudySlugs: [] })
      })
    return () => {
      cancelled = true
    }
  }, [])

  if (!study) {
    return (
      <main className="thanks-page" aria-label="Study not found">
        <div className="thanks-card">
          <p className="eyebrow">Study Hub</p>
          <h1>Study not found</h1>
          <p>The study you requested is not available yet.</p>
          <Link to="/study" className="btn-primary">Back to Studies</Link>
        </div>
      </main>
    )
  }

  const sections = study.sections
  const chapterSummaries = getChapterSummaries(study)
  const releasedSections = sections.filter(isSectionReleased)
  const firstReleasedSection = releasedSections[0]
  const populatedChapterCount = chapterSummaries.filter(chapter => chapter.lessonCount > 0).length
  const enrolled = isEnrolledInStudy(auth, study.slug)

  async function enrollInStudy() {
    if (!study) return
    setEnrollMessage('')
    setEnrolling(true)
    try {
      const response = await readJson<{ enrolledStudySlugs?: string[]; studyTitle?: string }>(`/api/study-enrollment/${encodeURIComponent(study.slug)}`, {
        method: 'POST',
      })
      setAuth(prev => ({
        ...prev,
        enrolledStudySlugs: normalizeEnrolledStudySlugs(response.enrolledStudySlugs),
      }))
      setEnrollMessage(response.studyTitle ? `You are enrolled in ${response.studyTitle}.` : 'You are now enrolled.')
    } catch (err) {
      setEnrollMessage(err instanceof Error ? err.message : 'Unable to enroll right now.')
    } finally {
      setEnrolling(false)
    }
  }

  return (
    <main className="study-index-page" aria-label={`${study.title} study`}>
      <section className="section-study-course-hero">
        <div className="section-inner study-course-hero-inner">
          <p className="eyebrow">Online Bible Class</p>
          <h1>{study.title}</h1>
          <p className="study-course-hero-copy">{study.description}</p>
          <div className="study-course-meta">
            <span>{releasedSections.length} lessons available now</span>
            <span>{chapterSummaries.length} chapters</span>
            <span>{populatedChapterCount} chapters with lessons</span>
            <span>Text + commentary + discussion</span>
            <span>Student notes enabled</span>
          </div>
          <div className="study-course-hero-actions">
            {enrolled && firstReleasedSection && <Link to={`/study/${study.slug}/${firstReleasedSection.id}`} className="btn-primary">Start Class</Link>}
            {!auth.authenticated && <Link to="/study/signup" className="btn-primary">Sign In to Enroll</Link>}
            {auth.authenticated && !enrolled && (
              <button type="button" className="btn-primary" disabled={enrolling} onClick={enrollInStudy}>
                {enrolling ? 'Enrolling...' : 'Enroll in This Study'}
              </button>
            )}
            {auth.authenticated && <Link to="/study/account" className="btn-secondary">My Account</Link>}
            {enrolled && <Link to={`/study/${study.slug}/notes`} className="btn-secondary">My Notes</Link>}
            <Link to="/study" className="btn-secondary">Back to Studies</Link>
          </div>
          {enrollMessage && <p className="study-note-status" style={{ marginTop: '0.75rem' }}>{enrollMessage}</p>}
        </div>
      </section>

      {auth.checked && auth.authenticated && !enrolled && (
        <section className="section-study-module" aria-label="Enrollment required">
          <div className="section-inner">
            <article className="study-module-row study-module-row--disabled" aria-disabled="true">
              <div className="study-module-row-left">
                <p className="study-module-lesson">Enrollment Required</p>
                <h3>Enroll before entering lessons</h3>
                <p>You must enroll in this study before opening lessons or notes.</p>
                <div style={{ marginTop: '0.75rem' }}>
                  <button type="button" className="btn-primary" disabled={enrolling} onClick={enrollInStudy}>
                    {enrolling ? 'Enrolling...' : `Enroll in ${study.title}`}
                  </button>
                </div>
              </div>
            </article>
          </div>
        </section>
      )}

      {sections.length === 0 && (
        <section className="section-study-module">
          <div className="section-inner">
            <article className="study-module-row study-module-row--disabled" aria-disabled="true">
              <div className="study-module-row-left">
                <p className="study-module-lesson">Planned</p>
                <h3>Lessons are being prepared</h3>
                <p>Use the admin Studies editor to add section lessons and publish when ready.</p>
              </div>
            </article>
          </div>
        </section>
      )}

      {sections.length > 0 && (
        <section className="section-study-module" aria-label="Course lessons">
          <div className="section-inner">
            <div className="study-module-header">
              <p>Course Lessons</p>
              <h2>{study.title}</h2>
            </div>
            <div className="study-module-list">
              {sections.map(section => {
                const lessonNumber = getLessonNumber(sections, section.id)
                const isNew = isNewLesson(section)
                const coming = isComingSoon(section)
                const isDisabled = coming || !enrolled
                
                return (
                  <Link key={section.id} to={isDisabled ? '#' : `/study/${study.slug}/${section.id}`} className={`study-module-row${isDisabled ? ' study-module-row--disabled' : ''}`} onClick={e => isDisabled && e.preventDefault()}>
                    <div className="study-module-row-left">
                      <div style={{ display: 'flex', alignItems: 'center', gap: '0.5rem', marginBottom: '0.25rem' }}>
                        <p className="study-module-lesson">Lesson {lessonNumber}</p>
                        {isNew && <span style={{ backgroundColor: '#4caf50', color: '#fff', padding: '0.2rem 0.5rem', borderRadius: '3px', fontSize: '0.75rem', fontWeight: '600' }}>New</span>}
                        {coming && <span style={{ backgroundColor: '#ffb74d', color: '#333', padding: '0.2rem 0.5rem', borderRadius: '3px', fontSize: '0.75rem', fontWeight: '600' }}>Coming {getReleaseDateDisplay(section)}</span>}
                        {!coming && !enrolled && <span style={{ backgroundColor: '#ef5350', color: '#fff', padding: '0.2rem 0.5rem', borderRadius: '3px', fontSize: '0.75rem', fontWeight: '600' }}>Enroll to open</span>}
                      </div>
                      <h3>{section.title}</h3>
                      <p>{section.summary}</p>
                    </div>
                    <div className="study-module-row-right">
                      <p className="study-section-reference">{section.reference}</p>
                      <p className="study-module-focus">Focus question</p>
                      <p>{getPrimaryQuestion(section)}</p>
                    </div>
                  </Link>
                )
              })}
            </div>
          </div>
        </section>
      )}
    </main>
  )
}

export function ColossiansStudySectionPage({ content }: Props) {
  const { studySlug, sectionId } = useParams<{ studySlug?: string; sectionId: string }>()
  const studies = getStudies(content)
  const study = getStudyBySlug(studies, studySlug)
  const sections = study?.sections ?? []
  const section = getSectionById(sections, sectionId)
  const sectionIndex = sections.findIndex(item => item.id === sectionId)
  const lessonNumber = getLessonNumber(sections, sectionId)
  const previousSection = sectionIndex > 0 ? sections[sectionIndex - 1] : null
  const nextSection = sectionIndex >= 0 && sectionIndex < sections.length - 1 ? sections[sectionIndex + 1] : null
  const sectionIsReleased = section ? isSectionReleased(section) : false

  const [auth, setAuth] = useState<StudyAuthState>({ checked: false, authenticated: false, username: '', enrolledStudySlugs: [] })
  const [usernameInput, setUsernameInput] = useState('')
  const [passwordInput, setPasswordInput] = useState('')
  const [authBusy, setAuthBusy] = useState(false)
  const [authMessage, setAuthMessage] = useState('')
  const [enrollBusy, setEnrollBusy] = useState(false)
  const [enrollMessage, setEnrollMessage] = useState('')

  const [noteText, setNoteText] = useState('')
  const [noteLoading, setNoteLoading] = useState(false)
  const [noteSaving, setNoteSaving] = useState(false)
  const [noteMessage, setNoteMessage] = useState('')

  const canSaveNote = auth.authenticated && !noteSaving && !noteLoading
  const lessonAudioEmbedUrl = useMemo(() => {
    const trimmed = section?.audioEmbedUrl?.trim() ?? ''
    if (!trimmed) return ''
    return /^https?:\/\//i.test(trimmed) ? trimmed : ''
  }, [section?.audioEmbedUrl])

  const currentStudySlug = study?.slug ?? 'colossians'
  const noteId = section?.id ? getNoteId(currentStudySlug, section.id) : ''
  const isEnrolled = isEnrolledInStudy(auth, currentStudySlug)

  useEffect(() => {
    document.title = section && study ? `${section.title} | ${study.title}` : 'Study'
  }, [section, study])

  useEffect(() => {
    let cancelled = false
    readJson<StudyAuthStatusResponse>('/api/study-auth/status')
      .then(data => {
        if (cancelled) return
        setAuth({
          checked: true,
          authenticated: Boolean(data.authenticated),
          username: data.username ?? '',
          enrolledStudySlugs: normalizeEnrolledStudySlugs(data.enrolledStudySlugs),
        })
      })
      .catch(() => {
        if (cancelled) return
        setAuth({ checked: true, authenticated: false, username: '', enrolledStudySlugs: [] })
      })

    return () => {
      cancelled = true
    }
  }, [])

  useEffect(() => {
    if (!auth.authenticated || !noteId || !isEnrolled) {
      setNoteText('')
      return
    }

    let cancelled = false
    setNoteLoading(true)
    setNoteMessage('')

    readJson<{ note: string }>(`/api/study-notes/${encodeURIComponent(noteId)}`)
      .then(data => {
        if (cancelled) return
        setNoteText(data.note ?? '')
      })
      .catch(err => {
        if (cancelled) return
        setNoteMessage(err instanceof Error ? err.message : 'Unable to load your note.')
      })
      .finally(() => {
        if (cancelled) return
        setNoteLoading(false)
      })

    return () => {
      cancelled = true
    }
  }, [auth.authenticated, noteId, isEnrolled])

  async function submitAuth(mode: 'login' | 'signup') {
    setAuthBusy(true)
    setAuthMessage('')

    try {
      const payload = { username: usernameInput, password: passwordInput }
      const data = await readJson<{ username: string; enrolledStudySlugs?: string[] }>(`/api/study-auth/${mode}`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(payload),
      })
      setAuth({
        checked: true,
        authenticated: true,
        username: data.username ?? usernameInput.trim().toLowerCase(),
        enrolledStudySlugs: normalizeEnrolledStudySlugs(data.enrolledStudySlugs),
      })
      setUsernameInput('')
      setPasswordInput('')
      setAuthMessage(mode === 'signup' ? 'Account created. You can now save notes for each lesson.' : 'Signed in successfully.')
    } catch (err) {
      setAuthMessage(err instanceof Error ? err.message : 'Sign-in failed.')
    } finally {
      setAuthBusy(false)
    }
  }

  async function logoutStudyUser() {
    setAuthBusy(true)
    setAuthMessage('')
    try {
      await readJson<{ ok: boolean }>('/api/study-auth/logout', { method: 'POST' })
      setAuth({ checked: true, authenticated: false, username: '', enrolledStudySlugs: [] })
      setNoteText('')
      setAuthMessage('Signed out.')
    } catch (err) {
      setAuthMessage(err instanceof Error ? err.message : 'Unable to sign out.')
    } finally {
      setAuthBusy(false)
    }
  }

  async function saveNote() {
    if (!noteId || !canSaveNote) return
    setNoteSaving(true)
    setNoteMessage('')
    try {
      const data = await readJson<{ ok: boolean; note: string }>(`/api/study-notes/${encodeURIComponent(noteId)}`, {
        method: 'PUT',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ note: noteText }),
      })
      setNoteText(data.note ?? '')
      setNoteMessage('Notes saved.')
    } catch (err) {
      setNoteMessage(err instanceof Error ? err.message : 'Unable to save note.')
    } finally {
      setNoteSaving(false)
    }
  }

  async function enrollInCurrentStudy() {
    if (!study) return
    setEnrollMessage('')
    setEnrollBusy(true)
    try {
      const response = await readJson<{ enrolledStudySlugs?: string[]; studyTitle?: string }>(`/api/study-enrollment/${encodeURIComponent(study.slug)}`, { method: 'POST' })
      setAuth(prev => ({ ...prev, enrolledStudySlugs: normalizeEnrolledStudySlugs(response.enrolledStudySlugs) }))
      setEnrollMessage(response.studyTitle ? `You are enrolled in ${response.studyTitle}.` : 'You are now enrolled.')
    } catch (err) {
      setEnrollMessage(err instanceof Error ? err.message : 'Unable to enroll right now.')
    } finally {
      setEnrollBusy(false)
    }
  }

  if (!study || !section) {
    return (
      <main className="thanks-page" aria-label="Section not found">
        <div className="thanks-card">
          <p className="eyebrow">Study Hub</p>
          <h1>Section not found</h1>
          <p>The section you requested is not available yet.</p>
          <Link to="/study" className="btn-primary">Back to Studies</Link>
        </div>
      </main>
    )
  }

  if (!sectionIsReleased) {
    return (
      <main className="thanks-page" aria-label="Lesson not yet available">
        <div className="thanks-card">
          <p className="eyebrow">{study.title}</p>
          <h1>Lesson Coming Soon</h1>
          <p>This lesson will be available on {getReleaseDateDisplay(section)}.</p>
          <Link to={`/study/${study.slug}`} className="btn-primary">Back to Lessons</Link>
        </div>
      </main>
    )
  }

  if (!auth.checked) {
    return (
      <main className="thanks-page" aria-label="Loading">
        <div className="thanks-card">
          <p className="eyebrow">{study.title}</p>
          <p>Loading lesson...</p>
        </div>
      </main>
    )
  }

  if (!auth.authenticated) {
    return (
      <main className="thanks-page" aria-label="Sign in required">
        <div className="thanks-card">
          <p className="eyebrow">{study.title}</p>
          <h1>Sign In to Continue</h1>
          <p>Create a free account or sign in to access lessons and save your personal notes.</p>
          <div className="study-signup-actions" style={{ marginTop: '1.5rem' }}>
            <Link to="/study/signup" className="btn-primary">Create Account or Sign In</Link>
            <Link to="/study/account" className="btn-secondary">My Account</Link>
            <Link to={`/study/${study.slug}`} className="btn-secondary">Back to Lessons</Link>
          </div>
        </div>
      </main>
    )
  }

  if (!isEnrolled) {
    return (
      <main className="thanks-page" aria-label="Enrollment required">
        <div className="thanks-card">
          <p className="eyebrow">{study.title}</p>
          <h1>Enrollment Required</h1>
          <p>You need to enroll in this study before entering lessons.</p>
          <div className="study-signup-actions" style={{ marginTop: '1.5rem' }}>
            <button type="button" className="btn-primary" disabled={enrollBusy} onClick={enrollInCurrentStudy}>
              {enrollBusy ? 'Enrolling...' : `Enroll in ${study.title}`}
            </button>
            <Link to="/study/account" className="btn-secondary">My Account</Link>
            <Link to={`/study/${study.slug}`} className="btn-secondary">Back to Study</Link>
          </div>
          {enrollMessage && <p className="study-note-status" style={{ marginTop: '0.75rem' }}>{enrollMessage}</p>}
        </div>
      </main>
    )
  }

  return (
    <main className="study-section-page" aria-label={section.title}>
      <section className="section-study-classroom">
        <div className="section-inner study-classroom-shell">
          <div className="study-classroom-main">
            <Link to={`/study/${study.slug}`} className="study-detail-back">Back to {study.title}</Link>
            <p className="study-lesson-label">Lesson {lessonNumber} of {sections.length}</p>
            <h1>{section.title}</h1>
            <p className="study-detail-reference">{section.reference}</p>
            <p className="study-detail-summary">{section.summary}</p>

            {lessonAudioEmbedUrl && (
              <article className="study-class-block">
                <h2>Lesson Audio</h2>
                <div className="study-audio-embed-wrap">
                  <iframe
                    src={lessonAudioEmbedUrl}
                    title={`${section.title} audio`}
                    width="100%"
                    height="152"
                    frameBorder="0"
                    allow="autoplay; clipboard-write; encrypted-media; fullscreen; picture-in-picture"
                    loading="lazy"
                  />
                </div>
              </article>
            )}

            <article className="study-class-block">
              <h2>Scripture Text</h2>
              <p className="study-detail-copy study-detail-copy--scripture">{section.passageText || `Add the passage text for ${section.reference} here when you move the guide online.`}</p>
            </article>

            <article className="study-class-block">
              <h2>Instructor Commentary</h2>
              <p className="study-detail-copy">{section.commentary}</p>
            </article>

            <article className="study-class-block">
              <h2>Discussion Questions</h2>
              <ol className="study-detail-list">
                {section.studyQuestions.map((question, index) => (
                  <li key={index}>{question}</li>
                ))}
              </ol>
            </article>
          </div>

          <aside className="study-classroom-sidebar" aria-label="Lesson tools">
            <article className="study-class-side-block">
              <h3>Study Track</h3>
              <p>{study.title}</p>
              <p>{study.description}</p>
            </article>

            <article className="study-class-side-block">
              <h3>Greek Word Study</h3>
              {section.greekNotes.length > 0 ? (
                <ul className="study-detail-list">
                  {section.greekNotes.map((note, index) => (
                    <li key={index}>{note}</li>
                  ))}
                </ul>
              ) : (
                <p className="study-detail-copy">Greek notes will be added for this lesson.</p>
              )}
            </article>

            <article className="study-class-side-block">
              <h3>Student Notes</h3>
              {!auth.checked && <p className="study-detail-copy">Checking sign-in status...</p>}
              {auth.checked && !auth.authenticated && (
                <div className="study-auth-box">
                  <p className="study-auth-why">Sign in to save notes for this lesson.</p>
                  <label htmlFor="study-email">Email</label>
                  <input id="study-email" type="email" value={usernameInput} onChange={e => setUsernameInput(e.target.value)} placeholder="your@email.com" autoComplete="email" />
                  <label htmlFor="study-password">Password</label>
                  <input id="study-password" type="password" value={passwordInput} onChange={e => setPasswordInput(e.target.value)} placeholder="At least 8 characters" autoComplete="current-password" />
                  <div className="study-auth-actions">
                    <button type="button" className="btn-secondary" disabled={authBusy} onClick={() => submitAuth('login')}>Sign In</button>
                    <button type="button" className="btn-primary" disabled={authBusy} onClick={() => submitAuth('signup')}>Create Account</button>
                  </div>
                </div>
              )}
              {auth.checked && auth.authenticated && (
                <div className="study-notes-box">
                  <p className="study-notes-user">Signed in as {auth.username}</p>
                  <div style={{ display: 'flex', gap: '0.5rem', flexWrap: 'wrap', marginBottom: '0.5rem' }}>
                    <Link to={`/study/${study.slug}/notes`} className="btn-secondary">Open My Notes</Link>
                    <Link to="/study/account" className="btn-secondary">My Account</Link>
                  </div>
                  <textarea
                    rows={8}
                    value={noteText}
                    onChange={e => setNoteText(e.target.value)}
                    placeholder="Write your lesson notes here..."
                    disabled={noteLoading || noteSaving}
                  />
                  <div className="study-auth-actions">
                    <button type="button" className="btn-primary" disabled={!canSaveNote} onClick={saveNote}>{noteSaving ? 'Saving...' : 'Save Notes'}</button>
                    <button type="button" className="btn-secondary" disabled={authBusy} onClick={logoutStudyUser}>Sign Out</button>
                  </div>
                </div>
              )}
              {(authMessage || noteMessage) && <p className="study-note-status">{authMessage || noteMessage}</p>}
            </article>

            <article className="study-class-side-block">
              <h3>Lesson Navigation</h3>
              <div className="study-detail-nav">
                {previousSection ? (
                  <Link to={`/study/${study.slug}/${previousSection.id}`} className="btn-secondary">Previous Lesson</Link>
                ) : <span className="study-nav-placeholder" />}
                {nextSection && isSectionReleased(nextSection) ? (
                  <Link to={`/study/${study.slug}/${nextSection.id}`} className="btn-secondary">Next Lesson</Link>
                ) : nextSection ? (
                  <span className="study-nav-placeholder">Available {getReleaseDateDisplay(nextSection)}</span>
                ) : <span className="study-nav-placeholder" />}
              </div>
            </article>
          </aside>
        </div>
      </section>
    </main>
  )
}

export function ColossiansStudyNotesPage({ content }: Props) {
  const { studySlug } = useParams<{ studySlug?: string }>()
  const studies = getStudies(content)
  const study = getStudyBySlug(studies, studySlug)
  const [auth, setAuth] = useState<StudyAuthState>({ checked: false, authenticated: false, username: '', enrolledStudySlugs: [] })
  const [notes, setNotes] = useState<StudyNotesMap>({})
  const [loading, setLoading] = useState(true)
  const [message, setMessage] = useState('')

  useEffect(() => {
    document.title = study ? `My Notes | ${study.title}` : 'My Study Notes'
  }, [study])

  useEffect(() => {
    let cancelled = false

    async function load() {
      try {
        const authData = await readJson<StudyAuthStatusResponse>('/api/study-auth/status')
        if (cancelled) return

        if (!authData.authenticated) {
          setAuth({ checked: true, authenticated: false, username: '', enrolledStudySlugs: [] })
          setLoading(false)
          return
        }

        const enrolledStudySlugs = normalizeEnrolledStudySlugs(authData.enrolledStudySlugs)
        setAuth({
          checked: true,
          authenticated: true,
          username: authData.username ?? '',
          enrolledStudySlugs,
        })

        if (!enrolledStudySlugs.includes((study?.slug ?? '').toLowerCase())) {
          setLoading(false)
          return
        }

        const notesData = await readJson<{ notes: StudyNotesMap }>('/api/study-notes')
        if (cancelled) return
        setNotes(notesData.notes ?? {})
      } catch (err) {
        if (cancelled) return
        setMessage(err instanceof Error ? err.message : 'Unable to load notes.')
      } finally {
        if (cancelled) return
        setLoading(false)
      }
    }

    load()
    return () => {
      cancelled = true
    }
  }, [])

  if (!study) {
    return (
      <main className="thanks-page" aria-label="Study not found">
        <div className="thanks-card">
          <p className="eyebrow">Study Hub</p>
          <h1>Study not found</h1>
          <p>The study you requested is not available yet.</p>
          <Link to="/study" className="btn-primary">Back to Studies</Link>
        </div>
      </main>
    )
  }

  const prefix = `${study.slug}--`
  const enrolled = isEnrolledInStudy(auth, study.slug)
  const entries = Object.entries(notes)
    .filter(([key]) => key.startsWith(prefix))
    .map(([key, note]) => {
      const sectionId = key.slice(prefix.length)
      const section = study.sections.find(item => item.id === sectionId)
      return { sectionId, section, note }
    })
    .filter(item => item.note && item.note.trim())

  return (
    <main className="study-section-page" aria-label="My study notes">
      <section className="section-study-classroom">
        <div className="section-inner">
          <Link to={`/study/${study.slug}`} className="study-detail-back">Back to {study.title}</Link>
          <p className="study-lesson-label">Student Workspace</p>
          <h1>My Lesson Notes</h1>
          {!loading && auth.authenticated && <p className="study-detail-summary">Signed in as {auth.username}</p>}
          {!loading && auth.authenticated && (
            <div className="study-signup-actions" style={{ marginBottom: '1rem' }}>
              <Link to="/study/account" className="btn-secondary">My Account</Link>
              <Link to={`/study/${study.slug}`} className="btn-secondary">Back to Lessons</Link>
            </div>
          )}

          {loading && <p className="study-detail-copy">Loading your notes...</p>}
          {!loading && !auth.authenticated && (
            <article className="study-class-block">
              <h2>Sign In Required</h2>
              <p className="study-detail-copy">Open any lesson and sign in from the Student Notes panel to see your saved notes here.</p>
              <Link to="/study/signup" className="btn-primary">Create Account or Sign In</Link>
            </article>
          )}
          {!loading && auth.authenticated && !enrolled && (
            <article className="study-class-block">
              <h2>Enrollment Required</h2>
              <p className="study-detail-copy">You need to enroll in this study before accessing your notes.</p>
              <Link to={`/study/${study.slug}`} className="btn-primary">Go to Study Enrollment</Link>
            </article>
          )}
          {!loading && auth.authenticated && enrolled && entries.length === 0 && (
            <article className="study-class-block">
              <h2>No Notes Yet</h2>
              <p className="study-detail-copy">You have not saved notes yet. Open a lesson and use the Student Notes area to start.</p>
              {study.sections[0] && <Link to={`/study/${study.slug}/${study.sections[0].id}`} className="btn-primary">Open First Lesson</Link>}
            </article>
          )}
          {!loading && auth.authenticated && enrolled && entries.length > 0 && (
            <div className="study-module-list">
              {entries.map(({ sectionId, section, note }) => (
                <article key={sectionId} className="study-module-row">
                  <div className="study-module-row-left">
                    <p className="study-module-lesson">{section ? `Lesson ${getLessonNumber(study.sections, section.id)}` : 'Saved Note'}</p>
                    <h3>{section?.title ?? sectionId}</h3>
                    <p>{section ? section.reference : 'Lesson reference unavailable'}</p>
                  </div>
                  <div className="study-module-row-right">
                    <p className="study-module-focus">Your Note</p>
                    <p className="study-detail-copy study-detail-copy--scripture">{note}</p>
                    {section && <Link to={`/study/${study.slug}/${section.id}`} className="btn-secondary">Open Lesson</Link>}
                  </div>
                </article>
              ))}
            </div>
          )}
          {message && <p className="study-note-status">{message}</p>}
        </div>
      </section>
    </main>
  )
}

export function StudyAccountPage() {
  const navigate = useNavigate()
  const location = useLocation()

  const [auth, setAuth] = useState<StudyAuthState>({ checked: false, authenticated: false, username: '', enrolledStudySlugs: [], displayName: '', subscribeNewsletter: true })
  const [overview, setOverview] = useState<StudyAccountOverview | null>(null)
  const [loadingOverview, setLoadingOverview] = useState(false)

  const [displayNameInput, setDisplayNameInput] = useState('')
  const [profileMessage, setProfileMessage] = useState('')
  const [profileBusy, setProfileBusy] = useState(false)

  const [subscribeNewsletter, setSubscribeNewsletter] = useState(true)
  const [prefMessage, setPrefMessage] = useState('')
  const [prefBusy, setPrefBusy] = useState(false)

  const [emailCurrentPassword, setEmailCurrentPassword] = useState('')
  const [emailNew, setEmailNew] = useState('')
  const [emailTokenInput, setEmailTokenInput] = useState('')
  const [emailMessage, setEmailMessage] = useState('')
  const [emailBusy, setEmailBusy] = useState(false)

  const [enrollBusySlug, setEnrollBusySlug] = useState('')
  const [enrollMessage, setEnrollMessage] = useState('')

  const [exporting, setExporting] = useState(false)
  const [exportMessage, setExportMessage] = useState('')

  const [pwCurrent, setPwCurrent] = useState('')
  const [pwNew, setPwNew] = useState('')
  const [pwConfirm, setPwConfirm] = useState('')
  const [pwBusy, setPwBusy] = useState(false)
  const [pwMessage, setPwMessage] = useState('')
  const [pwSuccess, setPwSuccess] = useState(false)

  const [signOutBusy, setSignOutBusy] = useState(false)

  const [deleteStep, setDeleteStep] = useState<'idle' | 'warn1' | 'warn2'>('idle')
  const [deleteConfirmInput, setDeleteConfirmInput] = useState('')
  const [deleteBusy, setDeleteBusy] = useState(false)
  const [deleteMessage, setDeleteMessage] = useState('')

  useEffect(() => {
    document.title = 'My Account | Study Hub'
    readJson<StudyAuthStatusResponse>('/api/study-auth/status')
      .then(data => {
        setAuth({
          checked: true,
          authenticated: Boolean(data.authenticated),
          username: data.username ?? '',
          displayName: data.displayName ?? '',
          subscribeNewsletter: data.subscribeNewsletter !== false,
          enrolledStudySlugs: normalizeEnrolledStudySlugs(data.enrolledStudySlugs),
        })
      })
      .catch(() => setAuth({ checked: true, authenticated: false, username: '', enrolledStudySlugs: [], displayName: '', subscribeNewsletter: true }))
  }, [])

  useEffect(() => {
    if (!auth.authenticated) return
    setLoadingOverview(true)
    readJson<StudyAccountOverview>('/api/study-account/overview')
      .then(data => {
        setOverview(data)
        setDisplayNameInput(data.profile.displayName ?? '')
        setSubscribeNewsletter(data.profile.subscribeNewsletter !== false)
      })
      .catch(() => {})
      .finally(() => setLoadingOverview(false))
  }, [auth.authenticated])

  useEffect(() => {
    if (!auth.authenticated) return
    const token = new URLSearchParams(location.search).get('verifyEmailToken')
    if (!token) return
    setEmailTokenInput(token)
    setEmailBusy(true)
    readJson<{ ok: boolean; username: string }>('/api/study-account/verify-email-change', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ token }),
    })
      .then(data => {
        setEmailMessage('Email address verified and updated successfully.')
        setAuth(prev => ({ ...prev, username: data.username }))
        navigate('/study/account', { replace: true })
      })
      .catch(err => setEmailMessage(err instanceof Error ? err.message : 'Unable to verify email token.'))
      .finally(() => setEmailBusy(false))
  }, [auth.authenticated, location.search, navigate])

  async function refreshOverview() {
    const data = await readJson<StudyAccountOverview>('/api/study-account/overview')
    setOverview(data)
    setDisplayNameInput(data.profile.displayName ?? '')
    setSubscribeNewsletter(data.profile.subscribeNewsletter !== false)
  }

  async function handleProfileSave() {
    setProfileBusy(true)
    setProfileMessage('')
    try {
      const data = await readJson<{ ok: boolean; displayName: string }>('/api/study-account/profile', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ displayName: displayNameInput }),
      })
      setAuth(prev => ({ ...prev, displayName: data.displayName }))
      setProfileMessage('Profile saved.')
      await refreshOverview()
    } catch (err) {
      setProfileMessage(err instanceof Error ? err.message : 'Unable to save profile.')
    } finally {
      setProfileBusy(false)
    }
  }

  async function handlePreferenceSave() {
    setPrefBusy(true)
    setPrefMessage('')
    try {
      const data = await readJson<{ ok: boolean; subscribeNewsletter: boolean }>('/api/study-account/preferences', {
        method: 'PATCH',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ subscribeNewsletter }),
      })
      setAuth(prev => ({ ...prev, subscribeNewsletter: data.subscribeNewsletter }))
      setPrefMessage('Preferences updated.')
      await refreshOverview()
    } catch (err) {
      setPrefMessage(err instanceof Error ? err.message : 'Unable to save preferences.')
    } finally {
      setPrefBusy(false)
    }
  }

  async function handleRequestEmailChange() {
    setEmailBusy(true)
    setEmailMessage('')
    try {
      await readJson<{ ok: boolean }>('/api/study-account/request-email-change', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ newEmail: emailNew, currentPassword: emailCurrentPassword }),
      })
      setEmailCurrentPassword('')
      setEmailMessage('Verification email sent. Open the link in that email to complete the change.')
    } catch (err) {
      setEmailMessage(err instanceof Error ? err.message : 'Unable to request email change.')
    } finally {
      setEmailBusy(false)
    }
  }

  async function handleVerifyTokenInput() {
    setEmailBusy(true)
    setEmailMessage('')
    try {
      const data = await readJson<{ ok: boolean; username: string }>('/api/study-account/verify-email-change', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ token: emailTokenInput }),
      })
      setAuth(prev => ({ ...prev, username: data.username }))
      setEmailTokenInput('')
      setEmailMessage('Email address verified and updated successfully.')
      await refreshOverview()
    } catch (err) {
      setEmailMessage(err instanceof Error ? err.message : 'Unable to verify email token.')
    } finally {
      setEmailBusy(false)
    }
  }

  async function handleEnrollmentToggle(studySlug: string, enrolled: boolean) {
    setEnrollBusySlug(studySlug)
    setEnrollMessage('')
    try {
      const data = await readJson<{ enrolledStudySlugs?: string[]; studyTitle?: string }>(`/api/study-enrollment/${encodeURIComponent(studySlug)}`, {
        method: enrolled ? 'DELETE' : 'POST',
      })
      const slugs = normalizeEnrolledStudySlugs(data.enrolledStudySlugs)
      setAuth(prev => ({ ...prev, enrolledStudySlugs: slugs }))
      setEnrollMessage(enrolled ? `Unenrolled from ${data.studyTitle ?? studySlug}.` : `Enrolled in ${data.studyTitle ?? studySlug}.`)
      await refreshOverview()
    } catch (err) {
      setEnrollMessage(err instanceof Error ? err.message : 'Unable to update enrollment.')
    } finally {
      setEnrollBusySlug('')
    }
  }

  async function handleExport() {
    setExporting(true)
    setExportMessage('')
    try {
      const res = await fetch('/api/study-account/export-notes')
      if (!res.ok) throw new Error('Export failed. Please try again.')
      const blob = await res.blob()
      const url = URL.createObjectURL(blob)
      const a = document.createElement('a')
      a.href = url
      a.download = `my-study-notes-${new Date().toISOString().slice(0, 10)}.docx`
      a.click()
      URL.revokeObjectURL(url)
      setExportMessage('Download started.')
    } catch (err) {
      setExportMessage(err instanceof Error ? err.message : 'Export failed.')
    } finally {
      setExporting(false)
    }
  }

  async function handleChangePassword() {
    setPwMessage('')
    setPwSuccess(false)
    if (!pwCurrent || !pwNew || !pwConfirm) { setPwMessage('Please fill in all password fields.'); return }
    if (pwNew !== pwConfirm) { setPwMessage('New passwords do not match.'); return }
    if (pwNew.length < 8) { setPwMessage('New password must be at least 8 characters.'); return }
    setPwBusy(true)
    try {
      await readJson<{ ok: boolean }>('/api/study-account/change-password', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ currentPassword: pwCurrent, newPassword: pwNew }),
      })
      setPwSuccess(true)
      setPwCurrent(''); setPwNew(''); setPwConfirm('')
    } catch (err) {
      setPwMessage(err instanceof Error ? err.message : 'Password change failed.')
    } finally {
      setPwBusy(false)
    }
  }

  async function handleSignOut() {
    setSignOutBusy(true)
    try {
      await readJson<{ ok: boolean }>('/api/study-auth/logout', { method: 'POST' })
      navigate('/study')
    } catch {
      setSignOutBusy(false)
    }
  }

  async function handleDeleteAccount() {
    setDeleteBusy(true)
    setDeleteMessage('')
    try {
      await readJson<{ ok: boolean }>('/api/study-account', { method: 'DELETE' })
      navigate('/study')
    } catch (err) {
      setDeleteMessage(err instanceof Error ? err.message : 'Unable to delete account. Please try again.')
      setDeleteBusy(false)
    }
  }

  if (!auth.checked) {
    return (
      <main className="thanks-page" aria-label="Loading">
        <div className="thanks-card"><p>Loading...</p></div>
      </main>
    )
  }

  if (!auth.authenticated) {
    return (
      <main className="thanks-page" aria-label="Sign in required">
        <div className="thanks-card">
          <p className="eyebrow">My Account</p>
          <h1>Sign In Required</h1>
          <p>Please sign in to manage your account.</p>
          <Link to="/study/signup" className="btn-primary" style={{ marginTop: '1rem', display: 'inline-block' }}>Sign In</Link>
        </div>
      </main>
    )
  }

  const divider = <hr style={{ margin: '0 0 2rem', border: 'none', borderTop: '1px solid #2a2518' }} />

  return (
    <main className="thanks-page" aria-label="My account">
      <div className="thanks-card" style={{ maxWidth: '760px', textAlign: 'left' }}>
        <p className="eyebrow">Student Account</p>
        <h1>My Account</h1>
        <p style={{ marginBottom: '1.5rem' }}>Signed in as <strong>{auth.username}</strong></p>

        {overview?.stats && (
          <>
            <div style={{ display: 'flex', gap: '1rem', flexWrap: 'wrap', marginBottom: '2rem' }}>
              <div style={{ flex: '1 1 150px', background: '#1a1a16', borderRadius: '8px', padding: '1rem', border: '1px solid #2a2518' }}>
                <p style={{ fontSize: '1.6rem', fontWeight: 700, margin: 0 }}>{overview.stats.noteCount}</p>
                <p style={{ margin: 0, fontSize: '0.85rem' }}>Total notes saved</p>
              </div>
              <div style={{ flex: '1 1 150px', background: '#1a1a16', borderRadius: '8px', padding: '1rem', border: '1px solid #2a2518' }}>
                <p style={{ fontSize: '1rem', fontWeight: 600, margin: 0 }}>{new Date(overview.stats.memberSince).toLocaleDateString('en-US', { month: 'short', day: 'numeric', year: 'numeric' })}</p>
                <p style={{ margin: 0, fontSize: '0.85rem' }}>Member since</p>
              </div>
            </div>
            {divider}
          </>
        )}

        <section style={{ marginBottom: '2rem' }}>
          <h2 style={{ marginTop: 0 }}>Enrollment Manager</h2>
          <p style={{ fontSize: '0.92rem' }}>Enroll or unenroll by study and track your progress.</p>
          {loadingOverview && <p>Loading studies...</p>}
          {!loadingOverview && overview?.studies?.map(study => (
            <div key={study.slug} style={{ border: '1px solid #2a2518', background: '#151511', borderRadius: '8px', padding: '0.9rem', marginBottom: '0.75rem', display: 'flex', justifyContent: 'space-between', gap: '1rem', alignItems: 'center', flexWrap: 'wrap' }}>
              <div>
                <p style={{ margin: 0, fontWeight: 600 }}>{study.title}</p>
                <p style={{ margin: '0.35rem 0 0', fontSize: '0.84rem' }}>
                  Status: <strong>{study.enrolled ? 'Enrolled' : 'Not Enrolled'}</strong>
                  {` • Progress: ${study.completedLessons}/${study.totalLessons || 0} lessons with notes`}
                  {` • Notes: ${study.noteCount}`}
                </p>
              </div>
              <button
                type="button"
                className={study.enrolled ? 'btn-secondary' : 'btn-primary'}
                disabled={study.status === 'planned' || enrollBusySlug === study.slug}
                onClick={() => handleEnrollmentToggle(study.slug, study.enrolled)}
              >
                {enrollBusySlug === study.slug ? 'Updating...' : (study.enrolled ? 'Unenroll' : 'Enroll')}
              </button>
            </div>
          ))}
          {enrollMessage && <p className="study-note-status">{enrollMessage}</p>}
        </section>

        {divider}

        <section style={{ marginBottom: '2rem' }}>
          <h2 style={{ marginTop: 0 }}>Profile Settings</h2>
          <label style={{ display: 'block', fontSize: '0.9rem', marginBottom: '0.5rem' }}>Display Name (optional)</label>
          <input
            type="text"
            value={displayNameInput}
            onChange={e => setDisplayNameInput(e.target.value)}
            placeholder="How your name appears in emails"
            style={{ width: '100%', maxWidth: '420px', marginBottom: '0.75rem', padding: '0.5rem', border: '1px solid #3a3320', borderRadius: '4px', background: '#14130f', color: '#f0ead8' }}
          />
          <div>
            <button type="button" className="btn-primary" disabled={profileBusy} onClick={handleProfileSave}>{profileBusy ? 'Saving...' : 'Save Display Name'}</button>
          </div>
          {profileMessage && <p className="study-note-status" style={{ marginTop: '0.5rem' }}>{profileMessage}</p>}

          <div style={{ marginTop: '1.5rem' }}>
            <label className="contact-consent">
              <input type="checkbox" checked={subscribeNewsletter} onChange={e => setSubscribeNewsletter(e.target.checked)} />
              <span>Subscribe to newsletter updates</span>
            </label>
            <button type="button" className="btn-secondary" disabled={prefBusy} onClick={handlePreferenceSave} style={{ marginTop: '0.5rem' }}>
              {prefBusy ? 'Saving...' : 'Save Preferences'}
            </button>
            {prefMessage && <p className="study-note-status" style={{ marginTop: '0.5rem' }}>{prefMessage}</p>}
          </div>
        </section>

        {divider}

        <section style={{ marginBottom: '2rem' }}>
          <h2 style={{ marginTop: 0 }}>Change Email (Verification Required)</h2>
          <p style={{ fontSize: '0.9rem' }}>Enter your new email and current password. We will send a verification link to the new email.</p>
          <div style={{ display: 'flex', flexDirection: 'column', gap: '0.5rem', maxWidth: '420px' }}>
            <input type="email" value={emailNew} onChange={e => setEmailNew(e.target.value)} placeholder="new@email.com" style={{ padding: '0.5rem', border: '1px solid #3a3320', borderRadius: '4px', background: '#14130f', color: '#f0ead8' }} />
            <input type="password" value={emailCurrentPassword} onChange={e => setEmailCurrentPassword(e.target.value)} placeholder="Current password" style={{ padding: '0.5rem', border: '1px solid #3a3320', borderRadius: '4px', background: '#14130f', color: '#f0ead8' }} />
          </div>
          <button type="button" className="btn-primary" disabled={emailBusy} onClick={handleRequestEmailChange} style={{ marginTop: '0.65rem' }}>
            {emailBusy ? 'Sending...' : 'Send Verification Email'}
          </button>
          <p style={{ marginTop: '1rem', fontSize: '0.85rem' }}>Have a token? Paste it here to verify manually.</p>
          <div style={{ display: 'flex', gap: '0.5rem', flexWrap: 'wrap' }}>
            <input type="text" value={emailTokenInput} onChange={e => setEmailTokenInput(e.target.value)} placeholder="Verification token" style={{ minWidth: '260px', padding: '0.5rem', border: '1px solid #3a3320', borderRadius: '4px', background: '#14130f', color: '#f0ead8' }} />
            <button type="button" className="btn-secondary" disabled={emailBusy || !emailTokenInput.trim()} onClick={handleVerifyTokenInput}>
              {emailBusy ? 'Verifying...' : 'Verify Token'}
            </button>
          </div>
          {emailMessage && <p className="study-note-status" style={{ marginTop: '0.5rem' }}>{emailMessage}</p>}
        </section>

        {divider}

        <section style={{ marginBottom: '2rem' }}>
          <h2 style={{ marginTop: 0 }}>Export My Notes</h2>
          <p style={{ fontSize: '0.9rem' }}>Download all your saved lesson notes as a Word document (.docx).</p>
          <button type="button" className="btn-primary" disabled={exporting} onClick={handleExport}>
            {exporting ? 'Preparing...' : 'Download Notes (.docx)'}
          </button>
          {exportMessage && <p className="study-note-status" style={{ marginTop: '0.5rem' }}>{exportMessage}</p>}
        </section>

        {divider}

        <section style={{ marginBottom: '2rem' }}>
          <h2 style={{ marginTop: 0 }}>Change Password</h2>
          <div style={{ display: 'flex', flexDirection: 'column', gap: '0.6rem', maxWidth: '420px' }}>
            <input type="password" value={pwCurrent} onChange={e => setPwCurrent(e.target.value)} placeholder="Current password" autoComplete="current-password" style={{ padding: '0.5rem', border: '1px solid #3a3320', borderRadius: '4px', background: '#14130f', color: '#f0ead8' }} />
            <input type="password" value={pwNew} onChange={e => setPwNew(e.target.value)} placeholder="New password" autoComplete="new-password" style={{ padding: '0.5rem', border: '1px solid #3a3320', borderRadius: '4px', background: '#14130f', color: '#f0ead8' }} />
            <input type="password" value={pwConfirm} onChange={e => setPwConfirm(e.target.value)} placeholder="Confirm new password" autoComplete="new-password" onKeyDown={e => e.key === 'Enter' && handleChangePassword()} style={{ padding: '0.5rem', border: '1px solid #3a3320', borderRadius: '4px', background: '#14130f', color: '#f0ead8' }} />
          </div>
          {pwMessage && <p style={{ color: '#e57373', fontSize: '0.875rem', marginTop: '0.5rem' }}>{pwMessage}</p>}
          {pwSuccess && <p style={{ color: '#81c784', fontSize: '0.875rem', marginTop: '0.5rem' }}>Password updated successfully.</p>}
          <button type="button" className="btn-primary" disabled={pwBusy} onClick={handleChangePassword} style={{ marginTop: '0.75rem' }}>
            {pwBusy ? 'Updating...' : 'Update Password'}
          </button>
        </section>

        {divider}

        <section style={{ marginBottom: '2rem' }}>
          <h2 style={{ marginTop: 0 }}>Sign Out</h2>
          <button type="button" className="btn-secondary" disabled={signOutBusy} onClick={handleSignOut}>
            {signOutBusy ? 'Signing out...' : 'Sign Out'}
          </button>
        </section>

        {divider}

        <section>
          <h2 style={{ marginTop: 0, color: '#e57373' }}>Delete Account</h2>
          {deleteStep === 'idle' && (
            <>
              <p style={{ fontSize: '0.9rem' }}>Permanently remove your account and all saved notes. This cannot be undone.</p>
              <button type="button" className="btn-admin-remove" onClick={() => setDeleteStep('warn1')}>Delete My Account</button>
            </>
          )}
          {deleteStep === 'warn1' && (
            <div style={{ background: '#2d2414', border: '1px solid #6b4b1f', borderRadius: '6px', padding: '1rem', marginBottom: '1rem' }}>
              <p style={{ fontWeight: 600 }}>Final warning: export your notes first.</p>
              <div style={{ display: 'flex', gap: '0.6rem', flexWrap: 'wrap' }}>
                <button type="button" className="btn-primary" onClick={handleExport} disabled={exporting}>Export Notes First</button>
                <button type="button" className="btn-admin-remove" onClick={() => setDeleteStep('warn2')}>Continue to Delete</button>
                <button type="button" className="btn-secondary" onClick={() => setDeleteStep('idle')}>Cancel</button>
              </div>
            </div>
          )}
          {deleteStep === 'warn2' && (
            <div style={{ background: '#2b1111', border: '1px solid #8a3b3b', borderRadius: '6px', padding: '1rem' }}>
              <p>Type <strong>DELETE</strong> to confirm permanent deletion:</p>
              <input type="text" value={deleteConfirmInput} onChange={e => setDeleteConfirmInput(e.target.value)} placeholder="DELETE" style={{ marginBottom: '0.8rem', padding: '0.5rem', border: '1px solid #8a3b3b', borderRadius: '4px', background: '#140f0f', color: '#f0ead8' }} />
              {deleteMessage && <p style={{ color: '#ef9a9a', fontSize: '0.875rem' }}>{deleteMessage}</p>}
              <div style={{ display: 'flex', gap: '0.6rem', flexWrap: 'wrap' }}>
                <button type="button" className="btn-admin-remove" disabled={deleteBusy || deleteConfirmInput.trim() !== 'DELETE'} onClick={handleDeleteAccount}>
                  {deleteBusy ? 'Deleting...' : 'Permanently Delete My Account'}
                </button>
                <button type="button" className="btn-secondary" onClick={() => { setDeleteStep('idle'); setDeleteConfirmInput('') }}>Cancel</button>
              </div>
            </div>
          )}
        </section>

        <div style={{ marginTop: '2rem' }}>
          <Link to="/study" className="btn-secondary">Back to Studies</Link>
        </div>
      </div>
    </main>
  )
}