import { randomUUID } from 'node:crypto'
import { Resend } from 'resend'
import { requireAdminAuth } from '../auth.js'
import { state } from '../state.js'
import { queueNewsletterIssuesWrite } from '../data.js'
import { escapeHtml } from '../helpers.js'
import { resendRetry } from '../email.js'

const BASE = 'https://versebyversewithnate.us'
const NEW_EPISODE_TOPIC_NAME = 'new episode'

function truncate(str, max) {
  const clean = String(str || '').trim()
  if (clean.length <= max) return clean
  return `${clean.slice(0, max - 1).trimEnd()}…`
}

function stripSubjectPrefix(subject) {
  return String(subject || '').replace(/^New Episode:?\s*-?\s*/i, '').trim()
}

function slugify(str) {
  return String(str || '')
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, 80)
}

function uniqueSlug(base) {
  const root = slugify(base) || 'issue'
  let candidate = root
  let n = 2
  while (state.newsletterIssues.some(i => i.slug === candidate)) {
    candidate = `${root}-${n}`
    n += 1
  }
  return candidate
}

function extractDescription(text, previewText) {
  if (previewText && previewText.trim()) return truncate(previewText, 200)
  const paragraphs = String(text || '')
    .split(/\n{2,}/)
    .map(p => p.replace(/\s+/g, ' ').trim())
    .filter(Boolean)
  const candidate = paragraphs.find(p => p.length > 60 && !/^[◆✦✍✎▶]/.test(p) && p !== p.toUpperCase())
  return truncate(candidate || paragraphs[paragraphs.length - 1] || '', 200)
}

// Strip the raw {{{RESEND_UNSUBSCRIBE_URL}}} placeholder link — it only resolves inside an actual sent email.
function stripUnsubscribeLink(html) {
  return String(html || '').replace(
    /<p[^>]*>\s*<a[^>]*href="\{\{\{RESEND_UNSUBSCRIBE_URL\}\}\}"[\s\S]*?<\/a>\s*<\/p>/i,
    '',
  )
}

function buildIssuePageHtml(issue) {
  const canonical = `${BASE}/newsletter/${encodeURIComponent(issue.slug)}`
  const ogImage = `${BASE}/images/banner.png`
  const title = escapeHtml(issue.title)
  const description = escapeHtml(issue.description)

  const metaBlock = `
<title>${title} — Verse by Verse with Nate</title>
<meta name="description" content="${description}"/>
<meta property="og:type" content="article"/>
<meta property="og:site_name" content="Verse by Verse with Nate"/>
<meta property="og:url" content="${escapeHtml(canonical)}"/>
<meta property="og:title" content="${title}"/>
<meta property="og:description" content="${description}"/>
<meta property="og:image" content="${escapeHtml(ogImage)}"/>
<meta property="og:image:alt" content="${title}"/>
<meta name="twitter:card" content="summary_large_image"/>
<meta name="twitter:title" content="${title}"/>
<meta name="twitter:description" content="${description}"/>
<meta name="twitter:image" content="${escapeHtml(ogImage)}"/>
<link rel="canonical" href="${escapeHtml(canonical)}"/>
<style>
/* The source HTML is a Resend/React Email template built for a narrow email-client
   viewport: its outer wrapper table uses align="left" (which browsers translate to
   float: left) and relies on the surrounding white to be invisible in a ~600px inbox
   pane. In a full-width browser tab that leaves a left-stuck column on a white field.
   Force it to sit centered on the site's dark background instead. */
html, body { background-color: #0a0a08 !important; margin: 0; padding: 0; }
table[align="left"] { float: none !important; margin-left: auto !important; margin-right: auto !important; }
</style>
</head>`

  const topBar = `
<div style="background:#050505;border-bottom:1px solid rgba(184,151,42,0.25);padding:14px 20px;font-family:Georgia,serif">
<div style="max-width:640px;margin:0 auto;display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap">
<a href="${BASE}/" style="color:#e8d9b5;text-decoration:none;font-size:15px;letter-spacing:0.04em">Verse by Verse with Nate</a>
<a href="${BASE}/newsletter" style="color:#B8972A;text-decoration:none;font-size:12px;letter-spacing:0.14em;text-transform:uppercase">&larr; All issues</a>
</div></div>`

  const ctaBlock = `
<table border="0" width="100%" cellpadding="0" cellspacing="0" role="presentation" align="center">
<tbody><tr><td align="center" style="padding:40px 20px 56px;background-color:#080807;border-top:1px solid rgba(184,151,42,0.2)">
<table width="580" border="0" cellpadding="0" cellspacing="0" role="presentation" style="max-width:580px;width:100%">
<tbody><tr><td align="center" style="padding:0;font-family:Georgia,serif">
<p style="margin:0 0 8px;font-size:12px;letter-spacing:0.18em;text-transform:uppercase;color:#B8972A">Stay in the Word</p>
<p style="margin:0 0 22px;font-size:22px;line-height:1.3;color:#f0e9cc">Get the next issue in your inbox</p>
<a href="${BASE}/subscribe" style="display:inline-block;padding:13px 34px;font-size:12px;letter-spacing:0.16em;text-transform:uppercase;color:#0c0c08;background:#B8972A;text-decoration:none;border-radius:4px;font-weight:bold">Subscribe by Email</a>
<p style="margin:26px 0 0;font-size:13px"><a href="${BASE}/newsletter" style="color:#8a7e55;text-decoration:none">&larr; Back to the newsletter archive</a></p>
</td></tr></tbody></table>
</td></tr></tbody></table>
</body>`

  let html = stripUnsubscribeLink(issue.html)
  html = html.replace(/<title>[\s\S]*?<\/title>/i, '')
  html = /<\/head>/i.test(html) ? html.replace(/<\/head>/i, metaBlock) : html.replace(/<head[^>]*>/i, m => `${m}${metaBlock.replace('</head>', '')}`)
  html = html.replace(/<body[^>]*>/i, m => `${m}${topBar}`)
  html = /<\/body>/i.test(html) ? html.replace(/<\/body>/i, ctaBlock) : `${html}${ctaBlock}`
  return html
}

export function register(app) {
  // ── Admin: browse Resend broadcasts, flagged by New Episode topic ────────

  app.get('/api/admin/newsletter/resend-broadcasts', requireAdminAuth, async (_req, res) => {
    if (!process.env.RESEND_API_KEY) {
      res.status(500).json({ message: 'RESEND_API_KEY is not configured.' }); return
    }
    try {
      const resend = new Resend(process.env.RESEND_API_KEY)
      const [{ data: topicsData, error: topicsError }, { data: listData, error: listError }] = await Promise.all([
        resendRetry(() => resend.topics.list()),
        resendRetry(() => resend.broadcasts.list()),
      ])
      if (topicsError) throw new Error(topicsError.message)
      if (listError) throw new Error(listError.message)

      const newEpisodeTopic = (topicsData?.data ?? []).find(t => String(t.name || '').trim().toLowerCase() === NEW_EPISODE_TOPIC_NAME)
      const sentBroadcasts = (listData?.data ?? []).filter(b => b.status === 'sent')

      // Fetch a few at a time so a long broadcast history can't exceed Resend's requests-per-second limit.
      const details = []
      for (let i = 0; i < sentBroadcasts.length; i += 4) {
        const chunk = await Promise.all(sentBroadcasts.slice(i, i + 4).map(b => resendRetry(() => resend.broadcasts.get(b.id))))
        details.push(...chunk)
      }

      const broadcasts = details.map(({ data }, i) => {
        const summary = sentBroadcasts[i]
        if (!data) return null
        return {
          id: data.id,
          name: data.name,
          subject: data.subject,
          sentAt: data.sent_at ?? summary.sent_at,
          topicId: data.topic_id ?? null,
          matchesNewEpisodeTopic: !!newEpisodeTopic && data.topic_id === newEpisodeTopic.id,
          alreadyPublished: state.newsletterIssues.some(issue => issue.resendBroadcastId === data.id),
        }
      }).filter(Boolean).sort((a, b) => new Date(b.sentAt ?? 0).getTime() - new Date(a.sentAt ?? 0).getTime())

      res.json({ broadcasts, newEpisodeTopicFound: !!newEpisodeTopic })
    } catch (err) {
      console.error('[newsletter] failed to list Resend broadcasts:', err)
      res.status(502).json({ message: 'Could not reach Resend.' })
    }
  })

  // ── Admin: manage published issues ────────────────────────────────────────

  app.get('/api/admin/newsletter/issues', requireAdminAuth, (_req, res) => {
    const issues = [...state.newsletterIssues]
      .sort((a, b) => new Date(b.sentAt ?? b.publishedAt).getTime() - new Date(a.sentAt ?? a.publishedAt).getTime())
      .map(({ html, ...rest }) => rest)
    res.json({ issues })
  })

  app.post('/api/admin/newsletter/issues', requireAdminAuth, async (req, res) => {
    const { broadcastId, title: titleOverride, slug: slugOverride, public: isPublic } = req.body ?? {}
    if (!broadcastId || typeof broadcastId !== 'string') {
      res.status(400).json({ message: 'broadcastId is required.' }); return
    }
    if (state.newsletterIssues.some(i => i.resendBroadcastId === broadcastId)) {
      res.status(409).json({ message: 'This broadcast has already been published.' }); return
    }
    if (!process.env.RESEND_API_KEY) {
      res.status(500).json({ message: 'RESEND_API_KEY is not configured.' }); return
    }

    try {
      const resend = new Resend(process.env.RESEND_API_KEY)
      const { data, error } = await resend.broadcasts.get(broadcastId)
      if (error || !data) throw new Error(error?.message ?? 'Broadcast not found.')
      if (!data.html) { res.status(400).json({ message: 'This broadcast has no HTML content.' }); return }

      const title = typeof titleOverride === 'string' && titleOverride.trim()
        ? titleOverride.trim().slice(0, 200)
        : stripSubjectPrefix(data.subject) || data.name || 'Newsletter Issue'
      const slug = typeof slugOverride === 'string' && slugOverride.trim()
        ? uniqueSlug(slugOverride)
        : uniqueSlug(title)

      const issue = {
        id: randomUUID(),
        resendBroadcastId: data.id,
        slug,
        title,
        subject: data.subject ?? '',
        description: extractDescription(data.text, data.preview_text),
        html: data.html,
        sentAt: data.sent_at ?? null,
        publishedAt: new Date().toISOString(),
        public: isPublic !== false,
      }

      state.newsletterIssues.push(issue)
      queueNewsletterIssuesWrite()
      const { html, ...rest } = issue
      res.json({ ok: true, issue: rest })
    } catch (err) {
      console.error('[newsletter] failed to publish issue:', err)
      res.status(502).json({ message: 'Could not fetch broadcast content from Resend.' })
    }
  })

  app.patch('/api/admin/newsletter/issues/:id', requireAdminAuth, (req, res) => {
    const issue = state.newsletterIssues.find(i => i.id === req.params.id)
    if (!issue) { res.status(404).json({ message: 'Issue not found.' }); return }

    if (typeof req.body?.title === 'string' && req.body.title.trim()) issue.title = req.body.title.trim().slice(0, 200)
    if (typeof req.body?.slug === 'string' && req.body.slug.trim() && req.body.slug.trim() !== issue.slug) {
      const candidate = slugify(req.body.slug)
      if (!candidate) { res.status(400).json({ message: 'Invalid slug.' }); return }
      if (state.newsletterIssues.some(i => i.id !== issue.id && i.slug === candidate)) {
        res.status(409).json({ message: 'That slug is already in use.' }); return
      }
      issue.slug = candidate
    }
    if (typeof req.body?.public === 'boolean') issue.public = req.body.public

    queueNewsletterIssuesWrite()
    const { html, ...rest } = issue
    res.json({ ok: true, issue: rest })
  })

  app.delete('/api/admin/newsletter/issues/:id', requireAdminAuth, (req, res) => {
    const idx = state.newsletterIssues.findIndex(i => i.id === req.params.id)
    if (idx === -1) { res.status(404).json({ message: 'Issue not found.' }); return }
    state.newsletterIssues.splice(idx, 1)
    queueNewsletterIssuesWrite()
    res.json({ ok: true })
  })

  // ── Public ─────────────────────────────────────────────────────────────────

  app.get('/api/newsletter/issues', (_req, res) => {
    const issues = state.newsletterIssues
      .filter(i => i.public !== false)
      .sort((a, b) => new Date(b.sentAt ?? b.publishedAt).getTime() - new Date(a.sentAt ?? a.publishedAt).getTime())
      .map(({ html, ...rest }) => rest)
    res.json({ issues })
  })

  app.get('/newsletter/:slug', (req, res, next) => {
    const issue = state.newsletterIssues.find(i => i.slug === req.params.slug && i.public !== false)
    if (!issue) { next(); return }
    res.type('html').send(buildIssuePageHtml(issue))
  })
}