// A one-page-per-session handout for a group: the passage, the outline, discussion questions and room to write.
// It opens as a print-friendly page ("Save as PDF" in the print dialog).
import { formatChunkReference, getChunkVerseEntries } from './bibleUtils.jsx';
import { flatten } from './outline.js';

const esc = (s) => String(s ?? '').replace(/[&<>"]/g, (c) => ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;' }[c]));
const lines = (text) => String(text ?? '').split('\n').map((l) => l.replace(/^\s*(?:[-*•–]|\d{1,2}[.)])\s+/, '').trim()).filter(Boolean);

// Every session (chunk) of the study, in order, with where it sits.
export function sessionsFor(project) {
  const out = [];
  (project?.chapters ?? []).forEach((chapter, chapterIndex) => {
    for (const chunk of chapter.chunks ?? []) out.push({ chunk, chapterIndex, number: out.length + 1, reference: formatChunkReference(project, chapterIndex, chunk, '–') });
  });
  return out;
}

// The outline points for a session: its own outline, else the study outline's points linked to it.
export function outlineForSession(project, chunk) {
  if ((chunk.outline ?? []).length) return chunk.outline;
  const linked = (project.outline ?? []).filter((n) => n.chunkId === chunk.id);
  return linked.length ? linked : [];
}

// The questions to print: the ones written for the session, else its Application notes as "Think about" prompts.
export function questionsFor(chunk) {
  const own = lines(chunk.discussionQuestions);
  if (own.length) return { kind: 'questions', items: own };
  const fallback = lines(chunk.application);
  return fallback.length ? { kind: 'think', items: fallback } : { kind: 'none', items: [] };
}

const STOP = new Set(['the','and','but','for','nor','yet','who','whom','whose','that','this','these','those','with','from','into','unto','upon','shall','will','have','has','had','was','were','been','are','not','his','her','him','their','them','they','you','your','our','out','all','when','then','than','what','which','there','here','also','because','therefore','said','says']);

// The words to leave blank in a fill-in passage: the English words you studied in this session (the word-study
// glosses) that appear in it; if there are none, the longer words that repeat, since a repeated word is usually
// what the passage is about. Returns lowercase words, most useful first, at most 12.
export function blankWordsFor(chunk, verses) {
  const text = verses.map((v) => v.text).join(' ');
  const counts = new Map();
  for (const w of text.toLowerCase().match(/[a-z]+(?:['’][a-z]+)?/g) ?? []) counts.set(w, (counts.get(w) ?? 0) + 1);
  const glossed = (chunk.greekWords ?? []).flatMap((w) => String(w.englishGloss ?? '').toLowerCase().match(/[a-z]+/g) ?? [])
    .filter((w) => w.length > 2 && !STOP.has(w) && counts.has(w));
  const chosen = [...new Set(glossed)];
  if (chosen.length === 0) {
    const repeated = [...counts].filter(([w, n]) => n >= 2 && w.length >= 5 && !STOP.has(w)).sort((a, b) => b[1] - a[1] || b[0].length - a[0].length).map(([w]) => w);
    chosen.push(...repeated);
  }
  return chosen.slice(0, 12);
}

// A verse's text with the chosen words replaced by a blank line of about the same length (each occurrence).
export function blankOut(text, words) {
  const set = new Set(words);
  // split keeps the words (odd entries) apart from the punctuation between them, so both are escaped
  return String(text ?? '').split(/([A-Za-z]+(?:['’][A-Za-z]+)?)/).map((part, i) => (
    i % 2 === 1 && set.has(part.toLowerCase()) ? `<span class="blank">${'&nbsp;'.repeat(Math.max(8, part.length + 2))}</span>` : esc(part)
  )).join('');
}

// layout: 'standard' (everything), 'questions' (passage + questions only, one page), 'large' (big print), 'notes' (passage and a blank page to write).
export const HANDOUT_LAYOUTS = [
  { id: 'standard', label: 'Standard: passage, outline, questions' },
  { id: 'questions', label: 'Questions only: passage and discussion questions' },
  { id: 'large', label: 'Large print: passage and questions' },
  { id: 'notes', label: 'Note-taking: passage and lots of lines' },
  { id: 'blanks', label: 'Fill in the blanks: key words left out of the passage' },
];

function sessionHtml(project, session, { answerLines, layout = 'standard' }) {
  const { chunk, chapterIndex, number, reference } = session;
  const series = (project.series ?? '').trim();
  const title = (chunk.episodeTitle ?? '').trim();
  const num = (chunk.episodeNumber ?? '').toString().trim() || number;
  const verses = getChunkVerseEntries(project, chapterIndex, chunk);
  const outline = layout === 'standard' ? flatten(outlineForSession(project, chunk)) : [];
  const q = layout === 'notes' ? { kind: 'none', items: [] } : questionsFor(chunk);
  const blanks = layout === 'blanks' ? blankWordsFor(chunk, verses) : [];
  const blank = (n) => Array.from({ length: n }, () => '<div class="rule"></div>').join('');
  return `<section class="page${layout === 'standard' ? '' : ` ${layout}`}">
  <header>
    <p class="kicker">${esc(series || project.title)}</p>
    <h1>Session ${esc(num)}${title ? `: ${esc(title)}` : ''}</h1>
    <p class="ref">${esc(reference)} <span>(${esc(project.translation ?? 'BSB')})</span></p>
    <p class="meta">Name: ____________________________ &nbsp;&nbsp; Date: ________________</p>
  </header>
  ${verses.length ? `<div class="passage">${verses.map((v) => `<p><sup>${esc(v.number)}</sup> ${layout === 'blanks' && blanks.length ? blankOut(v.text, blanks) : esc(v.text)}</p>`).join('')}</div>` : ''}
  ${blanks.length ? `<p class="bank"><b>Word bank:</b> ${[...blanks].sort().map(esc).join(' &middot; ')}</p>` : ''}
  ${outline.length ? `<h2>Outline</h2><ul class="outline">${outline.map(({ node, depth, label }) => `<li style="margin-left:${depth * 1.2}em"><b>${esc(label)}</b> ${esc(node.text || '')}${node.ref ? ` <i>(${esc(node.ref)})</i>` : ''}</li>`).join('')}</ul>` : ''}
  ${q.items.length ? `<h2>${q.kind === 'questions' ? 'Discussion questions' : 'Think about it'}</h2><ol class="questions">${q.items.map((item) => `<li>${esc(item)}${answerLines ? blank(2) : ''}</li>`).join('')}</ol>` : ''}
  ${answerLines || layout === 'notes' ? `<h2>Notes</h2>${blank(layout === 'notes' ? 16 : q.items.length ? 4 : 10)}` : ''}
  <footer>${esc(project.title)}</footer>
</section>`;
}

// ids: the chunk ids to include, or null for every session
export function buildHandoutHtml(project, ids = null, { answerLines = true, layout = 'standard' } = {}) {
  const sessions = sessionsFor(project).filter((s) => !ids || ids.includes(s.chunk.id));
  return `<!doctype html><html><head><meta charset="utf-8"><title>${esc(project.title)} — handout</title><style>
  @page { margin: 18mm 16mm; }
  body { font-family: Georgia, 'Times New Roman', serif; color: #1f1b16; line-height: 1.5; margin: 0; font-size: 12.5pt; }
  .page { page-break-after: always; min-height: 95vh; position: relative; }
  .page:last-child { page-break-after: auto; }
  .kicker { margin: 0; font: 600 9.5pt -apple-system, Helvetica, Arial, sans-serif; letter-spacing: .14em; text-transform: uppercase; color: #8a4a2a; }
  h1 { margin: .15em 0 0; font-size: 22pt; font-weight: 600; }
  .ref { margin: .2em 0 .4em; font-size: 13pt; color: #8a4a2a; font-weight: 600; } .ref span { color: #6b6458; font-weight: 400; font-size: 10pt; }
  .meta { color: #6b6458; font: 10pt -apple-system, Helvetica, Arial, sans-serif; margin: .2em 0 1em; }
  h2 { font: 600 10pt -apple-system, Helvetica, Arial, sans-serif; letter-spacing: .12em; text-transform: uppercase; color: #6b6458; border-bottom: 1px solid #d8cfbb; padding-bottom: 3px; margin: 1.3em 0 .5em; }
  .passage { background: #f6f1e6; border-left: 3px solid #a84e27; padding: .4em 1em; } .passage p { margin: .35em 0; } sup { color: #a84e27; font-size: 70%; font-family: -apple-system, Helvetica, Arial, sans-serif; }
  .outline { list-style: none; padding: 0; margin: 0; } .outline li { margin-bottom: .25em; } .outline b { color: #a84e27; }
  .questions { padding-left: 1.4em; } .questions li { margin-bottom: .7em; }
  .blank { display: inline-block; border-bottom: 1.5px solid #1f1b16; line-height: 1; vertical-align: baseline; }
  .bank { font: 10.5pt -apple-system, Helvetica, Arial, sans-serif; color: #6b6458; margin: .6em 0 0; }
  .rule { border-bottom: 1px solid #c9bfa8; height: 1.7em; }
  .large { font-size: 17pt; line-height: 1.55; } .large h1 { font-size: 30pt; } .large .rule { height: 2.2em; }
  footer { position: absolute; bottom: 0; left: 0; right: 0; text-align: center; color: #9b9484; font: 9pt -apple-system, Helvetica, Arial, sans-serif; }
</style></head><body>${sessions.map((s) => sessionHtml(project, s, { answerLines, layout })).join('')}</body></html>`;
}

export function printHandout(project, ids = null, options) {
  const win = window.open('', '_blank');
  if (!win) return false;
  win.document.write(buildHandoutHtml(project, ids, options));
  win.document.close();
  win.onload = () => { win.focus(); win.print(); };
  return true;
}