'use strict';

/**
 * Title matching for the PCO Plan module — the one answer to "is this
 * ProPresenter document that Planning Center thing?", used three ways:
 *
 *   - mapping the document ProPresenter has live to a plan item (the
 *     highlight and the item runtimes) — placeDocument(), below,
 *   - recognising the message document, which is named after the sermon
 *     and never after its plan item — the message rule, below, and
 *   - recognising the documents an admin picked as the service start / end
 *     cues (see service-timing.js).
 *
 * A ProPresenter name and a Planning Center title rarely agree letter for
 * letter ("This Is The Day - [ Full ]" vs "This Is The Day"), so both sides
 * are tidied the way propresenter-core.cleanItemName does (tags in brackets,
 * leading date codes and dash separators dropped), lower-cased, stripped of
 * punctuation and compared:
 *
 *   1.00  identical after tidying     "Post-Service Loop"  ≈ "Post Service Loop"
 *   0.85  one contains the other      "Welcome"            ≈ "Welcome & Announcements"
 *   Dice  2·shared words ÷ all words  "Pre Service Loop"   vs "Post Service Loop" → 0.67
 *
 * Filler words ("the", "of", "and"…) are ignored. The thresholds:
 *
 *   MATCH_THRESHOLD   0.6   plan items — two of three words is enough, because
 *                           the item that scores best *and* is next in the
 *                           plan wins, so a near miss lands on the right row.
 *   TRIGGER_THRESHOLD 0.75  service cues — a cue starts or freezes the service
 *                           clock, so one wrong word must not fire it: the
 *                           pre-service loop (0.67 against "Post Service Loop")
 *                           stays a non-match, while a renamed
 *                           "Post-Service Loop", a tagged "Post Service Loop
 *                           [Full]" (1.0) or a shortened "Post Service" (0.85)
 *                           still trigger.
 */

const MATCH_THRESHOLD = 0.6;
const TRIGGER_THRESHOLD = 0.75;

/** Same title tidying as propresenter-core.cleanItemName (drops [tags], date codes). */
function cleanTitle(raw) {
  const original = String(raw || '').trim();
  let s = original;
  s = s.replace(/[[({][^\])}]*[\])}]/g, ' ');
  s = s.replace(/^\s*\d{6,8}\b[\s\-–—:.]*/, '');
  s = s.replace(/\s[-–—]+\s/g, ' ');
  s = s.replace(/^[\s\-–—:.]+|[\s\-–—:.]+$/g, '');
  s = s.replace(/\s{2,}/g, ' ').trim();
  return s || original;
}

function normalize(raw) {
  return cleanTitle(raw)
    .toLowerCase()
    .replace(/&/g, ' and ')
    .replace(/[’'`]/g, '')
    .replace(/[^a-z0-9]+/g, ' ')
    .trim();
}

const STOPWORDS = new Set(['the', 'a', 'an', 'of', 'and', 'to', 'in', 'is', 'my', 'your', 'our']);
function tokens(norm) {
  return new Set(norm.split(' ').filter((t) => t && !STOPWORDS.has(t)));
}

/** 0..1 similarity between two titles. */
function similarity(a, b) {
  const na = normalize(a);
  const nb = normalize(b);
  if (!na || !nb) return 0;
  if (na === nb) return 1;
  if (na.length >= 4 && nb.length >= 4 && (na.includes(nb) || nb.includes(na))) return 0.85;
  const ta = tokens(na);
  const tb = tokens(nb);
  if (!ta.size || !tb.size) return 0;
  let common = 0;
  for (const t of ta) if (tb.has(t)) common += 1;
  return (2 * common) / (ta.size + tb.size); // Dice coefficient
}

/** Does a live ProPresenter document count as the cue document an admin picked? */
function isCue(liveName, cueDocument) {
  return Boolean(cueDocument) && similarity(liveName, cueDocument) >= TRIGGER_THRESHOLD;
}

/* ── the message rule ──────────────────────────────────────────────────
   A sermon's ProPresenter document is named after the sermon, never after
   the plan item that stands for it ("Message", "Resi Message"), so no name
   comparison can place it — and the previous song stayed "current" through
   a whole message. What the document's name does carry is the plan's own
   identity. Waters names them "YYMMDD Series Title - Part #": the plan's
   date, its series title and its title. A live document that reads like
   the plan is the plan's message, and lands on the plan's message item,
   however that item happens to be titled. */

const MESSAGE_WORDS = /\b(message|sermon|teaching|homily)\b/i;
const MESSAGE_WORD_ONLY = /^\s*(message|sermon|teaching|homily)\s*$/i;
/** Undated, the name must read like "Series Title Part #" at least this closely… */
const MESSAGE_THRESHOLD = 0.75;
/** …dated with this plan's date, it need only resemble the series or the title. */
const DATED_MESSAGE_THRESHOLD = 0.6;

/** The leading "YYMMDD" / "YYYYMMDD" of a document name as a calendar day, or null. */
function leadingDateCode(raw) {
  const m = /^\s*(\d{8}|\d{6})(?!\d)/.exec(String(raw || ''));
  if (!m) return null;
  const code = m[1];
  const y = code.length === 8 ? Number(code.slice(0, 4)) : 2000 + Number(code.slice(0, 2));
  const mo = Number(code.slice(-4, -2));
  const d = Number(code.slice(-2));
  if (mo < 1 || mo > 12 || d < 1 || d > 31) return null;
  return { y, m: mo, d };
}

/** The local calendar day of an epoch-ms instant, in the same shape. */
function dayOf(ms) {
  const t = new Date(Number(ms));
  if (!Number.isFinite(t.getTime())) return null;
  return { y: t.getFullYear(), m: t.getMonth() + 1, d: t.getDate() };
}

function sameDay(a, b) {
  return Boolean(a && b) && a.y === b.y && a.m === b.m && a.d === b.d;
}

/**
 * Does this live document read like the plan itself — "260927 Where is Your
 * Faith? - Part 6" for the plan "Where is Your Faith?" / "Part 6" dated
 * 27 Sept 2026? Returns { score, dated } or null.
 *
 * A date code naming another day is a firm no: last week's sermon is not
 * this plan's message. A date code naming the plan's day is strong evidence,
 * so the rest need only resemble the series or the title. Without a date
 * the name must read like series + title together — and carry the title
 * when the plan has both, so a series bumper ("Where is Your Faith?") is
 * not taken for the sermon.
 */
function messageDocumentScore(name, plan) {
  const series = String(plan?.seriesTitle || '').trim();
  const title = String(plan?.title || '').trim();
  if (!series && !title) return null;
  const code = leadingDateCode(name);
  const planDay = plan?.sortDate ? dayOf(plan.sortDate) : null;
  if (code && planDay && !sameDay(code, planDay)) return null;
  const dated = Boolean(code && planDay);
  const full = [series, title].filter(Boolean).join(' ');
  const fullScore = similarity(name, full);
  if (dated) {
    const score = Math.max(fullScore, series ? similarity(name, series) : 0, title ? similarity(name, title) : 0);
    return score >= DATED_MESSAGE_THRESHOLD ? { score, dated: true } : null;
  }
  if (fullScore < MESSAGE_THRESHOLD) return null;
  if (series && title && similarity(name, title) < DATED_MESSAGE_THRESHOLD) return null;
  return { score: fullScore, dated: false };
}

/**
 * The plan item that stands for the message: an item titled with the word
 * ("Message", "Resi Message" — a bare "Message" first), else the first item
 * under a header so titled (a "Sermon" section whose one item is the sermon's
 * own title). Null when the plan has no such slot.
 */
function messageItemOf(items) {
  let best = null;
  let inSection = false;
  for (const it of Array.isArray(items) ? items : []) {
    if (!it) continue;
    const title = String(it.title || '');
    if (it.itemType === 'header') {
      inSection = MESSAGE_WORDS.test(title);
      continue;
    }
    const rank = MESSAGE_WORD_ONLY.test(title) ? 3 : MESSAGE_WORDS.test(title) ? 2 : inSection ? 1 : 0;
    if (rank && (!best || rank > best.rank)) best = { item: it, rank };
    if (rank === 3) break;
  }
  return best ? best.item : null;
}

/**
 * Does ProPresenter's playlist mirror the plan item for item? ProPresenter
 * builds a Planning Center playlist that way — every plan item, headers
 * included, each flagged as PCO — until an operator adds something of their
 * own (a song tag, say), which shifts every position after it. Same length,
 * headers in the same places and every item PCO-flagged is the test.
 */
function playlistMirrorsPlan(ppItems, items) {
  if (!Array.isArray(ppItems) || !Array.isArray(items) || !items.length || ppItems.length !== items.length) return false;
  return ppItems.every((p, i) => Boolean(p?.isPco) && (p?.type === 'header') === (items[i]?.itemType === 'header'));
}

/** Best plan item by title, the ones ahead of the current item winning ties. */
function bestByName(name, items, all, ctx) {
  const currentIdx = items.findIndex((it) => it.id === ctx?.currentItemId);
  const hint = ctx?.hint;
  const wanted = hint && hint.mirror && Number.isInteger(hint.index) && hint.index >= 0 ? all[hint.index] : null;
  let best = null;
  for (let i = 0; i < items.length; i += 1) {
    const item = items[i];
    const score = Math.max(similarity(name, item.title), item.song ? similarity(name, item.song.title) : 0);
    if (score < MATCH_THRESHOLD) continue;
    // Distance ahead of the current item (wrapping so items behind rank last).
    const dist = currentIdx < 0 ? i : (i - currentIdx + items.length) % items.length;
    const atPosition = Boolean(wanted && item.id === wanted.id);
    const candidate = { item, score, dist, atPosition };
    if (!best || score > best.score + 0.001) {
      best = candidate;
      continue;
    }
    if (Math.abs(score - best.score) > 0.001) continue;
    if ((atPosition && !best.atPosition) || (atPosition === best.atPosition && dist < best.dist)) best = candidate;
  }
  return best ? { item: best.item, score: best.score, via: 'name' } : null;
}

/**
 * Where a live ProPresenter document sits in the plan: { item, score, via }
 * or null. `ctx` is { items, plan, currentItemId, hint }; `hint` (optional)
 * is { index, mirror } — the document's position in the ProPresenter
 * playlist and whether that playlist mirrors the plan (playlistMirrorsPlan).
 *
 * By name first: the item (or song) title most like the document's name,
 * the ones ahead of the current item winning ties — a near miss lands on the
 * right row. Then the message rule: a document that reads like the plan
 * itself lands on the plan's message item. It overrides a name hit that is
 * anything short of identical — a song called "Faith" must not catch
 * "260927 Where is Your Faith? - Part 6" — outright when the document is
 * dated with the plan's day, and when it reads better otherwise. Position
 * is never a match on its own: it only breaks a tie between equally good
 * names, and only while the playlist mirrors the plan.
 */
function placeDocument(name, ctx) {
  const all = Array.isArray(ctx?.items) ? ctx.items : [];
  const items = all.filter((it) => it && it.itemType !== 'header');
  if (!items.length) return null;
  const byName = bestByName(name, items, all, ctx);
  const asMessage = messageDocumentScore(name, ctx?.plan);
  const messageItem = asMessage ? messageItemOf(all) : null;
  if (messageItem && (!byName || (byName.score < 0.999 && (asMessage.dated || asMessage.score > byName.score)))) {
    return { item: messageItem, score: asMessage.score, via: asMessage.dated ? 'message document, dated' : 'message document' };
  }
  return byName;
}

module.exports = {
  MATCH_THRESHOLD,
  TRIGGER_THRESHOLD,
  MESSAGE_THRESHOLD,
  cleanTitle,
  normalize,
  similarity,
  isCue,
  leadingDateCode,
  messageDocumentScore,
  messageItemOf,
  playlistMirrorsPlan,
  placeDocument,
};