// The rules behind REVIEW.html, with no page code in them.
//
// review_page.py inlines this file into the page; test_review_page.mjs loads it under Node.
// It mirrors review_format.py, which stays the authority: apply_review.py checks the saved
// file again. The page applies the rules as the reviewer goes, so a problem shows where it
// happens instead of as an error message at the end.

const ReviewLogic = (() => {
  const SCHEMA_VERSION = 2;
  const ALLOWED = {
    accepted: ['keep', 'drop', 'same'],
    borderline: ['skip', 'keep', 'same'],
  };

  const orderedIds = (doc) => Object.keys(doc.candidates);
  const idsOfKind = (doc, kind) => orderedIds(doc).filter((id) => doc.candidates[id].kind === kind);
  const allowedDecisions = (kind) => ALLOWED[kind] ?? [];

  function displayName(doc, id) {
    const kind = doc.candidates[id].kind;
    const n = idsOfKind(doc, kind).indexOf(id) + 1;
    return kind === 'accepted' ? `Group ${n}` : `Extra group ${n}`;
  }

  function shortName(doc, id) {
    const kind = doc.candidates[id].kind;
    const n = idsOfKind(doc, kind).indexOf(id) + 1;
    return kind === 'accepted' ? String(n) : `+${n}`;
  }

  function blankEntry(id, kind) {
    return {
      id, decision: kind === 'accepted' ? null : 'skip', same_as: null,
      actor: '', wants: '', counterpart: '', excluded: [],
    };
  }

  const initialEntries = (doc) => orderedIds(doc).map((id) => blankEntry(id, doc.candidates[id].kind));
  const entryOf = (entries, id) => entries.find((e) => e.id === id);

  /** Groups this one could be marked the same as: every other group currently kept. */
  const keptTargets = (doc, entries, id) =>
    orderedIds(doc).filter((other) => other !== id && entryOf(entries, other)?.decision === 'keep');

  /** The ticked scenes of a group, plus the ticked scenes of every group marked the same as it. */
  function groupMembers(doc, entries, id) {
    const sources = [id, ...entries.filter((e) => e.decision === 'same' && e.same_as === id).map((e) => e.id)];
    const seen = new Set();
    const members = [];
    for (const source of sources) {
      const entry = entryOf(entries, source);
      const excluded = new Set(entry ? entry.excluded : []);
      for (const m of doc.candidates[source].members) {
        if (excluded.has(m.member) || seen.has(m.chunk)) continue;
        seen.add(m.chunk);
        members.push(m);
      }
    }
    return members;
  }

  function shapeCheck(members, rules) {
    const counts = new Map();
    for (const m of members) counts.set(m.story, (counts.get(m.story) ?? 0) + 1);
    const size = members.length;
    const stories = counts.size;
    const dominant = size ? Math.max(...counts.values()) / size : 0;
    const pct = (x) => Math.round(x * 100);
    const ok = size >= rules.minMembers && stories >= rules.minStories && dominant <= rules.maxDominant;
    const text = ok
      ? `${size} scenes from ${stories} stories: enough for a situation.`
      : `${size} scenes from ${stories} stories${dominant > rules.maxDominant ? `, ${pct(dominant)}% from one story` : ''}. ` +
        `A situation needs at least ${rules.minMembers} scenes from at least ${rules.minStories} stories, ` +
        `with no story over ${pct(rules.maxDominant)}%.`;
    return { size, stories, dominant, ok, text };
  }

  const blank = (s) => (typeof s === 'string' && s.trim() ? s.trim() : '___');
  const sentence = (entry) => `A ${blank(entry.actor)} wants ${blank(entry.wants)} from ${blank(entry.counterpart)}.`;
  const named = (entry) => ['actor', 'wants', 'counterpart'].every((k) => typeof entry[k] === 'string' && entry[k].trim());

  /** Where a group stands: todo, done, skipped or problem, with a sentence saying why. */
  function status(doc, entries, id) {
    const c = doc.candidates[id];
    const e = entryOf(entries, id);
    if (!e || e.decision === null) return { state: 'todo', message: 'Not decided yet.' };
    if (e.decision === 'skip') return { state: 'skipped', message: 'Optional: left out.' };
    if (e.decision === 'drop') return { state: 'done', message: 'Dropped.' };
    if (e.decision === 'same') {
      const target = entryOf(entries, e.same_as);
      if (!target || target.decision !== 'keep') {
        return { state: 'problem', message: `Marked the same as ${e.same_as ? displayName(doc, e.same_as) : 'another group'}, which is not kept.` };
      }
      return { state: 'done', message: `Same as ${displayName(doc, e.same_as)}.` };
    }
    if (e.decision === 'keep') {
      if (!named(e)) return { state: 'problem', message: 'Kept, but the name is not finished.' };
      const shape = shapeCheck(groupMembers(doc, entries, id), doc.rules);
      if (!shape.ok) return { state: 'problem', message: shape.text };
      return { state: 'done', message: `Kept: ${sentence(e)}` };
    }
    return { state: 'problem', message: `Unknown decision for a ${c.kind} group.` };
  }

  function progress(doc, entries) {
    const accepted = idsOfKind(doc, 'accepted');
    return {
      total: accepted.length,
      decided: accepted.filter((id) => entryOf(entries, id)?.decision !== null).length,
      problems: orderedIds(doc).filter((id) => status(doc, entries, id).state === 'problem').length,
    };
  }

  function toReviewFile(doc, entries, savedAt) {
    return {
      schema_version: SCHEMA_VERSION,
      run: doc.run.id,
      fingerprint: doc.run.fingerprint ?? null,
      saved_at: savedAt,
      entries: entries.map((e) => ({ ...e, excluded: [...e.excluded] })),
    };
  }

  /** Read a saved review back, repairing anything that does not fit this run rather than failing. */
  function fromReviewFile(doc, data) {
    if (!data || typeof data !== 'object') return { error: 'That is not a review file.' };
    if (data.schema_version !== SCHEMA_VERSION) {
      return { error: 'That review file was made by a different version of the review tool.' };
    }
    if (data.run !== doc.run.id) return { error: `That review file is for run ${data.run}, not ${doc.run.id}.` };
    if (doc.run.fingerprint && data.fingerprint && data.fingerprint !== doc.run.fingerprint) {
      return { error: 'That review file was made for a different set of groups with the same run name.' };
    }
    const stored = new Map((Array.isArray(data.entries) ? data.entries : [])
      .filter((x) => x && typeof x === 'object').map((x) => [x.id, x]));
    const max = doc.rules.maxFieldChars;
    const text = (v) => (typeof v === 'string' ? v.slice(0, max) : '');
    const entries = orderedIds(doc).map((id) => {
      const kind = doc.candidates[id].kind;
      const base = blankEntry(id, kind);
      const s = stored.get(id);
      if (!s) return base;
      const valid = new Set(doc.candidates[id].members.map((m) => m.member));
      const decisionOk = allowedDecisions(kind).includes(s.decision) || (kind === 'accepted' && s.decision === null);
      return {
        id,
        decision: decisionOk ? s.decision : base.decision,
        same_as: typeof s.same_as === 'string' && s.same_as in doc.candidates && s.same_as !== id ? s.same_as : null,
        actor: text(s.actor),
        wants: text(s.wants),
        counterpart: text(s.counterpart),
        excluded: [...new Set(Array.isArray(s.excluded) ? s.excluded.filter((x) => valid.has(x)) : [])],
      };
    });
    return { entries };
  }

  return {
    SCHEMA_VERSION, orderedIds, allowedDecisions, displayName, shortName, blankEntry, initialEntries,
    keptTargets, groupMembers, shapeCheck, sentence, status, progress, toReviewFile, fromReviewFile,
  };
})();

if (typeof module !== 'undefined') module.exports = ReviewLogic;