// Copyright (c) 未来飞马
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.
//
// Trademark Notice:
// The MPL-2.0 license grants copyright permissions for source code only.
// It does NOT grant any rights to use trademarks including "未来飞马",
// "Harness Loop", "RSI", and associated slogan "让AI进化提前发生，让AI落地快人一步".
// Any use of these trademarks requires separate written permission.
/**
 * 素材分组与阅读顺序
 *
 * 同事连发 6 张 / 9 张图，**不是多个素材，而是同一个素材**（朋友圈九宫格）。
 * 这里用三种信号判定「是否属于同一组」，并给出显式 order：
 *   ① 尺寸（宽高比）——九宫格同一批图通常同源同比例；
 *   ② 时间（mtime / 收图时间）——同一批连发的时间戳接近；
 *   ③ 内容相似度——OCR 文本 + 描述的词/字面重叠度。
 * 任两种信号一致即归为一组；只有一种信号可用时按该信号判定，并在 reasons 里说明。
 *
 * 顺序：同组内按「九宫格阅读顺序」= 左上 → 右下 = 从左到右、从上到下。
 * 由于原始排版位置通常已经丢失，用「收图时间升序 + 文件名自然序」近似还原发送顺序，
 * 并显式写出 orderingRule，供人工在 materialAssets[] 上再调整（reorderAssets）。
 */

import { uniq, truncate } from './lib.mjs';

export const DEFAULT_ORDERING_RULE = 'left-to-right,top-to-bottom';

// ---------------------------------------------------------------------------
// 相似度
// ---------------------------------------------------------------------------

function bigrams(text) {
  const clean = String(text || '').replace(/\s+/g, '').toLowerCase();
  if (clean.length < 2) return clean ? new Set([clean]) : new Set();
  const out = new Set();
  for (let i = 0; i < clean.length - 1; i++) out.add(clean.slice(i, i + 2));
  return out;
}

/** 字符二元组 Jaccard 相似度（0–1）。中文、英文都适用，无需分词。 */
export function textSimilarity(a, b) {
  const setA = bigrams(a);
  const setB = bigrams(b);
  if (!setA.size || !setB.size) return 0;
  let inter = 0;
  for (const g of setA) if (setB.has(g)) inter += 1;
  return inter / (setA.size + setB.size - inter);
}

/** 宽高比相似度（0–1）：同源同排版的图接近 1。 */
export function aspectSimilarity(a, b) {
  const ratioA = Number(a && a.width) > 0 && Number(a && a.height) > 0 ? a.width / a.height : null;
  const ratioB = Number(b && b.width) > 0 && Number(b && b.height) > 0 ? b.width / b.height : null;
  if (ratioA === null || ratioB === null) return null;
  const diff = Math.abs(ratioA - ratioB) / Math.max(ratioA, ratioB);
  return Math.max(0, 1 - diff);
}

/** 时间邻近度（0–1）：窗口内线性衰减。 */
export function timeProximity(a, b, windowMs) {
  const ta = Number(a && (a.mtimeMs ?? a.capturedAtMs));
  const tb = Number(b && (b.mtimeMs ?? b.capturedAtMs));
  if (!Number.isFinite(ta) || !Number.isFinite(tb)) return null;
  const gap = Math.abs(ta - tb);
  if (gap >= windowMs) return 0;
  return 1 - gap / windowMs;
}

// ---------------------------------------------------------------------------
// 排序：把「发送顺序」近似还原成九宫格阅读顺序
// ---------------------------------------------------------------------------

function naturalCompare(a, b) {
  return String(a).localeCompare(String(b), 'zh-Hans-CN', { numeric: true, sensitivity: 'base' });
}

function sourceName(item) {
  const p = item.localPath || item.url || '';
  return p.split(/[\\/]/).pop() || p;
}

/**
 * 同组内排序：时间优先（同一批连发的时间戳能还原发送顺序），
 * 时间相同/缺失时回落文件名自然序。
 */
export function orderWithinGroup(items) {
  return items
    .map((item, index) => ({ item, index }))
    .sort((a, b) => {
      const ta = Number(a.item.mtimeMs ?? a.item.capturedAtMs);
      const tb = Number(b.item.mtimeMs ?? b.item.capturedAtMs);
      const hasTa = Number.isFinite(ta);
      const hasTb = Number.isFinite(tb);
      if (hasTa && hasTb && ta !== tb) return ta - tb;
      const byName = naturalCompare(sourceName(a.item), sourceName(b.item));
      if (byName !== 0) return byName;
      return a.index - b.index;
    })
    .map((entry) => entry.item);
}

/**
 * 九宫格排版推断。
 * 9 → 3x3；4 → 2x2；6 → 3x2；2 → 2x1；其它按最接近方阵的因数对。
 */
export function inferLayout(count) {
  const n = Math.max(1, Number(count) || 1);
  const presets = { 1: [1, 1], 2: [2, 1], 3: [3, 1], 4: [2, 2], 6: [3, 2], 9: [3, 3], 12: [4, 3] };
  if (presets[n]) return `${presets[n][0]}x${presets[n][1]}`;
  for (let cols = Math.ceil(Math.sqrt(n)); cols <= n; cols++) {
    if (n % cols === 0) return `${cols}x${n / cols}`;
  }
  return `${n}x1`;
}

// ---------------------------------------------------------------------------
// 分组
// ---------------------------------------------------------------------------

const DEFAULTS = {
  timeWindowMs: 15 * 60 * 1000, // 连发 15 分钟内算同一批
  aspectThreshold: 0.88,        // 宽高比相似度阈值
  textThreshold: 0.25,          // 文本相似度阈值（同批截图常有共同话术）
};

/**
 * 把散图切成「素材组」。
 *
 * @param {Array<object>} items 每项：{localPath|url, kind, width, height, mtimeMs, ocrText, description}
 * @param {object} [options] timeWindowMs / aspectThreshold / textThreshold / groupIdPrefix
 * @returns {Array<{groupId, layout, count, orderingRule, kind, signals, reasons, items}>}
 */
export function groupMaterials(items, options = {}) {
  const opts = { ...DEFAULTS, ...options };
  const list = (items || []).filter(Boolean).map((item, index) => ({
    kind: 'image',
    ...item,
    _index: index,
  }));
  if (!list.length) return [];

  const groups = [];

  for (const item of list) {
    let best = null;
    let bestScore = -1;
    let bestReasons = [];

    for (const group of groups) {
      const { score, reasons } = groupAffinity(group, item, opts);
      if (score > bestScore) {
        best = group;
        bestScore = score;
        bestReasons = reasons;
      }
    }

    if (best && bestScore >= 0.5) {
      best.items.push(item);
      best.reasons = uniq([...best.reasons, ...bestReasons]);
      continue;
    }

    groups.push({
      groupId: `${opts.groupIdPrefix || 'g'}${groups.length + 1}`,
      items: [item],
      reasons: ['seed'],
      signals: [],
    });
  }

  // 组内排序 + 排版 + 显式 order
  return groups.map((group) => {
    const ordered = orderWithinGroup(group.items);
    const withOrder = ordered.map((item, index) => ({
      ...item,
      groupId: group.groupId,
      order: index + 1,
    }));
    const kind = withOrder.every((i) => i.kind === 'video') ? 'video' : 'image';
    const signals = uniq(withOrder.flatMap((i) => i._signals || []));
    return {
      groupId: group.groupId,
      layout: inferLayout(withOrder.length),
      count: withOrder.length,
      orderingRule: DEFAULT_ORDERING_RULE,
      kind,
      signals,
      reasons: group.reasons,
      items: withOrder,
      preview: withOrder.map((i) => truncate(i.ocrText || i.description || i.label || '', 40)).filter(Boolean).join(' / '),
    };
  });
}

/** 单张图与一个已有组的「亲缘度」：≥2 种信号一致 → 强；仅 1 种 → 弱。 */
function groupAffinity(group, item, opts) {
  const reasons = [];
  let aspectHits = 0;
  let aspectTotal = 0;
  let textBest = 0;
  let timeBest = 0;

  for (const member of group.items) {
    // 来自不同文档的内嵌图永不并组：它们是各自文档的配图，不是同一批发图。
    // （同一文档的两张图 sourceKey 相同，仍可正常成组。）
    if (item.sourceKey && member.sourceKey && item.sourceKey !== member.sourceKey) continue;
    const aspect = aspectSimilarity(member, item);
    if (aspect !== null) {
      aspectTotal += 1;
      if (aspect >= opts.aspectThreshold) aspectHits += 1;
    }
    const text = textSimilarity(member.ocrText || member.description || '', item.ocrText || item.description || '');
    if (text > textBest) textBest = text;
    const time = timeProximity(member, item, opts.timeWindowMs);
    if (time !== null && time > timeBest) timeBest = time;
  }

  const aspectOk = aspectTotal > 0 && aspectHits / aspectTotal >= 0.6;
  const textOk = textBest >= opts.textThreshold;
  const timeOk = timeBest > 0;

  const signals = [];
  if (aspectOk) signals.push('aspect');
  if (textOk) signals.push('text');
  if (timeOk) signals.push('time');

  if (aspectOk) reasons.push('aspect:同一排版比例');
  if (textOk) reasons.push(`text:内容相似度 ${textBest.toFixed(2)}`);
  if (timeOk) reasons.push(`time:${Math.round((1 - timeBest) * opts.timeWindowMs / 1000)}s 内连发`);

  // 亲缘分：3 信号 → 0.9；2 信号 → 0.7；1 信号 → 0.4（不足以成组）
  const score = signals.length >= 3 ? 0.9 : signals.length === 2 ? 0.7 : signals.length === 1 ? 0.4 : 0;
  item._signals = uniq([...(item._signals || []), ...signals]);
  return { score, reasons, signals };
}

/**
 * 应用显式分组/顺序覆盖（人工或上游 manifest 指定）。
 * override 形如：{ groups: [ { groupId, layout?, orderingRule?, items: [{ localPath|url, order }] } ] }
 */
export function applyGroupOverrides(groups, override) {
  if (!override || !Array.isArray(override.groups) || !override.groups.length) return groups;
  const result = [];
  const consumed = new Set();

  for (const spec of override.groups) {
    const wanted = new Set((spec.items || []).map((i) => i.localPath || i.url).filter(Boolean));
    const collected = [];
    for (const group of groups) {
      for (const item of group.items) {
        const key = item.localPath || item.url;
        if (wanted.has(key) && !consumed.has(key)) {
          consumed.add(key);
          const explicit = (spec.items || []).find((i) => (i.localPath || i.url) === key);
          collected.push({ ...item, order: Number(explicit && explicit.order) || collected.length + 1 });
        }
      }
    }
    if (!collected.length) continue;
    const ordered = collected.slice().sort((a, b) => a.order - b.order).map((item, index) => ({ ...item, order: index + 1 }));
    result.push({
      groupId: spec.groupId || `g${result.length + 1}`,
      layout: spec.layout || inferLayout(ordered.length),
      count: ordered.length,
      orderingRule: spec.orderingRule || DEFAULT_ORDERING_RULE,
      kind: ordered.every((i) => i.kind === 'video') ? 'video' : 'image',
      signals: uniq(ordered.flatMap((i) => i._signals || [])),
      reasons: ['manual-override'],
      items: ordered,
      preview: ordered.map((i) => truncate(i.ocrText || i.description || '', 40)).filter(Boolean).join(' / '),
    });
  }

  // 没被覆盖到的组，原样保留
  for (const group of groups) {
    const rest = group.items.filter((item) => !consumed.has(item.localPath || item.url));
    if (!rest.length) continue;
    result.push({ ...group, items: rest.map((item, index) => ({ ...item, order: index + 1 })), count: rest.length });
  }
  return result;
}