/* KBV5 純函式庫（可單元測試）。
 *
 * 把 app.js 裡「高回歸風險、純輸入→輸出」的資料轉換邏輯抽出來，讓 vitest 能直接測，
 * 同時 app.js 以 <script> 載入後用 window.KBV5Pure.xxx 呼叫——測到的就是線上跑的同一份。
 *
 * UMD：CommonJS（vitest require）與瀏覽器全域（window.KBV5Pure）雙支援。
 */
(function (root, factory) {
  const mod = factory();
  if (typeof module !== "undefined" && module.exports) module.exports = mod;
  root.KBV5Pure = mod;   // 瀏覽器 window / vitest globalThis 都掛上，測試與線上用同一份
})(typeof globalThis !== "undefined" ? globalThis : this, function () {
  "use strict";

  // 評論作者顯示名：display_name → username → 退回 #id（B2；避免顯示「#42」）
  function commentAuthorName(c) {
    if (!c) return "";
    return c.author_display_name || c.author_username || ("#" + c.author_id);
  }

  // 媒體庫卡片 thumb 類別（依 mime 分 image / video / pdf / doc）
  function mediaThumbKind(mime) {
    mime = mime || "";
    if (mime.indexOf("image/") === 0) return "image";
    if (mime.indexOf("video/") === 0) return "video";
    if (mime === "application/pdf") return "pdf";
    return "doc";
  }

  // library 套篩選後的 header 文案（B1）。narrowed = 篩選後比載入的少。
  function libFilterHeaderText(opts) {
    const baseTotal = opts.baseTotal || 0;
    const baseQuery = opts.baseQuery || "";
    const filteredLen = opts.filteredLen || 0;
    const loadedLen = opts.loadedLen || 0;
    const narrowed = filteredLen !== loadedLen;
    if (narrowed) {
      return (baseQuery ? `搜尋「${baseQuery}」· ` : "") + `篩選後顯示 ${filteredLen} 篇`;
    }
    return baseQuery ? `搜尋「${baseQuery}」· 找到 ${baseTotal} 篇` : `共 ${baseTotal} 篇文件`;
  }

  // 「全選 N 篇」標籤（#8）
  function selectAllLabel(total) {
    return `全選 ${total || 0} 篇`;
  }

  // 提交頁可見度標籤（從 wireSubmit 抽出的純函式；baseLabel 由呼叫端傳入避免耦合 VIS_BADGE）
  function visibilityLabel(cfg, baseLabel) {
    cfg = cfg || {};
    const extra = [];
    if (cfg.visibility === "selected_departments" &&
        cfg.allowed_departments && cfg.allowed_departments.length) {
      extra.push(`${cfg.allowed_departments.length} 部門`);
    }
    if (cfg.access_list && cfg.access_list.length) extra.push(`${cfg.access_list.length} 人`);
    return "可見度：" + baseLabel + (extra.length ? `（${extra.join("・")}）` : "");
  }

  // PII 關鍵字/片語比對（層1/2）。rules=[{rule, pattern, variants[]}] → 命中清單。
  function scanKeywords(text, rules) {
    const low = (text || "").toLowerCase();
    const hits = [];
    for (const k of (rules || [])) {
      const cands = [k.pattern].concat(k.variants || []);
      for (const c of cands) {
        if (c && low.includes(String(c).toLowerCase())) {
          hits.push({ name: k.rule, match: String(c), index: low.indexOf(String(c).toLowerCase()) });
          break;
        }
      }
    }
    return hits;
  }

  // 正則規則比對（scanPii 的純核心）。rules=[{name, re}] → 命中清單。
  function matchRegexRules(text, rules) {
    const hits = [];
    if (!text) return hits;
    for (const r of (rules || [])) {
      r.re.lastIndex = 0;
      let m;
      while ((m = r.re.exec(text)) !== null) {
        hits.push({ name: r.name, match: m[0], index: m.index });
        if (!r.re.global) break;   // 非 global 不會推進 lastIndex → 防無限迴圈
      }
    }
    return hits;
  }

  // 提交鈕閘門：依字數 / 上限 / PII 命中數，決定可否送出 / 存草稿。
  // 安全關鍵：PII 命中 → 一律不可送出（§9.1 鐵則的前端把關）。
  function submitGate(opts) {
    opts = opts || {};
    const empty = (opts.len || 0) === 0;
    const tooMany = (opts.len || 0) > (opts.max || 0);
    const piiBlocked = (opts.piiHitCount || 0) > 0;
    return {
      empty, tooMany, piiBlocked,
      canSubmit: !(empty || tooMany || piiBlocked),
      canDraft: !(empty || tooMany),
    };
  }

  // 相對時間標籤（「剛剛 / N 分鐘前 / N 天前」）。nowMs 由呼叫端傳入以利測試。
  function relativeTime(iso, nowMs) {
    if (!iso) return "";
    const t = new Date(iso.replace(" ", "T") + (iso.endsWith("Z") ? "" : "Z"));
    if (isNaN(t.getTime())) return iso;
    const diff = ((nowMs || 0) - t.getTime()) / 1000;
    if (diff < 60) return "剛剛";
    if (diff < 3600) return Math.floor(diff / 60) + " 分鐘前";
    if (diff < 86400) return Math.floor(diff / 3600) + " 小時前";
    if (diff < 604800) return Math.floor(diff / 86400) + " 天前";
    return t.toLocaleDateString("zh-TW");
  }

  // 逗號/頓號/換行分隔字串 → 去空白、去空項、去重 的陣列（標籤/清單輸入共用）。
  function parseCsvList(str) {
    const seen = new Set();
    const out = [];
    for (const x of String(str || "").split(/[,，、\n]/)) {
      const v = x.trim();
      if (v && !seen.has(v)) { seen.add(v); out.push(v); }
    }
    return out;
  }

  // 密碼強度評分（PRD §10.5：≥8 字、≥1 大寫、≥1 小寫；數字/特殊字元加分）。
  function gradePassword(p) {
    if (!p) return { score: 0, label: "—", color: "var(--text-3)", barColor: "transparent" };
    let s = 0;
    if (p.length >= 8) s++;
    if (/[A-Z]/.test(p)) s++;
    if (/[a-z]/.test(p)) s++;
    if (/[0-9]/.test(p) || /[^A-Za-z0-9]/.test(p)) s++;
    if (p.length >= 12 && /[0-9]/.test(p) && /[^A-Za-z0-9]/.test(p)) s++;
    const missing = [];
    if (p.length < 8) missing.push("≥ 8 字");
    if (!/[A-Z]/.test(p)) missing.push("1 大寫");
    if (!/[a-z]/.test(p)) missing.push("1 小寫");
    let label, color, barColor, width;
    if (s <= 1) { label = "弱"; color = "var(--danger)"; barColor = "var(--danger)"; width = "25%"; }
    else if (s === 2) { label = "中等"; color = "#d97706"; barColor = "#d97706"; width = "50%"; }
    else if (s === 3) { label = "良好"; color = "var(--ok)"; barColor = "var(--ok)"; width = "75%"; }
    else { label = "強"; color = "var(--ok)"; barColor = "var(--ok)"; width = "100%"; }
    let hint;
    if (missing.length) hint = "強度:" + label + " · 還需:" + missing.join("、");
    else if (s < 4) hint = "強度:" + label + " · 建議加入數字或特殊符號";
    else hint = "強度:" + label;
    return { score: s, label, color, barColor, width, hint, missing };
  }

  // 檔案大小格式化（bytes → KB / MB 字串，預設精度與既有顯示一致）
  function fmtKB(bytes) { return (Number(bytes || 0) / 1024).toFixed(1); }
  function fmtMB(bytes, digits) {
    return (Number(bytes || 0) / 1024 / 1024).toFixed(digits == null ? 2 : digits);
  }

  // token 數簡寫（1.2K / 3.4M）
  function fmtTok(n) {
    n = Number(n || 0);
    if (n >= 1e6) return (n / 1e6).toFixed(1) + "M";
    if (n >= 1e3) return (n / 1e3).toFixed(1) + "K";
    return String(n);
  }

  // email 網域是否在白名單內（公司網域限制，§10.5）
  function isAllowedEmailDomain(email, domains) {
    const m = String(email || "").match(/@([A-Za-z0-9.\-]+)$/);
    if (!m) return false;
    return (domains || []).map((d) => String(d).toLowerCase()).includes(m[1].toLowerCase());
  }

  // HTML 跳脫（XSS 防護，全站插 DOM 前用）
  function escapeHtml(s) {
    return String(s == null ? "" : s)
      .replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;")
      .replace(/"/g, "&quot;").replace(/'/g, "&#39;");
  }

  // ===== 字詞級 diff（LCS）：合併預覽 / 版本比對共用 =====
  function diffTokens(s) {
    return String(s || "").match(/[一-鿿]|[A-Za-z0-9_]+|\n|\s+|[^\s]/g) || [];
  }

  function lcsOps(a, b) {
    const n = a.length, m = b.length;
    const dp = Array.from({ length: n + 1 }, () => new Int32Array(m + 1));
    for (let i = n - 1; i >= 0; i--)
      for (let j = m - 1; j >= 0; j--)
        dp[i][j] = a[i] === b[j] ? dp[i + 1][j + 1] + 1 : Math.max(dp[i + 1][j], dp[i][j + 1]);
    const ops = []; let i = 0, j = 0;
    while (i < n && j < m) {
      if (a[i] === b[j]) { ops.push({ t: "eq", v: a[i] }); i++; j++; }
      else if (dp[i + 1][j] >= dp[i][j + 1]) { ops.push({ t: "del", v: a[i] }); i++; }
      else { ops.push({ t: "ins", v: b[j] }); j++; }
    }
    while (i < n) ops.push({ t: "del", v: a[i++] });
    while (j < m) ops.push({ t: "ins", v: b[j++] });
    return ops;
  }

  function wordDiffOps(base, merged) {
    const a = diffTokens(base), b = diffTokens(merged);
    if (a.length > 2600 || b.length > 2600) {   // 太長 → 改行級，避免 O(n*m) 爆量
      const al = String(base || "").split("\n"), bl = String(merged || "").split("\n");
      return lcsOps(al.map((x) => x + "\n"), bl.map((x) => x + "\n"));
    }
    return lcsOps(a, b);
  }

  // 回 {left, right}：left=既有(刪除紅底)、right=合併後(新增綠底)
  function diffSides(base, merged) {
    let left = "", right = "";
    for (const o of wordDiffOps(base, merged)) {
      const esc = escapeHtml(o.v);
      if (o.t === "eq") { left += esc; right += esc; }
      else if (o.t === "del") left += `<span style="background:#fecaca;">${esc}</span>`;
      else right += `<span style="background:#bbf7d0;">${esc}</span>`;
    }
    return { left, right };
  }

  // 行內 markdown（**粗體** *斜體* `code` [text](url)）。輸入須已 escapeHtml。
  // 連結只允許 https?:// → 擋 javascript: 等危險協定（XSS）。
  function inlineMarkdown(escaped) {
    let s = String(escaped || "");
    s = s.replace(/`([^`\n]+)`/g, '<code style="background:#f1f5f9;padding:1px 5px;border-radius:3px;font-family:ui-monospace,monospace;font-size:0.92em;">$1</code>');
    s = s.replace(/\*\*([^*\n]+)\*\*/g, "<strong>$1</strong>");
    s = s.replace(/(^|[^\\*])\*([^*\n]+)\*(?!\*)/g, "$1<em>$2</em>");
    s = s.replace(/\[([^\]\n]+)\]\((https?:\/\/[^)\s]+)\)/g,
      '<a href="$2" target="_blank" rel="noopener noreferrer">$1</a>');
    return s;
  }

  // 極簡 markdown 渲染（標題/清單/程式碼/段落）。先 escape 再轉 → XSS 安全。
  function renderMarkdown(md) {
    const lines = String(md || "").split(/\r?\n/);
    let html = "", inCode = false, inList = false;
    const closeList = () => { if (inList) { html += "</ul>"; inList = false; } };
    for (const line of lines) {
      if (line.trim().startsWith("```")) {
        if (!inCode) { closeList(); html += "<pre>"; inCode = true; }
        else { html += "</pre>"; inCode = false; }
        continue;
      }
      if (inCode) { html += escapeHtml(line) + "\n"; continue; }
      const h = line.match(/^(#{1,4})\s+(.*)$/);
      if (h) {
        closeList();
        const lvl = Math.min(h[1].length + 1, 6);
        html += `<h${lvl}>${inlineMarkdown(escapeHtml(h[2]))}</h${lvl}>`;
        continue;
      }
      const li = line.match(/^\s*[-*]\s+(.*)$/);
      if (li) {
        if (!inList) { html += "<ul>"; inList = true; }
        html += `<li>${inlineMarkdown(escapeHtml(li[1]))}</li>`;
        continue;
      }
      if (line.trim() === "") { closeList(); continue; }
      closeList();
      html += `<p>${inlineMarkdown(escapeHtml(line))}</p>`;
    }
    if (inCode) html += "</pre>";
    closeList();
    return html;
  }

  // 稽核 facet 真實統計（#9 的純運算部分）。
  // items: audit-log 列（含 category / risk / result / timestamp / display_name|username）
  // nowMs: 現在時間（ms）；上限 cap 命中時 capped=true。
  function tallyAuditFacets(items, nowMs) {
    items = items || [];
    const capped = items.length >= 500;
    const cat = {}, risk = {}, res = { success: 0, fail: 0 }, byUser = {};
    let d7 = 0, d30 = 0, d90 = 0;
    const within = (iso, days) => {
      const s = (iso || "").replace(" ", "T");
      const t = new Date(s + (s.endsWith("Z") ? "" : "Z")).getTime();
      return !isNaN(t) && t >= nowMs - days * 86400000;
    };
    items.forEach((it) => {
      cat[it.category] = (cat[it.category] || 0) + 1;
      risk[it.risk] = (risk[it.risk] || 0) + 1;
      if (it.result === "fail") res.fail++; else res.success++;
      const nm = it.display_name || it.username || "(未知)";
      byUser[nm] = (byUser[nm] || 0) + 1;
      if (within(it.timestamp, 7)) d7++;
      if (within(it.timestamp, 30)) d30++;
      if (within(it.timestamp, 90)) d90++;
    });
    const topUsers = Object.entries(byUser).sort((a, b) => b[1] - a[1]).slice(0, 6);
    return { cat, risk, res, d7, d30, d90, topUsers, capped };
  }

  return {
    commentAuthorName,
    mediaThumbKind,
    libFilterHeaderText,
    selectAllLabel,
    visibilityLabel,
    scanKeywords,
    matchRegexRules,
    submitGate,
    relativeTime,
    parseCsvList,
    gradePassword,
    fmtTok,
    fmtKB,
    fmtMB,
    isAllowedEmailDomain,
    escapeHtml,
    diffTokens,
    lcsOps,
    wordDiffOps,
    diffSides,
    inlineMarkdown,
    renderMarkdown,
    tallyAuditFacets,
  };
});