const STORAGE_KEY = "aiclient_custom_subtitle_templates";

let systemTemplatesCache = null;

/**
 * @typedef {Object} SubtitleTemplateItem
 * @property {string} id
 * @property {string} name
 * @property {string} [description]
 * @property {Record<string, unknown>} config
 * @property {boolean} [isSystem]
 * @property {number} [is_system]
 * @property {number} [createdAt]
 */

/**
 * @returns {Promise<SubtitleTemplateItem[]>}
 */
export async function loadSystemSubtitleTemplates() {
  if (systemTemplatesCache) return systemTemplatesCache;
  const res = await fetch("/subtitle-templates/system-templates.json");
  if (!res.ok) throw new Error("无法加载系统字幕模板");
  const data = await res.json();
  systemTemplatesCache = (data.subtitleTemplates || []).map((t) => ({
    ...t,
    isSystem: true,
    is_system: 1,
  }));
  return systemTemplatesCache;
}

/**
 * @returns {SubtitleTemplateItem[]}
 */
export function loadCustomSubtitleTemplates() {
  try {
    const raw = localStorage.getItem(STORAGE_KEY);
    if (!raw) return [];
    const parsed = JSON.parse(raw);
    return Array.isArray(parsed) ? parsed : [];
  } catch {
    return [];
  }
}

/**
 * @param {SubtitleTemplateItem[]} templates
 */
export function saveCustomSubtitleTemplates(templates) {
  localStorage.setItem(STORAGE_KEY, JSON.stringify(templates));
}

/**
 * @returns {Promise<SubtitleTemplateItem[]>}
 */
export async function loadAllSubtitleTemplates() {
  const system = await loadSystemSubtitleTemplates();
  const custom = loadCustomSubtitleTemplates();
  return [...system, ...custom];
}

/**
 * @param {string} id
 * @returns {Promise<SubtitleTemplateItem | null>}
 */
export async function getSubtitleTemplateById(id) {
  const all = await loadAllSubtitleTemplates();
  return all.find((t) => t.id === id) || null;
}

/**
 * @param {string} id
 */
export function isSystemSubtitleTemplateId(id) {
  return (
    String(id || "").startsWith("template_system") ||
    String(id || "").startsWith("system-")
  );
}

/**
 * @param {SubtitleTemplateItem} template
 */
export function cloneSubtitleTemplate(template) {
  const now = Date.now();
  return {
    ...JSON.parse(JSON.stringify(template)),
    id: `custom_${now}`,
    name: `${template.name} 副本`,
    isSystem: false,
    is_system: 0,
    createdAt: now,
  };
}

/**
 * @param {SubtitleTemplateItem[]} templates
 */
export function downloadSubtitleTemplatesJson(templates, filename = "subtitle-templates.json") {
  const blob = new Blob(
    [
      JSON.stringify(
        {
          version: "1.0.0",
          exportedAt: new Date().toISOString(),
          subtitleTemplates: templates,
        },
        null,
        2,
      ),
    ],
    { type: "application/json" },
  );
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = filename;
  a.click();
  URL.revokeObjectURL(url);
}

/**
 * @param {File} file
 * @returns {Promise<SubtitleTemplateItem[]>}
 */
export async function parseImportedSubtitleTemplates(file) {
  const text = await file.text();
  const data = JSON.parse(text);
  const list = data.subtitleTemplates || data.templates || data;
  if (!Array.isArray(list)) throw new Error("无效的模板文件格式");
  return list.map((t, i) => ({
    ...t,
    id: t.id || `imported_${Date.now()}_${i}`,
    isSystem: false,
    is_system: 0,
    createdAt: t.createdAt || Date.now(),
  }));
}