// ============================================================
// Storage — localStorage 封装
// 职责：会话配置持久化
// ============================================================

import type { ChatMessage, SessionConfig, SessionSummary, Theme } from "../types";

const CONFIG_KEY = "camtalk:config";
const THEME_KEY = "camtalk:theme";

const DEFAULT_CONFIG: SessionConfig = {
  ttsEnabled: true,
  detailLevel: "low",
  language: "zh-CN",
};

/** 加载配置，无存储时返回默认值 */
export function loadConfig(): SessionConfig {
  try {
    const raw = localStorage.getItem(CONFIG_KEY);
    if (!raw) return DEFAULT_CONFIG;
    const parsed = JSON.parse(raw) as Partial<SessionConfig>;
    return { ...DEFAULT_CONFIG, ...parsed };
  } catch {
    return DEFAULT_CONFIG;
  }
}

/** 保存配置到 localStorage */
export function saveConfig(config: SessionConfig): void {
  try {
    localStorage.setItem(CONFIG_KEY, JSON.stringify(config));
    // 派发自定义事件，通知 App 更新 locale
    window.dispatchEvent(new CustomEvent("camtalk-config-changed"));
  } catch {
    // localStorage 不可用时静默失败
  }
}

/** 加载主题偏好 */
export function loadTheme(): Theme {
  try {
    const raw = localStorage.getItem(THEME_KEY);
    if (raw === "light" || raw === "dark") return raw;
  } catch { /* ignore */ }
  return "dark";
}

/** 保存主题偏好 */
export function saveTheme(theme: Theme): void {
  try {
    localStorage.setItem(THEME_KEY, theme);
  } catch { /* ignore */ }
}

// ---- 会话历史存储 ----

const SESSIONS_KEY = "camtalk:sessions";
const SESSION_MSG_PREFIX = "camtalk:session:";

/** 加载所有会话摘要（按 lastActiveAt 倒序） */
export function loadSessionSummaries(): SessionSummary[] {
  try {
    const raw = localStorage.getItem(SESSIONS_KEY);
    if (!raw) return [];
    return (JSON.parse(raw) as SessionSummary[]).sort((a, b) => b.lastActiveAt - a.lastActiveAt);
  } catch {
    return [];
  }
}

/** 保存会话摘要列表 */
export function saveSessionSummaries(sessions: SessionSummary[]): void {
  try {
    localStorage.setItem(SESSIONS_KEY, JSON.stringify(sessions));
  } catch { /* ignore */ }
}

/** 加载单个会话的消息历史 */
export function loadSessionMessages(sessionId: string): ChatMessage[] {
  try {
    const raw = localStorage.getItem(SESSION_MSG_PREFIX + sessionId);
    if (!raw) return [];
    return JSON.parse(raw) as ChatMessage[];
  } catch {
    return [];
  }
}

/** 保存单个会话的消息历史 */
export function saveSessionMessages(sessionId: string, messages: ChatMessage[]): void {
  try {
    localStorage.setItem(SESSION_MSG_PREFIX + sessionId, JSON.stringify(messages));
  } catch { /* ignore */ }
}

/** 删除单个会话的消息历史 */
export function deleteSessionMessages(sessionId: string): void {
  try {
    localStorage.removeItem(SESSION_MSG_PREFIX + sessionId);
  } catch { /* ignore */ }
}