/**
 * API 通信模块 - HTTP 封装 + 错误拦截 + 参数映射
 *
 * 核心参数映射（SDK → 后端）：
 *   integrateId → roleId（客服角色 ID）
 *   userId      → accountId（客户账号 ID）
 *   chatId      → 自动管理的对话 ID（从 /ai/sdk/conversation/list 获取或自动生成）
 */
import { ResolvedConfig, ApiResponse, CategoryNode } from './types';
import { logger } from './logger';
import { t } from './i18n';

/** 请求超时时间（毫秒） */
const REQUEST_TIMEOUT = 30000;

let currentConfig: ResolvedConfig | null = null;

/** 运行时动态设置的角色 ID（通过角色选择器切换），优先于 currentConfig.integrateId */
let activeIntegrateId: string | null = null;

/** 设置当前配置 */
export function setApiConfig(config: ResolvedConfig): void {
  currentConfig = config;
}

/** 清空当前配置（销毁 SDK 时调用） */
export function clearApiConfig(): void {
  currentConfig = null;
  activeIntegrateId = null;
}

/** 设置当前活跃角色 ID（角色切换时调用），影响后续所有 API 调用的 roleId 参数 */
export function setActiveRoleId(roleId: string | null): void {
  activeIntegrateId = roleId;
}

/** 获取当前有效的 integrateId（优先使用运行时设置，回退到配置默认值） */
export function getActiveIntegrateId(): string {
  return activeIntegrateId ?? currentConfig?.integrateId ?? '';
}

/** 更新当前 chatId（对话 ID） */
export function updateChatId(chatId: string): void {
  if (currentConfig) {
    currentConfig.chatId = chatId;
  }
}

/** 获取当前 chatId */
export function getChatId(): string {
  return currentConfig?.chatId || '';
}

/** 构建完整请求 URL，自动防御双斜杠 */
function buildUrl(path: string): string {
  if (!currentConfig) {
    throw new Error('API 配置未初始化');
  }
  const domain = currentConfig.requestDomain.replace(/\/+$/, '');
  const cleanPath = path.startsWith('/') ? path : `/${path}`;
  return `${domain}${cleanPath}`;
}

/**
 * 安全设置可选参数：仅当 value 非空时追加
 */
function setIfPresent(params: URLSearchParams, key: string, value: string | number | undefined): void {
  if (value === undefined || value === null) return;
  if (typeof value === 'string' && value.trim() === '') return;
  params.set(key, String(value));
}

// ==================== 对话接口 URL 构建 ====================

/**
 * 构建同步对话请求 URL
 * - integrateId → roleId
 * - userId → accountId
 * - chatId → 自动管理的对话 ID
 */
function buildChatUrl(message: string): string {
  const params = new URLSearchParams();
  params.set('message', message);
  params.set('chatId', currentConfig!.chatId);

  // integrateId 映射为 roleId
  setIfPresent(params, 'roleId', getActiveIntegrateId());
  // userId 映射为 accountId
  setIfPresent(params, 'accountId', currentConfig!.userId);

  return buildUrl(`/ai/assistant_app/chat/sync?${params.toString()}`);
}

/**
 * 构建 SSE 流式请求 URL
 */
function buildChatSSEUrl(message: string, categoryId?: number): string {
  const params = new URLSearchParams();
  params.set('message', message);
  params.set('chatId', currentConfig!.chatId);

  setIfPresent(params, 'roleId', getActiveIntegrateId());
  setIfPresent(params, 'accountId', currentConfig!.userId);
  setIfPresent(params, 'categoryId', categoryId ?? currentConfig!.categoryId);

  return buildUrl(`/ai/assistant_app/chat/sse?${params.toString()}`);
}

/**
 * 构建 RAG 增强流式请求 URL
 */
function buildChatRAGSSEUrl(message: string, categoryId?: number): string {
  const params = new URLSearchParams();
  params.set('message', message);
  params.set('chatId', currentConfig!.chatId);
  params.set('rewriteStrategy', currentConfig!.rewriteStrategy || 'REWRITE');

  setIfPresent(params, 'roleId', getActiveIntegrateId());
  setIfPresent(params, 'accountId', currentConfig!.userId);
  setIfPresent(params, 'categoryId', categoryId ?? currentConfig!.categoryId);

  return buildUrl(`/ai/assistant_app/chat/rag/sse?${params.toString()}`);
}

/**
 * 构建 RAG 引用来源请求 URL
 */
function buildRagSourcesUrl(message: string, categoryId?: number): string {
  const params = new URLSearchParams();
  params.set('message', message);
  params.set('chatId', currentConfig!.chatId);
  params.set('rewriteStrategy', currentConfig!.rewriteStrategy || 'REWRITE');

  setIfPresent(params, 'roleId', getActiveIntegrateId());
  setIfPresent(params, 'accountId', currentConfig!.userId);
  setIfPresent(params, 'categoryId', categoryId ?? currentConfig!.categoryId);

  return buildUrl(`/ai/assistant_app/rag/sources?${params.toString()}`);
}

// ==================== HTTP 基础封装 ====================

/** 带超时的 fetch 封装，支持外部 AbortSignal（用于流式主动中断） */
async function safeFetch(
  url: string,
  options: RequestInit = {},
  timeout: number = REQUEST_TIMEOUT,
  externalSignal?: AbortSignal
): Promise<Response> {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), timeout);

  // 外部信号触发时同步中断内部请求
  if (externalSignal) {
    if (externalSignal.aborted) {
      controller.abort();
    } else {
      externalSignal.addEventListener('abort', () => controller.abort(), { once: true });
    }
  }

  try {
    // 注入 SDK Token 认证头（仅对 /ai/ 路径注入，避免将 SDK Token 发送到管理接口）
    const headers: Record<string, string> = {};
    if (options.headers) {
      if (options.headers instanceof Headers) {
        options.headers.forEach((value, key) => { headers[key] = value; });
      } else if (Array.isArray(options.headers)) {
        options.headers.forEach(([key, value]) => { headers[key] = value; });
      } else {
        Object.assign(headers, options.headers as Record<string, string>);
      }
    }
    if (currentConfig?.token && url.includes('/ai/')) {
      headers['Authorization'] = `Bearer ${currentConfig.token}`;
    }

    const response = await fetch(url, {
      ...options,
      headers,
      signal: controller.signal,
      mode: 'cors',
      credentials: 'include',
    });
    if (response.status === 401 && url.includes('/ai/')) {
      logger.error('SDK 认证失败：Token 缺失或已过期，请重新调用 /open-api/auth/token 换取 Token');
    }
    return response;
  } catch (err: unknown) {
    // 用户主动中断（停止生成），不算错误
    if (externalSignal?.aborted) {
      throw new CskError('aborted', 'aborted');
    }
    if (err instanceof DOMException && err.name === 'AbortError') {
      throw new CskError(t('error_timeout'), 'timeout');
    }
    if (err instanceof TypeError && err.message.includes('Failed to fetch')) {
      throw new CskError(t('error_cors'), 'cors');
    }
    throw new CskError(t('error_network'), 'network');
  } finally {
    clearTimeout(timer);
  }
}

/** 自定义错误类型 */
export class CskError extends Error {
  type: string;
  constructor(message: string, type: string) {
    super(message);
    this.name = 'CskError';
    this.type = type;
  }
}

/** 根据 HTTP 状态码返回对应的国际化错误消息 */
function getHttpErrorMessage(status: number): string {
  switch (status) {
    case 401: return t('error_auth');
    case 403: return t('error_forbidden');
    case 404: return t('error_not_found');
    case 429: return t('error_rate_limit');
    case 500: return t('error_server');
    case 502:
    case 503: return t('error_unavailable');
    default: return `${t('error_unknown')}（${status}）`;
  }
}

// ==================== 对话请求 ====================

/**
 * 同步对话请求
 */
export async function chatRequest(message: string): Promise<string> {
  const url = buildChatUrl(message);
  logger.lifecycleSend(getActiveIntegrateId(), message.length);

  try {
    const response = await safeFetch(url);
    if (!response.ok) {
      const errorMsg = getHttpErrorMessage(response.status);
      logger.lifecycleError(getActiveIntegrateId(), String(response.status), errorMsg);
      throw new CskError(errorMsg, `http_${response.status}`);
    }

    const text = await response.text();
    logger.lifecycleReply(getActiveIntegrateId(), text.length);
    return text;
  } catch (err) {
    if (err instanceof CskError) throw err;
    logger.lifecycleError(getActiveIntegrateId(), 'unknown', String(err));
    throw new CskError(t('error_unknown'), 'unknown');
  }
}

/**
 * SSE 流式对话请求
 * @param useRag 是否使用 RAG 增强对话
 * @param categoryId 知识库分类 ID
 */
export async function chatSSERequest(
  message: string,
  onChunk: (text: string) => void,
  onDone: () => void,
  onError: (error: CskError) => void,
  categoryId?: number,
  useRag?: boolean,
  signal?: AbortSignal
): Promise<void> {
  const url = useRag
    ? buildChatRAGSSEUrl(message, categoryId)
    : buildChatSSEUrl(message, categoryId);
  let totalText = '';

  logger.lifecycleSend(getActiveIntegrateId(), message.length);

  try {
    const response = await safeFetch(url, {}, REQUEST_TIMEOUT * 2, signal);

    if (!response.ok) {
      const errorMsg = getHttpErrorMessage(response.status);
      logger.lifecycleError(getActiveIntegrateId(), String(response.status), errorMsg);
      onError(new CskError(errorMsg, `http_${response.status}`));
      return;
    }

    const reader = response.body?.getReader();
    if (!reader) {
      onError(new CskError(t('error_stream_unsupported'), 'stream_unsupported'));
      return;
    }

    const decoder = new TextDecoder('utf-8', { stream: true } as TextDecoderOptions);
    let buffer = '';

    try {
      while (true) {
        const { done, value } = await reader.read();
        if (done) break;

        buffer += decoder.decode(value, { stream: true });
        const lines = buffer.split('\n');
        buffer = lines.pop() || '';

        for (const line of lines) {
          const trimmed = line.trim();
          if (!trimmed || trimmed.startsWith(':')) continue;

          if (trimmed.startsWith('data:')) {
            const data = trimmed.substring(5).trim();
            if (data) { totalText += data; onChunk(data); }
          } else if (trimmed === '[DONE]') {
            break;
          } else if (!trimmed.startsWith('event:') && !trimmed.startsWith('id:') && !trimmed.startsWith('retry:')) {
            totalText += trimmed;
            onChunk(trimmed);
          }
        }
      }

      if (buffer.trim()) {
        const trimmed = buffer.trim();
        if (trimmed.startsWith('data:')) {
          const data = trimmed.substring(5).trim();
          if (data) { totalText += data; onChunk(data); }
        } else if (trimmed !== '[DONE]') {
          totalText += trimmed;
          onChunk(trimmed);
        }
      }
    } catch (readErr: unknown) {
      // 用户主动中断：视为正常结束，保留已生成内容
      if (signal?.aborted) {
        logger.info(`流式被用户中断，保留已生成内容 length=${totalText.length}`);
      } else if (totalText.length > 0) {
        onChunk('\n\n' + t('stream_unstable'));
      } else {
        throw readErr;
      }
    } finally {
      reader.releaseLock();
    }

    logger.lifecycleStreamDone(getActiveIntegrateId(), totalText.length);
    onDone();
  } catch (err) {
    // 用户主动中断不触发 onError，走 onDone
    if (signal?.aborted || (err instanceof CskError && err.type === 'aborted')) {
      onDone();
      return;
    }
    if (err instanceof CskError) {
      onError(err);
    } else {
      logger.lifecycleError(getActiveIntegrateId(), 'unknown', String(err));
      onError(new CskError(t('error_network'), 'network'));
    }
  }
}

// ==================== P1: 知识库分类 ====================

/**
 * 获取知识库分类树
 */
export async function fetchCategoryTree(): Promise<CategoryNode[]> {
  const url = buildUrl('/category/tree');
  try {
    const response = await safeFetch(url);
    if (!response.ok) throw new CskError(getHttpErrorMessage(response.status), `http_${response.status}`);
    const json: ApiResponse<CategoryNode[]> = await response.json();
    if (json.success && Array.isArray(json.data)) {
      logger.info(`加载分类树成功 count=${json.data.length}`);
      return json.data;
    }
    return [];
  } catch (err) {
    if (err instanceof CskError) logger.error(`加载分类树失败: ${err.message}`);
    else logger.error('加载分类树失败', err);
    return [];
  }
}

// ==================== P1: RAG 引用来源 ====================

/** RAG 来源响应数据项 */
interface RagSourceData {
  documentId?: string;
  title?: string;
  sourceName?: string;
  chunkIndex?: number;
  score?: number;
  snippet?: string;
}

/**
 * 获取 RAG 引用来源
 */
export async function fetchRagSources(message: string, categoryId?: number): Promise<RagSourceData[]> {
  const url = buildRagSourcesUrl(message, categoryId);
  try {
    const response = await safeFetch(url);
    if (!response.ok) throw new CskError(getHttpErrorMessage(response.status), `http_${response.status}`);
    const json: ApiResponse<RagSourceData[]> = await response.json();
    if (json.success && Array.isArray(json.data)) {
      logger.info(`获取引用来源 count=${json.data.length}`);
      return json.data;
    }
    return [];
  } catch (err) {
    logger.error('获取引用来源失败', err);
    return [];
  }
}

// ==================== P0-002: 消息反馈 ====================

/**
 * 提交消息反馈（点赞/点踩）
 */
export async function submitFeedbackApi(
  messageId: string,
  feedbackType: 'THUMBS_UP' | 'THUMBS_DOWN'
): Promise<boolean> {
  if (!currentConfig) return false;
  const url = buildUrl('/feedback');
  try {
    const response = await safeFetch(url, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        messageId: String(messageId),
        conversationId: currentConfig.chatId,
        feedbackType,
      }),
    });
    if (!response.ok) {
      logger.error(`反馈提交失败 status=${response.status}`);
      return false;
    }
    const json: ApiResponse = await response.json();
    return json.success || false;
  } catch (err) {
    logger.error('反馈提交异常', err);
    return false;
  }
}

// ==================== P2: 会话管理 + chatId 初始化 ====================

/** 会话列表项 */
interface ConversationItem {
  conversationId?: string;
  chatId?: string;
  accountId?: string;
  roleId?: number;
  roleName?: string;
  messageCount?: number;
  lastMessageTime?: string;
  firstMessageTime?: string;
  lastMessagePreview?: string;
  createdAt?: string;
}

/**
 * 获取会话列表（SDK 安全端点）
 * 使用 /ai/sdk/conversation/list，强制按 accountId + roleId 过滤
 */
export async function fetchConversationList(
  page: number = 1,
  size: number = 20,
  accountId?: string,
  roleId?: string
): Promise<{
  list: ConversationItem[];
  total: number;
  pages: number;
}> {
  const params = new URLSearchParams();
  params.set('page', String(page));
  params.set('size', String(size));
  if (accountId) params.set('accountId', accountId);
  if (roleId) params.set('roleId', roleId);
  const url = buildUrl(`/ai/sdk/conversation/list?${params.toString()}`);

  try {
    const response = await safeFetch(url);
    if (!response.ok) throw new CskError(getHttpErrorMessage(response.status), `http_${response.status}`);
    const json: ApiResponse<ConversationItem[]> = await response.json();
    return {
      list: json.success && Array.isArray(json.data) ? json.data : [],
      total: json.total || 0,
      pages: json.pages || 0,
    };
  } catch (err) {
    logger.error('加载会话列表失败', err);
    return { list: [], total: 0, pages: 0 };
  }
}

/**
 * 获取会话消息（SDK 安全端点）
 * 使用 /ai/sdk/conversation/{id}/messages，含账户归属校验
 */
export async function fetchConversationMessages(conversationId: string): Promise<{
  messages: Array<{ messageType: string; content: string; createTime: string }>;
  total: number;
}> {
  const params = new URLSearchParams();
  if (currentConfig?.userId) params.set('accountId', currentConfig.userId);
  if (getActiveIntegrateId()) params.set('roleId', getActiveIntegrateId());
  const url = buildUrl(`/ai/sdk/conversation/${conversationId}/messages?${params.toString()}`);
  try {
    const response = await safeFetch(url);
    if (!response.ok) throw new CskError(getHttpErrorMessage(response.status), `http_${response.status}`);
    const json = await response.json();
    return {
      messages: json.success && Array.isArray(json.data) ? json.data : [],
      total: json.total || 0,
    };
  } catch (err) {
    logger.error('加载会话消息失败', err);
    return { messages: [], total: 0 };
  }
}

/**
 * 删除会话（SDK 安全端点）
 * 使用 DELETE /ai/sdk/conversation/{id}，含账户归属校验
 */
export async function deleteConversation(conversationId: string): Promise<boolean> {
  const params = new URLSearchParams();
  if (currentConfig?.userId) params.set('accountId', currentConfig.userId);
  if (getActiveIntegrateId()) params.set('roleId', getActiveIntegrateId());
  const url = buildUrl(`/ai/sdk/conversation/${conversationId}?${params.toString()}`);
  try {
    const response = await safeFetch(url, { method: 'DELETE' });
    if (!response.ok) throw new CskError(getHttpErrorMessage(response.status), `http_${response.status}`);
    const json: ApiResponse = await response.json();
    logger.info(`删除会话 id=${conversationId} success=${json.success}`);
    return json.success || false;
  } catch (err) {
    logger.error('删除会话失败', err);
    return false;
  }
}

/**
 * 导出会话 URL（SDK 安全端点）
 * 使用 /ai/sdk/conversation/{id}/export，含账户归属参数
 */
export function getConversationExportUrl(conversationId: string): string {
  const params = new URLSearchParams();
  if (currentConfig?.userId) params.set('accountId', currentConfig.userId);
  if (getActiveIntegrateId()) params.set('roleId', getActiveIntegrateId());
  return buildUrl(`/ai/sdk/conversation/${conversationId}/export?${params.toString()}`);
}

// ==================== chatId 自动初始化 ====================

/**
 * 初始化 chatId：查询后端已有会话，找到则复用，否则生成新的
 *
 * @param forceRefresh 为 true 时跳过 localStorage 缓存，强制查询后端
 */
export async function initChatId(forceRefresh: boolean = false): Promise<string> {
  if (!currentConfig) return '';

  const activeId = getActiveIntegrateId();

  // 1. 先从 localStorage 恢复（非强制刷新时）
  if (!forceRefresh) {
    const cachedChatId = loadCachedChatId(activeId, currentConfig.userId);
    if (cachedChatId) {
      currentConfig.chatId = cachedChatId;
      logger.info(`从缓存恢复 chatId=${cachedChatId}`);
      return cachedChatId;
    }
  }

  // 2. 查询后端会话列表
  try {
    const result = await fetchConversationList(1, 5, currentConfig.userId, activeId);
    if (result.list.length > 0) {
      // 使用最新会话的 conversationId 作为 chatId
      const latestConv = result.list[0];
      const chatId = latestConv.conversationId || latestConv.chatId || '';
      if (chatId) {
        currentConfig.chatId = chatId;
        saveCachedChatId(activeId, currentConfig.userId, chatId);
        logger.info(`从后端恢复会话 chatId=${chatId} messageCount=${latestConv.messageCount}`);
        return chatId;
      }
    }
  } catch (err) {
    logger.warn('查询后端会话列表失败，将生成新 chatId', err);
  }

  // 3. 生成新的 chatId
  const newChatId = generateChatId();
  currentConfig.chatId = newChatId;
  saveCachedChatId(activeId, currentConfig.userId, newChatId);
  logger.info(`生成新 chatId=${newChatId}`);
  return newChatId;
}

/** 生成 chatId（格式：sdk_timestamp_random） */
function generateChatId(): string {
  const random = typeof crypto !== 'undefined' && crypto.randomUUID
    ? crypto.randomUUID().substring(0, 8)
    : Math.random().toString(36).substring(2, 10);
  return `sdk_${Date.now()}_${random}`;
}

/** localStorage key 格式 */
function chatIdStorageKey(integrateId: string, userId?: string): string {
  return `csk_chatId_${integrateId}${userId ? '_' + userId : ''}`;
}

/** 从 localStorage 加载 chatId */
function loadCachedChatId(integrateId: string, userId?: string): string {
  try {
    return localStorage.getItem(chatIdStorageKey(integrateId, userId)) || '';
  } catch {
    return '';
  }
}

/** 保存 chatId 到 localStorage */
export function saveCachedChatId(integrateId: string, userId?: string, chatId?: string): void {
  try {
    if (chatId) {
      localStorage.setItem(chatIdStorageKey(integrateId, userId), chatId);
    } else {
      localStorage.removeItem(chatIdStorageKey(integrateId, userId));
    }
  } catch {
    // localStorage 不可用则忽略
  }
}