import axios, { AxiosInstance, AxiosError } from 'axios';
import type { RegisterResponse, TokenResponse, User } from '@/types';

const BASE_URL = import.meta.env.VITE_API_URL
  ? `${import.meta.env.VITE_API_URL}/api/v1`
  : '/api/v1';

// ── Axios Instance ───────────────────────────────────────────
const api: AxiosInstance = axios.create({
  baseURL: BASE_URL,
  headers: { 'Content-Type': 'application/json' },
  timeout: 60000,
});

// ── Token Storage ────────────────────────────────────────────
const TOKEN_KEY = 'copilot_access_token';
const REFRESH_KEY = 'copilot_refresh_token';

export const tokenStorage = {
  getAccess: () => localStorage.getItem(TOKEN_KEY),
  getRefresh: () => localStorage.getItem(REFRESH_KEY),
  setTokens: (access: string, refresh: string) => {
    localStorage.setItem(TOKEN_KEY, access);
    localStorage.setItem(REFRESH_KEY, refresh);
  },
  clear: () => {
    localStorage.removeItem(TOKEN_KEY);
    localStorage.removeItem(REFRESH_KEY);
  },
};

// ── Request Interceptor: attach token ────────────────────────
api.interceptors.request.use((config) => {
  const token = tokenStorage.getAccess();
  if (token) {
    config.headers.Authorization = `Bearer ${token}`;
  }
  return config;
});

// ── Response Interceptor: auto-refresh on 401 ────────────────
let isRefreshing = false;
let failedQueue: Array<{ resolve: (token: string) => void; reject: (err: unknown) => void }> = [];

const processQueue = (error: unknown, token: string | null = null) => {
  failedQueue.forEach((p) => (token ? p.resolve(token) : p.reject(error)));
  failedQueue = [];
};

api.interceptors.response.use(
  (response) => response,
  async (error: AxiosError) => {
    const originalRequest = error.config as typeof error.config & { _retry?: boolean };
    if (error.response?.status === 401 && !originalRequest._retry) {
      if (isRefreshing) {
        return new Promise((resolve, reject) => {
          failedQueue.push({ resolve, reject });
        })
          .then((token) => {
            originalRequest.headers!['Authorization'] = `Bearer ${token}`;
            return api(originalRequest);
          })
          .catch((err) => Promise.reject(err));
      }

      originalRequest._retry = true;
      isRefreshing = true;

      const refreshToken = tokenStorage.getRefresh();
      if (!refreshToken) {
        tokenStorage.clear();
        window.location.href = '/login';
        return Promise.reject(error);
      }

      try {
        const { data } = await axios.post<TokenResponse>(`${BASE_URL}/auth/refresh`, {
          refresh_token: refreshToken,
        });
        tokenStorage.setTokens(data.access_token, data.refresh_token);
        processQueue(null, data.access_token);
        originalRequest.headers!['Authorization'] = `Bearer ${data.access_token}`;
        return api(originalRequest);
      } catch (refreshError) {
        processQueue(refreshError, null);
        tokenStorage.clear();
        window.location.href = '/login';
        return Promise.reject(refreshError);
      } finally {
        isRefreshing = false;
      }
    }
    return Promise.reject(error);
  }
);

// ── Auth API ──────────────────────────────────────────────────
export const authApi = {
  register: (data: { email: string; password: string; full_name: string; tenant_name: string }) =>
    api.post<RegisterResponse>('/auth/register', data).then((r) => r.data),

  login: (email: string, password: string) => {
    const form = new URLSearchParams();
    form.append('username', email);
    form.append('password', password);
    return api
      .post<TokenResponse>('/auth/login', form, {
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      })
      .then((r) => r.data);
  },

  logout: () => api.post('/auth/logout').then((r) => r.data),

  me: () => api.get<User>('/auth/me').then((r) => r.data),

  refresh: (refresh_token: string) =>
    api.post<TokenResponse>('/auth/refresh', { refresh_token }).then((r) => r.data),
};

// ── Chat API ──────────────────────────────────────────────────
export const chatApi = {
  sendMessage: (message: string, session_id?: string) =>
    api
      .post('/chat/', { message, session_id })
      .then((r) => r.data),

  streamMessage: async (
    message: string,
    session_id: string | undefined,
    onToken: (token: string) => void,
    onMeta: (meta: { session_id: string; agent_type: string; routing_decision: string }) => void,
    onSources: (sources: any) => void,
    onDone: (info: { tokens_used: number; latency_ms: number }) => void,
    onError: (error: string) => void,
  ) => {
    const token = tokenStorage.getAccess();
    try {
      const res = await fetch(`${BASE_URL}/chat/stream`, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          Authorization: `Bearer ${token}`,
        },
        body: JSON.stringify({ message, session_id }),
      });

      if (!res.ok) {
        onError(`HTTP ${res.status}`);
        return;
      }

      const reader = res.body?.getReader();
      if (!reader) { onError('No response stream'); return; }

      const decoder = new TextDecoder();
      let buffer = '';

      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) {
          if (!line.startsWith('data: ')) continue;
          try {
            const data = JSON.parse(line.slice(6));
            switch (data.type) {
              case 'meta': onMeta(data); break;
              case 'token': onToken(data.content); break;
              case 'sources': onSources(data); break;
              case 'done': onDone(data); break;
            }
          } catch {
            // skip malformed JSON
          }
        }
      }
    } catch (err: any) {
      onError(err.message || 'Stream connection failed');
    }
  },

  getSessions: () => api.get('/chat/sessions').then((r) => r.data),

  getSessionMessages: (sessionId: string) =>
    api.get(`/chat/sessions/${sessionId}`).then((r) => r.data),

  deleteSession: (sessionId: string) =>
    api.delete(`/chat/sessions/${sessionId}`).then((r) => r.data),
};

// ── Documents API ─────────────────────────────────────────────
export const documentsApi = {
  upload: (file: File, docType: string = 'general') => {
    const formData = new FormData();
    formData.append('file', file);
    formData.append('doc_type', docType);
    return api
      .post('/documents/upload', formData, {
        headers: { 'Content-Type': 'multipart/form-data' },
      })
      .then((r) => r.data);
  },

  list: (docType?: string) => {
    const params: Record<string, string> = {};
    if (docType) params['doc_type'] = docType;
    return api.get('/documents/', { params }).then((r) => r.data);
  },

  get: (id: string) => api.get(`/documents/${id}`).then((r) => r.data),

  getStatus: (id: string) => api.get(`/documents/${id}/status`).then((r) => r.data),

  delete: (id: string) => api.delete(`/documents/${id}`).then((r) => r.data),
};

// ── Admin API ─────────────────────────────────────────────────
export const adminApi = {
  getUsers: () => api.get('/admin/users').then((r) => r.data),
  inviteUser: (data: { email: string; full_name: string; role: string; password?: string }) =>
    api.post('/admin/users/invite', data).then((r) => r.data),
  getAuditLogs: () => api.get('/admin/audit-logs').then((r) => r.data),
  getTenant: () => api.get('/admin/tenant').then((r) => r.data),
};

// ── Health API ────────────────────────────────────────────────
export const healthApi = {
  check: () => api.get('/health', { baseURL: '' }).then((r) => r.data),
};

export default api;