import axios, {
  AxiosError,
  type AxiosInstance,
  type AxiosRequestConfig,
} from "axios";

import { getApiBaseUrl } from "@/lib/env";

/**
 * 业务后端接口约定：
 * - 一律使用 POST（含「查询类」路径），新接口请用 {@link apiPost}。
 * - 响应体若包含 `code` 字段，仅当 `code === 200` 视为成功；否则抛出 {@link ApiError}，优先使用 `msg`。
 * 若接入后端 JWT，可把 token 写入该 key，请求会自动带 Authorization。
 */
export const API_TOKEN_STORAGE_KEY = "jchl_api_token";
export const API_ACCESS_TOKEN_HEADER = "access-token";

export const api: AxiosInstance = axios.create({
  timeout: 30_000,
  headers: {
    "Content-Type": "application/json",
  },
});

/**
 * 每次请求解析 baseURL，以便 `__ORIGIN__` 与 window / 部署域名一致。
 * - `baseURL: ""`：走当前站点根路径（如 `/api/...` 的 Route Handler）。
 * - 调用方已传入非空 `baseURL`（如 {@link postRemittance} 的 `/api-backend-remittance`）：不得覆盖，否则会误打到主后端 `/api-backend`。
 */
api.interceptors.request.use((config) => {
  if (config.baseURL === "") {
    config.baseURL =
      typeof window !== "undefined"
        ? undefined
        : (process.env.NEXT_PUBLIC_SITE_URL?.trim().replace(/\/$/, "") || undefined);
    return config;
  }
  const callerBase =
    config.baseURL !== undefined &&
    config.baseURL !== null &&
    String(config.baseURL).trim() !== "";
  if (callerBase) {
    return config;
  }
  const base = getApiBaseUrl();
  config.baseURL = base || undefined;
  return config;
});

api.interceptors.request.use((config) => {
  if (typeof window !== "undefined") {
    const token = localStorage.getItem(API_TOKEN_STORAGE_KEY);
    if (token) {
      config.headers[API_ACCESS_TOKEN_HEADER] = token;
      config.headers.Authorization = `Bearer ${token}`;
    }
  }
  return config;
});

export class ApiError extends Error {
  constructor(
    message: string,
    public status?: number,
    public payload?: unknown,
  ) {
    super(message);
    this.name = "ApiError";
  }
}

let authTimeoutDialogShown = false;

function notifySessionTimeoutAndRedirect() {
  if (typeof window === "undefined") return;
  if (authTimeoutDialogShown) return;
  authTimeoutDialogShown = true;
  window.alert("登录超时，请重新登录");
  window.location.assign("/auth/login");
}

function isPlainObject(v: unknown): v is Record<string, unknown> {
  return typeof v === "object" && v !== null && !Array.isArray(v);
}

/** 业务层约定：响应体含 `code` 时，仅 `200` 为成功，其余走失败（含 HTTP 200 但 code≠200） */
function businessMessage(body: Record<string, unknown>): string {
  const msg = body.msg;
  if (typeof msg === "string" && msg.trim()) return msg.trim();
  const message = body.message;
  if (typeof message === "string" && message.trim()) return message.trim();
  return "请求失败";
}

function isBusinessSuccessCode(code: unknown): boolean {
  return code === 200 || code === "200";
}

api.interceptors.response.use(
  (res) => {
    const body = res.data;
    if (!isPlainObject(body) || !("code" in body)) return res;
    if (body.code === 600 || body.code === "600") {
      setApiAuthToken(null);
      notifySessionTimeoutAndRedirect();
      return Promise.reject(new ApiError("登录状态失效，请重新登录", 600, body));
    }
    if (isBusinessSuccessCode(body.code)) return res;
    const msg = businessMessage(body);
    const codeNum =
      typeof body.code === "number"
        ? body.code
        : Number(body.code) || res.status || 400;
    return Promise.reject(new ApiError(msg, codeNum, body));
  },
  (error: AxiosError<{ message?: string; error?: string; msg?: string }>) => {
    const status = error.response?.status;
    const body = error.response?.data;
    const msg =
      (typeof body === "object" && body !== null && "msg" in body
        ? String((body as { msg?: unknown }).msg)
        : undefined) ??
      (typeof body === "object" && body !== null && "message" in body
        ? body.message
        : undefined) ??
      (typeof body === "object" && body !== null && "error" in body
        ? String((body as { error?: unknown }).error)
        : undefined) ??
      (error.message?.trim() || "请求失败");
    return Promise.reject(new ApiError(String(msg), status, body));
  },
);

export function setApiAuthToken(token: string | null) {
  if (typeof window === "undefined") return;
  if (token) localStorage.setItem(API_TOKEN_STORAGE_KEY, token);
  else localStorage.removeItem(API_TOKEN_STORAGE_KEY);
}

export async function apiPost<T, B = unknown>(
  url: string,
  body?: B,
  config?: AxiosRequestConfig,
): Promise<T> {
  const { data } = await api.post<T>(url, body, config);
  return data;
}

export async function apiPut<T, B = unknown>(
  url: string,
  body?: B,
  config?: AxiosRequestConfig,
): Promise<T> {
  const { data } = await api.put<T>(url, body, config);
  return data;
}

export async function apiPatch<T, B = unknown>(
  url: string,
  body?: B,
  config?: AxiosRequestConfig,
): Promise<T> {
  const { data } = await api.patch<T>(url, body, config);
  return data;
}

export async function apiDelete<T>(
  url: string,
  config?: AxiosRequestConfig,
): Promise<T> {
  const { data } = await api.delete<T>(url, config);
  return data;
}