import axios, { AxiosError, AxiosResponse, CancelTokenSource, InternalAxiosRequestConfig } from 'axios';
import { toast } from 'sonner';
import { showRiskWarningToast } from '@/components/common/risk/risk-warning-toast';
import { apiConfig } from './config';
import {
  ApiErrorBase,
  NetworkError,
  TimeoutError,
  ForbiddenError,
  NotFoundError,
  ServerError,
  ValidationError,
} from './errors';
import { ApiError, ApiResponse } from './types';

/**
 * API 客户端实例
 * 统一处理请求配置、响应解析和错误处理
 */
const apiClient = axios.create({
  baseURL: apiConfig.baseURL,
  timeout: apiConfig.timeout,
  withCredentials: apiConfig.withCredentials,
  headers: {
    'Content-Type': 'application/json',
  },
});

/**
 * 请求取消令牌存储
 */
const cancelTokens = new Map<string, CancelTokenSource>();

/**
 * 请求缓存存储
 * 存储正在进行的请求 Promise，避免重复请求
 */
const pendingRequests = new Map<string, Promise<AxiosResponse<ApiResponse>>>();

const RISK_LEVEL_HEADER = 'x-credit-risk-level';
const RISK_LABELS_HEADER = 'x-credit-risk-labels';
const RISK_ITEMS_HEADER = 'x-credit-risks';
const RISK_BLOCKED_CODE = 'RISK_BLOCKED';
const RISK_BLOCKED_EVENT = 'credit-risk-blocked';

interface RiskItem {
  label: string;
  value?: string;
  desc?: string;
}

interface RiskInfo {
  risk_level: string;
  risk_labels: string[];
  risks: RiskItem[];
}

function decodeBase64JSON(value?: string): unknown {
  if (!value || typeof window === 'undefined') return [];

  try {
    const binary = window.atob(value);
    const bytes = Uint8Array.from(binary, char => char.charCodeAt(0));
    const json = new TextDecoder().decode(bytes);
    return JSON.parse(json);
  } catch {
    return [];
  }
}

function normalizeRiskItems(value: unknown): RiskItem[] {
  if (!Array.isArray(value)) return [];

  return value.reduce<RiskItem[]>((items, item) => {
    if (!item || typeof item !== 'object') return items;

    const label = 'label' in item ? (item as { label?: unknown }).label : undefined;
    if (typeof label !== 'string' || !label.trim()) return items;

    const value = 'value' in item ? (item as { value?: unknown }).value : undefined;
    const desc = 'desc' in item ? (item as { desc?: unknown }).desc : undefined;
    items.push({
      label: label.trim(),
      value: typeof value === 'string' ? value.trim() : undefined,
      desc: typeof desc === 'string' ? desc.trim() : undefined,
    });

    return items;
  }, []);
}

function normalizeRiskLabels(value: unknown): string[] {
  return Array.isArray(value) ? value.filter((label): label is string => typeof label === 'string' && !!label.trim()).map(label => label.trim()) : [];
}

function riskLabelsFromItems(items: RiskItem[]): string[] {
  return items.map(item => item.label).filter(Boolean);
}

function riskInfoFromHeaders(headers: AxiosResponse['headers']): RiskInfo | null {
  const riskLevel = headers[RISK_LEVEL_HEADER];
  if (typeof riskLevel !== 'string' || !riskLevel) return null;

  const riskLabelsHeader = headers[RISK_LABELS_HEADER];
  const riskItemsHeader = headers[RISK_ITEMS_HEADER];
  const risks = typeof riskItemsHeader === 'string' ? normalizeRiskItems(decodeBase64JSON(riskItemsHeader)) : [];
  const labels = typeof riskLabelsHeader === 'string' ? normalizeRiskLabels(decodeBase64JSON(riskLabelsHeader)) : riskLabelsFromItems(risks);

  return {
    risk_level: riskLevel,
    risk_labels: labels,
    risks,
  };
}

function riskInfoFromDetails(details: unknown): RiskInfo | null {
  if (!details || typeof details !== 'object') return null;

  const riskLevel = 'risk_level' in details ? (details as { risk_level?: unknown }).risk_level : undefined;
  const riskLabels = 'risk_labels' in details ? (details as { risk_labels?: unknown }).risk_labels : undefined;
  const riskItems = 'risks' in details ? (details as { risks?: unknown }).risks : undefined;
  if (typeof riskLevel !== 'string' || !riskLevel) return null;

  const risks = normalizeRiskItems(riskItems);
  const labels = normalizeRiskLabels(riskLabels);

  return {
    risk_level: riskLevel,
    risk_labels: labels.length ? labels : riskLabelsFromItems(risks),
    risks,
  };
}

function showRiskWarning(riskInfo: RiskInfo): void {
  showRiskWarningToast(riskInfo);
}

function showRiskBlockedDialog(riskInfo: RiskInfo): void {
  if (typeof window === 'undefined') return;
  window.dispatchEvent(new CustomEvent<RiskInfo>(RISK_BLOCKED_EVENT, { detail: riskInfo }));
}

/**
 * 生成请求的唯一键
 * 包含方法、URL 和请求数据的哈希，确保不同参数的请求不会被误取消
 */
function getRequestKey(config: { method?: string; url?: string; data?: unknown }): string {
  const baseKey = `${ config.method?.toUpperCase() }_${ config.url }`;

  /* 序列化加入键中 */
  if (config.data) {
    try {
      const dataHash = JSON.stringify(config.data);
      return `${ baseKey }_${ dataHash }`;
    } catch {
      // 失败使用基础键
      return baseKey;
    }
  }

  return baseKey;
}

/**
 * 请求拦截器
 * 添加取消令牌和其他配置
 */
apiClient.interceptors.request.use(
  (config: InternalAxiosRequestConfig) => {
    const requestKey = getRequestKey(config);
    const source = axios.CancelToken.source();
    config.cancelToken = source.token;
    cancelTokens.set(requestKey, source);

    return config;
  },
  (error: unknown) => Promise.reject(error),
);

/**
 * 直接启动登录流程
 * @param currentPath - 当前路径，用于登录成功后重定向回来
 */
function initiateLogin(currentPath: string): Promise<never> {
  if (!currentPath.startsWith('/login') && !currentPath.startsWith('/callback')) {
    if (typeof window !== 'undefined') {
      sessionStorage.setItem('redirect_after_login', currentPath);
      const loginUrl = new URL('/login', window.location.origin);
      loginUrl.searchParams.set('callbackUrl', currentPath);
      window.location.href = loginUrl.toString();
    }
  }

  return new Promise<never>(() => { });
}

/**
 * 响应拦截器
 * 处理 API 响应和统一错误处理
 */
apiClient.interceptors.response.use(
  (response: AxiosResponse<ApiResponse>) => {
    const requestKey = getRequestKey(response.config);
    cancelTokens.delete(requestKey);
    pendingRequests.delete(requestKey);

    const riskInfo = riskInfoFromHeaders(response.headers);
    if (riskInfo) {
      showRiskWarning(riskInfo);
    }

    return response;
  },
  (error: AxiosError<ApiError>) => {
    if (error.config) {
      const requestKey = getRequestKey(error.config);
      cancelTokens.delete(requestKey);
      pendingRequests.delete(requestKey);
    }

    /* 请求被取消时静默处理 */
    if (axios.isCancel(error)) {
      const cancelError = new Error(error.message || '请求已被取消') as Error & { __CANCEL__?: boolean };
      cancelError.__CANCEL__ = true;
      return Promise.reject(cancelError);
    }

    /* 401 未授权错误 */
    if (error.response?.status === 401) {
      return initiateLogin(window.location.pathname + window.location.search);
    }

    /* 403 权限不足错误 */
    if (error.response?.status === 403) {
      if (error.response.data?.error_code === RISK_BLOCKED_CODE) {
        const riskInfo = riskInfoFromDetails(error.response.data.details) || riskInfoFromHeaders(error.response.headers);
        if (riskInfo) {
          showRiskBlockedDialog(riskInfo);
        }

        return Promise.reject(
          new ForbiddenError(error.response.data?.error_msg || '账号存在风险', RISK_BLOCKED_CODE, error.response.data?.details),
        );
      }

      return Promise.reject(
        new ForbiddenError(error.response.data?.error_msg || '权限不足，请过盾后重试', error.response.data?.error_code, error.response.data?.details),
      );
    }

    /* 404 资源未找到错误 */
    if (error.response?.status === 404) {
      return Promise.reject(
        new NotFoundError(error.response.data?.error_msg || '请求的资源不存在'),
      );
    }

    /* 400 验证错误 */
    if (error.response?.status === 400) {
      return Promise.reject(
        new ValidationError(
          error.response.data?.error_msg || '请求参数验证失败',
          error.response.data?.details,
        ),
      );
    }

    /* 429 速率限制错误 */
    if (error.response?.status === 429) {
      const retryAfter = error.response.headers?.['retry-after'];
      const message = error.response.data?.error_msg ||
        `请求过于频繁，请 ${ retryAfter || '稍后' } 秒后重试`;

      toast.error('请求频率限制', {
        description: message,
        id: 'rate-limit-error',
      });

      return Promise.reject(
        new ApiErrorBase(message, 'RATE_LIMITED', 429),
      );
    }

    /* 5xx 服务器错误 */
    if (error.response && error.response.status >= 500) {
      return Promise.reject(
        new ServerError(
          error.response.data?.error_msg || '服务器内部错误，请稍后重试',
          error.response.status,
        ),
      );
    }

    /* 网络超时错误 */
    if (error.code === 'ECONNABORTED' || error.code === 'ETIMEDOUT') {
      return Promise.reject(new TimeoutError());
    }

    /* 网络连接错误（ECONNREFUSED, ERR_NETWORK 等） */
    if (
      !error.response ||
      error.code === 'ECONNREFUSED' ||
      error.code === 'ERR_NETWORK' ||
      error.message?.includes('Network Error') ||
      error.message?.includes('Failed to fetch')
    ) {
      return Promise.reject(
        new NetworkError('无法连接到服务器，请确认后端服务已启动'),
      );
    }

    /* 其他后端返回的错误 */
    if (error.response?.data?.error_msg) {
      return Promise.reject(
        new ApiErrorBase(
          error.response.data.error_msg,
          error.response.data.error_code,
          error.response.status,
          error.response.data.details,
        ),
      );
    }

    /* 兜底错误 */
    return Promise.reject(
      new ApiErrorBase(error.message || '网络请求失败'),
    );
  },
);

/**
 * 取消指定请求
 * @param method - 请求方法
 * @param url - 请求 URL
 */
export function cancelRequest(method: string, url: string): void {
  const requestKey = `${ method.toUpperCase() }_${ url }`;
  const source = cancelTokens.get(requestKey);
  if (source) {
    source.cancel('请求已被手动取消');
    cancelTokens.delete(requestKey);
  }
}

/**
 * 取消所有请求
 */
export function cancelAllRequests(): void {
  cancelTokens.forEach((source) => {
    source.cancel('所有请求已被取消');
  });
  cancelTokens.clear();
}

/**
 * 创建带有请求去重功能的请求方法
 * @param method HTTP 方法名
 * @param hasBody 是否包含请求体
 */
function createRequestMethod(
  method: 'get' | 'post' | 'put' | 'patch' | 'delete',
  hasBody: boolean
) {
  if (hasBody) {
    return <T = ApiResponse>(url: string, data?: unknown, config?: InternalAxiosRequestConfig) => {
      const requestKey = getRequestKey({ method: method.toUpperCase(), url, data });

      if (pendingRequests.has(requestKey)) {
        return pendingRequests.get(requestKey) as Promise<AxiosResponse<T>>;
      }

      const promise = apiClient[method]<T>(url, data, config);
      pendingRequests.set(requestKey, promise as Promise<AxiosResponse<ApiResponse>>);

      promise.finally(() => {
        pendingRequests.delete(requestKey);
      });

      return promise;
    };
  }

  return <T = ApiResponse>(url: string, config?: InternalAxiosRequestConfig) => {
    const requestKey = getRequestKey({ method: method.toUpperCase(), url, data: config?.params });

    if (pendingRequests.has(requestKey)) {
      return pendingRequests.get(requestKey) as Promise<AxiosResponse<T>>;
    }

    const promise = apiClient[method]<T>(url, config);
    pendingRequests.set(requestKey, promise as Promise<AxiosResponse<ApiResponse>>);

    promise.finally(() => {
      pendingRequests.delete(requestKey);
    });

    return promise;
  };
}

/**
 * 包装的 API 客户端
 * 在原有 axios 实例基础上添加请求缓存功能
 */
const wrappedApiClient = {
  get: createRequestMethod('get', false) as <T = ApiResponse>(url: string, config?: InternalAxiosRequestConfig) => Promise<AxiosResponse<T>>,
  post: createRequestMethod('post', true) as <T = ApiResponse>(url: string, data?: unknown, config?: InternalAxiosRequestConfig) => Promise<AxiosResponse<T>>,
  put: createRequestMethod('put', true) as <T = ApiResponse>(url: string, data?: unknown, config?: InternalAxiosRequestConfig) => Promise<AxiosResponse<T>>,
  patch: createRequestMethod('patch', true) as <T = ApiResponse>(url: string, data?: unknown, config?: InternalAxiosRequestConfig) => Promise<AxiosResponse<T>>,
  delete: createRequestMethod('delete', false) as <T = ApiResponse>(url: string, config?: InternalAxiosRequestConfig) => Promise<AxiosResponse<T>>,
};

export default wrappedApiClient;