import { STATUS_CODE } from "@common/const/const";

const urlWhiteList = [/api.example.com\/users/, /api.example2.com\/products/]; // 正则白名单

function shouldNotTransform(url:string) {
    return urlWhiteList.some(regex => regex.test(url));
}

function toCamel(s:string) {
    return s.replace(/(_\w)/g, k => k[1].toUpperCase());
}

function toSnake(s:string) {
    return s.replace(/([A-Z])/g, '_$1').toLowerCase();
}

function isObject(obj:unknown) {
    return obj === Object(obj) && !Array.isArray(obj) && typeof obj !== 'function';
}

// 将对象的键从下划线转为驼峰
function keysToCamel(o:unknown,transformKeys:string[]):unknown {
    if (isObject(o)) {
        const n:{[k:string]:unknown}  = {};
        Object.keys(o as object).forEach(k => {
            const newKey = transformKeys.includes(k) ? toCamel(k) : k;
            n[newKey] = keysToCamel((o as {[k:string]:unknown})[k],transformKeys);
        });
        return n;
    }
    else if (Array.isArray(o)) {
        return o.map(i => keysToCamel(i,transformKeys));
    }
    return o;
}

// 将对象的键从驼峰转为下划线
function keysToSnake(o:unknown,transformKeys:string[]):unknown {
    if (isObject(o)) {
        const n:{[k:string]:unknown} = {};
        Object.keys(o as object).forEach(k => {
            const newKey = transformKeys.includes(k) ? toSnake(k) : k;
            n[newKey] = keysToSnake((o as {[k:string]:unknown})[k],transformKeys);
        });
        return n;
    }else if (Array.isArray(o)) {
        return o.map(i => keysToSnake(i,transformKeys));
    }
    return o;
}

// 将查询字符串的键从驼峰转换为下划线
function convertQueryParamsToSnake(
    params: { [k: string]: unknown },
    shouldTransformKeys: boolean,
    transformKeys: string[]
  ) {
    const newParams = new URLSearchParams();
  
    for (const key in params) {
      if (shouldTransformKeys && transformKeys?.includes(key)) {
        const newKey = toSnake(key);
        const value = params[key];
        appendParam(newParams, newKey, value as Array<string> | string);
      } else {
        appendParam(newParams, key, params[key] as Array<string> | string);
      }
    }
  
    return newParams;
  }
  
  function appendParam(params: URLSearchParams, key: string, value: Array<string> | string) {
    if (value !== undefined && value !== null) {
      if (Array.isArray(value)) {
        value.forEach((item) => params.append(key, item));
      } else {
        params.append(key, value as string);
      }
    }
  }


function isJsonHttp(headers: Headers | {[k:string]:string}): boolean {
    const contentType = headers instanceof Headers ? headers.get('Content-Type') : headers['Content-Type'];
    return contentType?.includes('application/json') ?? false;
}

const trimStringValuesInObject = (obj: unknown): unknown => {
    if (typeof obj === 'string') {
        return (obj as string).trim();
    } 
    if (Array.isArray(obj)) {
        return obj.map(trimStringValuesInObject);
    } 
    if (typeof obj === 'object' && obj !== null) {
        return Object.fromEntries(
            Object.entries(obj).map(([key, value]) => [key, trimStringValuesInObject(value)])
        );
    } 
    return obj;
}

const processQueryParams = (url: string, options: EoRequest, shouldTransformKeys: boolean) => {
    if (options.eoParams) {
        const cleanParams = Object.fromEntries(
            Object.entries(options.eoParams)
                .filter(([, value]) => value !== undefined)
                .map(([key, value]) => [key, typeof value === 'string' ? value.trim() : value])
        );
        const queryParams = convertQueryParamsToSnake(cleanParams, shouldTransformKeys, options.eoTransformKeys as string[]);
        const queryString = queryParams.toString();
        url += (url.includes('?') ? '&' : '?') + queryString;  // 添加查询字符串到URL
    }
    return url;
}


const processRequestBody = (options: EoRequest, headers: EoHeaders, shouldTransformKeys: boolean) => {
    let newBody:{[k:string]:unknown}|undefined
    if (shouldTransformKeys && isJsonHttp(headers) && options.eoBody) {
        newBody = keysToSnake(options.eoBody, options.eoTransformKeys as string[]) as {[k:string]:unknown};
    }

    if (isJsonHttp(headers) && (newBody || options.eoBody)) {
        options.body = JSON.stringify(trimStringValuesInObject(newBody || options.eoBody));
    }
    return options.body;
}

const DEFAULT_HEADERS = {
    'Content-Type': 'application/json',
    namespace:'default'
};

type EoRequest = RequestInit & {eoParams?:{[k:string]:unknown},eoTransformKeys?:string[],eoApiPrefix?:string,eoBody?:{[k:string]:unknown}|Array<unknown>|string}

type EoHeaders = Headers  | {[k:string]:string}

export function useFetch(){
    function fetchData<T>(url:string, options: EoRequest ) {
        // 合并传入的headers与默认headers
        const headers = { ...(options.body ?  {}:DEFAULT_HEADERS), ...options.headers };

        // 检查是否需要转换键
        const shouldTransformKeys = !shouldNotTransform(url) && options?.eoTransformKeys && options?.eoTransformKeys?.length > 0;
        
        // 处理URL查询参数
        url = processQueryParams(url, options, !!shouldTransformKeys);

        // 处理请求体, 当请求头为json时，fetch的body应当是json字符串
        options.body = processRequestBody(options, headers as EoHeaders, !!shouldTransformKeys);
        // 全局请求前拦截
        const finalOptions = {
            ...(options || {}),
            headers: {
                ...headers
                // Authorization: 'Bearer your-token', // 示例：添加统一的Token认证
            },
        };

        return fetch(`${options?.eoApiPrefix === undefined? '/api/v1/':options.eoApiPrefix}${url}`, finalOptions)
            .then(async response => {
                if (response.status === STATUS_CODE.UNANTHORIZED) {
                    // 处理401未登录的逻辑，比如跳转到登录页面或弹出登录框
                    console.log('Unauthorized access, redirecting to login...');
                    window.location.href = '/login' // 示例：重定向到登录
                    
                    return; // 返回或抛出错误，确保不继续执行后续的响应处理
                }

                if (response.status === STATUS_CODE.FORBIDDEN) {
                    // 处理403无权限，比如跳转到登录页面或弹出登录框
                    console.log('Unauthorized access, redirecting to login...');
                    // window.location.href = '/login' // 示例：重定向到登录
                    
                    return; // 返回或抛出错误，确保不继续执行后续的响应处理
                }

                if (!response.ok) {
                    throw new Error(`HTTP error! status: ${response.status}`);
                }

                // 如果响应体为JSON且指定了转换键，则转换响应数据
                if ( isJsonHttp(response.headers)) {
                    const data = await response.json();
                    return shouldTransformKeys ?  keysToCamel(data,options.eoTransformKeys as string[]) as T:data
                }

                return response;
            })
            .catch(error => {
                // 全局错误处理
                console.error('Global error handler:', error);
                throw error; // 可选择重新抛出错误，让组件处理或显示错误信息
            });
    }
    return { fetchData }

}