/************************************************************************
 * Copyright (c) 2023 sunking framework
 * Author    : Shao
 * Mail      : yi-shaoye@163.com
 * Date      : 2021-10-28
 * Use       : 加载模块
 ************************************************************************/
import * as fs from 'fs';
import myLogger from '@wingyi8/sk-logger';
const logger = myLogger.getLogger('sunking/util/loader');


const httpMethodRegex = /\.(connect|delete|get|head|options|patch|post|put|trace)/;

/**
 * 加载路径下的模块.
 * @param {String} mpath 模块的路径 加载路径下的所有文件，如果路径包含子目录，则递归加载。
 * @param {String} prefix 默认路由前缀。
 * @param {String} method 默认通讯方式。
 */
export function load(mpath: string, prefix: string = "/", method: string = 'all', callback: (handler: ServerEventHandler, index: number) => void) {
    if (!mpath) {
        logger.error('加载路由模块为空');
        return;
    }
    let path = `${process.cwd()}/${mpath}`;
    try {
        path = fs.realpathSync(path);
    } catch (err: any) {
        logger.error(err.stack);
        return;
    }
    if (!fs.statSync(path).isDirectory()) {
        logger.error(`${path} 不是文件夹.`);
        return;
    }
    loadPath(path, prefix, method, callback, 0);
}

/**
 * 加载文件
 * @param dir 文件路径
 */
function loadPath(dir: string, parent: string, method: string, callback: (handler: ServerEventHandler, index: number) => void, total: number) {
    let files = fs.readdirSync(dir);
    if (files.length === 0) {
        logger.error(`${dir} 目录为空`);
        return 0;
    }
    if (dir.charAt(dir.length - 1) !== '/') {
        dir += '/';
    }

    let fp: string, fn: string, m, count = 0;
    for (let i = 0, l = files.length; i < l; ++i) {
        fn = files[i];
        fp = dir + fn;
        // 遍历子文件夹
        if (fs.statSync(fp).isDirectory()) {
            count += loadPath(fp, `${parent}/${fn}`, method, callback, total + count);
            continue;
        }
        // 只加载 js/ts 文件
        if (!checkFileType(fn, 'ts,mjs,js,cjs')) {
            continue;
        }
        try {
            m = require(fp);
        } catch (err: any) {
            logger.error(err.stack);
            continue;
        }
        if (!m) {
            continue;
        }
        // 过滤文件名
        let fileName = fn
            .replace(/\.[A-Za-z]+$/, "")
            .replace(/\[\.{3}]/g, "**")
            .replace(/\[\.{3}(\w+)]/g, "**:$1")
            .replace(/\[(\w+)]/g, ":$1");

        // 获取通讯方式类型
        let curMethod = method;
        const methodMatch = fileName.match(httpMethodRegex);
        if (methodMatch) {
            fileName = fileName.slice(0, Math.max(0, methodMatch.index));
            curMethod = methodMatch[1];
        }
        // 过滤路由
        let url = `${parent}/${fileName}`
        url = url.replace(/\/index$/, "").replace(/\/\//, "/") || "/";
        // 获取描述
        let description = m['description'] || '';
        // 获取处理函数
        let cls = m['default'];
        if (!cls) {
            logger.error(`获取路由处理函数为空 ${url}`);
            continue;
        }
        callback({
            'url': url,
            'handler': cls,
            'method': curMethod,
            'description': description
        }, total + count);
        count++
    }
    return count;
}
/**
* 检测文件后缀
* @param fn {String} 文件名
* @param patterns {String} 后缀名 比如 .js .ts 等
*/
function checkFileType(fn: string, patterns: string) {
    let ary = patterns.split(',');
    let res = false;
    for (let n in ary) {
        let suffix = ary[n];
        if (suffix.charAt(0) !== '.') {
            suffix = '.' + suffix;
        }
        let str = fn.substring(fn.length - suffix.length).toLowerCase();
        if (fn.length <= suffix.length) {
            return false;
        }
        suffix = suffix.toLowerCase();
        if (str === suffix) {
            res = true;
            break;
        }
    }
    return res;
}

/**
 * 服务器路由处理
 */
export interface ServerEventHandler {
    /**
     * 路由
     */
    url: string;
    /**
     * 事件处理函数
     */
    handler: Function;
    /**
     * 路由器方法
     */
    method: string;
    /**
     * 描述
     */
    description: string;
}