/**
 *****************************************
 * Created by edonet@163.com
 * Created on 2020-07-04 21:01:05
 *****************************************
 */
'use strict';


/**
 *****************************************
 * 加载依赖
 *****************************************
 */
import * as fs from 'fs';
import * as transform from './transform';
import { json } from './helpers/json';


/**
 *****************************************
 * 处理函数
 *****************************************
 */
interface Handler {
    (script: Script, filename: string): void;
}


/**
 *****************************************
 * 脚本对象
 *****************************************
 */
export interface Script<T = unknown> {

    /** 模块ID */
    id: string;

    /** 文件名 */
    filename: string;

    /** 子模块 */
    children: Script[];

    /** 抛出接口 */
    exports: T;

    /** 源码 */
    _code?: string;

    /** 加载文件 */
    load(filename: string): void;

    /** 导入模块 */
    require(id: string): unknown;

    /** 编译模块 */
    _compile(code: string, filename: string): void;
}


/**
 *****************************************
 * 脚本对象
 *****************************************
 */
const Script = require('module') as {

    /** 缓存对象 */
    _cache: Record<string, Script>;

    /** 扩展对象 */
    _extensions: Record<string, void | Handler>;

    /** 初始化对象 */
    new <T>(filename: string, script: Script): Script<T>;
};


/**
 *****************************************
 * 模块加载函数
 *****************************************
 */
const moduleExtensions = Script._extensions;
const moduleImportHandler = Script.prototype.require;


/**
 *****************************************
 * 脚本转换函数
 *****************************************
 */
type TransformHandler = (filename: string, code: string) => string;


/**
 *****************************************
 * 生成脚本解析函数
 *****************************************
 */
function makeCompileHandler(transformScript: TransformHandler): Handler {
    return function compile(script, filename) {
        const code = script._code ?? fs.readFileSync(filename, 'utf8');

        // 转换代码
        const source = transformScript(filename, code);

        // 更新加载函数
        script.require = dynamicImportScript;

        // 编译内容
        script._compile(transformScript(filename, source), filename);
    };
}


/**
 *****************************************
 * 模块解析器
 *****************************************
 */
const moduleCompiler = {
    js: makeCompileHandler(transform.transformJavaScript),
    ts: makeCompileHandler(transform.transformTypeScript),
    jsx: makeCompileHandler(transform.transformJSXScript),
    tsx: makeCompileHandler(transform.transformTSXScript),
    json: json,
};


/**
 *****************************************
 * 执行函数
 *****************************************
 */
function invoke<T>(handler: () => T): T {
    const cached = { ...Script._extensions };

    // 更新处理函数
    moduleExtensions['.ts'] = moduleCompiler.ts;
    moduleExtensions['.js'] = moduleCompiler.js;
    moduleExtensions['.mjs'] = moduleCompiler.js;
    moduleExtensions['.jsx'] = moduleCompiler.jsx;
    moduleExtensions['.tsx'] = moduleCompiler.tsx;
    moduleExtensions['.json'] = moduleCompiler.json;

    // 执行函数
    const result = handler();

    // 恢复处理函数
    moduleExtensions['.ts'] = cached['.ts'];
    moduleExtensions['.js'] = cached['.js'];
    moduleExtensions['.mjs'] = cached['.mjs'];
    moduleExtensions['.jsx'] = cached['.jsx'];
    moduleExtensions['.tsx'] = cached['.tsx'];
    moduleExtensions['.json'] = cached['.json'];

    // 返回结果
    return result;
}


/**
 *****************************************
 * 动态载入脚本
 *****************************************
 */
function dynamicImportScript<T>(this: Script, id: string): T {
    return invoke<T>(() => moduleImportHandler.call(this, id));
}


/**
 *****************************************
 * 加载脚本
 *****************************************
 */
export function load<T>(filename: string, code: string): Script<T> {
    const script = new Script<T>(filename, module as unknown as Script);

    // 设置代码
    script._code = code;

    // 加载文件
    invoke(() => script.load(filename));

    // 返回结果
    return script;
}


/**
 *****************************************
 * 清除缓存
 *****************************************
 */
export function clear(file: string): string {

    // 清除缓存
    if (Script._cache[file]) {
        Script._cache[file] = undefined as unknown as Script;
    }

    // 返回文件地址
    return file;
}


/**
 *****************************************
 * 刷新脚本依赖
 *****************************************
 */
export function refresh(script: Script, files: string[]): void {
    const refreshAll = !files.length;

    // 清除子脚本
    function refreshChildren(children: Script[]): void | Script[] {
        if (children && children.length) {
            return children.filter(refreshScript);
        }
    }

    // 清除函数
    function refreshScript(script: Script): void | boolean {
        const file = script.filename;
        const children = refreshChildren(script.children);

        // 清除当前模块
        if (refreshAll || files.includes(file) || (children && children.length)) {
            return !!clear(file);
        }
    }

    // 清除缓存
    script.children && script.children.forEach(refreshScript);
}


/**
 *****************************************
 * 解析依赖
 *****************************************
 */
export function findDependencies(script: Script): string[] {
    const cached = new Set<Script>();
    const deps: string[] = [];

    // 遍历函数
    function each(list: Script[]): string[] {

        // 遍历子模块
        if (list && list.length) {
            list.forEach(script => cached.has(script) || add(script));
        }

        // 返回依赖列表
        return deps;
    }

    // 添加依赖
    function add(script: Script): void {
        const filename = script.filename;

        // 添加缓存
        cached.add(script);

        // 过滤三方模块
        if (filename.indexOf('node_modules') === -1) {

            // 添加文件
            deps.push(filename);

            // 处理子模块
            each(script.children);
        }
    }

    // 遍历子节点
    return each(script.children);
}