const fs = require("fs")
const path = require("path")
const uglify = require("uglify-js")
const CleanCSS = require("clean-css")
const brotli = require('brotli');
const base122 = require("./base122")

/** 一些配置参数
 * - [注意] 路径问题.start脚本与web-mobile同层级,因此相对路径需要带上web-mobile;cocos在调用资源时没有web-mobile,需要在最后去掉
 */
const C = {
    BASE_PATH: "web-mobile",            // web-mobile包基础路径
    RES_PATH: "web-mobile/assets",         // web-mobile包下的res路径
    RES_BASE64_EXTNAME_SET: new Set([       // 需要使用base64编码的资源后缀(根据项目自行扩充)
        ".png", ".jpg", ".webp", ".mp3",
    ]),
    INPUT_LOADER_STARTER_JS: "single-html/loader-and-starter.js",          
    OUTPUT_RES_JS: "./web-mobile/asset-map.js",           // 输出文件asset-map.js
    OUTPUT_LOADER_STARTER_JS: "./web-mobile/loader-and-starter.js",          
    OUTPUT_INDEX_HTML: "dist/index.html",   // 输出文件index.html的路径
    INPUT_HTML_FILE: "./web-mobile/index.html",
}

/**
 * 读取文件内容
 * - 特定后缀返回base64编码后字符串,否则直接返回文件内容字符串
 * @param filepath
 */
function get_file_content(filepath) {
    let file = fs.readFileSync(filepath)
    return C.RES_BASE64_EXTNAME_SET.has(path.extname(filepath)) ? file.toString("base64") : file.toString()
}

/**
 * 获取路径下的所有子文件路径(深度遍历)
 * @param filepath
 */
function get_all_child_file(filepath) {
    let children = [filepath]
    for (; ;) {
        // 如果都是file类型的,则跳出循环
        if (children.every(v => fs.statSync(v).isFile())) { break }
        // 如果至少有1个directroy类型,则删除这一项,并加入其子项
        children.forEach((child, i) => {
            if (fs.statSync(child).isDirectory()) {
                delete children[i]
                let child_children = fs.readdirSync(child).map(v => `${child}/${v}`)
                children.push(...child_children)
            }
        })
    }
    return children
}

/**
 * 将所有res路径下的资源转化为res.js
 * - 存储方式为:res-url(注意是相对的),res文件内容字符串或编码
 */
function write_resjs() {
    // 读取并写入到一个对象中
    let res_object = {}
    get_all_child_file(C.RES_PATH).forEach(path => {
        // 注意,存储时删除BASE_PATH前置
        let store_path = path.replace(new RegExp(`^${C.BASE_PATH}/`), "")
        res_object[store_path] = get_file_content(path)
    })
    // 写入文件
    var compressedAssetsJs = Buffer.from(base122.encode(brotli.compress(new TextEncoder().encode(`window.assetMap=${JSON.stringify(res_object)}`))), 'utf-8')
    fs.writeFileSync(C.OUTPUT_RES_JS, `eval(new TextDecoder().decode(window.unbrotli(base122ToArrayBuffer("${compressedAssetsJs}"))))`)
}

/** 将js文件转化为html文件内容(包括压缩过程) */
function get_html_code_by_js_file(js_filepath) {
    let js = get_file_content(js_filepath)
    let min_js = uglify.minify(js).code
    return `<script type="text/javascript" charset="utf-8">${min_js}`
}

/** 将css文件转化为html文件内容(包括压缩过程) */
function get_html_code_by_css_file(css_filepath) {
    let css = get_file_content(css_filepath)
    let min_css = new CleanCSS().minify(css).styles
    return `<style>${min_css}</style>`
}

function replaceRelativeCss(html) {
    var reg = /\<link rel\="stylesheet" type\="text\/css" href\="(.+)"\/\>/g
    var matchedCsss = html.match(reg);
    
    matchedCsss.forEach((script) => {
      var CssPath = reg.exec(script)[1];
      html = html.replace(script, () => get_html_code_by_css_file(path.resolve(C.BASE_PATH, CssPath)))
    });
  
    return html;
  }

function replaceRelativeScript(html) {
    var matchedScripts = html.match(/\<script src\="(.+)"\>/g);
    matchedScripts.forEach((script) => {
      var reg = /(\<script src\=")(.+\.js)(".*>)/g;
      var jsPath = reg.exec(script)[2];
      console.log("写入", jsPath)
      html = html.replace(script, () => get_html_code_by_js_file(path.resolve(C.BASE_PATH, jsPath)))
    });
  
    return html;
  }

/** 执行任务 */
function do_task() {
    // 前置:将res资源写成res.js
    console.time("写入res")
    write_resjs()
    console.timeEnd("写入res")

    fs.writeFileSync(C.OUTPUT_LOADER_STARTER_JS, get_file_content(C.INPUT_LOADER_STARTER_JS))

    let html = get_file_content(C.INPUT_HTML_FILE)

    console.time("替换js")
    html = replaceRelativeScript(html)
    html = replaceRelativeCss(html)
    console.timeEnd("替换js")

    // 写入文件并提示成功
    console.time("输出html文件")
    fs.writeFileSync(C.OUTPUT_INDEX_HTML, html)
    console.timeEnd("输出html文件")
}

// 导出
module.exports = do_task