import fs from "node:fs/promises";
import {constants} from "node:fs";
import path from "path";
import htmlMinifier from "html-minifier-terser";
import esbuild from "esbuild";

const parseComponent = async (file)=>{
    const dir = path.dirname(file);
    let data = {};
    if(path.extname(file) === ".neovan"){
        data = await getNeovanData(file);
    }else{
        data = await parseHtml(file);
    }
    return await createBundle(data);
}

const getNeovanData = async (index)=>{
    const neovan = await fs.readFile(index, "utf-8");
    const parentPath = path.dirname(index);
    
    const html = neovan.slice(neovan.indexOf("<contents>") + 10, neovan.indexOf("</contents>"));
    let css = "";
    let js = "";
    const cssIndex = neovan.indexOf("<style>");
    if(cssIndex >= 0){
        css = neovan.slice(cssIndex + 7, neovan.indexOf("</style>"));
    }
    const jsIndex = neovan.indexOf("<script>")
    if(jsIndex >= 0){
        js = neovan.slice(jsIndex + 8, neovan.indexOf("</script>"));
    }

    const cssFile = path.join(parentPath, `tmp/${path.basename(index, ".neovan")}.css`);
    const jsFile = path.join(parentPath, `tmp/${path.basename(index, ".neovan")}.js`);

    await fs.mkdir(path.join(parentPath, "tmp/"));

    await Promise.all([
        fs.writeFile(cssFile, css),
        fs.writeFile(jsFile, js)
    ]);

    return {
        html: html,
        css: cssFile,
        js: jsFile,
        dir: parentPath
    };
}

const parseHtml = async (index)=>{
    const parentPath = path.dirname(index);
    const basename = path.basename(index, ".html");

    const cssPath = path.join(parentPath, `${basename}.css`);
    const jsPath = path.join(parentPath, `${basename}.js`);

    const proms = [
        fs.readFile(index, "utf-8"),
        fs.access(cssPath, constants.F_OK),
        fs.access(jsPath, constants.F_OK)
    ];

    let [html, css, js] = await Promise.allSettled(proms);

    return {
        html: html.value,
        css: css.status === "fulfilled" ? cssPath : null,
        js: js.status === "fulfilled" ? jsPath : null,
        dir: parentPath
    };
}

const createBundle = async (data)=>{
    const entryPoints = [];
    if(data.css) entryPoints.push(data.css);
    if(data.js) entryPoints.push(data.js);

    data.html = await addComponents(data.html, data.dir);

    const esbuildProm = esbuild.build({
        entryPoints: entryPoints,
        bundle: true,
        minify: true,
        write: false,
        outdir: "/"
    });
    const htmlProm = htmlMinifier.minify(data.html, {
        collapseBooleanAttributes: true,
        collapseInlineTagWhitespace: true,
        collapseWhitespace: true,
        decodeEntities: true,
        html5: true,
        includeAutoGeneratedTags: false,
        noNewlinesBeforeTagClose: true,
        removeComments: true,
        useShortDoctype: true
    });

    const [buildData, html] = await Promise.all([esbuildProm, htmlProm]);

    const comps = {html: html};
    for(let i = 0; i < buildData.outputFiles.length; i++){
        const ext = path.extname(buildData.outputFiles[i].path).replace(".", "");
        comps[ext] = buildData.outputFiles[i].text;
    }

    return mergeFiles(comps);
}

const mergeFiles = (comps)=>{
    let cssIndex = comps.html.indexOf("</head>");
    cssIndex = cssIndex < 0 ? 0 : cssIndex;
    comps.css = comps.css ? `<style>${comps.css}</style>` : "";
    const html = `${comps.html.slice(0, cssIndex)}${comps.css}${comps.html.slice(cssIndex)}`;

    let jsIndex = html.indexOf("</body>");
    jsIndex = jsIndex < 0 ? html.length : jsIndex;
    comps.js = comps.js ? `<script>${comps.js}</script>` : "";
    return `${html.slice(0, jsIndex)}${comps.js}${html.slice(jsIndex)}`;
}

const addComponents = async (html, dir)=>{
    let importStart = 0;
    for(let i = 0; i < html.length; i++){
        if(html[i] === "@"){
            if(html[i-1] === "<"){
                importStart = i + 1;
            }else if(html[i+1] === ">"){
                const importString = html.substring(importStart, i).trim();
                const comp = await parseComponent(path.join(dir, importString))
                html = html.slice(0, importStart - 2) + comp + html.slice(i+2);
            }
        }
    }
    return html;
}

export default parseComponent;