x/patchers/b2spatch.mjs

/**
 * Script to convert a BemaniPatcher HTML to a spice2x patch JSON.
 * 
 * Usage:
 * - node b2spatch.js <patcher URL | local patcher HTML> <gameCode>
 */

import vm from "vm";
import * as cheerio from "cheerio";
import { readFileSync, writeFileSync } from "fs";
import path from "path";

/**
 * 
 * @param {number[]} bytes 
 */
function bytesToHex(bytes) {
    return bytes.reduce((acc, c) => acc + c.toString(16).padStart(2, "0").toUpperCase(), "");
}

/**
 * Parse a BemaniPatcher HTML for patches.
 * @param {string} contents
 */
function parsePatcherHtml(filename, contents) {
    const $ = cheerio.load(contents);

    let script = "";

    for (const element of $("script").get()) {
        const code = $(element).html();

        if (!code.includes("new Patcher")) {
            continue;
        }

        script += code;
        script += "\n";
    }

    if (script.length === 0) {
        console.warn(`Failed to find any BemaniPatcher patches in ${filename}.`);
        return [];
    }

    const patchers = [];
    const context = {
        window: {
            addEventListener: (type, cb) => cb(),
        },
        Patcher: class {
            constructor(fname, description, patches) {
                patchers.push({ fname, description, patches });
            }
        },
        PatchContainer: class {
            constructor(patchers) {}
        }
    };

    vm.createContext(context);
    vm.runInContext(script, context);
    
    return patchers;
}

function convertToSpicePatch(bmPatch, gameCode, dllName) {
    let description = "";

    if (bmPatch.tooltip) {
        description += bmPatch.tooltip + "\n";
    }

    if (bmPatch.danger) {
        description += `WARNING: ${bmPatch.danger}`
    }
    
    description = description.trim()

    const patch = {
        name: bmPatch.name,
        description,
        gameCode,
    }

    if (bmPatch.type) {
        if (bmPatch.type === "union") {
            patch.type = "union";
            patch.patches = bmPatch.patches.map((p) => ({
                name: p.name,
                patch: {
                    dllName,
                    data: bytesToHex(p.patch),
                    offset: bmPatch.offset,
                }
            }));
        } else if (bmPatch.type === "number") {
            patch.type = "number";
            patch.patch = {
                dllName,
                offset: bmPatch.offset,
                min: bmPatch.min,
                max: bmPatch.max,
                size: bmPatch.size,
            };
        } else {
            console.warn(`Unsupported BemaniPatcher patch type ${bmPatch.type}`, bmPatch);
        }
    } else {
        patch.type = "memory";
        patch.patches = bmPatch.patches.map((p) => ({
            offset: p.offset,
            dllName,
            dataDisabled: bytesToHex(p.off),
            dataEnabled: bytesToHex(p.on),
        }));
    }

    return patch;
}

async function main() {
    if (process.argv.length < 4) {
        console.log("Usage: node b2spatch.js <patcher URL | local patcher HTML> <gameCode> [output dir]")
        process.exit(1);
    }
    
    const location = process.argv[2];
    const gameCode = process.argv[3];
    const output = process.argv[4] ?? ".";
    const locationIsUrl = location.startsWith("http://") || location.startsWith("https://");
    let html = "";
    
    if (locationIsUrl) {
        html = await fetch(location).then((r) => r.text());
    } else {
        html = readFileSync(location, { encoding: "utf-8" });
    }

    const patchers = parsePatcherHtml(location, html);
    
    for (const patcher of patchers) {
        const lastUpdated = new Date()
        const spice = [
            {
                gameCode,
                version: patcher.description,
                lastUpdated: `${lastUpdated.getFullYear()}-${(lastUpdated.getMonth() + 1).toString().padStart(2, "0")}-${lastUpdated.getDate().toString().padStart(2, "0")} ${lastUpdated.getHours().toString().padStart(2, "0")}:${lastUpdated.getMinutes().toString().padStart(2, "0")}:${lastUpdated.getSeconds().toString().padStart(2, "0")}`,
                source: locationIsUrl ? location : "https://sp2x.two-torial.xyz/",
            }
        ];

        for (const patch of patcher.patches) {
            spice.push(convertToSpicePatch(patch, gameCode, patcher.fname));
        }

        writeFileSync(
            path.join(output, `${gameCode}-${patcher.description}.json`),
            JSON.stringify(spice, null, 4)
        );
    }
}

main();