/**
 * 构建前扫描 `demos/gen_attribute/*.json`，写入 `ts/demos/genAttributeBundledDemoManifest.generated.ts`，供 bundle 内联 slug 列表。
 * 并为该目录注册 contextDependencies，便于 watch 下增减 demo JSON 时触发重编。
 */
const path = require('path');
const fs = require('fs');

const REL_DIR = 'demos/gen_attribute';
const GENERATED_BASENAME = 'genAttributeBundledDemoManifest.generated.ts';

function collectSlugs(srcDir) {
    if (!fs.existsSync(srcDir)) return [];
    const files = fs.readdirSync(srcDir).filter((f) => f.endsWith('.json'));
    const slugs = files
        .map((f) => f.replace(/\.json$/i, ''))
        .filter((s) => s.length > 0);
    // UTF-16 码元序，与 locale 无关，避免不同构建机生成顺序不一致
    slugs.sort((a, b) => (a < b ? -1 : a > b ? 1 : 0));
    return slugs;
}

function writeGeneratedModule(srcDir, outPath) {
    const slugs = collectSlugs(srcDir);
    const content =
        '/**\n' +
        ' * Generated by GenAttributeDemoManifestPlugin — do not edit.\n' +
        ' */\n' +
        `export const GEN_ATTRIBUTE_BUNDLED_DEMO_SLUGS: readonly string[] = ${JSON.stringify(slugs)};\n`;
    if (fs.existsSync(outPath) && fs.readFileSync(outPath, 'utf8') === content) return;
    fs.mkdirSync(path.dirname(outPath), { recursive: true });
    fs.writeFileSync(outPath, content, 'utf8');
}

class GenAttributeDemoManifestPlugin {
    apply(compiler) {
        const srcDir = path.join(__dirname, '..', REL_DIR);
        const outPath = path.join(__dirname, '..', 'ts', 'demos', GENERATED_BASENAME);

        compiler.hooks.beforeCompile.tapAsync('GenAttributeDemoManifestPlugin', (_params, callback) => {
            try {
                writeGeneratedModule(srcDir, outPath);
                callback();
            } catch (e) {
                callback(e);
            }
        });

        compiler.hooks.thisCompilation.tap('GenAttributeDemoManifestPlugin', (compilation) => {
            compilation.contextDependencies.add(srcDir);
        });
    }
}

module.exports = { GenAttributeDemoManifestPlugin };