/**
 * Runs after `tsc`:
 * 1. Copies `src/base.css` into `dist/` (tsc only emits TS output).
 * 2. Adds file extensions to relative imports (see addExtensions).
 * 3. Prepends `"use client"` to component/hook modules so they work as
 *    client components under the Next.js App Router. Pure modules (utils,
 *    types, the barrel) are left alone so they stay usable on the server.
 */
import { Glob } from "bun";
import path from "node:path";

const root = path.resolve(import.meta.dir, "..");
const dist = path.join(root, "dist");

await Bun.write(
    path.join(dist, "base.css"),
    Bun.file(path.join(root, "src", "base.css")),
);

/**
 * tsc keeps extensionless relative specifiers ("./layout/Button"), which only
 * bundlers resolve. Rewrite them to full paths so plain Node ESM (e.g. SSR
 * with the package left external) can load the output too.
 */
async function resolveSpecifier(fromFile: string, specifier: string) {
    if (/\.(js|css|json)$/.test(specifier)) return specifier;

    const base = path.resolve(path.dirname(fromFile), specifier);

    if (await Bun.file(`${base}.js`).exists()) return `${specifier}.js`;
    if (await Bun.file(path.join(base, "index.js")).exists()) {
        return `${specifier}/index.js`;
    }

    return specifier;
}

const RELATIVE_IMPORT =
    /(\bfrom\s*|\bimport\s*\(\s*|\bimport\s+)(["'])(\.{1,2}\/[^"']*)\2/g;

async function addExtensions(filePath: string, content: string) {
    let result = "";
    let lastIndex = 0;

    for (const match of content.matchAll(RELATIVE_IMPORT)) {
        const [full, prefix, quote, specifier] = match;
        const resolved = await resolveSpecifier(filePath, specifier!);
        result += content.slice(lastIndex, match.index);
        result += `${prefix}${quote}${resolved}${quote}`;
        lastIndex = match.index! + full.length;
    }

    return result + content.slice(lastIndex);
}

const SERVER_SAFE = [/^index\.js$/, /^types\.js$/, /^utils\//, /^\(utils\)\//];

let count = 0;

for (const file of new Glob("**/*.{js,d.ts}").scanSync(dist)) {
    const filePath = path.join(dist, file);
    let content = await addExtensions(
        filePath,
        await Bun.file(filePath).text(),
    );

    const isClientModule =
        file.endsWith(".js") &&
        !SERVER_SAFE.some((pattern) => pattern.test(file)) &&
        !content.startsWith('"use client"');

    if (isClientModule) {
        content = `"use client";\n${content}`;
        count++;
    }

    await Bun.write(filePath, content);
}

console.log(`post-compile: copied base.css, marked ${count} client modules`);