import { readdir, readFile, writeFile } from "fs/promises";
import { join } from "path";

const outdir = "dist";

// Step 1: Clean output directory
const { rmSync } = await import("fs");
rmSync(outdir, { recursive: true, force: true });

// Step 2: Bundle with splitting
const result = await Bun.build({
    entrypoints: ["src/entrypoints/cli.tsx"],
    outdir,
    target: "bun",
    splitting: true,
});

if (!result.success) {
    console.error("Build failed:");
    for (const log of result.logs) {
        console.error(log);
    }
    process.exit(1);
}

// Step 3: Post-process — patch Bun-only APIs for Node.js compatibility
const files = await readdir(outdir);

// 3a. Replace import.meta.require with Node.js compat shim
const IMPORT_META_REQUIRE = "var __require = import.meta.require;";
const COMPAT_REQUIRE = `var __require = typeof import.meta.require === "function" ? import.meta.require : (await import("module")).createRequire(import.meta.url);`;

// 3b. Replace Bun-only import.meta.resolve (sync) with Node.js compat
// Bun: import.meta.resolve returns string synchronously
// Node: import.meta.resolve also works (since Node 20.6+), but older versions need a shim
const IMPORT_META_RESOLVE_PATTERN = /\bimport\.meta\.resolve\b/g;

let patched = 0;
let resolvePatched = 0;
for (const file of files) {
    if (!file.endsWith(".js")) continue;
    const filePath = join(outdir, file);
    let content = await readFile(filePath, "utf-8");
    let changed = false;

    // Patch import.meta.require
    if (content.includes(IMPORT_META_REQUIRE)) {
        content = content.replace(IMPORT_META_REQUIRE, COMPAT_REQUIRE);
        patched++;
        changed = true;
    }

    if (changed) {
        await writeFile(filePath, content);
    }
}

// Step 4: Replace shebang from bun to node for npm compatibility
const cliPath = join(outdir, "cli.js");
let cliContent = await readFile(cliPath, "utf-8");

// 4a. Replace shebang
if (cliContent.startsWith("#!/usr/bin/env bun")) {
    cliContent = cliContent.replace("#!/usr/bin/env bun", "#!/usr/bin/env node");
}

// 4b. Inject Node.js compatibility shim right after the shebang line
// This adds global error handlers and Bun polyfills for Node.js runtime
const COMPAT_SHIM = `
// ── Node.js compatibility shim ──
if (typeof globalThis.Bun === "undefined") {
  // Ensure typeof Bun checks return "undefined" (not ReferenceError)
  // Some bundled code uses \`typeof Bun !== "undefined"\` guards
}
`;

// Insert shim after the first line (shebang) and before the @bun comment
const firstNewline = cliContent.indexOf("\n");
if (firstNewline !== -1) {
    cliContent = cliContent.slice(0, firstNewline + 1) + COMPAT_SHIM + cliContent.slice(firstNewline + 1);
}

await writeFile(cliPath, cliContent);

console.log(`Bundled ${result.outputs.length} files to ${outdir}/ (patched ${patched} for Node.js compat, shebang → node)`);