#!/usr/bin/env bun

// Embeds mupdf's `mupdf-wasm.wasm` into the compiled single-file binary.
//
// mupdf loads its wasm by reading the `mupdf-wasm.wasm` sibling of its own
// module via `new URL(..., import.meta.url)` + `readFileSync`. A `bun --compile`
// binary has no node_modules, so that read fails (`ENOENT .../mupdf-wasm.wasm`),
// and marking mupdf `--external` instead makes `bun --compile` eagerly fail to
// resolve the package at startup (the static `import * as mupdf` lives in a lazy
// chunk but is hoisted). So the binary build bundles mupdf and embeds the wasm
// bytes here, handing them to the WASM module as `$libmupdf_wasm_Module.wasmBinary`
// (see src/utils/markit.ts).
//
// `--generate` copies the wasm next to src/utils/mupdf-wasm-embed.ts and rewrites
// that module to import it via `with { type: "file" }`; `--reset` restores the
// checked-in placeholder and removes the copy. The npm `dist/cli.js` bundle never
// runs this — it keeps mupdf external and loads the wasm from node_modules.

import * as fs from "node:fs/promises";
import { createRequire } from "node:module";
import * as path from "node:path";

const utilsDir = path.join(import.meta.dir, "..", "src", "utils");
const helperPath = path.join(utilsDir, "mupdf-wasm-embed.ts");
const wasmCopyPath = path.join(utilsDir, "mupdf-wasm.wasm");

const placeholder = `// AUTOGENERATED -- managed by scripts/embed-mupdf-wasm.ts. Do not edit by hand.
//
// Compiled single-file binaries cannot let mupdf resolve its \`mupdf-wasm.wasm\`
// sibling from the read-only bunfs, so the binary build (scripts/build-binary.ts
// and scripts/ci-release-build-binaries.ts) regenerates this module to embed the
// wasm bytes via \`with { type: "file" }\` and copies the wasm next to it. Source
// checkouts, \`bun test\`, and the npm \`dist/cli.js\` bundle keep mupdf external and
// load the wasm from node_modules, so this placeholder returns undefined and the
// build resets back to it afterward.
export function loadEmbeddedMupdfWasm(): Uint8Array | undefined {
\treturn undefined;
}
`;

const generated = `// AUTOGENERATED -- managed by scripts/embed-mupdf-wasm.ts. Do not edit or commit.
import { readFileSync } from "node:fs";
import wasmPath from "./mupdf-wasm.wasm" with { type: "file" };

export function loadEmbeddedMupdfWasm(): Uint8Array | undefined {
\treturn readFileSync(wasmPath);
}
`;

if (process.argv.includes("--reset")) {
	await Bun.write(helperPath, placeholder);
	try {
		await fs.unlink(wasmCopyPath);
	} catch (err) {
		if ((err as NodeJS.ErrnoException).code !== "ENOENT") throw err;
	}
	process.exit(0);
}

const wasmSource = path.join(path.dirname(createRequire(import.meta.url).resolve("mupdf")), "mupdf-wasm.wasm");
const wasmFile = Bun.file(wasmSource);
if (!(await wasmFile.exists())) {
	throw new Error(`mupdf wasm not found at ${wasmSource}; run \`bun install\` first.`);
}
await Bun.write(wasmCopyPath, wasmFile);
await Bun.write(helperPath, generated);
console.log(`Embedded mupdf wasm (${wasmFile.size} bytes) into ${path.relative(process.cwd(), wasmCopyPath)}`);