import { copyFile } from "fs/promises";
import { promises as fs } from "fs";
import md5 from "md5";
import path, { basename } from "node:path";

import _locreq from "locreq";
import { embeddable_file_extensions } from "../embeddable-file-extensions.js";
import { PluginBuild } from "esbuild";
const target_locreq = _locreq(process.cwd());

function addSuffix(filename: string, suffix: string) {
	return filename.replace(/(\.[a-zA-Z0-9]+)?$/, suffix + "$1");
}

async function makeResourceURL(file_path: string) {
	const hash_base = file_path + (await fs.stat(file_path)).mtimeMs.toString();
	const hash = md5(hash_base);
	const public_url =
		"dist/" + addSuffix(basename(file_path), "-" + hash.slice(0, 8));
	const public_dir = "public";
	await copyFile(
		file_path,
		target_locreq.resolve(path.resolve(public_dir, public_url))
	);
	return "/" + public_url;
}

export const load_assets_plugin = {
	name: "sealgen-load-assets",
	setup(build: PluginBuild) {
		build.onLoad(
			{
				filter: new RegExp(
					`\\.(${embeddable_file_extensions.join("|")})$`
				),
			},
			async (args) => {
				const contents = `export const url =  "${await makeResourceURL(
					args.path
				)}";

const path = "${args.path}";

import fs from "fs";
let buffer_promise = null;

export const getBuffer = function(){
	if(buffer_promise) return buffer_promise;
	buffer_promise = fs.promises.readFile("${args.path}");
	return buffer_promise;
}

export const getContent = async function(){
    const buffer = await getBuffer();
	return buffer.toString("utf-8");
}

export const getBase64 = async function(){
    const buffer = await getBuffer();
    return buffer.toString("base64");
}

export default { getContent, url, getBase64, getBuffer, path };
`;
				return {
					contents,
				};
			}
		);
	},
};