import {createLogger} from "@gongt/ts-stl-library/debug/create-logger";
import {LOG_LEVEL} from "@gongt/ts-stl-library/debug/levels";
import {transformFile as transformFileType, TransformOptions} from "babel-core";
import {Handler} from "express-serve-static-core"
import {ensureDir, ensureDirSync, readFile, writeFile} from "fs-extra";
import {tmpdir} from "os";
import {dirname, resolve} from "path";
import {fileExists} from "../../file-operation/file-exists";
import {STL_SERVER_PACKAGE_ROOT} from "../../STL_SERVER_PACKAGE_ROOT";
import {createServeStatic} from "../inject/serve-static";

let transformFile: typeof transformFileType;
const debug = createLogger(LOG_LEVEL.DEBUG, 'jspm-plug:ie');

const tempDir = resolve(tmpdir(), 'compile-ie');
ensureDirSync(tempDir);

const isJs = /\.js$/;

export function InternetExplorerProviders(clientPath: string, clientSource: string): Handler[] {
	if (!transformFile) {
		transformFile = require('babel-core').transformFile;
	}
	const tempMiddleware = createServeStatic(tempDir, {
		fallthrough: true,
	});
	const clientProvider = [
		tempMiddleware,
		(req, res, next) => {
			req.url = req.url.replace(/^\/_IE_/, '');
			
			if (isJs.test(req.url)) {
				compileFile(clientPath, req.url.replace(/^\//g, '')).then(() => {
					tempMiddleware(req, res, next);
				}, (e) => {
					next(e);
				});
			} else {
				next();
			}
		},
	];
	if (clientSource) {
		clientProvider.push(
			createServeStatic(clientPath, {
				fallthrough: true,
			}),
			createServeStatic(clientSource),
		);
	} else {
		clientProvider.push(
			createServeStatic(clientPath),
		);
	}
	
	return clientProvider;
}

async function compileFile(root: string, file: string) {
	const source = resolve(root, file);
	const target = resolve(tempDir, file);
	debug('transpile: %s -> %s', source, target);
	
	await ensureDir(dirname(target));
	
	const source_map = source + '.map';
	let sourceMap: object;
	if (await fileExists(source_map)) {
		sourceMap = JSON.parse(await readFile(source_map, {encoding: 'utf8'}));
	}
	const {code, map} = await new Promise<any>((resolve, reject) => {
		const opt: TransformOptions = {
			ast: false,
			code: true,
			sourceMaps: true,
			comments: true,
			babelrc: true,
			"extends": STL_SERVER_PACKAGE_ROOT + '/.babelrc',
			inputSourceMap: sourceMap,
			minified: false,
			only: source,
		};
		transformFile(source, opt, (err, data) => {
			err? reject(err) : resolve(data);
		});
	});
	await writeFile(target, code, {encoding: 'utf8'});
	await writeFile(target + '.map', JSON.stringify(map), {encoding: 'utf8'});
}