import * as http from "node:http";
import * as posix from "node:path/posix";

function writeResponse(
	response: http.ServerResponse,
	statusCode: number,
	statusMessage: string,
	mimeType: string | undefined,
	content: Buffer,
	suppressContent = false,
) {
	response.statusCode = statusCode;
	response.statusMessage = statusMessage;
	if (mimeType !== undefined) {
		response.setHeader("Content-Type", mimeType);
	}
	response.setHeader("Content-Length", content.length);
	if (!suppressContent) {
		response.end(content);
	} else {
		response.end();
	}
};

function writeNotFound(response: http.ServerResponse, suppressContent = false) {
	writeResponse(
		response,
		404, "Not Found",
		"text/plain",
		Buffer.from("404 Not Found"),
		suppressContent,
	);
}

function writeBadRequest(response: http.ServerResponse, suppressContent = false) {
	writeResponse(
		response,
		400, "Bad Request",
		"text/plain",
		Buffer.from("400 Bad Request"),
		suppressContent,
	);
}

const extToMimeType = new Map([
	[".js", "text/javascript"],
	[".html", "text/html"],
	[".css", "text/css"],
]);

export function createServer(
	get: (ref: string) => Buffer | undefined
) {
	const server = http.createServer(
		{
			joinDuplicateHeaders: true,
			// @ts-expect-error missing in type declaration
			rejectNonStandardBodyWrites: true,
		},
		(request, response) => {
			const url = new URL(`http://localhost${request.url}`);
			if (request.method === "GET" || request.method === "HEAD") {
				const content = get(url.pathname);
				const isHead = request.method === "HEAD";
				if (!content) {
					writeNotFound(response, isHead);
					return;
				}
				writeResponse(
					response,
					200, "OK",
					extToMimeType.get(posix.extname(url.pathname)),
					content,
					isHead,
				)
				return;
			}
			writeBadRequest(response);
		},
	);
	return server;
}