// Adapted from https://deno.land/std@0.106.0/http/file_server.ts
import {
  listenAndServe,
  posix,
  readAll,
  serveFile,
  ServerRequest,
  ServerResponse,
  Sys,
} from "../deps.ts";

export function runDevServer(): void {
  const target = posix.resolve("./web/");

  const handler = async (req: ServerRequest) => {
    let response: ServerResponse | undefined;
    try {
      const normalizedUrl = normalizeURL(req.url);
      let fsPath = posix.join(target, normalizedUrl);
      if (fsPath.indexOf(target) !== 0) {
        fsPath = target;
      }

      const srcPath = fsPath.replace(/\/web\/(.*)\.js$/, "/$1.ts");
      if (srcPath != fsPath) {
        // TODO check only local
        await bundle(srcPath, fsPath);
      }

      const fileInfo = await Deno.stat(fsPath);
      if (fileInfo.isDirectory) {
        response = await serveFile(req, posix.join(fsPath, "index.html"));
      } else {
        response = await serveFile(req, fsPath);
      }
    } catch (e) {
      console.error(e.message);
      response = await serveFallback(req, e);
    } finally {
      serverLog(req, response!);
      try {
        await req.respond(response!);
      } catch (e) {
        console.error(e.message);
      }
    }
  };

  const port = 4507;
  const host = "0.0.0.0";
  const addr = `${host}:${port}`;

  listenAndServe(addr, handler);
  console.log(`Dev server listening on http://${addr}/`);
}

export function normalizeURL(url: string): string {
  let normalizedUrl = url;
  try {
    normalizedUrl = decodeURI(normalizedUrl);
  } catch (e) {
    if (!(e instanceof URIError)) {
      throw e;
    }
  }

  try {
    //allowed per https://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html
    const absoluteURI = new URL(normalizedUrl);
    normalizedUrl = absoluteURI.pathname;
  } catch (e) { //wasn't an absoluteURI
    if (!(e instanceof TypeError)) {
      throw e;
    }
  }

  if (normalizedUrl[0] !== "/") {
    throw new URIError("The request URI is malformed.");
  }

  normalizedUrl = posix.normalize(normalizedUrl);
  const startOfParams = normalizedUrl.indexOf("?");
  return startOfParams > -1
    ? normalizedUrl.slice(0, startOfParams)
    : normalizedUrl;
}

const encoder = new TextEncoder();
function serveFallback(_req: ServerRequest, e: Error): Promise<ServerResponse> {
  if (e instanceof URIError) {
    return Promise.resolve({
      status: 400,
      body: encoder.encode("Bad Request"),
    });
  } else if (e instanceof Deno.errors.NotFound) {
    return Promise.resolve({
      status: 404,
      body: encoder.encode("Not Found"),
    });
  } else {
    return Promise.resolve({
      status: 500,
      body: encoder.encode("Internal server error"),
    });
  }
}

function serverLog(req: ServerRequest, res: ServerResponse): void {
  const d = new Date().toISOString();
  const dateFmt = `[${d.slice(0, 10)} ${d.slice(11, 19)}]`;
  const s = `${dateFmt} "${req.method} ${req.url} ${req.proto}" ${res.status}`;
  console.log(s);
}

async function run(...cmd: string[]): Promise<boolean> {
  const process = Sys.run({ cmd });
  const result = await process.status();
  return result.success;
}

async function deno(cmd: string, ...args: string[]): Promise<boolean> {
  const flags = await readConfigFlags(cmd);
  return await run("deno", cmd, ...flags, ...args);
}

async function readConfigFlags(cmd: string): Promise<string[]> {
  const path = `config/${cmd}.flags`;
  try {
    const f = await Sys.open(path);
    const content = await readAll(f);
    return new TextDecoder()
      .decode(content)
      .split(" ")
      .filter((part) => part && part.startsWith("--"));
  } catch {
  }
  return [];
}

async function bundle(
  source: string,
  destination: string,
): Promise<void> {
  if (
    await deno("bundle", "-q", source, destination) &&
    await deno("fmt", "-q", destination)
  ) {
    console.log(`Bundled : ${source} -> ${destination}`);
  } else {
    console.error(`Bundle failed for: ${source}`);
  }
}