#!/usr/bin/env -S deno run --allow-net --allow-read
// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.

// This program serves files in the current directory over HTTP.
// TODO Stream responses instead of reading them into memory.
// TODO Add tests like these:
// https://github.com/indexzero/http-server/blob/master/test/http-server-test.js

import { extname, posix } from "../path/mod.ts";
import {
  HTTPSOptions,
  listenAndServe,
  listenAndServeTLS,
  Response,
  ServerRequest,
} from "./server.ts";
import { parse } from "../flags/mod.ts";
import { assert } from "../_util/assert.ts";

interface EntryInfo {
  mode: string;
  size: string;
  url: string;
  name: string;
}

export interface FileServerArgs {
  _: string[];
  // -p --port
  p?: number;
  port?: number;
  // --cors
  cors?: boolean;
  // --no-dir-listing
  "dir-listing"?: boolean;
  // --host
  host?: string;
  // -c --cert
  c?: string;
  cert?: string;
  // -k --key
  k?: string;
  key?: string;
  // -h --help
  h?: boolean;
  help?: boolean;
}

const encoder = new TextEncoder();

const serverArgs = parse(Deno.args) as FileServerArgs;
const target = posix.resolve(serverArgs._[0] ?? "");

const MEDIA_TYPES: Record<string, string> = {
  ".md": "text/markdown",
  ".html": "text/html",
  ".htm": "text/html",
  ".json": "application/json",
  ".map": "application/json",
  ".txt": "text/plain",
  ".ts": "text/typescript",
  ".tsx": "text/tsx",
  ".js": "application/javascript",
  ".jsx": "text/jsx",
  ".gz": "application/gzip",
  ".css": "text/css",
  ".wasm": "application/wasm",
  ".mjs": "application/javascript",
};

/** Returns the content-type based on the extension of a path. */
function contentType(path: string): string | undefined {
  return MEDIA_TYPES[extname(path)];
}

function modeToString(isDir: boolean, maybeMode: number | null): string {
  const modeMap = ["---", "--x", "-w-", "-wx", "r--", "r-x", "rw-", "rwx"];

  if (maybeMode === null) {
    return "(unknown mode)";
  }
  const mode = maybeMode.toString(8);
  if (mode.length < 3) {
    return "(unknown mode)";
  }
  let output = "";
  mode
    .split("")
    .reverse()
    .slice(0, 3)
    .forEach((v): void => {
      output = modeMap[+v] + output;
    });
  output = `(${isDir ? "d" : "-"}${output})`;
  return output;
}

function fileLenToString(len: number): string {
  const multiplier = 1024;
  let base = 1;
  const suffix = ["B", "K", "M", "G", "T"];
  let suffixIndex = 0;

  while (base * multiplier < len) {
    if (suffixIndex >= suffix.length - 1) {
      break;
    }
    base *= multiplier;
    suffixIndex++;
  }

  return `${(len / base).toFixed(2)}${suffix[suffixIndex]}`;
}

/**
 * Returns an HTTP Response with the requested file as the body
 * @param req The server request context used to cleanup the file handle
 * @param filePath Path of the file to serve
 */
export async function serveFile(
  req: ServerRequest,
  filePath: string,
): Promise<Response> {
  const [file, fileInfo] = await Promise.all([
    Deno.open(filePath),
    Deno.stat(filePath),
  ]);
  const headers = new Headers();
  headers.set("content-length", fileInfo.size.toString());
  const contentTypeValue = contentType(filePath);
  if (contentTypeValue) {
    headers.set("content-type", contentTypeValue);
  }
  req.done.then(() => {
    file.close();
  });
  return {
    status: 200,
    body: file,
    headers,
  };
}

// TODO: simplify this after deno.stat and deno.readDir are fixed
async function serveDir(
  req: ServerRequest,
  dirPath: string,
): Promise<Response> {
  const dirUrl = `/${posix.relative(target, dirPath)}`;
  const listEntry: EntryInfo[] = [];
  for await (const entry of Deno.readDir(dirPath)) {
    const filePath = posix.join(dirPath, entry.name);
    const fileUrl = posix.join(dirUrl, entry.name);
    if (entry.name === "index.html" && entry.isFile) {
      // in case index.html as dir...
      return serveFile(req, filePath);
    }
    // Yuck!
    let fileInfo = null;
    try {
      fileInfo = await Deno.stat(filePath);
    } catch (e) {
      // Pass
    }
    listEntry.push({
      mode: modeToString(entry.isDirectory, fileInfo?.mode ?? null),
      size: entry.isFile ? fileLenToString(fileInfo?.size ?? 0) : "",
      name: entry.name,
      url: fileUrl,
    });
  }
  listEntry.sort((a, b) =>
    a.name.toLowerCase() > b.name.toLowerCase() ? 1 : -1
  );
  const formattedDirUrl = `${dirUrl.replace(/\/$/, "")}/`;
  const page = encoder.encode(dirViewerTemplate(formattedDirUrl, listEntry));

  const headers = new Headers();
  headers.set("content-type", "text/html");

  const res = {
    status: 200,
    body: page,
    headers,
  };
  return res;
}

function serveFallback(req: ServerRequest, e: Error): Promise<Response> {
  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: Response): 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);
}

function setCORS(res: Response): void {
  if (!res.headers) {
    res.headers = new Headers();
  }
  res.headers.append("access-control-allow-origin", "*");
  res.headers.append(
    "access-control-allow-headers",
    "Origin, X-Requested-With, Content-Type, Accept, Range",
  );
}

function dirViewerTemplate(dirname: string, entries: EntryInfo[]): string {
  return html`
    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <meta http-equiv="X-UA-Compatible" content="ie=edge" />
        <title>Deno File Server</title>
        <style>
          :root {
            --background-color: #fafafa;
            --color: rgba(0, 0, 0, 0.87);
          }
          @media (prefers-color-scheme: dark) {
            :root {
              --background-color: #303030;
              --color: #fff;
            }
          }
          @media (min-width: 960px) {
            main {
              max-width: 960px;
            }
            body {
              padding-left: 32px;
              padding-right: 32px;
            }
          }
          @media (min-width: 600px) {
            main {
              padding-left: 24px;
              padding-right: 24px;
            }
          }
          body {
            background: var(--background-color);
            color: var(--color);
            font-family: "Roboto", "Helvetica", "Arial", sans-serif;
            font-weight: 400;
            line-height: 1.43;
            font-size: 0.875rem;
          }
          a {
            color: #2196f3;
            text-decoration: none;
          }
          a:hover {
            text-decoration: underline;
          }
          table th {
            text-align: left;
          }
          table td {
            padding: 12px 24px 0 0;
          }
        </style>
      </head>
      <body>
        <main>
          <h1>Index of ${dirname}</h1>
          <table>
            <tr>
              <th>Mode</th>
              <th>Size</th>
              <th>Name</th>
            </tr>
            ${
    entries.map(
      (entry) =>
        html`
                  <tr>
                    <td class="mode">
                      ${entry.mode}
                    </td>
                    <td>
                      ${entry.size}
                    </td>
                    <td>
                      <a href="${entry.url}">${entry.name}</a>
                    </td>
                  </tr>
                `,
    )
  }
          </table>
        </main>
      </body>
    </html>
  `;
}

function html(strings: TemplateStringsArray, ...values: unknown[]): string {
  const l = strings.length - 1;
  let html = "";

  for (let i = 0; i < l; i++) {
    let v = values[i];
    if (v instanceof Array) {
      v = v.join("");
    }
    const s = strings[i] + v;
    html += s;
  }
  html += strings[l];
  return html;
}

function normalizeURL(url: string): string {
  let normalizedUrl = url;
  try {
    normalizedUrl = decodeURI(normalizedUrl);
  } catch (e) {
    if (!(e instanceof URIError)) {
      throw e;
    }
  }
  normalizedUrl = posix.normalize(normalizedUrl);
  const startOfParams = normalizedUrl.indexOf("?");
  return startOfParams > -1
    ? normalizedUrl.slice(0, startOfParams)
    : normalizedUrl;
}

function main(): void {
  const CORSEnabled = serverArgs.cors ? true : false;
  const port = serverArgs.port ?? serverArgs.p ?? 4507;
  const host = serverArgs.host ?? "0.0.0.0";
  const addr = `${host}:${port}`;
  const tlsOpts = {} as HTTPSOptions;
  tlsOpts.certFile = serverArgs.cert ?? serverArgs.c ?? "";
  tlsOpts.keyFile = serverArgs.key ?? serverArgs.k ?? "";
  const dirListingEnabled = serverArgs["dir-listing"] ?? true;

  if (tlsOpts.keyFile || tlsOpts.certFile) {
    if (tlsOpts.keyFile === "" || tlsOpts.certFile === "") {
      console.log("--key and --cert are required for TLS");
      serverArgs.h = true;
    }
  }

  if (serverArgs.h ?? serverArgs.help) {
    console.log(`Deno File Server
    Serves a local directory in HTTP.

  INSTALL:
    deno install --allow-net --allow-read https://deno.land/std/http/file_server.ts

  USAGE:
    file_server [path] [options]

  OPTIONS:
    -h, --help          Prints help information
    -p, --port <PORT>   Set port
    --cors              Enable CORS via the "Access-Control-Allow-Origin" header
    --host     <HOST>   Hostname (default is 0.0.0.0)
    -c, --cert <FILE>   TLS certificate file (enables TLS)
    -k, --key  <FILE>   TLS key file (enables TLS)
    --no-dir-listing    Disable directory listing

    All TLS options are required when one is provided.`);
    Deno.exit();
  }

  const handler = async (req: ServerRequest): Promise<void> => {
    const normalizedUrl = normalizeURL(req.url);
    const fsPath = posix.join(target, normalizedUrl);

    let response: Response | undefined;
    try {
      const fileInfo = await Deno.stat(fsPath);
      if (fileInfo.isDirectory) {
        if (dirListingEnabled) {
          response = await serveDir(req, fsPath);
        } else {
          throw new Deno.errors.NotFound();
        }
      } else {
        response = await serveFile(req, fsPath);
      }
    } catch (e) {
      console.error(e.message);
      response = await serveFallback(req, e);
    } finally {
      if (CORSEnabled) {
        assert(response);
        setCORS(response);
      }
      serverLog(req, response!);
      try {
        await req.respond(response!);
      } catch (e) {
        console.error(e.message);
      }
    }
  };

  let proto = "http";
  if (tlsOpts.keyFile || tlsOpts.certFile) {
    proto += "s";
    tlsOpts.hostname = host;
    tlsOpts.port = port;
    listenAndServeTLS(tlsOpts, handler);
  } else {
    listenAndServe(addr, handler);
  }
  console.log(`${proto.toUpperCase()} server listening on ${proto}://${addr}/`);
}

if (import.meta.main) {
  main();
}