const http = require("http");
const fs = require("fs");
const path = require("path");
const { URL } = require("url");

const repoRoot = path.resolve(__dirname, "..", "..");
const port = Number(process.env.MAP_EDITOR_PORT || process.env.PORT || 8787);

const contentTypes = {
  ".html": "text/html; charset=utf-8",
  ".js": "text/javascript; charset=utf-8",
  ".css": "text/css; charset=utf-8",
  ".map": "text/plain; charset=utf-8",
  ".png": "image/png",
  ".jpg": "image/jpeg",
  ".jpeg": "image/jpeg",
  ".gif": "image/gif",
  ".svg": "image/svg+xml",
  ".json": "application/json; charset=utf-8",
};

const sourceMapPath = path.join(repoRoot, "game", "assets", "map", "stage_01.map");
const deployTargets = [
  sourceMapPath,
  path.join(repoRoot, "build", "windows", "x64", "release", "assets", "map", "stage_01.map"),
  path.join(repoRoot, "build", "switch", "aarch64", "release", "switch_game", "assets", "map", "stage_01.map"),
  path.join(repoRoot, "build", "switch", "aarch64", "release", "switch_game", "romfs", "assets", "map", "stage_01.map"),
];

const server = http.createServer(async (request, response) => {
  try {
    const url = new URL(request.url, `http://${request.headers.host || "localhost"}`);
    if (url.pathname === "/api/map-editor/status" && request.method === "GET") {
      sendJson(response, 200, { ok: true, writable: true });
      return;
    }
    if (url.pathname === "/api/map-editor/save" && request.method === "POST") {
      const { mapText } = await readJsonBody(request);
      const targets = writeMapToTargets(mapText, [sourceMapPath]);
      sendJson(response, 200, { ok: true, targets });
      return;
    }
    if (url.pathname === "/api/map-editor/deploy" && request.method === "POST") {
      const { mapText } = await readJsonBody(request);
      const targets = writeMapToTargets(mapText, deployTargets, { skipMissingParents: true });
      sendJson(response, 200, { ok: true, targets });
      return;
    }
    if (request.method !== "GET" && request.method !== "HEAD") {
      sendJson(response, 405, { ok: false, error: "Method not allowed" });
      return;
    }
    serveStatic(url.pathname, request, response);
  } catch (error) {
    sendJson(response, 500, { ok: false, error: error.message });
  }
});

server.listen(port, "127.0.0.1", () => {
  console.log(`Map editor: http://127.0.0.1:${port}/tools/map_editor/`);
});

function writeMapToTargets(mapText, targets, options = {}) {
  validateMapText(mapText);
  const written = [];
  for (const target of targets) {
    const parent = path.dirname(target);
    if (options.skipMissingParents && !fs.existsSync(parent)) continue;
    fs.mkdirSync(parent, { recursive: true });
    fs.writeFileSync(target, normalizeText(mapText), "utf8");
    written.push(path.relative(repoRoot, target).replace(/\\/g, "/"));
  }
  return written;
}

function validateMapText(mapText) {
  if (typeof mapText !== "string" || !mapText.trim()) {
    throw new Error("mapText is empty");
  }
  if (!/^map\s+\S+/m.test(mapText) || !/^world\s+[-.\d]+\s+[-.\d]+/m.test(mapText)) {
    throw new Error("mapText does not look like a .map file");
  }
}

function normalizeText(text) {
  return `${text.replace(/\r\n/g, "\n").replace(/\s+$/g, "")}\n`;
}

function serveStatic(urlPath, request, response) {
  const pathname = decodeURIComponent(urlPath === "/" ? "/tools/map_editor/" : urlPath);
  const relative = pathname.replace(/^\/+/, "");
  const target = path.resolve(repoRoot, relative);
  if (!target.startsWith(repoRoot + path.sep) && target !== repoRoot) {
    sendText(response, 403, "Forbidden");
    return;
  }

  let filePath = target;
  if (fs.existsSync(filePath) && fs.statSync(filePath).isDirectory()) {
    filePath = path.join(filePath, "index.html");
  }
  if (!fs.existsSync(filePath) || !fs.statSync(filePath).isFile()) {
    sendText(response, 404, "Not found");
    return;
  }

  response.writeHead(200, {
    "Content-Type": contentTypes[path.extname(filePath).toLowerCase()] || "application/octet-stream",
    "Cache-Control": "no-store",
  });
  if (request.method === "HEAD") {
    response.end();
    return;
  }
  fs.createReadStream(filePath).pipe(response);
}

function readJsonBody(request) {
  return new Promise((resolve, reject) => {
    let body = "";
    request.setEncoding("utf8");
    request.on("data", (chunk) => {
      body += chunk;
      if (body.length > 1024 * 1024) {
        reject(new Error("Request body too large"));
        request.destroy();
      }
    });
    request.on("end", () => {
      try {
        resolve(JSON.parse(body || "{}"));
      } catch (error) {
        reject(new Error("Invalid JSON body"));
      }
    });
    request.on("error", reject);
  });
}

function sendJson(response, status, payload) {
  response.writeHead(status, {
    "Content-Type": "application/json; charset=utf-8",
    "Cache-Control": "no-store",
  });
  response.end(JSON.stringify(payload));
}

function sendText(response, status, text) {
  response.writeHead(status, {
    "Content-Type": "text/plain; charset=utf-8",
    "Cache-Control": "no-store",
  });
  response.end(text);
}