// Frame Control as a desktop app (macOS, Windows, Linux): starts ui/server.py on
// a free loopback port and shows it in a native window. The server does all the
// work over the `frame` SSH alias; this file only hosts it.
const { app, BrowserWindow, Menu, clipboard, dialog, ipcMain, shell } = require("electron");
const { execFile, spawn } = require("child_process");
const { promisify } = require("util");
const fs = require("fs");
const http = require("http");
const net = require("net");
const os = require("os");
const path = require("path");

const run = promisify(execFile);

const IS_MAC = process.platform === "darwin";
const IS_WIN = process.platform === "win32";

// Packaged: <resources>/{ui,scripts,python}. Dev: the repo checkout.
const ROOT = app.isPackaged ? process.resourcesPath : path.join(__dirname, "..");
const TOOLS = path.join(ROOT, "tools");  // bundled adb
const SERVER = path.join(ROOT, "ui", "server.py");
const SCRIPTS = path.join(ROOT, "scripts");
const LOG_DIR = IS_MAC ? path.join(os.homedir(), "Library", "Logs", "Frame Control")
                       : path.join(app.getPath("userData"), "logs");
const LOG = path.join(LOG_DIR, "server.log");
const BG = "#0d1117";
const FRAME = process.env.FRAME_ALIAS || "frame";

let server = null;
let url = null;
let win = null;
let quitting = false;
let python = null;

// Apps launched from Finder get PATH=/usr/bin:/bin:/usr/sbin:/sbin, which misses
// Homebrew's python3, rsync and adb (desktop launchers on Linux can be as bare).
// Take PATH from the login shell instead. Windows has no login shell to ask.
// Runs asynchronously so a slow shell profile can't freeze the window.
let cachedPath = null;
async function loginPath() {
  if (IS_WIN) return process.env.PATH || "";
  if (cachedPath) return cachedPath;
  const shellPath = os.userInfo().shell || process.env.SHELL || (IS_MAC ? "/bin/zsh" : "/bin/sh");
  const extra = IS_MAC ? ["/opt/homebrew/bin", "/usr/local/bin", path.join(os.homedir(), ".homebrew", "bin")] : [];
  let fromShell = "";
  try {
    const { stdout } = await run(shellPath, ["-ilc", 'printf "\\n__PATH__%s__PATH__" "$PATH"'],
                                 { encoding: "utf8", timeout: 5000 });
    fromShell = (stdout.match(/__PATH__(.*)__PATH__/) || [])[1] || "";
  } catch {}
  const parts = [...fromShell.split(":"), ...(process.env.PATH || "").split(":"), ...extra];
  const joined = [...new Set(parts.filter(Boolean))].join(":");
  if (fromShell) cachedPath = joined;  // retry next time if the shell didn't answer
  return joined;
}

// The Windows build bundles Python; elsewhere use the system's python3 (3.8+).
// -I ignores PYTHON* variables and user site-packages, so a PYTHONHOME or
// PYTHONPATH set for another Python can't break the bundled one. That makes these
// flags stand in for PYTHONUNBUFFERED, PYTHONDONTWRITEBYTECODE (no __pycache__
// inside the signed app) and PYTHONUTF8.
const PY_FLAGS = ["-I", "-u", "-B", "-X", "utf8"];

async function findPython(env) {
  const names = IS_WIN ? ["python.exe", "python3.exe"] : ["python3"];
  // The packaged app bundles Python (app/build/fetch-deps.js); a checkout uses PATH.
  const candidates = [path.join(ROOT, "python", ...(IS_WIN ? ["python.exe"] : ["bin", "python3"]))];
  for (const dir of env.PATH.split(path.delimiter)) {
    // The WindowsApps "python.exe" is a stub that opens the Microsoft Store.
    if (!dir || (IS_WIN && /\\WindowsApps\\?$/i.test(dir))) continue;
    for (const name of names) candidates.push(path.join(dir, name));
  }
  for (const p of candidates) {
    try {
      fs.accessSync(p, fs.constants.X_OK);
      // /usr/bin/python3 on macOS is a stub until the Command Line Tools are installed.
      await run(p, [...PY_FLAGS, "-c", "import http.server, sys; assert sys.version_info >= (3, 8)"],
                { timeout: 10000, env, windowsHide: true });
      return p;
    } catch {}
  }
  return null;
}

async function hasSsh(env) {
  try { await run("ssh", ["-V"], { timeout: 5000, env, windowsHide: true }); return true; } catch { return false; }
}

const PYTHON_HELP = app.isPackaged ? "The bundled Python is missing; reinstall Frame Control."
  : "Install Python 3.8 or later, then reopen the app.";
const SSH_HELP = IS_WIN
  ? "Turn on Windows' OpenSSH client: Settings → System → Optional features → Add a feature → OpenSSH Client."
  : "Install the OpenSSH client (e.g. sudo apt install openssh-client).";

function freePort() {
  return new Promise((resolve, reject) => {
    const s = net.createServer();
    s.once("error", reject);
    s.listen(0, "127.0.0.1", () => { const { port } = s.address(); s.close(() => resolve(port)); });
  });
}

// Ready once the port answers with our Server header.
function ping(target) {
  return new Promise((resolve) => {
    const req = http.get(target, { timeout: 1000 }, (res) => {
      res.resume();
      resolve(/^FrameControl/.test(res.headers.server || ""));
    });
    req.on("error", () => resolve(false));
    req.on("timeout", () => { req.destroy(); resolve(false); });
  });
}

async function startServer() {
  const env = { ...process.env, PATH: await loginPath(), FRAME_CONTROL_APP: "1",
                ...(fs.existsSync(TOOLS) ? { FRAME_CONTROL_TOOLS: TOOLS } : {}) };
  python = await findPython(env);
  if (!python) throw new Error(`Frame Control needs Python 3.8 or later. ${PYTHON_HELP}`);
  if (!await hasSsh(env)) throw new Error(`Frame Control needs the ssh command. ${SSH_HELP}`);
  const port = await freePort();
  fs.mkdirSync(LOG_DIR, { recursive: true });
  const log = fs.openSync(LOG, "a");
  fs.writeSync(log, `\n--- ${new Date().toISOString()} ${python} ${SERVER} --port ${port}\n`);
  // stdin stays open while the app runs; the server exits cleanly when it closes.
  const child = spawn(python, [...PY_FLAGS, SERVER, "--port", String(port), "--exit-on-eof"],
                      { env, stdio: ["pipe", log, log], windowsHide: true });
  child.stdin.on("error", () => {});
  fs.closeSync(log);
  server = child;
  let exited = null;
  child.once("error", (err) => {
    exited = err.message;
    if (server === child) { server = null; if (!quitting && url) serverDied(err.message); }
  });
  child.once("exit", (code, signal) => {
    exited = signal || code;
    if (server !== child) return;  // replaced by Restart Server
    server = null;
    if (!quitting && url) serverDied(exited);
  });

  const target = `http://127.0.0.1:${port}/`;
  for (let i = 0; i < 100; i++) {
    if (exited !== null) throw new Error(`The server exited (${exited}). See ${LOG}.`);
    if (await ping(target)) { url = target; return; }
    await new Promise((r) => setTimeout(r, 100));
  }
  if (server === child) server = null;
  endServer(child);
  throw new Error(`The server didn't start within 10 seconds. See ${LOG}.`);
}

// Closing stdin lets server.py close its SSH connections and exit (the only clean
// way on Windows); SIGTERM does the same elsewhere.
function endServer(child) {
  try { child.stdin.end(); } catch {}
  if (!IS_WIN) child.kill("SIGTERM");
  setTimeout(() => { if (child.exitCode === null && child.signalCode === null) child.kill(); }, 5000).unref();
}

function stopServer() {
  if (server) endServer(server);
}

function errorPage(message) {
  const esc = (s) => s.replace(/[&<>]/g, (c) => ({ "&": "&amp;", "<": "&lt;", ">": "&gt;" }[c]));
  const html = `<!doctype html><meta charset="utf-8"><body style="margin:0;height:100vh;display:grid;
    place-items:center;background:${BG};color:#e6edf3;font:14px -apple-system,sans-serif">
    <div style="max-width:560px;padding:32px;line-height:1.5"><h2>Frame Control couldn't start</h2>
    <p>${esc(message)}</p><p style="color:#8b98a8">Fix it, then choose Frame → Restart Server.</p></div>`;
  return "data:text/html;charset=utf-8," + encodeURIComponent(html);
}

function serverDied(why) {
  url = null;
  if (win) win.loadURL(errorPage(`The server stopped unexpectedly (${why}). See ${LOG}.`));
}

async function restartServer() {
  const old = server;
  server = null;
  url = null;
  if (old) endServer(old);
  await load();
}

// On macOS the page's sticky header becomes the title bar, clear of the traffic lights.
const CHROME_CSS = IS_MAC && `
  header { padding-left: 92px !important; -webkit-app-region: drag; user-select: none; }
  header a, header button, header input, header .chip { -webkit-app-region: no-drag; }
`;

// Restart Server can start a new load while an older one is still waiting for
// its server; only the newest load may touch the window.
let loadGen = 0;
async function load() {
  const gen = ++loadGen;
  try {
    if (!url) await startServer();
    if (gen === loadGen && win) { await win.loadURL(url); firstRunCheck(); }
  } catch (e) {
    if (gen === loadGen && win) await win.loadURL(errorPage(e.message));
  }
}

// `ssh -G` prints the effective config. An alias nobody configured keeps its
// own name as HostName; connect.sh always writes a HostName.
async function aliasConfigured(env) {
  try {
    const { stdout } = await run("ssh", ["-G", FRAME], { encoding: "utf8", timeout: 5000, env });
    return (stdout.match(/^hostname (.*)$/m) || [])[1] !== FRAME;
  } catch {
    return true;  // can't tell; don't nag
  }
}

let setupOffered = false;
async function firstRunCheck() {
  if (setupOffered || !url) return;  // not on the error page, and once per launch
  if (await aliasConfigured({ ...process.env, PATH: await loginPath() })) return;
  if (!win || setupOffered) return;
  setupOffered = true;
  const { response } = await dialog.showMessageBox(win, {
    type: "info",
    message: "Connect to your Steam Frame",
    detail: `There's no "${FRAME}" SSH alias yet. On the Frame, turn on Steam Settings → System → `
          + "Enable Developer Mode, then Developer → Set User Password. Then run the setup: it finds the "
          + "headset, creates a key, and asks for that password once in a terminal window.",
    buttons: ["Set Up Connection…", "Later"],
    defaultId: 0, cancelId: 1,
  });
  if (response === 0) setUpConnection();
}

ipcMain.handle("clipboard:read", (e) => {
  if (!win || e.sender !== win.webContents || !url || new URL(e.senderFrame.url).origin !== new URL(url).origin) return "";
  return clipboard.readText();
});

function createWindow() {
  win = new BrowserWindow({
    width: 1400, height: 950, minWidth: 760, minHeight: 560,
    title: "Frame Control", backgroundColor: BG, show: false,
    ...(IS_MAC ? { titleBarStyle: "hiddenInset", trafficLightPosition: { x: 18, y: 26 } }
               : { icon: path.join(__dirname, "build", "icon.png") }),
    webPreferences: { contextIsolation: true, nodeIntegration: false, sandbox: true,
                      preload: path.join(__dirname, "preload.js") },
  });
  win.once("ready-to-show", () => win.show());
  if (CHROME_CSS) win.webContents.on("did-finish-load", () => win.webContents.insertCSS(CHROME_CSS));
  // External links open in the default browser; the app never navigates away.
  win.webContents.setWindowOpenHandler(({ url: target }) => {
    if (/^https?:\/\//.test(target)) shell.openExternal(target);
    return { action: "deny" };
  });
  win.webContents.on("will-navigate", (e, target) => {
    if (!url || new URL(target).origin !== new URL(url).origin) e.preventDefault();
  });
  win.on("closed", () => { win = null; });
  load();
}

// Opens a terminal window (Terminal, a Linux terminal emulator or a console) via
// ui/frame_host.py, which the server uses too: setup and power actions ask for the
// Developer Mode password there.
async function runInTerminal(argv) {
  try {
    const env = { ...process.env, PATH: await loginPath() };
    const py = python || await findPython(env);
    if (!py) throw new Error(`Python 3.8 or later is needed. ${PYTHON_HELP}`);
    await run(py, [...PY_FLAGS, path.join(ROOT, "ui", "frame_host.py"), "terminal", "--", ...argv],
              { env, timeout: 15000, windowsHide: true });
  } catch (err) {
    dialog.showErrorBox("Couldn't open a terminal", String((err.stderr || err.message || err)).trim());
  }
}

async function setUpConnection() {
  const alias = `FRAME_ALIAS=${FRAME}`;
  if (IS_MAC) return runInTerminal(["env", alias, "zsh", path.join(SCRIPTS, "connect.sh")]);
  const py = python || await findPython({ ...process.env, PATH: await loginPath() });
  const setup = [py || "python3", ...PY_FLAGS, path.join(ROOT, "ui", "frame_connect.py")];
  // A new console inherits our environment on Windows; Linux terminals may not.
  runInTerminal(IS_WIN ? setup : ["env", alias, ...setup]);
}

function buildMenu() {
  const template = [
    ...(IS_MAC ? [{ role: "appMenu" }] : []),
    { role: "fileMenu" },
    { role: "editMenu" },
    {
      label: "Frame",
      submenu: [
        { label: "Set Up Connection…", click: setUpConnection },
        { label: IS_MAC ? "Open SSH in Terminal" : "Open SSH in a Terminal", click: () => runInTerminal(["ssh", FRAME]) },
        { type: "separator" },
        { label: "Open in Browser", click: () => url && shell.openExternal(url) },
        { label: "Restart Server", click: () => win ? restartServer() : createWindow() },
        { label: "Show Server Log", click: () => shell.openPath(fs.existsSync(LOG) ? LOG : LOG_DIR) },
        ...(IS_WIN ? [] : [{ label: "Reveal Helper Scripts", click: () => shell.openPath(SCRIPTS) }]),
      ],
    },
    {
      label: "View",
      submenu: [
        { role: "reload" }, { role: "forceReload" }, { role: "toggleDevTools" },
        { type: "separator" },
        { role: "resetZoom" }, { role: "zoomIn" }, { role: "zoomOut" },
        { type: "separator" }, { role: "togglefullscreen" },
      ],
    },
    ...(IS_MAC ? [{ role: "windowMenu" }] : []),
    {
      role: "help",
      submenu: [{ label: "Project on GitHub", click: () => shell.openExternal("https://github.com/saphid/steam-frame") }],
    },
  ];
  Menu.setApplicationMenu(Menu.buildFromTemplate(template));
}

if (!app.requestSingleInstanceLock()) {
  app.quit();
} else {
  app.on("second-instance", () => {
    if (win) { if (win.isMinimized()) win.restore(); win.focus(); }
  });
  app.whenReady().then(() => {
    buildMenu();
    createWindow();
  });
  app.on("activate", () => { if (!win) createWindow(); });
  app.on("window-all-closed", () => app.quit());
  app.on("before-quit", () => { quitting = true; stopServer(); });
  process.on("exit", stopServer);
}