const { app, BrowserWindow, session, desktopCapturer, ipcMain, clipboard } = require('electron');
const { autoUpdater } = require('electron-updater');
const path = require('path');
const packageJson = require('./package.json');
const PERIODIC_UPDATE_CHECK_INTERVAL_MS = 1 * 60 * 1000;

const updateState = {
    status: 'idle', // idle | checking | available | downloading | downloaded | installing | not-available | error
    info: null,
    error: null,
};

function broadcastUpdateState() {
    const wins = BrowserWindow.getAllWindows();
    for (const win of wins) {
        if (!win.isDestroyed()) {
            win.webContents.send('update-state', updateState);
        }
    }
}

function isNewerVersionAvailable(info) {
    const next = info && typeof info.version === 'string' ? info.version : '';
    return Boolean(next) && next !== app.getVersion();
}

let updateCheckInProgress = false;
let installInProgress = false;
let periodicUpdateTimer = null;

function resolveBackendUrl() {
    const configuredUrl = (process.env.CHATTZ_URL || process.env.APP_BASE_URL || '').trim();
    if (configuredUrl) {
        return configuredUrl.replace(/\/$/, '');
    }

    const packagedFallback = typeof packageJson.homepage === 'string'
        ? packageJson.homepage.trim()
        : '';
    if (app.isPackaged && packagedFallback) {
        return packagedFallback.replace(/\/$/, '');
    }

    return 'http://localhost:3000';
}

function webContentsOrigin(webContents) {
    if (!webContents || typeof webContents.getURL !== 'function') {
        return null;
    }
    return safeOrigin(webContents.getURL());
}

async function runUpdateCheck(reason = 'manual') {
    if (installInProgress) {
        console.log(`Update check skipped (${reason}): install already in progress`);
        return;
    }
    if (updateCheckInProgress) {
        console.log(`Update check skipped (${reason}): another check is already in progress`);
        return;
    }
    updateCheckInProgress = true;
    updateState.status = 'checking';
    updateState.error = null;
    try {
        const result = await autoUpdater.checkForUpdates();
        const info = result && result.updateInfo ? result.updateInfo : null;
        if (isNewerVersionAvailable(info)) {
            updateState.status = 'available';
            updateState.info = info;
            updateState.error = null;
        } else {
            updateState.status = 'not-available';
            updateState.info = info;
            updateState.error = null;
        }
    } catch (err) {
        updateState.status = 'error';
        updateState.error = err && err.message ? err.message : String(err);
        console.error(`Update check failed (${reason})`, err);
    } finally {
        updateCheckInProgress = false;
        broadcastUpdateState();
    }
}

function installDownloadedUpdate() {
    if (installInProgress) {
        console.log('Update install already in progress');
        return;
    }

    installInProgress = true;
    updateState.status = 'installing';
    updateState.error = null;
    broadcastUpdateState();

    const wins = BrowserWindow.getAllWindows();
    for (const win of wins) {
        if (win.isDestroyed()) continue;
        try {
            win.removeAllListeners('close');
            win.destroy();
        } catch (err) {
            console.warn('Failed to destroy window before update install', err);
        }
    }

    setImmediate(() => {
        try {
            autoUpdater.quitAndInstall(false, true);
        } catch (err) {
            installInProgress = false;
            updateState.status = 'error';
            updateState.error = err && err.message ? err.message : String(err);
            broadcastUpdateState();
            console.error('quitAndInstall failed', err);
        }
    });

    setTimeout(() => {
        if (installInProgress) {
            console.warn('Update install is still waiting for app shutdown');
        }
    }, 15000);
}

function startPeriodicUpdateChecks() {
    if (periodicUpdateTimer || !app.isPackaged) {
        return;
    }

    periodicUpdateTimer = setInterval(() => {
        void runUpdateCheck('periodic');
    }, PERIODIC_UPDATE_CHECK_INTERVAL_MS);
}

function createWindow() {
    const sess = session.fromPartition('persist:chattz');
    const backendUrl = resolveBackendUrl();
    const backendOrigin = new URL(backendUrl).origin;
    console.log(`Desktop backend URL: ${backendUrl}`);

    const win = new BrowserWindow({
        width: 1200,
        height: 800,
        title: "Chattz Desktop",
        webPreferences: {
            nodeIntegration: false,
            contextIsolation: true,
            session: sess,
            preload: path.join(__dirname, 'desktop', 'preload.js')
        }
    });

    win.setAutoHideMenuBar(true);
    win.setMenuBarVisibility(true);

    sess.setPermissionCheckHandler((webContents, permission) => {
        const origin = webContentsOrigin(webContents);
        if (origin !== backendOrigin) return false;
        return permission === 'media' || permission === 'clipboard-write';
    });

    sess.setPermissionRequestHandler((webContents, permission, callback) => {
        const origin = webContentsOrigin(webContents);
        if (origin === backendOrigin && (permission === 'media' || permission === 'clipboard-write')) {
            callback(true);
        } else {
            callback(false);
        }
    });

    sess.setDisplayMediaRequestHandler((request, callback) => {
        const origin = safeOrigin(request.frame?.url || win.webContents.getURL());
        if (origin !== backendOrigin) {
            callback(null);
            return;
        }
        desktopCapturer.getSources({ types: ['screen', 'window'] }).then((sources) => {
            if (sources && sources.length > 0) {
                const screenSource = sources.find(s => s.id.startsWith('screen')) || sources[0];
                callback({ video: screenSource, audio: 'loopback' });
            } else {
                callback(null);
            }
        }).catch(err => {
            console.error("Failed to get desktop sources for screen share", err);
            callback(null);
        });
    });

    win.loadURL(backendUrl).catch((err) => {
        console.error(`Failed to load desktop app: ${err}`);
    });

    // Ensure renderer receives latest updater state after any (re)load.
    // Delay broadcast by 300ms to give the renderer time to register its
    // onUpdateState IPC listener before we push state.
    win.webContents.on('did-finish-load', () => {
        setTimeout(() => {
            if (!win.isDestroyed()) broadcastUpdateState();
        }, 300);
    });

    // Uncomment to debug
    // win.webContents.openDevTools();
}

app.commandLine.appendSwitch('disable-webrtc-hw-encoding'); // Sometime helps resolve codec mismatch behavior
app.commandLine.appendSwitch('log-level', '3'); // Silences standard Chromium warning logs (like SRTP transport unprotect logs which are benign timing issues)

app.whenReady().then(() => {
    ipcMain.handle('clipboard-write', (event, text) => {
        clipboard.writeText(text);
        return true;
    });

    ipcMain.handle('get-update-state', () => ({ ...updateState }));
    ipcMain.handle('check-for-updates-now', async () => {
        await runUpdateCheck('renderer-direct');
        return { ...updateState };
    });

    createWindow();

    // Configure Auto-Updater
    autoUpdater.autoDownload = false;
    autoUpdater.logger = console;

    autoUpdater.on('update-available', (info) => {
        updateState.status = 'available';
        updateState.info = info;
        updateState.error = null;
        broadcastUpdateState();
        const wins = BrowserWindow.getAllWindows();
        if (wins.length > 0) wins[0].webContents.send('update-available', info);
    });

    autoUpdater.on('update-not-available', (info) => {
        updateState.status = 'not-available';
        updateState.info = info || null;
        updateState.error = null;
        broadcastUpdateState();
    });

    autoUpdater.on('update-downloaded', (info) => {
        updateState.status = 'downloaded';
        updateState.info = info;
        updateState.error = null;
        broadcastUpdateState();
        const wins = BrowserWindow.getAllWindows();
        if (wins.length > 0) wins[0].webContents.send('update-downloaded', info);
    });

    autoUpdater.on('error', (err) => {
        updateState.status = 'error';
        updateState.error = err.message;
        broadcastUpdateState();
        const wins = BrowserWindow.getAllWindows();
        if (wins.length > 0) wins[0].webContents.send('update-error', err.message);
    });

    ipcMain.on('check-for-updates', () => {
        void runUpdateCheck('manual');
    });

    ipcMain.on('download-update', () => {
        if (installInProgress) return;
        updateState.status = 'downloading';
        updateState.error = null;
        broadcastUpdateState();
        autoUpdater.downloadUpdate();
    });

    ipcMain.on('quit-and-install', () => {
        installDownloadedUpdate();
    });

    // Check once on startup
    setTimeout(() => {
        void runUpdateCheck('startup');
    }, 5000);
    startPeriodicUpdateChecks();

    app.on('activate', () => {
        if (BrowserWindow.getAllWindows().length === 0) {
            createWindow();
        }
    });
});

app.on('window-all-closed', () => {
    if (process.platform !== 'darwin') {
        app.quit();
    }
});

app.on('before-quit', () => {
    if (periodicUpdateTimer) {
        clearInterval(periodicUpdateTimer);
        periodicUpdateTimer = null;
    }
});

function safeOrigin(value) {
    try {
        return new URL(value).origin;
    } catch (_) {
        return null;
    }
}