/* Atlus — Core shell: app switching, WebSocket stats, panel updates */
(function () {
    'use strict';

    // =====================================================================
    // Auth guard
    // =====================================================================
    const TOKEN = localStorage.getItem('atlus_token');
    const USER = localStorage.getItem('atlus_user');
    if (!TOKEN) {
        window.location.href = '/';
        return;
    }

    // =====================================================================
    // Globals
    // =====================================================================
    window.Atlus = {
        token: TOKEN,
        user: USER,
        apps: {},          // registered app modules { id: { init, destroy, title } }
        openApps: [],      // ordered list of open app ids
        activeApp: null,   // currently focused app id
        layout: 'single',  // 'single' | 'split'
        secondaryApp: null,

        /** Authenticated fetch wrapper */
        async apiFetch(url, opts = {}) {
            opts.headers = Object.assign({ 'Authorization': `Bearer ${TOKEN}` }, opts.headers || {});
            if (opts.body && typeof opts.body === 'object' && !(opts.body instanceof FormData)) {
                opts.headers['Content-Type'] = 'application/json';
                opts.body = JSON.stringify(opts.body);
            }
            const res = await fetch(url, opts);
            if (res.status === 401) {
                localStorage.removeItem('atlus_token');
                localStorage.removeItem('atlus_user');
                window.location.href = '/';
                return;
            }
            return res;
        },

        /** Create an authenticated WebSocket URL */
        wsUrl(path) {
            const proto = location.protocol === 'https:' ? 'wss:' : 'ws:';
            const sep = path.includes('?') ? '&' : '?';
            return `${proto}//${location.host}${path}${sep}token=${TOKEN}`;
        },

        /** Register an app module */
        registerApp(id, module) {
            this.apps[id] = module;
        },

        /** Format bytes to human readable */
        formatBytes(bytes) {
            if (bytes === 0) return '0 B';
            const k = 1024;
            const sizes = ['B', 'KB', 'MB', 'GB', 'TB'];
            const i = Math.floor(Math.log(bytes) / Math.log(k));
            return parseFloat((bytes / Math.pow(k, i)).toFixed(1)) + ' ' + sizes[i];
        },
    };

    // =====================================================================
    // DOM refs
    // =====================================================================
    const $ = (sel) => document.querySelector(sel);
    const $$ = (sel) => document.querySelectorAll(sel);

    const stageTabs = $('#stageTabs');
    const paneA = $('#paneContentA');
    const paneB = $('#paneContentB');
    const paneTitleA = $('#paneTitleA');
    const paneTitleB = $('#paneTitleB');
    const paneBEl = $('#paneB');
    const welcomeScreen = $('#welcomeScreen');

    // =====================================================================
    // App switching
    // =====================================================================

    function openApp(appId) {
        const app = Atlus.apps[appId];
        if (!app) return;

        // Already open — just focus
        if (Atlus.openApps.includes(appId)) {
            focusApp(appId);
            return;
        }

        Atlus.openApps.push(appId);
        addTab(appId, app.title || appId);

        // Create app container
        const container = document.createElement('div');
        container.className = 'app-view';
        container.id = `app-${appId}`;
        container.style.display = 'none';
        paneA.appendChild(container);

        // Initialize app
        if (app.init) app.init(container);

        focusApp(appId);
        saveDesktopState();
    }

    function focusApp(appId) {
        if (welcomeScreen) welcomeScreen.style.display = 'none';

        // Hide all apps in pane A
        paneA.querySelectorAll('.app-view').forEach(el => el.style.display = 'none');

        // Show target
        const target = $(`#app-${appId}`);
        if (target) target.style.display = 'flex';

        // Update tabs
        stageTabs.querySelectorAll('.stage-tab').forEach(tab => {
            tab.classList.toggle('active', tab.dataset.app === appId);
        });

        // Update dock
        $$('.dock-item[data-app]').forEach(item => {
            item.classList.toggle('active', item.dataset.app === appId);
        });

        // Update titlebar
        const app = Atlus.apps[appId];
        paneTitleA.textContent = app ? app.title : appId;

        Atlus.activeApp = appId;

        // Notify app it got focus
        if (app && app.onFocus) app.onFocus();

        saveDesktopState();
    }

    function closeApp(appId) {
        const app = Atlus.apps[appId];
        if (app && app.destroy) app.destroy();

        // Remove DOM
        const container = $(`#app-${appId}`);
        if (container) container.remove();

        // Remove from open list
        Atlus.openApps = Atlus.openApps.filter(id => id !== appId);

        // Remove tab
        const tab = stageTabs.querySelector(`.stage-tab[data-app="${appId}"]`);
        if (tab) tab.remove();

        // Update dock
        const dockItem = $(`.dock-item[data-app="${appId}"]`);
        if (dockItem) dockItem.classList.remove('active');

        // Focus next app or show welcome
        if (Atlus.activeApp === appId) {
            if (Atlus.openApps.length > 0) {
                focusApp(Atlus.openApps[Atlus.openApps.length - 1]);
            } else {
                Atlus.activeApp = null;
                paneTitleA.textContent = '';
                if (welcomeScreen) welcomeScreen.style.display = 'flex';
            }
        }
        saveDesktopState();
    }

    function addTab(appId, title) {
        const tab = document.createElement('button');
        tab.className = 'stage-tab';
        tab.dataset.app = appId;
        tab.innerHTML = `<span>${title}</span><span class="tab-close">&times;</span>`;
        tab.addEventListener('click', (e) => {
            if (e.target.classList.contains('tab-close')) {
                closeApp(appId);
            } else {
                focusApp(appId);
            }
        });
        stageTabs.appendChild(tab);
    }

    // =====================================================================
    // Dock clicks
    // =====================================================================
    $$('.dock-item[data-app]').forEach(item => {
        item.addEventListener('click', () => openApp(item.dataset.app));
    });

    // Layout toggle
    $$('.layout-btn').forEach(btn => {
        btn.addEventListener('click', () => {
            const layout = btn.dataset.layout;
            Atlus.layout = layout;
            $$('.layout-btn').forEach(b => b.classList.toggle('active', b.dataset.layout === layout));
            paneBEl.classList.toggle('hidden', layout === 'single');
        });
    });

    // =====================================================================
    // System menu
    // =====================================================================
    const systemMenu = $('#systemMenu');
    const logoBtn = $('.dock-logo');

    logoBtn.addEventListener('click', () => {
        systemMenu.classList.toggle('hidden');
    });

    systemMenu.addEventListener('click', async (e) => {
        const action = e.target.dataset.action;
        if (!action) {
            // Clicked backdrop
            if (e.target === systemMenu) systemMenu.classList.add('hidden');
            return;
        }
        systemMenu.classList.add('hidden');

        if (action === 'logout') {
            await Atlus.apiFetch('/api/auth/logout', { method: 'POST' });
            localStorage.removeItem('atlus_token');
            localStorage.removeItem('atlus_user');
            window.location.href = '/';
        }
    });

    // =====================================================================
    // Panel — Clock
    // =====================================================================
    function updateClock() {
        const now = new Date();
        $('#panelDate').textContent = now.toLocaleDateString('en-US', {
            weekday: 'short', month: 'short', day: 'numeric'
        });
        $('#panelTime').textContent = now.toLocaleTimeString('en-US', {
            hour: '2-digit', minute: '2-digit', hour12: false
        });
    }
    updateClock();
    setInterval(updateClock, 1000);

    // =====================================================================
    // Panel — WebSocket stats
    // =====================================================================
    let statsWs = null;

    function connectStats() {
        statsWs = new WebSocket(Atlus.wsUrl('/api/stats/ws'));

        statsWs.onmessage = (e) => {
            const data = JSON.parse(e.data);
            updatePanel(data);
        };

        statsWs.onclose = () => {
            setTimeout(connectStats, 3000);
        };

        statsWs.onerror = () => {
            statsWs.close();
        };
    }

    function updatePanel(data) {
        // CPU
        const cpuPct = Math.round(data.cpu_percent);
        $('#statCpu').textContent = cpuPct + '%';
        updateBar($('#statCpuBar'), cpuPct);

        // Memory
        const memPct = Math.round(data.memory.percent);
        const memUsed = Atlus.formatBytes(data.memory.used);
        const memTotal = Atlus.formatBytes(data.memory.total);
        $('#statMem').textContent = `${memUsed} / ${memTotal}`;
        updateBar($('#statMemBar'), memPct);

        // Disk
        const diskPct = Math.round(data.disk.percent);
        $('#statDisk').textContent = diskPct + '%';
        updateBar($('#statDiskBar'), diskPct);

        // Temp
        if (data.cpu_temp !== null) {
            const temp = Math.round(data.cpu_temp);
            $('#statTemp').textContent = temp + '\u00B0C';
            // Temp bar: 0-85°C range
            const tempPct = Math.min(100, Math.round((temp / 85) * 100));
            updateBar($('#statTempBar'), tempPct);
        }

        // Network
        const netContainer = $('#panelNetwork');
        netContainer.innerHTML = '';
        const ifaces = data.network.interfaces;
        for (const [name, info] of Object.entries(ifaces)) {
            const item = document.createElement('div');
            item.className = 'panel-net-item';
            item.innerHTML = `
                <span class="panel-net-dot ${info.up ? 'up' : 'down'}"></span>
                <span class="panel-net-name">${name}</span>
                <span class="panel-net-ip">${info.ipv4 || '--'}</span>
            `;
            netContainer.appendChild(item);
        }
    }

    function updateBar(barEl, percent) {
        barEl.style.width = percent + '%';
        barEl.className = 'stat-bar-fill';
        if (percent >= 90) barEl.classList.add('crit');
        else if (percent >= 70) barEl.classList.add('warn');
    }

    // =====================================================================
    // Panel — Hostname
    // =====================================================================
    async function loadHostname() {
        try {
            const res = await Atlus.apiFetch('/api/settings/system');
            if (res.ok) {
                const data = await res.json();
                $('#panelHostname').textContent = data.hostname;
            }
        } catch (e) { /* ignore */ }
    }

    // =====================================================================
    // Panel — Services
    // =====================================================================
    async function loadPanelServices() {
        try {
            const cfgRes = await Atlus.apiFetch('/api/settings');
            if (!cfgRes.ok) return;
            const cfg = await cfgRes.json();
            const panelUnits = cfg.panel_services || [];

            if (panelUnits.length === 0) {
                $('#panelServices').innerHTML = '<div style="color:var(--text-muted);font-size:12px;font-family:var(--font-mono);padding:4px 0;">No services pinned</div>';
                return;
            }

            const container = $('#panelServices');
            container.innerHTML = '';

            for (const unit of panelUnits) {
                const res = await Atlus.apiFetch(`/api/services/${unit}`);
                if (!res.ok) continue;
                const svc = await res.json();
                const isActive = svc.active === 'active';
                const name = svc.name || unit.replace('.service', '');

                const row = document.createElement('div');
                row.className = 'panel-service-row';
                row.innerHTML = `
                    <button class="service-toggle ${isActive ? 'on' : ''}" data-unit="${unit}"></button>
                    <span class="service-name">${name}</span>
                    <button class="service-open" data-unit="${unit}">&nearr;</button>
                `;
                container.appendChild(row);
            }

            // Toggle handlers
            container.querySelectorAll('.service-toggle').forEach(btn => {
                btn.addEventListener('click', async () => {
                    const unit = btn.dataset.unit;
                    const action = btn.classList.contains('on') ? 'stop' : 'start';
                    await Atlus.apiFetch('/api/services/action', {
                        method: 'POST',
                        body: { unit, action },
                    });
                    loadPanelServices();
                });
            });

            // Open handlers
            container.querySelectorAll('.service-open').forEach(btn => {
                btn.addEventListener('click', () => {
                    openApp('services');
                });
            });
        } catch (e) { /* ignore */ }
    }

    // =====================================================================
    // Panel — Update checker
    // =====================================================================

    async function checkForUpdates() {
        const panel = $('#panelUpdates');
        if (!panel) return;
        try {
            const res = await Atlus.apiFetch('/api/updates/check');
            if (!res || !res.ok) {
                // Show error state if endpoint fails (503 = git not found, etc.)
                panel.classList.remove('hidden');
                const status = res ? res.status : 0;
                const detail = res ? await res.json().catch(() => ({})) : {};
                panel.innerHTML = `
                    <div class="update-status">
                        <span class="update-status-dot" style="background:var(--text-muted);"></span>
                        <div class="update-status-text">
                            <div class="update-status-title">Updates unavailable</div>
                            <div class="update-status-hash">${detail.detail || 'Could not check'}</div>
                        </div>
                    </div>
                `;
                return;
            }
            const data = await res.json();

            panel.classList.remove('hidden');

            if (data.error) {
                showUpdateError(panel, data);
            } else if (data.available && data.behind_count > 0) {
                showUpdateAvailable(panel, data);
            } else {
                showUpToDate(panel, data);
            }
        } catch (e) {
            console.warn('Update check failed:', e);
        }
    }

    function showUpToDate(panel, data) {
        panel.innerHTML = `
            <div class="update-status update-current">
                <span class="update-status-dot current"></span>
                <div class="update-status-text">
                    <div class="update-status-title">Up to date</div>
                    <div class="update-status-hash">${data.local_hash}</div>
                </div>
            </div>
        `;
    }

    function showUpdateError(panel, data) {
        panel.innerHTML = `
            <div class="update-status">
                <span class="update-status-dot" style="background:var(--status-red);"></span>
                <div class="update-status-text">
                    <div class="update-status-title">Check failed</div>
                    <div class="update-status-hash">${data.error}</div>
                </div>
            </div>
        `;
    }

    function showUpdateAvailable(panel, data) {
        panel.innerHTML = `
            <div class="update-status update-available">
                <span class="update-status-dot available"></span>
                <div class="update-status-text">
                    <div class="update-status-title">Update available</div>
                    <div class="update-status-hash">${data.behind_count} commit${data.behind_count !== 1 ? 's' : ''} behind (${data.remote_hash})</div>
                </div>
                <button class="update-install-btn" title="Install update">Update</button>
            </div>
        `;

        panel.querySelector('.update-install-btn').addEventListener('click', async (e) => {
            const btn = e.target;
            btn.disabled = true;
            btn.textContent = 'Updating…';

            try {
                const res = await Atlus.apiFetch('/api/updates/apply', { method: 'POST' });
                if (res.ok) {
                    btn.textContent = 'Restarting…';
                    setTimeout(() => attemptReload(0), 4000);
                } else {
                    btn.textContent = 'Failed';
                    btn.disabled = false;
                }
            } catch (e) {
                // Connection lost = server restarting
                btn.textContent = 'Restarting…';
                setTimeout(() => attemptReload(0), 4000);
            }
        });
    }

    function attemptReload(attempt) {
        if (attempt > 10) return; // Give up after ~30s
        fetch('/desktop', { method: 'HEAD' })
            .then(() => window.location.reload())
            .catch(() => setTimeout(() => attemptReload(attempt + 1), 3000));
    }

    // =====================================================================
    // Panel — Desktop Apps (X11 tray)
    // =====================================================================

    async function pollDesktopApps() {
        const trayPanel = $('#panelTray');
        const trayList = $('#panelTrayApps');
        if (!trayPanel || !trayList) return;

        try {
            const res = await Atlus.apiFetch('/api/display/apps');
            if (!res || !res.ok) {
                trayPanel.classList.add('hidden');
                return;
            }
            const data = await res.json();
            const apps = data.apps || [];

            if (apps.length === 0) {
                trayPanel.classList.add('hidden');
                return;
            }

            trayPanel.classList.remove('hidden');
            trayList.innerHTML = '';

            apps.forEach(app => {
                const row = document.createElement('div');
                row.className = 'panel-tray-item';
                row.innerHTML = `
                    <span class="panel-tray-dot ${app.alive ? 'running' : 'stopped'}"></span>
                    <span class="panel-tray-name">${app.name}</span>
                    <button class="panel-tray-open" title="Open Display">&nearr;</button>
                `;
                // Click app name or open button → switch to display app
                row.querySelector('.panel-tray-open').addEventListener('click', () => {
                    openApp('xdisplay');
                });
                row.querySelector('.panel-tray-name').addEventListener('click', () => {
                    openApp('xdisplay');
                });
                trayList.appendChild(row);
            });
        } catch (e) {
            // Display API not available (no X11 deps) — hide tray
            trayPanel.classList.add('hidden');
        }
    }

    // =====================================================================
    // Session persistence — save/restore desktop state
    // =====================================================================
    let _saveTimer = null;

    function saveDesktopState() {
        // Debounce — save at most once per second
        if (_saveTimer) clearTimeout(_saveTimer);
        _saveTimer = setTimeout(_doSaveState, 1000);
    }

    function _doSaveState() {
        const termApp = Atlus.apps.terminal;
        const terminalTabs = (termApp && termApp.getTerminalIds)
            ? termApp.getTerminalIds()
            : [];

        const state = {
            open_apps: Atlus.openApps.slice(),
            active_app: Atlus.activeApp,
            terminal_tabs: terminalTabs,
        };

        Atlus.apiFetch('/api/session/state', {
            method: 'PUT',
            body: state,
        }).catch(() => {}); // best-effort
    }

    async function restoreSession() {
        try {
            const res = await Atlus.apiFetch('/api/session');
            if (!res || !res.ok) return;
            const session = await res.json();
            const state = session.desktop_state || {};
            const openApps = state.open_apps || [];
            const activeApp = state.active_app;
            const serverTerminals = session.terminals || {};

            // Store terminal info for the terminal app to use when it inits
            Atlus._restoredTerminals = Object.values(serverTerminals);
            Atlus._restoredTerminalTabs = state.terminal_tabs || [];

            // Re-open apps in saved order
            for (const appId of openApps) {
                if (Atlus.apps[appId]) {
                    openApp(appId);
                }
            }

            // Focus the previously active app
            if (activeApp && Atlus.openApps.includes(activeApp)) {
                focusApp(activeApp);
            }
        } catch (e) {
            // First visit or server error — no session to restore
        }
    }

    // Save state on visibility change (tab switch / minimize)
    document.addEventListener('visibilitychange', () => {
        if (document.visibilityState === 'hidden') {
            _doSaveState(); // immediate save on hide
        }
    });

    // Save state before unload (use sendBeacon for reliability)
    window.addEventListener('beforeunload', () => {
        const termApp = Atlus.apps.terminal;
        const terminalTabs = (termApp && termApp.getTerminalIds)
            ? termApp.getTerminalIds() : [];
        const state = {
            open_apps: Atlus.openApps.slice(),
            active_app: Atlus.activeApp,
            terminal_tabs: terminalTabs,
        };
        const blob = new Blob([JSON.stringify(state)], { type: 'application/json' });
        navigator.sendBeacon('/api/session/state?token=' + TOKEN, blob);
    });

    // =====================================================================
    // Init
    // =====================================================================
    loadHostname();
    loadPanelServices();
    connectStats();
    checkForUpdates();
    pollDesktopApps();

    // Refresh services panel periodically
    setInterval(loadPanelServices, 30000);

    // Check for updates every 60 seconds
    setInterval(checkForUpdates, 60 * 1000);

    // Poll desktop apps every 5 seconds
    setInterval(pollDesktopApps, 5000);

    // Expose for app modules
    window.Atlus.openApp = openApp;
    window.Atlus.closeApp = closeApp;
    window.Atlus.focusApp = focusApp;
    window.Atlus.saveDesktopState = saveDesktopState;

    // Restore previous session (after a brief delay to let app modules register)
    setTimeout(restoreSession, 100);
})();