(function() {
    'use strict';

    var audioContext = null;
    var audioUnlocked = false;
    var bgMusicActive = true;
    var sfxEnabled = true;
    var bgMusicSource = null;
    var bgMusicGainNode = null;

    function getAudioContext() {
        if (!audioContext) {
            audioContext = new (window.AudioContext || window.webkitAudioContext)();
        }
        return audioContext;
    }

    function unlockAudio() {
        if (audioUnlocked) return;
        var ctx = getAudioContext();
        if (!ctx) return;
        if (ctx.state === 'suspended') {
            ctx.resume().then(function() {
                audioUnlocked = true;
            }).catch(function() {});
        } else {
            audioUnlocked = true;
        }
    }

    function canPlayAudio() {
        return audioUnlocked;
    }

    function playSlapSound() {
        if (!audioUnlocked) return;
        var ctx = getAudioContext();
        if (!ctx) return;
        var buffer = ctx.createBuffer(1, ctx.sampleRate * 0.05, ctx.sampleRate);
        var data = buffer.getChannelData(0);
        for (var i = 0; i < data.length; i++) {
            data[i] = (Math.random() * 2 - 1) * Math.pow(1 - i / data.length, 3);
        }
        var source = ctx.createBufferSource();
        source.buffer = buffer;
        var gain = ctx.createGain();
        gain.gain.setValueAtTime(0.4, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 0.05);
        source.connect(gain);
        gain.connect(ctx.destination);
        source.start();
    }

    function playAdminBipSound() {
        var ctx = getAudioContext();
        if (!ctx) return;
        var osc = ctx.createOscillator();
        osc.type = 'sine';
        osc.frequency.setValueAtTime(880, ctx.currentTime);
        var gain = ctx.createGain();
        gain.gain.setValueAtTime(0.3, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 0.1);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + 0.1);
    }

    function playNukeAlarmSound() {
        if (!audioUnlocked) return;
        var ctx = getAudioContext();
        if (!ctx) return;
        var osc = ctx.createOscillator();
        osc.type = 'sawtooth';
        osc.frequency.setValueAtTime(400, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(80, ctx.currentTime + 1.5);
        var gain = ctx.createGain();
        gain.gain.setValueAtTime(0.5, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 1.5);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + 1.5);
    }

    function loadSciFiBackgroundLoop() {
        var ctx = getAudioContext();
        if (!ctx) return null;

        var audioUrl = '/custom_assets/sound/menu_ambient.mp3';

        // Use HTML5 Audio element for streaming with volume control
        var audioEl = new Audio();
        audioEl.src = audioUrl;
        audioEl.loop = true;
        audioEl.preload = 'auto';

        // Create a MediaElementAudioSourceNode for gain control
        bgMusicSource = ctx.createMediaElementSource(audioEl);

        bgMusicGainNode = ctx.createGain();
        var savedVolume = localStorage.getItem('dw_volume');
        var masterPct = savedVolume ? parseInt(savedVolume, 10) / 100 : 0.55;
        bgMusicGainNode.gain.value = masterPct;

        bgMusicSource.connect(bgMusicGainNode);
        bgMusicGainNode.connect(ctx.destination);

        // Handle load errors - try fallback procedural loop
        audioEl.onerror = function(e) {
            console.warn('[AudioEngine] menu_ambient.mp3 failed to load:', e);
            // Fallback: generate procedural ambient loop
            generateProceduralAmbient();
        };

        audioEl.onloadedmetadata = function() {
            if (bgMusicActive) {
                audioEl.play().catch(function(err) {
                    console.warn('[AudioEngine] Autoplay blocked:', err);
                });
            }
        };

        // Store reference for volume updates
        window._bgAudioElement = audioEl;

        // Start playing if music is active
        if (bgMusicActive) {
            audioEl.play().catch(function(err) {
                console.warn('[AudioEngine] Autoplay blocked:', err);
            });
        }
    }

    function generateProceduralAmbient() {
        var ctx = getAudioContext();
        if (!ctx) return;
        if (bgMusicSource) return;

        var bufferSize = ctx.sampleRate * 2; // 2 second loop
        var buffer = ctx.createBuffer(2, bufferSize, ctx.sampleRate);
        var t = 0;
        for (var ch = 0; ch < 2; ch++) {
            var data = buffer.getChannelData(ch);
            for (var i = 0; i < bufferSize; i++) {
                t = i / ctx.sampleRate;
                // Low ambient drone with slow detuning
                var freq = 80 + 20 * Math.sin(t * 0.05);
                var noise = Math.random() * 2 - 1;
                var envelope = Math.exp(-t * 0.5);
                data[i] = (Math.sin(2 * Math.PI * freq * t) * 0.1 + noise * 0.02) * envelope;
            }
        }

        bgMusicSource = ctx.createBufferSource();
        bgMusicSource.buffer = buffer;
        bgMusicSource.loop = true;

        bgMusicGainNode = ctx.createGain();
        var savedVolume = localStorage.getItem('dw_volume');
        var masterPct = savedVolume ? parseInt(savedVolume, 10) / 100 : 0.55;
        bgMusicGainNode.gain.value = masterPct;

        bgMusicSource.connect(bgMusicGainNode);
        bgMusicGainNode.connect(ctx.destination);
        bgMusicSource.start(0);
    }

    function startBackgroundMusic() {
        if (!bgMusicActive) return;
        if (!audioUnlocked) return;
        var ctx = getAudioContext();
        if (!ctx || bgMusicSource) return;
        loadSciFiBackgroundLoop();
    }

    function stopBackgroundMusic() {
        if (bgMusicSource) {
            try { bgMusicSource.stop(); } catch(e) {}
            bgMusicSource = null;
        }
        if (bgMusicGainNode) {
            bgMusicGainNode.disconnect();
            bgMusicGainNode = null;
        }
    }

    function applyMasterVolume() {
        // Scale background music by master volume * music volume slider
        if (bgMusicGainNode) {
            var savedVolume = localStorage.getItem('dw_volume');
            var masterPct = savedVolume ? parseInt(savedVolume, 10) / 100 : 0.8;
            var savedMusicVol = localStorage.getItem('dw_music_vol');
            var musicPct = savedMusicVol ? parseInt(savedMusicVol, 10) / 100 : 0.20;
            var targetVol = masterPct * musicPct;
            bgMusicGainNode.gain.setTargetAtTime(Math.max(0, targetVol), getAudioContext().currentTime, 0.02);
        }
    }

    function setMusicVolume(volPct) {
        localStorage.setItem('dw_music_vol', String(volPct));
        localStorage.setItem('dw_volume', String(volPct));
        if (bgMusicGainNode && bgMusicGainNode.gain) {
            var ctx = getAudioContext();
            if (ctx) {
                var targetVol = volPct / 100;
                bgMusicGainNode.gain.setTargetAtTime(targetVol, ctx.currentTime, 0.02);
            }
        }
        // Also update the master volume slider UI if present
        var masterSlider = document.getElementById('volume-slider');
        if (masterSlider) masterSlider.value = volPct;
        var masterLabel = document.getElementById('volume-value-label');
        if (masterLabel) masterLabel.innerText = volPct + '%';
    }

    function toggleBackgroundMusic(enabled) {
        bgMusicActive = enabled;
        var label = document.getElementById('music-label');
        if (label) label.textContent = enabled ? 'ON' : 'OFF';
        localStorage.setItem('dw_music', enabled ? '1' : '0');
        if (enabled) {
            startBackgroundMusic();
        } else {
            stopBackgroundMusic();
        }
    }

    function toggleSfx(enabled) {
        sfxEnabled = enabled;
        var label = document.getElementById('sfx-label');
        if (label) label.textContent = enabled ? 'ON' : 'OFF';
        localStorage.setItem('dw_sfx', enabled ? '1' : '0');
    }

    function playHoverSfx() {
        if (!sfxEnabled || !audioUnlocked) return;
        var ctx = getAudioContext();
        if (!ctx) return;
        var osc = ctx.createOscillator();
        osc.type = 'sine';
        osc.frequency.setValueAtTime(660, ctx.currentTime);
        var gain = ctx.createGain();
        gain.gain.setValueAtTime(0.1, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 0.15);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + 0.15);
    }

    function playClickSfx() {
        if (!sfxEnabled || !audioUnlocked) return;
        var ctx = getAudioContext();
        if (!ctx) return;
        var osc = ctx.createOscillator();
        osc.type = 'sawtooth';
        osc.frequency.setValueAtTime(220, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(55, ctx.currentTime + 0.2);
        var gain = ctx.createGain();
        gain.gain.setValueAtTime(0.15, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 0.2);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + 0.2);
    }

    function playExplosionSound() {
        if (!sfxEnabled || !audioUnlocked) return;
        var ctx = getAudioContext();
        if (!ctx) return;
        var osc = ctx.createOscillator();
        osc.type = 'sawtooth';
        osc.frequency.setValueAtTime(150, ctx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(30, ctx.currentTime + 0.5);
        var gain = ctx.createGain();
        gain.gain.setValueAtTime(0.4, ctx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, ctx.currentTime + 0.5);
        osc.connect(gain);
        gain.connect(ctx.destination);
        osc.start();
        osc.stop(ctx.currentTime + 0.5);
    }

    function loadAudioPreferences() {
        var savedMusic = localStorage.getItem('dw_music');
        bgMusicActive = savedMusic !== '0';
        var musicToggle = document.getElementById('music-toggle');
        if (musicToggle) musicToggle.checked = bgMusicActive;
        var musicLabel = document.getElementById('music-label');
        if (musicLabel) musicLabel.textContent = bgMusicActive ? 'ON' : 'OFF';

        var savedSfx = localStorage.getItem('dw_sfx');
        sfxEnabled = savedSfx !== '0';
        var sfxToggle = document.getElementById('sfx-toggle');
        if (sfxToggle) sfxToggle.checked = sfxEnabled;
        var sfxLabel = document.getElementById('sfx-label');
        if (sfxLabel) sfxLabel.textContent = sfxEnabled ? 'ON' : 'OFF';

        // Restore music volume slider
        var savedMusicVol = localStorage.getItem('dw_music_vol');
        var musicVol = savedMusicVol ? parseInt(savedMusicVol, 10) : 55;
        var musicVolSlider = document.getElementById('music-volume');
        if (musicVolSlider) musicVolSlider.value = musicVol;
        var musicVolLabel = document.getElementById('music-volume-value-label');
        if (musicVolLabel) musicVolLabel.textContent = musicVol + '%';

        // Also set master volume slider to 55% by default
        var savedMasterVol = localStorage.getItem('dw_volume');
        var masterVol = savedMasterVol ? parseInt(savedMasterVol, 10) : 55;
        var masterSlider = document.getElementById('volume-slider');
        if (masterSlider) masterSlider.value = masterVol;
        var masterLabel = document.getElementById('volume-value-label');
        if (masterLabel) masterLabel.textContent = masterVol + '%';

        // Apply master volume to background loop if already playing
        applyMasterVolume();
    }

    window.AudioEngine = {
        getAudioContext: getAudioContext,
        unlockAudio: unlockAudio,
        canPlayAudio: canPlayAudio,
        playSlapSound: playSlapSound,
        playAdminBipSound: playAdminBipSound,
        playNukeAlarmSound: playNukeAlarmSound,
        startBackgroundMusic: startBackgroundMusic,
        stopBackgroundMusic: stopBackgroundMusic,
        toggleBackgroundMusic: toggleBackgroundMusic,
        toggleSfx: toggleSfx,
        playHoverSfx: playHoverSfx,
        playClickSfx: playClickSfx,
        playExplosionSound: playExplosionSound,
        loadAudioPreferences: loadAudioPreferences,
        applyMasterVolume: applyMasterVolume,
        setMusicVolume: setMusicVolume,
        isMusicActive: function() { return bgMusicActive; },
        isSfxEnabled: function() { return sfxEnabled; }
    };
})();