const codeDisplay = document.getElementById('code-display');
const codeContainer = document.getElementById('code-container');
const hiddenInput = document.getElementById('hidden-input');
const wpmDisplay = document.getElementById('wpm');
const accuracyDisplay = document.getElementById('accuracy');
const progressDisplay = document.getElementById('progress');
const langSelect = document.getElementById('lang-select');
const resultOverlay = document.getElementById('result-overlay');
const finalWpmDisplay = document.getElementById('final-wpm');
const finalAccuracyDisplay = document.getElementById('final-accuracy');
const restartBtn = document.getElementById('restart-btn');
const soundToggleBtn = document.getElementById('sound-toggle');
const soundIcon = document.getElementById('sound-icon');
const focusHint = document.getElementById('focus-hint');
const bestWpmDisplay = document.getElementById('best-wpm');

// Custom Code Elements
const customCodeBtn = document.getElementById('custom-code-btn');
const customModal = document.getElementById('custom-modal');
const customInput = document.getElementById('custom-input');
const customConfirm = document.getElementById('custom-confirm');
const customCancel = document.getElementById('custom-cancel');

// State
let currentCode = "";
let currentIndex = 0;
let startTime = null;
let timer = null;
let mistakes = 0;
let totalTyped = 0;
let isFinished = false;
let soundEnabled = localStorage.getItem('code-typing-sound-enabled') !== 'false'; // Default true
let audioCtx = null;
let bestWpm = parseInt(localStorage.getItem('code-typing-best-wpm') || '0');

// Initialize
async function init() {
    updateSoundIcon();
    bestWpmDisplay.textContent = bestWpm;
    
    await fetchLanguages();
    
    // Check if we just finished a custom game? No, always fetch new or use custom logic if implemented later.
    // For now, default to fetch snippet.
    fetchSnippet();
    
    setupEventListeners();
}

async function fetchLanguages() {
    try {
        const response = await fetch('/api/languages');
        const languages = await response.json();
        
        // Preserve selection if possible
        const currentSelection = langSelect.value;
        
        langSelect.innerHTML = '';
        languages.forEach(lang => {
            const option = document.createElement('option');
            option.value = lang;
            option.textContent = lang;
            // Style options (black text on white background for visibility in dropdown)
            option.className = "text-slate-900 bg-slate-200"; 
            langSelect.appendChild(option);
        });
        
        if (languages.includes(currentSelection)) {
            langSelect.value = currentSelection;
        }
    } catch (e) {
        console.error("Failed to fetch languages", e);
    }
}

async function fetchSnippet() {
    const lang = langSelect.value;
    try {
        const response = await fetch(`/api/snippet?lang=${lang}`);
        const data = await response.json();
        setupGame(data.code, data.language);
    } catch (e) {
        console.error("Failed to fetch snippet", e);
        setupGame("print('Hello World')", "Python");
    }
}

function setupGame(code, language) {
    // Reset state
    currentCode = code.replace(/\t/g, "    "); // Replace tabs with spaces
    currentIndex = 0;
    startTime = null;
    mistakes = 0;
    totalTyped = 0;
    isFinished = false;
    
    if (timer) clearInterval(timer);
    
    // Update UI
    wpmDisplay.textContent = '0';
    accuracyDisplay.textContent = '100%';
    progressDisplay.textContent = '0%';
    resultOverlay.classList.add('hidden');
    
    // Render Code
    renderCode();
    
    // Scroll to top
    codeContainer.scrollTop = 0;
    
    hiddenInput.value = '';
    hiddenInput.focus();
}

function renderCode() {
    codeDisplay.innerHTML = '';
    currentCode.split('').forEach((char, index) => {
        const span = document.createElement('span');
        span.innerText = char;
        if (index === 0) span.classList.add('cursor');
        
        // Visual tweak for spaces/newlines
        if (char === '\n') {
            span.innerHTML = '↵\n';
            span.classList.add('text-slate-700', 'opacity-50');
        }
        
        codeDisplay.appendChild(span);
    });
}

function startTimer() {
    if (!startTime) {
        startTime = new Date();
        timer = setInterval(updateStats, 1000);
        initAudio(); // Ensure audio context is ready
    }
}

function updateStats() {
    if (!startTime) return;
    
    const now = new Date();
    const timeDiff = (now - startTime) / 1000 / 60; // in minutes
    
    let wpm = 0;
    if (timeDiff > 0) {
        // WPM = (Characters / 5) / Minutes
        wpm = Math.round((currentIndex / 5) / timeDiff);
        wpmDisplay.textContent = wpm;
    }
    
    const accuracy = totalTyped === 0 ? 100 : Math.round(((totalTyped - mistakes) / totalTyped) * 100);
    accuracyDisplay.textContent = accuracy + '%';
    
    const progress = Math.round((currentIndex / currentCode.length) * 100);
    progressDisplay.textContent = progress + '%';
}

function finishGame() {
    isFinished = true;
    clearInterval(timer);
    updateStats();
    
    const finalWpm = parseInt(wpmDisplay.textContent);
    finalWpmDisplay.textContent = finalWpm;
    finalAccuracyDisplay.textContent = accuracyDisplay.textContent;
    
    // Update Best WPM
    if (finalWpm > bestWpm) {
        bestWpm = finalWpm;
        localStorage.setItem('code-typing-best-wpm', bestWpm);
        bestWpmDisplay.textContent = bestWpm;
        // Could play a victory sound here
    }
    
    resultOverlay.classList.remove('hidden');
    restartBtn.focus();
}

// Audio System
function initAudio() {
    if (!audioCtx) {
        const AudioContext = window.AudioContext || window.webkitAudioContext;
        audioCtx = new AudioContext();
    }
    if (audioCtx.state === 'suspended') {
        audioCtx.resume();
    }
}

function playClickSound() {
    if (!soundEnabled || !audioCtx) return;
    
    const osc = audioCtx.createOscillator();
    const gain = audioCtx.createGain();
    
    // Mechanical switch sound simulation (High pitch short burst)
    osc.type = 'triangle'; 
    osc.frequency.setValueAtTime(600, audioCtx.currentTime);
    osc.frequency.exponentialRampToValueAtTime(300, audioCtx.currentTime + 0.05);
    
    gain.gain.setValueAtTime(0.05, audioCtx.currentTime);
    gain.gain.exponentialRampToValueAtTime(0.001, audioCtx.currentTime + 0.05);
    
    osc.connect(gain);
    gain.connect(audioCtx.destination);
    
    osc.start();
    osc.stop(audioCtx.currentTime + 0.05);
}

function playErrorSound() {
    if (!soundEnabled || !audioCtx) return;
    
    const osc = audioCtx.createOscillator();
    const gain = audioCtx.createGain();
    
    // Low thud
    osc.type = 'sine'; 
    osc.frequency.setValueAtTime(150, audioCtx.currentTime);
    osc.frequency.exponentialRampToValueAtTime(50, audioCtx.currentTime + 0.1);
    
    gain.gain.setValueAtTime(0.1, audioCtx.currentTime);
    gain.gain.exponentialRampToValueAtTime(0.001, audioCtx.currentTime + 0.1);
    
    osc.connect(gain);
    gain.connect(audioCtx.destination);
    
    osc.start();
    osc.stop(audioCtx.currentTime + 0.1);
}

function updateSoundIcon() {
    soundIcon.textContent = soundEnabled ? '🔊' : '🔇';
    soundToggleBtn.classList.toggle('text-blue-400', soundEnabled);
    soundToggleBtn.classList.toggle('text-slate-500', !soundEnabled);
}

// Event Listeners
function setupEventListeners() {
    
    // Focus management
    document.addEventListener('click', (e) => {
        // Don't autofocus if clicking on buttons or modal
        if (e.target.closest('button') || e.target.closest('select') || e.target.closest('textarea') || e.target.closest('#custom-modal')) return;
        
        if (!isFinished) {
            hiddenInput.focus();
            initAudio(); // Initialize audio on first user interaction
        }
    });

    hiddenInput.addEventListener('blur', () => {
        if (!isFinished) focusHint.classList.remove('opacity-0');
    });

    hiddenInput.addEventListener('focus', () => {
        focusHint.classList.add('opacity-0');
    });

    // Language Change
    langSelect.addEventListener('change', () => {
        fetchSnippet();
        hiddenInput.focus();
    });

    // Sound Toggle
    soundToggleBtn.addEventListener('click', () => {
        soundEnabled = !soundEnabled;
        localStorage.setItem('code-typing-sound-enabled', soundEnabled);
        updateSoundIcon();
        hiddenInput.focus();
    });

    // Custom Code Logic
    customCodeBtn.addEventListener('click', () => {
        customModal.classList.remove('hidden');
        customInput.focus();
    });

    customCancel.addEventListener('click', () => {
        customModal.classList.add('hidden');
        hiddenInput.focus();
    });

    customConfirm.addEventListener('click', () => {
        const code = customInput.value.trim();
        if (code) {
            setupGame(code, "Custom");
            customModal.classList.add('hidden');
        }
    });

    // Restart
    restartBtn.addEventListener('click', () => {
        if (langSelect.value === 'Custom') {
             // Rerun the custom code
             setupGame(currentCode, "Custom");
        } else {
             fetchSnippet();
        }
    });

    // Typing Logic
    window.addEventListener('keydown', handleKeydown);
}

function handleKeydown(e) {
    if (customModal.classList.contains('hidden') === false) return; // Don't type if modal is open

    if (isFinished) {
        if (e.key === 'Enter') {
            restartBtn.click();
        }
        return;
    }
    
    // Shortcuts
    if (e.key === 'Tab') {
        e.preventDefault();
        fetchSnippet(); // Quick restart
        return;
    }
    
    // Prevent default scrolling for Space
    if (e.key === ' ' && e.target === document.body) {
        e.preventDefault();
    }

    // Ignore non-character keys
    if (e.key.length > 1 && e.key !== 'Enter' && e.key !== 'Backspace') return;
    
    hiddenInput.focus();
    startTimer();
    
    const charToType = currentCode[currentIndex];
    const spans = codeDisplay.querySelectorAll('span');
    
    if (e.key === 'Backspace') {
        if (currentIndex > 0) {
            currentIndex--;
            const span = spans[currentIndex];
            span.className = ''; // Reset classes
            
            // Restore visual tweak for newline
            if (span.innerText.includes('↵')) {
                span.classList.add('text-slate-700', 'opacity-50');
            }
            
            span.classList.add('cursor');
            
            if (currentIndex + 1 < spans.length) {
                spans[currentIndex + 1].classList.remove('cursor');
            }
        }
        return;
    }
    
    let typedChar = e.key;
    if (typedChar === 'Enter') typedChar = '\n';
    
    totalTyped++;
    
    const currentSpan = spans[currentIndex];
    
    if (typedChar === charToType) {
        playClickSound();
        currentSpan.classList.add('text-emerald-400', 'opacity-100'); 
        currentSpan.classList.remove('text-red-500', 'bg-red-900/50', 'text-slate-700', 'opacity-50', 'cursor');
        
        currentIndex++;
        
        if (currentIndex >= currentCode.length) {
            finishGame();
        } else {
            spans[currentIndex].classList.add('cursor');
            
            // Auto-scroll logic
            const cursorRect = spans[currentIndex].getBoundingClientRect();
            const containerRect = codeContainer.getBoundingClientRect();
            
            // Keep cursor in the middle third of the screen vertically
            const relativeTop = cursorRect.top - containerRect.top;
            if (relativeTop > containerRect.height * 0.6) {
                codeContainer.scrollTop += 30; // Smooth scroll handled by CSS
            }
        }
    } else {
        mistakes++;
        playErrorSound();
        currentSpan.classList.add('text-red-500', 'bg-red-900/50', 'opacity-100');
    }
}

// Start
init();