/**
 * Interactive Reader Module
 * Handles text display, word highlighting, and audio sync
 */

// ==========================================
// READER STATE VARIABLES
// ==========================================

let allWordSpans = [];
let wordMap = [];
let sentenceData = [];
let lastHighlightedWordSpan = null;
let lastHighlightedSentenceSpans = [];

// ==========================================
// READER INITIALIZATION
// ==========================================

/**
 * Initialize reader with markdown text
 * @param {string} markdownText - Text content in markdown format
 */
function initReader(markdownText) {
    const container = document.getElementById('readerContent');
    container.innerHTML = '';
    allWordSpans = [];
    wordMap = [];
    
    const html = marked.parse(markdownText || '', { breaks: true });
    const tempDiv = document.createElement('div');
    tempDiv.innerHTML = html;
    
    // Process nodes to wrap words in spans
    processNode(tempDiv);
    
    while (tempDiv.firstChild) {
        container.appendChild(tempDiv.firstChild);
    }
    
    runSmartSync();
}

/**
 * Process DOM node to wrap words in clickable spans
 * @param {Node} node - DOM node to process
 */
function processNode(node) {
    if (node.nodeType === Node.TEXT_NODE) {
        const words = node.textContent.split(/(\s+|[^\w'])/g);
        const fragment = document.createDocumentFragment();
        
        words.forEach(part => {
            if (part.trim().length > 0) {
                const span = document.createElement('span');
                span.className = 'word';
                span.textContent = part;
                span.onclick = handleWordClick;
                allWordSpans.push(span);
                fragment.appendChild(span);
            } else {
                fragment.appendChild(document.createTextNode(part));
            }
        });
        
        node.parentNode.replaceChild(fragment, node);
    } else if (node.nodeType === Node.ELEMENT_NODE) {
        Array.from(node.childNodes).forEach(processNode);
    }
}

/**
 * Handle click on a word span
 * @param {MouseEvent} e - Click event
 */
function handleWordClick(e) {
    e.stopPropagation();
    const spanIndex = allWordSpans.indexOf(e.target);
    const aiIdx = wordMap[spanIndex];
    
    if (aiIdx !== undefined && transcriptionData[aiIdx] && wavesurfer) {
        wavesurfer.setTime(transcriptionData[aiIdx].start);
        wavesurfer.play();
    }
}

// ==========================================
// TEXT-AUDIO SYNC FUNCTIONS
// ==========================================

/**
 * Run smart sync between text words and transcription data
 */
function runSmartSync() {
    wordMap = new Array(allWordSpans.length).fill(undefined);
    let aiIdx = 0;
    let matchCount = 0;
    
    allWordSpans.forEach((span, i) => {
        const clean = span.textContent.toLowerCase().replace(/[^\w]/g, '');
        
        if (clean.length === 0) {
            span.classList.add('unmatched');
            return;
        }
        
        // Look ahead up to 5 positions for a match
        for (let off = 0; off < 5; off++) {
            if (aiIdx + off >= transcriptionData.length) break;
            
            const transcriptWord = transcriptionData[aiIdx + off].word.toLowerCase().replace(/[^\w]/g, '');
            
            if (transcriptWord === clean) {
                wordMap[i] = aiIdx + off;
                aiIdx += off + 1;
                span.classList.remove('unmatched');
                matchCount++;
                return;
            }
        }
        
        span.classList.add('unmatched');
    });
    
    mapSentences();
    updateSyncStatus(matchCount);
}

/**
 * Update sync status badge
 * @param {number} matchCount - Number of matched words
 */
function updateSyncStatus(matchCount) {
    const badge = document.getElementById('syncStatus');
    badge.textContent = `Synced (${matchCount}/${allWordSpans.length})`;
    badge.className = matchCount > allWordSpans.length * 0.8 
        ? 'badge bg-success' 
        : 'badge bg-warning text-dark';
}

/**
 * Map sentences for sentence-level highlighting
 */
function mapSentences() {
    sentenceData = [];
    let buffer = [];
    let startIdx = 0;
    
    allWordSpans.forEach((span, i) => {
        buffer.push(span);
        
        // Check for sentence-ending punctuation
        if (/[.!?]["']?$/.test(span.textContent.trim())) {
            let startT = 0;
            let endT = 0;
            
            // Find start time
            for (let k = startIdx; k <= i; k++) {
                if (wordMap[k] !== undefined) {
                    startT = transcriptionData[wordMap[k]].start;
                    break;
                }
            }
            
            // Find end time
            for (let k = i; k >= startIdx; k--) {
                if (wordMap[k] !== undefined) {
                    endT = transcriptionData[wordMap[k]].end;
                    break;
                }
            }
            
            if (endT > startT) {
                sentenceData.push({
                    spans: [...buffer],
                    start: startT,
                    end: endT
                });
            }
            
            buffer = [];
            startIdx = i + 1;
        }
    });
}

/**
 * Sync reader highlighting with audio playback time
 * @param {number} t - Current playback time in seconds
 */
function syncReader(t) {
    // Highlight current word
    highlightCurrentWord(t);
    
    // Highlight current sentence
    highlightCurrentSentence(t);
}

/**
 * Highlight the current word based on playback time
 * @param {number} t - Current playback time
 */
function highlightCurrentWord(t) {
    const aiIdx = transcriptionData.findIndex(d => t >= d.start && t < d.end);
    
    if (aiIdx !== -1) {
        const txtIdx = wordMap.findIndex(i => i === aiIdx);
        
        if (txtIdx !== -1 && allWordSpans[txtIdx] !== lastHighlightedWordSpan) {
            // Remove previous highlight
            if (lastHighlightedWordSpan) {
                lastHighlightedWordSpan.classList.remove('current-word');
            }
            
            // Add new highlight
            lastHighlightedWordSpan = allWordSpans[txtIdx];
            lastHighlightedWordSpan.classList.add('current-word');
            
            // Scroll into view if needed
            scrollWordIntoView(lastHighlightedWordSpan);
        }
    }
}

/**
 * Highlight the current sentence based on playback time
 * @param {number} t - Current playback time
 */
function highlightCurrentSentence(t) {
    const sent = sentenceData.find(s => t >= s.start && t <= s.end);
    
    if (sent && sent.spans !== lastHighlightedSentenceSpans) {
        // Remove previous highlight
        if (lastHighlightedSentenceSpans) {
            lastHighlightedSentenceSpans.forEach(s => s.classList.remove('current-sentence-bg'));
        }
        
        // Add new highlight
        lastHighlightedSentenceSpans = sent.spans;
        lastHighlightedSentenceSpans.forEach(s => s.classList.add('current-sentence-bg'));
    }
}

/**
 * Scroll word into view if outside visible area
 * @param {Element} wordSpan - Word span element
 */
function scrollWordIntoView(wordSpan) {
    const r = wordSpan.getBoundingClientRect();
    const c = document.querySelector('.reader-section').getBoundingClientRect();
    
    if (r.top < c.top || r.bottom > c.bottom) {
        wordSpan.scrollIntoView({
            behavior: 'smooth',
            block: 'center'
        });
    }
}

// ==========================================
// MISMATCH TOGGLE
// ==========================================

/**
 * Toggle display of mismatched words
 */
function toggleMismatches() {
    const toggle = document.getElementById('mismatchToggle');
    document.getElementById('readerContent').classList.toggle('show-mismatches', toggle.checked);
}