/**
 * 交互式英语学习应用 - 阅读页面逻辑
 * 支持点读、翻译显示和音频播放功能
 * 适配新的 data 数据结构
 */

class InteractiveLearningApp {
    constructor() {
        this.bookId = null;
        this.bookInfo = null;
        this.pages = [];
        this.catalog = [];
        this.currentPageIndex = 0;
        this.currentAudio = null;
        this.isPlaying = false;
        this.showTranslation = false;
        this.showInteractiveAreas = false;
        this.bookmarks = [];
        this.searchResults = [];
        this.debugMode = false;
        this.settings = {
            autoTranslation: false,
            playbackSpeed: 1,
            autoPlayNext: false
        };
        
        this.init();
    }

    async init() {
        try {
            // 从URL获取书籍ID
            const urlParams = new URLSearchParams(window.location.search);
            this.bookId = urlParams.get('book_id');
            
            if (!this.bookId) {
                throw new Error('未指定书籍ID');
            }
            
            await this.loadBookInfo();
            await this.loadBookPages();
            await this.loadBookCatalog();
            this.setupEventListeners();
            this.loadSettings();
            this.loadBookmarks();
            await this.renderCurrentPage();
            this.updateUI();
        } catch (error) {
            console.error('应用初始化失败:', error);
            this.showToast('应用初始化失败: ' + error.message, 'error');
        }
    }

    /**
     * 加载书籍信息
     */
    async loadBookInfo() {
        try {
            const response = await fetch(`/api/v2/books/${this.bookId}`);
            if (!response.ok) {
                throw new Error('获取书籍信息失败');
            }
            
            const result = await response.json();
            if (!result.success) {
                throw new Error(result.error || '获取书籍信息失败');
            }
            
            this.bookInfo = result.book;
            
            // 更新页面标题
            document.getElementById('bookTitle').innerHTML = `
                <i class="fas fa-book-open"></i>
                ${this.bookInfo.market_book_name}
            `;
            document.title = `${this.bookInfo.market_book_name} - 交互式英语学习`;
            
            console.log('书籍信息:', this.bookInfo);
        } catch (error) {
            console.error('加载书籍信息失败:', error);
            throw error;
        }
    }

    /**
     * 加载书籍页面列表
     */
    async loadBookPages() {
        try {
            const response = await fetch(`/api/v2/books/${this.bookId}/pages`);
            if (!response.ok) {
                throw new Error('获取页面列表失败');
            }
            
            const result = await response.json();
            if (!result.success) {
                throw new Error(result.error || '获取页面列表失败');
            }
            
            this.pages = result.pages || [];
            console.log(`加载了 ${this.pages.length} 页`);
        } catch (error) {
            console.error('加载页面列表失败:', error);
            throw error;
        }
    }

    /**
     * 加载书籍目录
     */
    async loadBookCatalog() {
        try {
            const response = await fetch(`/api/v2/books/${this.bookId}/catalog`);
            if (!response.ok) {
                console.warn('获取目录失败');
                return;
            }
            
            const result = await response.json();
            if (result.success) {
                this.catalog = result.catalog || [];
                console.log(`加载了 ${this.catalog.length} 个目录项`);
            }
        } catch (error) {
            console.warn('加载目录失败:', error);
        }
    }

    /**
     * 获取资源URL（支持本地data目录）
     */
    getResourceUrl(relativePath) {
        if (!relativePath) return '';
        // 资源路径格式: "168_一年级上册/images/page_001.jpg"
        return `data/${relativePath}`;
    }

    setupEventListeners() {
        // 返回按钮
        document.getElementById('backBtn').addEventListener('click', () => {
            window.location.href = '/';
        });
        
        // 目录按钮
        document.getElementById('catalogBtn').addEventListener('click', () => this.showCatalog());
        
        // 页面导航
        document.getElementById('prevBtn').addEventListener('click', () => this.previousPage());
        document.getElementById('nextBtn').addEventListener('click', () => this.nextPage());
        
        // 控制按钮
        document.getElementById('translationToggle').addEventListener('click', () => this.toggleTranslation());
        document.getElementById('interactiveToggle').addEventListener('click', () => this.toggleInteractiveAreas());
        document.getElementById('playAllBtn').addEventListener('click', () => this.playAllPieces());
        document.getElementById('bookmarkBtn').addEventListener('click', () => this.toggleBookmark());
        document.getElementById('searchBtn').addEventListener('click', () => this.showSearch());
        document.getElementById('settingsBtn').addEventListener('click', () => this.showSettings());
        
        // 音频控制
        document.getElementById('playPauseBtn').addEventListener('click', () => this.togglePlayPause());
        document.getElementById('repeatBtn').addEventListener('click', () => this.repeatAudio());
        document.getElementById('audioTimeline').addEventListener('click', (e) => this.seekAudio(e));
        
        // 关闭按钮
        document.getElementById('closeCatalog')?.addEventListener('click', () => this.hideCatalog());
        document.getElementById('closeSettings').addEventListener('click', () => this.hideSettings());
        document.getElementById('closeSearch').addEventListener('click', () => this.hideSearch());
        document.getElementById('closeBookmark')?.addEventListener('click', () => this.hideBookmarks());
        
        // 搜索
        document.getElementById('doSearch').addEventListener('click', () => this.performSearch());
        document.getElementById('searchInput').addEventListener('keypress', (e) => {
            if (e.key === 'Enter') this.performSearch();
        });
        
        // 设置
        document.getElementById('autoTranslation').addEventListener('change', (e) => {
            this.settings.autoTranslation = e.target.checked;
            this.saveSettings();
            if (e.target.checked) {
                document.getElementById('textOverlays').classList.add('show-translation');
            }
        });
        document.getElementById('playbackSpeed').addEventListener('change', (e) => {
            this.settings.playbackSpeed = parseFloat(e.target.value);
            this.saveSettings();
            if (this.currentAudio) {
                this.currentAudio.playbackRate = this.settings.playbackSpeed;
            }
        });
        document.getElementById('autoPlayNext').addEventListener('change', (e) => {
            this.settings.autoPlayNext = e.target.checked;
            this.saveSettings();
        });
        
        // 键盘快捷键
        document.addEventListener('keydown', (e) => this.handleKeyPress(e));
        
        // 音频事件
        const audio = document.getElementById('audio');
        audio.addEventListener('loadedmetadata', () => this.updateAudioUI());
        audio.addEventListener('timeupdate', () => this.updateAudioProgress());
        audio.addEventListener('ended', () => this.onAudioEnded());
        audio.addEventListener('error', (e) => {
            console.error('音频播放失败:', e);
            this.showToast('音频播放失败', 'error');
        });
    }

    /**
     * 渲染当前页面
     */
    async renderCurrentPage() {
        if (!this.pages || this.currentPageIndex >= this.pages.length) {
            return;
        }

        const pageContainer = document.getElementById('pageContent');
        const loading = document.getElementById('loading');
        
        loading.style.display = 'block';
        pageContainer.style.display = 'none';
        
        try {
            // 获取页面信息
            const pageInfo = this.pages[this.currentPageIndex];
            const pageNumber = pageInfo.page_number;
            
            // 加载页面详细内容
            const response = await fetch(`/api/v2/books/${this.bookId}/pages/${pageNumber}`);
            if (!response.ok) {
                throw new Error(`加载第 ${pageNumber} 页失败`);
            }
            
            const result = await response.json();
            if (!result.success) {
                throw new Error(result.error || '加载页面内容失败');
            }
            
            const page = result.page;
            
            // 加载页面图片
            const pageImage = document.getElementById('pageImage');
            pageImage.onload = () => {
                loading.style.display = 'none';
                pageContainer.style.display = 'block';
                this.renderTextPieces(page);
            };
            
            pageImage.onerror = () => {
                loading.style.display = 'none';
                this.showToast('页面图片加载失败', 'error');
            };
            
            const imageUrl = this.getResourceUrl(page.origin_img_url);
            pageImage.src = imageUrl;
            pageImage.alt = `第${pageNumber}页`;
            
        } catch (error) {
            loading.style.display = 'none';
            console.error('渲染页面失败:', error);
            this.showToast('页面加载失败: ' + error.message, 'error');
        }
    }

    /**
     * 渲染文本片段
     */
    renderTextPieces(page) {
        const textOverlays = document.getElementById('textOverlays');
        const pageImage = document.getElementById('pageImage');
        
        textOverlays.innerHTML = '';
        
        const renderPieces = () => {
            const imageRect = pageImage.getBoundingClientRect();
            const overlayRect = textOverlays.getBoundingClientRect();
            
            const offsetX = imageRect.left - overlayRect.left;
            const offsetY = imageRect.top - overlayRect.top;
            const imageWidth = imageRect.width;
            const imageHeight = imageRect.height;
            
            if (!page.pieces || page.pieces.length === 0) {
                console.warn('页面没有内容片段');
                return;
            }
            
            page.pieces.forEach((piece, index) => {
                const textPiece = document.createElement('div');
                textPiece.className = 'text-piece';
                textPiece.dataset.pieceIndex = index;
                
                if (this.debugMode) {
                    textPiece.style.border = '2px solid red';
                    textPiece.style.backgroundColor = 'rgba(255, 0, 0, 0.2)';
                }
                
                // 设置位置和大小
                const coord = piece.coordinate;
                const left = offsetX + (coord.x * imageWidth);
                const top = offsetY + (coord.y * imageHeight);
                const width = coord.width * imageWidth;
                const height = coord.height * imageHeight;
                
                textPiece.style.left = `${left}px`;
                textPiece.style.top = `${top}px`;
                textPiece.style.width = `${width}px`;
                textPiece.style.height = `${height}px`;
                
                // 创建文本内容
                const originalText = document.createElement('div');
                originalText.className = 'piece-text';
                originalText.textContent = piece.original;
                
                const translationText = document.createElement('div');
                translationText.className = 'piece-translation';
                translationText.textContent = piece.translation;
                
                textPiece.appendChild(originalText);
                textPiece.appendChild(translationText);
                
                // 点击事件
                textPiece.addEventListener('click', () => this.playPiece(piece, textPiece));
                
                textOverlays.appendChild(textPiece);
            });
            
            // 根据设置显示翻译
            if (this.showTranslation || this.settings.autoTranslation) {
                textOverlays.classList.add('show-translation');
            }
        };
        
        if (pageImage.complete && pageImage.naturalHeight !== 0) {
            renderPieces();
        } else {
            pageImage.addEventListener('load', renderPieces, { once: true });
        }
        
        // 监听窗口大小变化
        let resizeTimeout;
        const handleResize = () => {
            clearTimeout(resizeTimeout);
            resizeTimeout = setTimeout(() => {
                if (pageImage.complete && pageImage.naturalHeight !== 0) {
                    renderPieces();
                }
            }, 100);
        };
        
        if (pageImage.resizeObserver) {
            pageImage.resizeObserver.disconnect();
        }
        
        pageImage.resizeObserver = new ResizeObserver(handleResize);
        pageImage.resizeObserver.observe(pageImage);
        window.addEventListener('resize', handleResize);
    }

    /**
     * 播放片段音频
     */
    async playPiece(piece, element) {
        try {
            document.querySelectorAll('.text-piece').forEach(el => {
                el.classList.remove('active', 'playing');
            });
            
            element.classList.add('active');
            
            const audioPlayer = document.getElementById('audioPlayer');
            audioPlayer.style.display = 'block';
            
            const audioText = document.getElementById('audioText');
            audioText.innerHTML = `
                <div style="font-weight: 600; margin-bottom: 0.5rem;">${piece.original}</div>
                <div style="color: var(--text-secondary); font-size: 0.9rem;">${piece.translation}</div>
            `;
            
            const audio = document.getElementById('audio');
            const audioUrl = piece.origin_sound_url || piece.encrypt_sound_url;
            
            if (!audioUrl) {
                this.showToast('该片段没有可用的音频', 'warning');
                return;
            }
            
            if (this.currentAudio && !this.currentAudio.paused) {
                this.currentAudio.pause();
            }
            
            const fullAudioUrl = this.getResourceUrl(audioUrl);
            audio.src = fullAudioUrl;
            audio.playbackRate = this.settings.playbackSpeed;
            this.currentAudio = audio;
            
            await audio.play();
            this.isPlaying = true;
            element.classList.add('playing');
            this.updatePlayButton();
            
        } catch (error) {
            console.error('音频播放失败:', error);
            this.showToast('音频播放失败', 'error');
            element.classList.remove('active', 'playing');
        }
    }

    /**
     * 播放整页音频
     */
    async playAllPieces() {
        this.showToast('整页播放功能开发中...', 'info');
    }

    /**
     * 目录相关
     */
    showCatalog() {
        const panel = document.getElementById('catalogPanel');
        panel.style.display = 'flex';
        this.renderCatalog();
    }

    hideCatalog() {
        document.getElementById('catalogPanel').style.display = 'none';
    }

    renderCatalog() {
        const catalogList = document.getElementById('catalogList');
        
        if (!this.catalog || this.catalog.length === 0) {
            // 空目录时，显示页码列表
            catalogList.innerHTML = `
                <div class="catalog-empty">
                    <p>📖 此书暂无目录信息</p>
                    <p style="margin-top: 1rem; font-size: 0.9rem; color: var(--text-secondary);">
                        共 ${this.pages.length} 页，可通过页面导航按钮浏览
                    </p>
                </div>
            `;
            return;
        }
        
        catalogList.innerHTML = '';
        
        // 如果只有一个目录项，也显示提示
        if (this.catalog.length === 1) {
            const notice = document.createElement('div');
            notice.style.cssText = 'padding: 0.75rem; background: #fef3c7; border-radius: 8px; margin-bottom: 1rem; font-size: 0.9rem;';
            notice.innerHTML = `
                <i class="fas fa-info-circle"></i>
                此书仅有 1 个目录项，建议使用页面导航浏览
            `;
            catalogList.appendChild(notice);
        }
        
        this.catalog.forEach(item => {
            const catalogItem = document.createElement('div');
            catalogItem.className = 'catalog-item';
            catalogItem.innerHTML = `
                <div class="catalog-name">
                    <div class="catalog-name-en">${item.catalog_name || ''}</div>
                    <div class="catalog-name-cn">${item.catalog_name_cn || ''}</div>
                </div>
                <div class="catalog-pages">P${item.start_page}${item.start_page !== item.end_page ? '-' + item.end_page : ''}</div>
            `;
            
            catalogItem.addEventListener('click', () => {
                this.goToPage(item.start_page);
                this.hideCatalog();
            });
            
            catalogList.appendChild(catalogItem);
        });
    }

    goToPage(pageNumber) {
        // 找到对应的页面索引
        const index = this.pages.findIndex(p => p.page_number === pageNumber);
        if (index >= 0) {
            this.currentPageIndex = index;
            this.renderCurrentPage();
            this.updateUI();
            this.stopCurrentAudio();
        }
    }

    /**
     * 页面导航
     */
    previousPage() {
        if (this.currentPageIndex > 0) {
            this.currentPageIndex--;
            this.renderCurrentPage();
            this.updateUI();
            this.stopCurrentAudio();
        }
    }

    nextPage() {
        if (this.currentPageIndex < this.pages.length - 1) {
            this.currentPageIndex++;
            this.renderCurrentPage();
            this.updateUI();
            this.stopCurrentAudio();
        }
    }

    /**
     * UI更新
     */
    updateUI() {
        const currentPage = this.pages[this.currentPageIndex];
        document.getElementById('currentPage').textContent = currentPage ? currentPage.page_number : 0;
        document.getElementById('totalPages').textContent = this.pages.length || 0;
        
        const progress = this.pages.length ? ((this.currentPageIndex + 1) / this.pages.length) * 100 : 0;
        document.getElementById('progressFill').style.width = `${progress}%`;
        
        document.getElementById('prevBtn').disabled = this.currentPageIndex === 0;
        document.getElementById('nextBtn').disabled = this.currentPageIndex === this.pages.length - 1;
        
        this.updateBookmarkButton();
    }

    /**
     * 翻译和交互区域切换
     */
    toggleTranslation() {
        this.showTranslation = !this.showTranslation;
        const textOverlays = document.getElementById('textOverlays');
        const translationBtn = document.getElementById('translationToggle');
        
        if (this.showTranslation) {
            textOverlays.classList.add('show-translation');
            translationBtn.classList.add('active');
        } else {
            textOverlays.classList.remove('show-translation');
            translationBtn.classList.remove('active');
        }
    }

    toggleInteractiveAreas() {
        this.showInteractiveAreas = !this.showInteractiveAreas;
        const textOverlays = document.getElementById('textOverlays');
        const interactiveBtn = document.getElementById('interactiveToggle');
        
        if (this.showInteractiveAreas) {
            textOverlays.classList.add('show-interactive-areas');
            interactiveBtn.classList.add('active');
        } else {
            textOverlays.classList.remove('show-interactive-areas');
            interactiveBtn.classList.remove('active');
        }
    }

    /**
     * 音频控制
     */
    togglePlayPause() {
        const audio = document.getElementById('audio');
        if (!audio.src) return;
        
        if (this.isPlaying) {
            audio.pause();
            this.isPlaying = false;
        } else {
            audio.play().then(() => {
                this.isPlaying = true;
            }).catch(error => {
                console.error('播放失败:', error);
                this.showToast('播放失败', 'error');
            });
        }
        
        this.updatePlayButton();
    }

    repeatAudio() {
        const audio = document.getElementById('audio');
        if (audio.src) {
            audio.currentTime = 0;
            if (!this.isPlaying) {
                this.togglePlayPause();
            }
        }
    }

    seekAudio(event) {
        const audio = document.getElementById('audio');
        if (!audio.src || !audio.duration) return;
        
        const timeline = document.getElementById('audioTimeline');
        const rect = timeline.getBoundingClientRect();
        const percentage = (event.clientX - rect.left) / rect.width;
        const newTime = percentage * audio.duration;
        
        audio.currentTime = newTime;
    }

    updatePlayButton() {
        const playPauseBtn = document.getElementById('playPauseBtn');
        const icon = playPauseBtn.querySelector('i');
        
        if (this.isPlaying) {
            icon.className = 'fas fa-pause';
        } else {
            icon.className = 'fas fa-play';
        }
    }

    updateAudioUI() {
        const audio = document.getElementById('audio');
        const totalTime = document.getElementById('totalTime');
        
        if (audio.duration) {
            totalTime.textContent = this.formatTime(audio.duration);
        }
    }

    updateAudioProgress() {
        const audio = document.getElementById('audio');
        const progressBar = document.getElementById('audioProgressBar');
        const currentTime = document.getElementById('currentTime');
        
        if (audio.duration) {
            const percentage = (audio.currentTime / audio.duration) * 100;
            progressBar.style.width = `${percentage}%`;
            currentTime.textContent = this.formatTime(audio.currentTime);
        }
    }

    onAudioEnded() {
        this.isPlaying = false;
        this.updatePlayButton();
        
        document.querySelectorAll('.text-piece').forEach(el => {
            el.classList.remove('playing');
        });
    }

    stopCurrentAudio() {
        if (this.currentAudio && !this.currentAudio.paused) {
            this.currentAudio.pause();
            this.isPlaying = false;
            this.updatePlayButton();
        }
        
        document.getElementById('audioPlayer').style.display = 'none';
        
        document.querySelectorAll('.text-piece').forEach(el => {
            el.classList.remove('active', 'playing');
        });
    }

    /**
     * 搜索功能
     */
    showSearch() {
        document.getElementById('searchPanel').style.display = 'flex';
        document.getElementById('searchInput').focus();
    }

    hideSearch() {
        document.getElementById('searchPanel').style.display = 'none';
        document.getElementById('searchInput').value = '';
    }

    async performSearch() {
        const keyword = document.getElementById('searchInput').value.trim();
        if (!keyword) {
            this.showToast('请输入搜索关键词', 'warning');
            return;
        }
        
        try {
            const response = await fetch(`/api/v2/books/${this.bookId}/search?keyword=${encodeURIComponent(keyword)}&limit=20`);
            if (!response.ok) {
                throw new Error('搜索失败');
            }
            
            const result = await response.json();
            if (!result.success) {
                throw new Error(result.error || '搜索失败');
            }
            
            this.searchResults = result.results || [];
            this.displaySearchResults(keyword);
        } catch (error) {
            console.error('搜索失败:', error);
            this.showToast('搜索失败: ' + error.message, 'error');
        }
    }

    displaySearchResults(keyword) {
        const resultsContainer = document.getElementById('searchResults');
        
        if (this.searchResults.length === 0) {
            resultsContainer.innerHTML = '<div class="search-empty">未找到匹配的内容</div>';
            return;
        }
        
        resultsContainer.innerHTML = '';
        
        this.searchResults.forEach((result, index) => {
            const resultItem = document.createElement('div');
            resultItem.className = 'search-result-item';
            resultItem.innerHTML = `
                <div class="search-result-page">第 ${result.page_number} 页</div>
                <div class="search-result-text">${this.highlightKeyword(result.original, keyword)}</div>
                <div class="search-result-translation">${this.highlightKeyword(result.translation, keyword)}</div>
            `;
            
            resultItem.addEventListener('click', () => {
                this.goToPage(result.page_number);
                this.hideSearch();
            });
            
            resultsContainer.appendChild(resultItem);
        });
    }

    highlightKeyword(text, keyword) {
        if (!text || !keyword) return text;
        const regex = new RegExp(`(${keyword})`, 'gi');
        return text.replace(regex, '<span class="search-highlight">$1</span>');
    }

    /**
     * 设置相关
     */
    showSettings() {
        document.getElementById('settingsPanel').style.display = 'flex';
        document.getElementById('autoTranslation').checked = this.settings.autoTranslation;
        document.getElementById('playbackSpeed').value = this.settings.playbackSpeed;
        document.getElementById('autoPlayNext').checked = this.settings.autoPlayNext;
    }

    hideSettings() {
        document.getElementById('settingsPanel').style.display = 'none';
    }

    loadSettings() {
        const saved = localStorage.getItem('learningAppSettings');
        if (saved) {
            try {
                this.settings = { ...this.settings, ...JSON.parse(saved) };
            } catch (error) {
                console.error('设置加载失败:', error);
            }
        }
    }

    saveSettings() {
        localStorage.setItem('learningAppSettings', JSON.stringify(this.settings));
    }

    /**
     * 书签功能
     */
    toggleBookmark() {
        this.showToast('书签功能开发中...', 'info');
    }

    updateBookmarkButton() {
        // 实现书签按钮更新逻辑
    }

    loadBookmarks() {
        // 实现书签加载逻辑
    }

    hideBookmarks() {
        document.getElementById('bookmarkPanel').style.display = 'none';
    }

    /**
     * 键盘快捷键
     */
    handleKeyPress(event) {
        if (document.getElementById('settingsPanel').style.display === 'flex' ||
            document.getElementById('searchPanel').style.display === 'flex') {
            if (event.key === 'Escape') {
                this.hideSettings();
                this.hideSearch();
            }
            return;
        }
        
        switch (event.key) {
            case 'ArrowLeft':
                event.preventDefault();
                this.previousPage();
                break;
            case 'ArrowRight':
                event.preventDefault();
                this.nextPage();
                break;
            case ' ':
                event.preventDefault();
                this.togglePlayPause();
                break;
            case 't':
            case 'T':
                event.preventDefault();
                this.toggleTranslation();
                break;
            case 'i':
            case 'I':
                event.preventDefault();
                this.toggleInteractiveAreas();
                break;
        }
    }

    /**
     * 工具方法
     */
    formatTime(seconds) {
        const mins = Math.floor(seconds / 60);
        const secs = Math.floor(seconds % 60);
        return `${mins}:${secs.toString().padStart(2, '0')}`;
    }

    showToast(message, type = 'info') {
        const toast = document.getElementById('toast');
        toast.textContent = message;
        toast.className = `toast ${type} show`;
        
        setTimeout(() => {
            toast.classList.remove('show');
        }, 3000);
    }
}

// 页面加载完成后初始化应用
document.addEventListener('DOMContentLoaded', () => {
    new InteractiveLearningApp();
});

// 处理页面可见性变化
document.addEventListener('visibilitychange', () => {
    if (document.hidden) {
        const audio = document.getElementById('audio');
        if (audio && !audio.paused) {
            audio.pause();
        }
    }
});