const uploadArea = document.getElementById('upload-area');
const fileInput = document.getElementById('file-input');
const documentList = document.getElementById('document-list');
const chatMessages = document.getElementById('chat-messages');
const questionInput = document.getElementById('question-input');
const docCount = document.getElementById('doc-count');
const charCount = document.getElementById('char-count');
const toast = document.getElementById('toast');

function showToast(message, duration = 3000) {
    toast.textContent = message;
    toast.classList.add('show');
    
    setTimeout(() => {
        toast.classList.remove('show');
    }, duration);
}

uploadArea.addEventListener('click', () => fileInput.click());

uploadArea.addEventListener('dragover', (e) => {
    e.preventDefault();
    uploadArea.style.borderColor = '#1e3c72';
    uploadArea.style.background = '#e8f0fe';
});

uploadArea.addEventListener('dragleave', () => {
    uploadArea.style.borderColor = '#cbd5e0';
    uploadArea.style.background = 'transparent';
});

uploadArea.addEventListener('drop', (e) => {
    e.preventDefault();
    uploadArea.style.borderColor = '#cbd5e0';
    uploadArea.style.background = 'transparent';
    
    const files = e.dataTransfer.files;
    if (files.length > 0) {
        uploadFile(files[0]);
    }
});

fileInput.addEventListener('change', (e) => {
    if (e.target.files.length > 0) {
        uploadFile(e.target.files[0]);
    }
});

async function uploadFile(file) {
    const formData = new FormData();
    formData.append('file', file);
    
    try {
        showToast('⏳ 正在上传文档...');
        
        const response = await fetch('/api/upload', {
            method: 'POST',
            body: formData
        });
        
        const data = await response.json();
        
        if (data.error) {
            showToast(`❌ ${data.error}`);
            return;
        }
        
        loadDocuments();
        showToast(`✅ 文档 "${data.name}" 上传成功，正在处理中...`);
        addMessage('bot', `📄 文档 "${data.name}" 已上传，系统正在智能解析文档内容...`);
        
        setTimeout(() => {
            loadDocuments();
        }, 2000);
        
    } catch (error) {
        showToast('❌ 上传失败，请重试');
        console.error(error);
    }
}

async function loadDocuments() {
    try {
        const response = await fetch('/api/documents');
        const documents = await response.json();
        
        docCount.textContent = `${documents.length} 个文档`;
        
        if (documents.length === 0) {
            documentList.innerHTML = `
                <div class="empty-state">
                    <div class="empty-icon">📭</div>
                    <p>暂无文档</p>
                    <p class="empty-hint">上传文档后即可开始问答</p>
                </div>
            `;
            return;
        }
        
        documentList.innerHTML = documents.map(doc => `
            <div class="document-item">
                <div class="document-info">
                    <div class="document-name">📄 ${doc.name}</div>
                    <div class="document-status ${doc.status}">
                        ${doc.status === 'processing' ? '⏳ 处理中...' : '✅ 已完成'}
                    </div>
                </div>
                <button class="delete-btn" onclick="deleteDocument('${doc.id}')">🗑️ 删除</button>
            </div>
        `).join('');
        
    } catch (error) {
        console.error(error);
        showToast('❌ 加载文档列表失败');
    }
}

async function deleteDocument(docId) {
    if (!confirm('确定要删除这个文档吗？')) {
        return;
    }
    
    try {
        showToast('⏳ 正在删除文档...');
        
        await fetch(`/api/documents/${docId}`, {
            method: 'DELETE'
        });
        
        loadDocuments();
        showToast('✅ 文档已删除');
        addMessage('bot', '🗑️ 文档已从知识库中删除');
        
    } catch (error) {
        showToast('❌ 删除失败，请重试');
        console.error(error);
    }
}

async function askQuestion() {
    const question = questionInput.value.trim();
    
    if (!question) {
        showToast('⚠️ 请输入问题');
        questionInput.focus();
        return;
    }
    
    if (question.length < 3) {
        showToast('⚠️ 问题太短，请输入至少3个字符');
        questionInput.focus();
        return;
    }
    
    addMessage('user', question);
    questionInput.value = '';
    updateCharCount();
    
    try {
        showToast('🤖 正在思考中...');
        
        const response = await fetch('/api/ask', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({ question })
        });
        
        const data = await response.json();
        
        if (data.error) {
            showToast(`❌ ${data.error}`);
            addMessage('bot', `❌ 抱歉，${data.error}`);
            return;
        }
        
        let answerHtml = `<p>${data.answer}</p>`;
        
        if (data.sources && data.sources.length > 0) {
            answerHtml += `
                <div class="sources">
                    <div class="sources-title">📚 参考来源：</div>
                    ${data.sources.map(source => `
                        <div class="source-item">📄 ${source.name} (第${source.page}页)</div>
                    `).join('')}
                </div>
            `;
        }
        
        showToast('✅ 回答完成');
        addMessage('bot', answerHtml);
        
    } catch (error) {
        showToast('❌ 回答问题时出错了，请重试');
        addMessage('bot', '❌ 抱歉，回答问题时出错了，请重试');
        console.error(error);
    }
}

function addMessage(type, content) {
    const messageDiv = document.createElement('div');
    messageDiv.className = `message ${type}`;
    messageDiv.innerHTML = `
        <div class="message-content">
            ${content}
        </div>
    `;
    
    chatMessages.appendChild(messageDiv);
    chatMessages.scrollTop = chatMessages.scrollHeight;
}

function updateCharCount() {
    const length = questionInput.value.length;
    charCount.textContent = `${length} 字`;
    
    if (length > 500) {
        charCount.style.color = '#e53e3e';
    } else if (length > 300) {
        charCount.style.color = '#d69e2e';
    } else {
        charCount.style.color = '#718096';
    }
}

async function loadConversationHistory() {
    try {
        const response = await fetch('/api/conversations');
        const conversations = await response.json();
        
        if (conversations.length === 0) {
            addMessage('bot', '👋 欢迎使用智能知识库问答系统！上传文档后，您可以向我提问任何与文档相关的问题。');
            return;
        }
        
        conversations.forEach(conv => {
            addMessage('user', conv.question);
            
            let answerHtml = `<p>${conv.answer}</p>`;
            
            if (conv.sources && conv.sources.length > 0) {
                answerHtml += `
                    <div class="sources">
                        <div class="sources-title">📚 参考来源：</div>
                        ${conv.sources.map(source => `
                            <div class="source-item">📄 ${source.name} (第${source.page}页)</div>
                        `).join('')}
                    </div>
                `;
            }
            
            addMessage('bot', answerHtml);
        });
        
    } catch (error) {
        console.error(error);
        addMessage('bot', '👋 欢迎使用智能知识库问答系统！上传文档后，您可以向我提问任何与文档相关的问题。');
    }
}

questionInput.addEventListener('input', updateCharCount);

questionInput.addEventListener('keydown', (e) => {
    if (e.key === 'Enter' && !e.shiftKey) {
        e.preventDefault();
        askQuestion();
    }
});

loadDocuments();
loadConversationHistory();