const ChatManager = {
    isStreaming: false,
    messages: [],

    init() {
        const input = document.getElementById('messageInput');
        if (input) {
            input.addEventListener('keydown', (e) => {
                if (e.key === 'Enter' && e.ctrlKey) {
                    e.preventDefault();
                    this.sendMessage();
                }
            });
            // 自适应高度
            input.addEventListener('input', () => {
                input.style.height = 'auto';
                input.style.height = Math.min(input.scrollHeight, 120) + 'px';
            });
        }

        const sendBtn = document.getElementById('sendBtn');
        if (sendBtn) {
            sendBtn.addEventListener('click', () => this.sendMessage());
        }

        UploadManager.init();
    },

    async loadMessages(sessionId) {
        try {
            const res = await api.get('/sessions/' + sessionId + '/messages');
            this.messages = res.data || [];
            this.renderMessages();
            Storage.setCachedMessages(sessionId, this.messages);
        } catch (err) {
            // 尝试从缓存加载
            const cached = Storage.getCachedMessages(sessionId);
            if (cached) {
                this.messages = cached;
                this.renderMessages();
            }
        }
    },

    renderMessages() {
        const container = document.getElementById('messagesContainer');
        if (!container) return;

        if (this.messages.length === 0) {
            container.innerHTML = '<div class="empty-state"><h3>开始新的对话</h3><p>输入消息开始聊天</p></div>';
            return;
        }

        container.innerHTML = this.messages.map(msg => {
            if (msg.role === 'user') {
                return `<div class="message user">${this.escapeHtml(msg.content)}</div>`;
            } else {
                let html = `<div class="message assistant">`;
                if (msg.thinking_content) {
                    html += `<div class="thinking-toggle" onclick="this.nextElementSibling.classList.toggle('expanded')">💭 思考过程 ▾</div>`;
                    html += `<div class="thinking-content">${MarkdownRenderer.render(msg.thinking_content)}</div>`;
                }
                html += `<div class="markdown-body">${MarkdownRenderer.render(msg.content)}</div>`;
                html += `</div>`;
                return html;
            }
        }).join('');

        container.scrollTop = container.scrollHeight;
    },

    async sendMessage() {
        if (this.isStreaming) return;

        const input = document.getElementById('messageInput');
        const content = input.value.trim();
        if (!content) return;

        if (!SessionManager.currentSessionId) {
            await SessionManager.createSession();
        }

        // 清空输入
        input.value = '';
        input.style.height = 'auto';

        // 构建消息
        const userMessage = { role: 'user', content };
        if (UploadManager.getFiles().length > 0) {
            userMessage.file_info = UploadManager.getFiles();
        }
        this.messages.push(userMessage);
        this.renderMessages();

        // 保存用户消息到数据库
        api.post('/sessions/' + SessionManager.currentSessionId + '/messages', userMessage).catch(console.error);

        // 清除文件
        UploadManager.clearFiles();

        // 获取当前配置
        const provider = document.getElementById('providerSelect')?.value || 'newapi';
        const model = document.getElementById('modelSelect')?.value || 'gpt-3.5-turbo';
        const thinkingMode = document.getElementById('thinkingMode')?.checked || false;

        // SSE 流式请求
        this.isStreaming = true;
        this.updateSendButton();

        try {
            await this.streamChat(provider, model, thinkingMode);
        } catch (err) {
            this.addErrorMessage(err.message);
        } finally {
            this.isStreaming = false;
            this.updateSendButton();
        }
    },

    async streamChat(provider, model, thinkingMode) {
        const token = Storage.getToken();
        
        // 构建消息历史（只取 role 和 content）
        const messages = this.messages.map(m => ({
            role: m.role,
            content: m.content
        }));

        // 添加 AI 消息占位
        const assistantEl = this.addAssistantPlaceholder();
        let fullContent = '';
        let thinkingContent = '';

        const response = await fetch('/api/chat/completions', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
                'Authorization': 'Bearer ' + token
            },
            body: JSON.stringify({
                provider, model, messages, stream: true, thinkingMode
            })
        });

        if (!response.ok) {
            const err = await response.json();
            throw new Error(err.message || 'AI 请求失败');
        }

        const reader = response.body.getReader();
        const decoder = new TextDecoder();
        let buffer = '';

        while (true) {
            const { done, value } = await reader.read();
            if (done) break;

            buffer += decoder.decode(value, { stream: true });
            const lines = buffer.split('\n');
            buffer = lines.pop() || '';

            for (const line of lines) {
                if (!line.startsWith('data: ')) continue;
                const data = line.slice(6).trim();

                if (data === '[DONE]') {
                    continue;
                }

                try {
                    const parsed = JSON.parse(data);
                    
                    if (parsed.type === 'error') {
                        throw new Error(parsed.message);
                    }

                    if (parsed.thinking) {
                        thinkingContent += parsed.thinking;
                        this.updateThinkingContent(assistantEl, thinkingContent);
                    }

                    if (parsed.content) {
                        fullContent += parsed.content;
                        this.updateAssistantContent(assistantEl, fullContent);
                    }
                } catch (e) {
                    if (e.message && !e.message.includes('JSON')) throw e;
                }
            }
        }

        // 流结束，保存 AI 消息
        const assistantMessage = {
            role: 'assistant',
            content: fullContent,
            thinking_content: thinkingContent || null
        };
        this.messages.push(assistantMessage);

        // 保存到数据库
        api.post('/sessions/' + SessionManager.currentSessionId + '/messages', assistantMessage).catch(console.error);
        
        // 缓存到 localStorage
        Storage.setCachedMessages(SessionManager.currentSessionId, this.messages);

        // 移除打字机光标
        this.removeTypingCursor(assistantEl);
    },

    addAssistantPlaceholder() {
        const container = document.getElementById('messagesContainer');
        const empty = container.querySelector('.empty-state');
        if (empty) empty.remove();

        const el = document.createElement('div');
        el.className = 'message assistant';
        el.innerHTML = '<span class="typing-cursor"></span>';
        container.appendChild(el);
        container.scrollTop = container.scrollHeight;
        return el;
    },

    updateAssistantContent(el, content) {
        const cursor = el.querySelector('.typing-cursor');
        const body = el.querySelector('.markdown-body');
        
        if (body) {
            body.innerHTML = MarkdownRenderer.render(content);
            if (cursor) body.appendChild(cursor);
        } else {
            const thinking = el.querySelector('.thinking-content, .thinking-toggle');
            const md = document.createElement('div');
            md.className = 'markdown-body';
            md.innerHTML = MarkdownRenderer.render(content);
            if (cursor) md.appendChild(cursor);
            
            if (thinking) {
                el.appendChild(md);
            } else {
                el.innerHTML = '';
                el.appendChild(md);
            }
        }
        
        el.parentElement.scrollTop = el.parentElement.scrollHeight;
    },

    updateThinkingContent(el, content) {
        let toggle = el.querySelector('.thinking-toggle');
        let container = el.querySelector('.thinking-content');
        
        if (!toggle) {
            toggle = document.createElement('div');
            toggle.className = 'thinking-toggle expanded';
            toggle.textContent = '💭 思考过程 ▾';
            toggle.onclick = function() {
                container.classList.toggle('expanded');
                this.textContent = container.classList.contains('expanded') ? '💭 思考过程 ▴' : '💭 思考过程 ▾';
            };
            el.insertBefore(toggle, el.firstChild);
        }
        
        if (!container) {
            container = document.createElement('div');
            container.className = 'thinking-content expanded';
            el.insertBefore(container, toggle.nextSibling);
        }
        
        container.innerHTML = MarkdownRenderer.render(content);
        el.parentElement.scrollTop = el.parentElement.scrollHeight;
    },

    removeTypingCursor(el) {
        const cursor = el.querySelector('.typing-cursor');
        if (cursor) cursor.remove();
    },

    addErrorMessage(message) {
        const container = document.getElementById('messagesContainer');
        const el = document.createElement('div');
        el.className = 'message assistant';
        el.innerHTML = `<div class="alert alert-error">❌ ${this.escapeHtml(message)} <button class="btn btn-sm btn-secondary" onclick="ChatManager.retryLast()">重试</button></div>`;
        container.appendChild(el);
        container.scrollTop = container.scrollHeight;
    },

    clearMessages() {
        const container = document.getElementById('messagesContainer');
        if (container) {
            container.innerHTML = '<div class="empty-state"><h3>开始新的对话</h3><p>输入消息开始聊天</p></div>';
        }
        this.messages = [];
    },

    updateSendButton() {
        const btn = document.getElementById('sendBtn');
        if (btn) {
            btn.disabled = this.isStreaming;
            btn.textContent = this.isStreaming ? '回复中...' : '发送';
        }
    },

    escapeHtml(text) {
        const div = document.createElement('div');
        div.textContent = text;
        return div.innerHTML;
    }
};