import { pipeline, TextStreamer } from 'https://cdn.jsdelivr.net/npm/@huggingface/transformers@3.7.3';

class StreamingChatbot {
    constructor() {
        this.generator = null;
        this.messages = [];
        this.isProcessing = false;
        this.useWebGPU = false;
        this.currentStreamer = null;
        this.initElements();
        this.initEventListeners();
        this.initModel();
    }

    initElements() {
        this.chatMessages = document.getElementById('chatMessages');
        this.userInput = document.getElementById('userInput');
        this.sendButton = document.getElementById('sendButton');
        this.clearButton = document.getElementById('clearButton');
        this.loadingIndicator = document.getElementById('loadingIndicator');
        this.initLoader = document.getElementById('initLoader');
        this.deviceToggle = document.getElementById('deviceToggle');
        this.deviceLabel = document.getElementById('deviceLabel');
        this.charCount = document.getElementById('charCount');
    }

    initEventListeners() {
        this.sendButton.addEventListener('click', () => this.sendMessage());
        this.clearButton.addEventListener('click', () => this.clearChat());
        
        this.userInput.addEventListener('keydown', (e) => {
            if (e.key === 'Enter' && !e.shiftKey) {
                e.preventDefault();
                this.sendMessage();
            }
        });

        this.userInput.addEventListener('input', () => {
            this.updateCharCount();
            this.autoResize();
        });

        this.deviceToggle.addEventListener('change', async (e) => {
            if (!this.isProcessing) {
                this.useWebGPU = e.target.checked;
                this.deviceLabel.textContent = this.useWebGPU ? 'GPU' : 'CPU';
                await this.reinitModel();
            } else {
                e.target.checked = !e.target.checked;
                this.showNotification('Please wait for the current process to complete');
            }
        });

        this.checkWebGPUSupport();
    }

    async checkWebGPUSupport() {
        try {
            if (!navigator.gpu) {
                this.deviceToggle.disabled = true;
                this.deviceLabel.textContent = 'CPU (GPU not available)';
                return;
            }
            
            const adapter = await navigator.gpu.requestAdapter();
            if (!adapter) {
                this.deviceToggle.disabled = true;
                this.deviceLabel.textContent = 'CPU (GPU not available)';
            }
        } catch (error) {
            console.error('WebGPU check failed:', error);
            this.deviceToggle.disabled = true;
            this.deviceLabel.textContent = 'CPU (GPU not available)';
        }
    }

    updateCharCount() {
        const count = this.userInput.value.length;
        this.charCount.textContent = `${count} / 1000`;
        if (this.charCount) {
            this.charCount.style.color = count > 900 ? '#ef4444' : '#64748b';
        }
    }

    autoResize() {
        this.userInput.style.height = 'auto';
        const maxHeight = 120;
        const newHeight = Math.min(this.userInput.scrollHeight, maxHeight);
        this.userInput.style.height = newHeight + 'px';
    }

    async initModel() {
        try {
            this.initLoader.style.display = 'flex';
            
            const options = { 
                dtype: this.useWebGPU ? "q4" : "fp32",
                device: this.useWebGPU ? 'webgpu' : 'wasm'
            };

            this.generator = await pipeline(
                "text-generation",
                "onnx-community/MobileLLM-R1-140M-ONNX",
                options
            );

            this.sendButton.disabled = false;
            this.showNotification('Model loaded successfully!', 'success');
        } catch (error) {
            console.error('Error loading model:', error);
            this.showNotification('Failed to load model. Please refresh and try again.', 'error');
        } finally {
            this.initLoader.style.display = 'none';
        }
    }

    async reinitModel() {
        this.initLoader.style.display = 'flex';
        this.sendButton.disabled = true;
        await this.initModel();
    }

    async sendMessage() {
        const message = this.userInput.value.trim();
        if (!message || this.isProcessing || !this.generator) return;

        this.isProcessing = true;
        this.sendButton.disabled = true;
        
        // Add user message to chat
        this.addMessage(message, 'user');
        this.messages.push({ role: "user", content: message });
        
        // Clear input
        this.userInput.value = '';
        this.updateCharCount();
        this.autoResize();
        
        // Show loading
        this.loadingIndicator.classList.remove('hidden');
        
        try {
            // Create container for streaming response
            const responseContainer = this.addMessage('', 'assistant', true);
            const messageContent = responseContainer.querySelector('.message-content');
            
            // Add streaming indicator
            const streamingIndicator = document.createElement('span');
            streamingIndicator.className = 'streaming-indicator';
            streamingIndicator.textContent = '●';
            streamingIndicator.style.animation = 'pulse 1.5s infinite';
            streamingIndicator.style.color = '#10b981';
            streamingIndicator.style.marginLeft = '4px';
            messageContent.appendChild(streamingIndicator);

            // Create enhanced TextStreamer with proper callback handling
            this.currentStreamer = new TextStreamer(this.generator.tokenizer, {
                skip_prompt: true,
                skip_special_tokens: true,
                callback_function: (text) => {
                    // Remove streaming indicator on first text
                    if (streamingIndicator.parentNode) {
                        streamingIndicator.remove();
                    }
                    // Append new text and scroll
                    messageContent.textContent += text;
                    this.scrollToBottom();
                }
            });

            // Use the original working format - messages array with streamer
            const output = await this.generator(this.messages, {
                max_new_tokens: 500,
                do_sample: false,
                streamer: this.currentStreamer,
            });

            // Clean up streaming indicator if still present
            if (streamingIndicator.parentNode) {
                streamingIndicator.remove();
            }

            // Get the generated text and add to conversation history
            const generatedText = output[0].generated_text || messageContent.textContent;
            if (generatedText && !messageContent.textContent) {
                messageContent.textContent = generatedText;
            }

            // Add assistant's response to message history
            const finalResponse = messageContent.textContent.trim();
            if (finalResponse) {
                this.messages.push({ role: "assistant", content: finalResponse });
            }
            
        } catch (error) {
            console.error('Error generating response:', error);
            // Remove any existing content and show error
            const responseContainer = this.chatMessages.lastElementChild;
            if (responseContainer && responseContainer.classList.contains('assistant')) {
                responseContainer.remove();
            }
            this.addMessage('Sorry, I encountered an error while generating the response. Please try again.', 'error');
        } finally {
            this.loadingIndicator.classList.add('hidden');
            this.isProcessing = false;
            this.sendButton.disabled = false;
            this.currentStreamer = null;
            this.userInput.focus();
            this.scrollToBottom();
        }
    }

    addMessage(content, type, isStreaming = false) {
        // Remove welcome message if it exists
        const welcomeMessage = this.chatMessages.querySelector('.welcome-message');
        if (welcomeMessage) {
            welcomeMessage.remove();
        }

        const messageDiv = document.createElement('div');
        messageDiv.className = `message ${type}`;
        
        const avatar = document.createElement('div');
        avatar.className = 'avatar';
        avatar.textContent = type === 'user' ? '👤' : type === 'error' ? '⚠️' : '🤖';
        
        const messageContent = document.createElement('div');
        messageContent.className = 'message-content';
        messageContent.textContent = content;
        
        messageDiv.appendChild(avatar);
        messageDiv.appendChild(messageContent);
        
        this.chatMessages.appendChild(messageDiv);
        this.scrollToBottom();
        
        return messageDiv;
    }

    scrollToBottom() {
        requestAnimationFrame(() => {
            this.chatMessages.scrollTop = this.chatMessages.scrollHeight;
        });
    }

    clearChat() {
        if (this.isProcessing) {
            this.showNotification('Please wait for the current response to complete');
            return;
        }
        
        this.messages = [];
        this.chatMessages.innerHTML = `
            <div class="welcome-message">
                <div class="welcome-icon">🤖</div>
                <h2>Welcome to AI Assistant</h2>
                <p>I'm powered by MobileLLM with real-time streaming. Ask me anything!</p>
            </div>
        `;
        this.showNotification('Chat cleared!', 'info');
    }

    showNotification(message, type = 'info') {
        const notification = document.createElement('div');
        notification.className = `notification ${type}`;
        notification.textContent = message;
        notification.style.cssText = `
            position: fixed;
            top: 20px;
            right: 20px;
            padding: 12px 20px;
            border-radius: 8px;
            color: white;
            font-weight: 500;
            transform: translateX(100%);
            transition: all 0.3s;
            z-index: 1001;
            background: ${type === 'success' ? '#10b981' : type === 'error' ? '#ef4444' : '#3b82f6'};
        `;
        
        document.body.appendChild(notification);
        
        setTimeout(() => {
            notification.style.transform = 'translateX(0)';
        }, 10);
        
        setTimeout(() => {
            notification.style.transform = 'translateX(100%)';
            setTimeout(() => notification.remove(), 300);
        }, 3000);
    }
}

// Initialize chatbot when DOM is ready
document.addEventListener('DOMContentLoaded', () => {
    new StreamingChatbot();
});