import requests
import os
import json
import streamlit as st
from datetime import datetime, timedelta
import time
import uuid

# Page configuration
st.set_page_config(
    page_title="Chat Flow 🕷",
    page_icon="💬",
    initial_sidebar_state="expanded"
)

# Enhanced CSS with chat history styling and BLACK NEW CHAT BUTTON
st.markdown("""
<style>
    .stApp {
        background: white;
    }
    
    .main .block-container {
        max-width: 800px;
    }
    
    #MainMenu {visibility: hidden;}
    footer {visibility: hidden;}
    header {visibility: hidden;}
    .stDeployButton {display: none;}
    
    .model-id {
        color: #28a745;
        font-family: monospace;
    }
    
    .model-attribution {
        color: #28a745;
        font-size: 0.8em;
        font-style: italic;
    }
    
    /* NEW CHAT BUTTON - Black background, white text */
    .stButton > button[kind="primary"] {
        background-color: #000000 !important;
        border-color: #000000 !important;
        color: #ffffff !important;
    }
    
    .stButton > button[kind="primary"]:hover {
        background-color: #333333 !important;
        border-color: #333333 !important;
        color: #ffffff !important;
    }
    
    .stButton > button[kind="primary"]:active {
        background-color: #1a1a1a !important;
        border-color: #1a1a1a !important;
        color: #ffffff !important;
    }
    
    .stButton > button[kind="primary"]:focus {
        background-color: #000000 !important;
        border-color: #000000 !important;
        color: #ffffff !important;
        box-shadow: 0 0 0 0.2rem rgba(0, 0, 0, 0.25) !important;
    }
    
    /* Chat history styling */
    .chat-history-item {
        padding: 8px 12px;
        margin: 4px 0;
        border-radius: 8px;
        border: 1px solid #e0e0e0;
        background: #f8f9fa;
        cursor: pointer;
        transition: all 0.2s;
    }
    
    .chat-history-item:hover {
        background: #e9ecef;
        border-color: #28a745;
    }
    
    .chat-history-item.active {
        background: #28a745;
        color: white;
        border-color: #28a745;
    }
    
    .chat-title {
        font-weight: 500;
        font-size: 0.9em;
        margin-bottom: 2px;
    }
    
    .chat-date {
        font-size: 0.75em;
        opacity: 0.7;
    }
    
    .new-chat-btn {
        width: 100%;
        margin-bottom: 16px;
    }
</style>
""", unsafe_allow_html=True)

# File to store chat history
HISTORY_FILE = "chat_history.json"
USERS_FILE = "online_users.json"
SESSIONS_FILE = "chat_sessions.json"

# ================= USER FUNCTIONS =================

def get_user_id():
    """Get unique ID for this user session"""
    if 'user_id' not in st.session_state:
        st.session_state.user_id = str(uuid.uuid4())[:8]
    return st.session_state.user_id

def update_online_users():
    """Update user status"""
    try:
        # Load current users
        users = {}
        if os.path.exists(USERS_FILE):
            with open(USERS_FILE, 'r') as f:
                users = json.load(f)

        user_id = get_user_id()

        # Update user info
        users[user_id] = {
            'last_seen': datetime.now().isoformat(),
            'name': f'User-{user_id}',
            'session_start': users.get(user_id, {}).get('session_start', datetime.now().isoformat())
        }

        # Clean up old users (not seen in 5 minutes)
        current_time = datetime.now()
        active_users = {}
        for uid, data in users.items():
            try:
                last_seen = datetime.fromisoformat(data['last_seen'])
                if current_time - last_seen < timedelta(minutes=5):
                    active_users[uid] = data
            except:
                continue

        # Save updated users
        with open(USERS_FILE, 'w') as f:
            json.dump(active_users, f, indent=2)

        return len(active_users)
        
    except Exception as e:
        st.error(f"User tracking error: {e}")
        return 1

def show_online_users():
    """Display online users count"""
    st.header("👥 Who's Online")
    
    try:
        if not os.path.exists(USERS_FILE):
            st.info("No user data yet")
            return 0
            
        with open(USERS_FILE, 'r') as f:
            users = json.load(f)
        
        if not users:
            st.info("No active users")
            return 0
        
        online_count = len(users)
        
        # Show count
        if online_count == 1:
            st.success("🟢 Just you online")
        else:
            st.success(f"🟢 {online_count} people online")
        
        st.divider()
        
        # Show each user
        current_user_id = get_user_id()
        for user_id, data in users.items():
            is_current_user = (user_id == current_user_id)
            
            # User header
            if is_current_user:
                st.markdown("**👤 You**")
            else:
                st.markdown(f"**👤 {data.get('name', user_id)}**")
            
            # Show session info
            try:
                session_start = datetime.fromisoformat(data['session_start'])
                duration = datetime.now() - session_start
                minutes = int(duration.total_seconds() / 60)
                st.caption(f"🕐 Online for {minutes} minutes")
            except:
                st.caption("🕐 Session time unknown")
            
            st.divider()
        
        return online_count
        
    except Exception as e:
        st.error(f"Error showing users: {e}")
        return 0

# ================= CHAT FUNCTIONS =================

def load_chat_history():
    """Load chat history from file"""
    try:
        if os.path.exists(HISTORY_FILE):
            with open(HISTORY_FILE, 'r', encoding='utf-8') as f:
                return json.load(f)
    except Exception as e:
        st.error(f"Error loading chat history: {e}")
    return []

def save_chat_history(messages):
    """Save chat history to file"""
    try:
        with open(HISTORY_FILE, 'w', encoding='utf-8') as f:
            json.dump(messages, f, ensure_ascii=False, indent=2)
    except Exception as e:
        st.error(f"Error saving chat history: {e}")

def clear_chat_history():
    """Clear chat history file"""
    try:
        if os.path.exists(HISTORY_FILE):
            os.remove(HISTORY_FILE)
        st.session_state.messages = []
    except Exception as e:
        st.error(f"Error clearing chat history: {e}")

def load_chat_sessions():
    """Load all chat sessions"""
    try:
        if os.path.exists(SESSIONS_FILE):
            with open(SESSIONS_FILE, 'r', encoding='utf-8') as f:
                return json.load(f)
    except Exception as e:
        st.error(f"Error loading chat sessions: {e}")
    return {}

def save_chat_sessions(sessions):
    """Save chat sessions to file"""
    try:
        with open(SESSIONS_FILE, 'w', encoding='utf-8') as f:
            json.dump(sessions, f, ensure_ascii=False, indent=2)
    except Exception as e:
        st.error(f"Error saving chat sessions: {e}")

def get_session_id():
    """Get or create session ID"""
    if 'session_id' not in st.session_state:
        st.session_state.session_id = str(uuid.uuid4())
    return st.session_state.session_id

def get_chat_title(messages):
    """Generate a title for the chat based on conversation content using AI"""
    if not messages:
        return "New Chat"
    
    if len(messages) <= 1:
        for msg in messages:
            if msg["role"] == "user":
                content = msg["content"]
                if len(content) > 30:
                    return content[:30] + "..."
                return content
        return "New Chat"
    
    try:
        return generate_smart_title(messages)
    except:
        for msg in messages:
            if msg["role"] == "user":
                content = msg["content"]
                if len(content) > 30:
                    return content[:30] + "..."
                return content
        return "New Chat"

def generate_smart_title(messages):
    """Use AI to generate a smart title for the conversation"""
    if not OPENROUTER_API_KEY:
        for msg in messages:
            if msg["role"] == "user":
                content = msg["content"]
                if len(content) > 30:
                    return content[:30] + "..."
                return content
        return "New Chat"
    
    conversation_text = ""
    message_count = 0
    
    for msg in messages:
        if message_count >= 6:
            break
        if msg["role"] in ["user", "assistant"]:
            role = "User" if msg["role"] == "user" else "Assistant"
            content = msg["content"]
            if "Response created by:" in content:
                content = content.split("\n\n---\n*Response created by:")[0]
            conversation_text += f"{role}: {content[:200]}...\n"
            message_count += 1
    
    title_prompt = f"""Based on this conversation, generate a short, descriptive title (2-5 words max):

{conversation_text}

Generate only a brief title that captures the main topic. Examples:
- "Python Code Help"
- "Recipe Ideas"
- "Travel Planning"
- "Math Problem"
- "Writing Assistance"

Title:"""

    url = "https://openrouter.ai/api/v1/chat/completions"
    headers = {
        "Content-Type": "application/json",
        "Authorization": f"Bearer {OPENROUTER_API_KEY}",
        "HTTP-Referer": "http://localhost:8501",
        "X-Title": "Streamlit AI Assistant"
    }

    data = {
        "model": "openai/gpt-3.5-turbo",
        "messages": [{"role": "user", "content": title_prompt}],
        "max_tokens": 20,
        "temperature": 0.3,
        "stream": False
    }

    try:
        response = requests.post(url, headers=headers, json=data, timeout=10)
        if response.status_code == 200:
            result = response.json()
            title = result["choices"][0]["message"]["content"].strip()
            title = title.replace('"', '').replace("Title:", "").strip()
            if len(title) > 40:
                title = title[:40] + "..."
            return title if title else "New Chat"
    except Exception as e:
        pass
    
    for msg in messages:
        if msg["role"] == "user":
            content = msg["content"]
            if len(content) > 30:
                return content[:30] + "..."
            return content
    return "New Chat"

def save_current_session():
    """Save current chat session with smart AI-generated title"""
    if not st.session_state.messages:
        return
        
    sessions = load_chat_sessions()
    session_id = get_session_id()
    
    user_messages = [msg for msg in st.session_state.messages if msg["role"] == "user"]
    assistant_messages = [msg for msg in st.session_state.messages if msg["role"] == "assistant"]
    
    if len(user_messages) >= 1 and len(assistant_messages) >= 1:
        title = get_chat_title(st.session_state.messages)
    else:
        title = "New Chat"
        if user_messages:
            first_message = user_messages[0]["content"]
            if len(first_message) > 30:
                title = first_message[:30] + "..."
            else:
                title = first_message
    
    sessions[session_id] = {
        "title": title,
        "messages": st.session_state.messages,
        "created_at": sessions.get(session_id, {}).get("created_at", datetime.now().isoformat()),
        "updated_at": datetime.now().isoformat()
    }
    
    save_chat_sessions(sessions)

def load_session(session_id):
    """Load a specific chat session"""
    sessions = load_chat_sessions()
    if session_id in sessions:
        st.session_state.messages = sessions[session_id]["messages"]
        st.session_state.session_id = session_id
        return True
    return False

def delete_session(session_id):
    """Delete a chat session"""
    sessions = load_chat_sessions()
    if session_id in sessions:
        del sessions[session_id]
        save_chat_sessions(sessions)
        return True
    return False

def start_new_chat():
    """Start a new chat session"""
    if st.session_state.messages:
        save_current_session()
    st.session_state.messages = []
    st.session_state.session_id = str(uuid.uuid4())

# Initialize session state
if "messages" not in st.session_state:
    st.session_state.messages = load_chat_history()

if "session_id" not in st.session_state:
    st.session_state.session_id = str(uuid.uuid4())

# Get API key
OPENROUTER_API_KEY = os.environ.get("OPENROUTER_API_KEY")

@st.cache_data(ttl=300)
def check_api_status():
    if not OPENROUTER_API_KEY:
        return "No API Key"
    try:
        url = "https://openrouter.ai/api/v1/models"
        headers = {"Authorization": f"Bearer {OPENROUTER_API_KEY}"}
        response = requests.get(url, headers=headers, timeout=10)
        return "Connected" if response.status_code == 200 else "Error"
    except:
        return "Error"

def get_ai_response(messages, model="openai/gpt-3.5-turbo"):
    if not OPENROUTER_API_KEY:
        return "No API key found. Please add OPENROUTER_API_KEY to environment variables."

    url = "https://openrouter.ai/api/v1/chat/completions"
    headers = {
        "Content-Type": "application/json",
        "Authorization": f"Bearer {OPENROUTER_API_KEY}",
        "HTTP-Referer": "http://localhost:8501",
        "X-Title": "Streamlit AI Assistant"
    }

    api_messages = [
        {"role": "system", "content": "You are a helpful AI assistant. Provide clear and helpful responses."}]
    api_messages.extend(messages)

    data = {
        "model": model,
        "messages": api_messages,
        "stream": True,
        "max_tokens": 2000,
        "temperature": 0.7,
        "top_p": 1,
        "frequency_penalty": 0,
        "presence_penalty": 0
    }

    try:
        response = requests.post(url, headers=headers, json=data, stream=True, timeout=60)

        if response.status_code != 200:
            error_detail = ""
            try:
                error_data = response.json()
                error_detail = error_data.get('error', {}).get('message', f"HTTP {response.status_code}")
            except:
                error_detail = f"HTTP {response.status_code}: {response.reason}"
            yield f"API Error: {error_detail}. Please try a different model or check your API key."
            return

        full_response = ""
        for line in response.iter_lines():
            if line:
                if line.startswith(b"data: "):
                    data_str = line[len(b"data: "):].decode("utf-8")
                    if data_str.strip() == "[DONE]":
                        break
                    try:
                        data = json.loads(data_str)
                        delta = data["choices"][0]["delta"].get("content", "")
                        if delta:
                            full_response += delta
                            yield full_response
                    except (json.JSONDecodeError, KeyError, IndexError):
                        continue

    except requests.exceptions.Timeout:
        yield "Request timed out. Please try again with a shorter message or different model."
    except requests.exceptions.ConnectionError:
        yield "Connection error. Please check your internet connection and try again."
    except requests.exceptions.RequestException as e:
        yield f"Request error: {str(e)}. Please try again."
    except Exception as e:
        yield f"Unexpected error: {str(e)}. Please try again or contact support."

# ================= MAIN APP =================

# Header
st.title("Chat Flow 🕷")
st.caption("10 powerful Models, one simple chat.")

# Sidebar
with st.sidebar:
    # New Chat Button (BLACK)
    if st.button("➕ New Chat", use_container_width=True, type="primary"):
        start_new_chat()
        st.rerun()
    
    st.divider()
    
    # ONLINE USERS SECTION
    online_count = show_online_users()
    
    # Update user tracking
    update_online_users()
    
    # Quick refresh for users
    if st.button("🔄 Refresh Users", use_container_width=True):
        st.rerun()
    
    st.divider()
    
    # Chat Sessions
    sessions = load_chat_sessions()
    current_session_id = get_session_id()
    
    if sessions:
        st.subheader("Previous Chats")
        sorted_sessions = sorted(sessions.items(), key=lambda x: x[1].get("updated_at", x[1].get("created_at", "")), reverse=True)
        
        for session_id, session_data in sorted_sessions:
            if session_id == current_session_id:
                st.markdown(f"🔹 **{session_data['title']}**")
            else:
                col_load, col_delete = st.columns([3, 1])
                with col_load:
                    if st.button(f"💭 {session_data['title']}", key=f"load_{session_id}", use_container_width=True):
                        if st.session_state.messages:
                            save_current_session()
                        load_session(session_id)
                        st.rerun()
                with col_delete:
                    if st.button("✕", key=f"delete_{session_id}"):
                        delete_session(session_id)
                        if session_id == current_session_id:
                            start_new_chat()
                        st.rerun()
                
                if "updated_at" in session_data:
                    update_time = datetime.fromisoformat(session_data["updated_at"])
                    st.caption(f"Updated: {update_time.strftime('%m/%d %H:%M')}")
                st.markdown("---")
    else:
        st.info("No previous chats yet")
    
    if st.session_state.messages:
        save_current_session()
    
    st.divider()

    # Settings Section
    st.header("Settings")
    status = check_api_status()
    if status == "Connected":
        st.success("🟢 API Connected")
    elif status == "No API Key":
        st.error("No API Key")
    else:
        st.warning("Connection Issue")

    st.divider()

    # Model Selection
    models = [
        ("GPT-3.5 Turbo", "openai/gpt-3.5-turbo"),
        ("LLaMA 3.1 8B", "meta-llama/llama-3.1-8b-instruct"),
        ("LLaMA 3.1 70B", "meta-llama/llama-3.1-70b-instruct"),
        ("DeepSeek Chat v3", "deepseek/deepseek-chat-v3-0324:free"),
        ("DeepSeek R1", "deepseek/deepseek-r1-0528:free"),
        ("Qwen3 Coder", "qwen/qwen3-coder:free"),
        ("Microsoft MAI DS R1", "microsoft/mai-ds-r1:free"),
        ("Gemma 3 27B", "google/gemma-3-27b-it:free"),
        ("Gemma 3 4B", "google/gemma-3-4b-it:free"),
        ("Auto (Best Available)", "openrouter/auto")
    ]

    model_names = [name for name, _ in models]
    model_ids = [model_id for _, model_id in models]

    selected_index = st.selectbox("Model", range(len(model_names)),
                                  format_func=lambda x: model_names[x],
                                  index=0)
    selected_model = model_ids[selected_index]

    # Show selected model ID in green
    st.markdown(f"**Model ID:** <span class='model-id'>{selected_model}</span>", unsafe_allow_html=True)

    st.divider()

    # Chat History Controls
    st.header("Chat History")

    # Show number of messages
    if st.session_state.messages:
        st.info(f"Messages stored: {len(st.session_state.messages)}")

    # Auto-save toggle
    auto_save = st.checkbox("Auto-save messages", value=True)

    # Manual save/load buttons
    col1, col2 = st.columns(2)
    with col1:
        if st.button("Save History", use_container_width=True):
            save_chat_history(st.session_state.messages)
            st.success("History saved!")

    with col2:
        if st.button("Load History", use_container_width=True):
            st.session_state.messages = load_chat_history()
            st.success("History loaded!")
            st.rerun()

    st.divider()

    # View History
    if st.button("View History File", use_container_width=True):
        if os.path.exists(HISTORY_FILE):
            with open(HISTORY_FILE, 'r', encoding='utf-8') as f:
                history_content = f.read()
            st.text_area("Chat History (JSON)", history_content, height=200)
        else:
            st.warning("No history file found")

    # Download History
    if os.path.exists(HISTORY_FILE):
        with open(HISTORY_FILE, 'rb') as f:
            st.download_button(
                label="Download History",
                data=f.read(),
                file_name=f"chat_history_{datetime.now().strftime('%Y%m%d_%H%M%S')}.json",
                mime="application/json",
                use_container_width=True
            )

    st.divider()

    # Clear controls
    if st.button("Clear Chat", use_container_width=True, type="secondary"):
        clear_chat_history()
        st.success("Chat cleared!")
        st.rerun()

# ================= MAIN CHAT AREA =================

# Display chat messages
for message in st.session_state.messages:
    with st.chat_message(message["role"]):
        # Check if this is an assistant message with attribution
        if message["role"] == "assistant" and "Response created by:" in message["content"]:
            # Split content and attribution
            parts = message["content"].split("\n\n---\n*Response created by:")
            main_content = parts[0]
            if len(parts) > 1:
                model_name = parts[1].replace("***", "").replace("**", "")
                st.markdown(main_content)
                st.markdown(
                    f"<div class='model-attribution'>Response created by: <strong>{model_name}</strong></div>", 
                    unsafe_allow_html=True)
            else:
                st.markdown(message["content"])
        else:
            st.markdown(message["content"])

# Chat input - MAIN CHAT FUNCTIONALITY
if prompt := st.chat_input("Chat Smarter. Chat many Brains"):
    # Update user tracking when user sends message
    update_online_users()

    # Add user message
    user_message = {"role": "user", "content": prompt}
    st.session_state.messages.append(user_message)

    # Auto-save if enabled
    if 'auto_save' not in locals():
        auto_save = True
    
    if auto_save:
        save_chat_history(st.session_state.messages)
    
    # Always auto-save the current session
    save_current_session()

    # Display user message
    with st.chat_message("user"):
        st.markdown(prompt)

    # Get AI response
    with st.chat_message("assistant"):
        placeholder = st.empty()

        full_response = ""
        try:
            for response in get_ai_response(st.session_state.messages, selected_model):
                full_response = response
                placeholder.markdown(full_response + "▌")

            # Remove cursor and show final response
            placeholder.markdown(full_response)

        except Exception as e:
            error_msg = f"An error occurred: {str(e)}"
            placeholder.markdown(error_msg)
            full_response = error_msg

    # Add AI response to messages with attribution
    full_response_with_attribution = full_response + f"\n\n---\n*Response created by: **{model_names[selected_index]}***"
    assistant_message = {"role": "assistant", "content": full_response_with_attribution}
    st.session_state.messages.append(assistant_message)

    # Auto-save if enabled
    if auto_save:
        save_chat_history(st.session_state.messages)
    
    # Always auto-save the current session
    save_current_session()

# Show currently using model
st.caption(f"Currently using: **{model_names[selected_index]}**")