# components/chat.py
import streamlit as st
from datetime import datetime
from langchain_core.messages import HumanMessage, AIMessage
from backend import get_embeddings_model, initialize_qa_system
from utils.persistence import PersistenceManager


def ensure_embeddings_initialized():
    """Ensure embeddings model is initialized in session state."""
    if 'embeddings' not in st.session_state:
        try:
            st.session_state.embeddings = get_embeddings_model()
        except Exception as e:
            st.error(f"Error initializing embeddings model: {e}")
            return False
    return True


def format_session_date(session_id: str) -> str:
    """Format session ID into readable date."""
    try:
        # Handle different possible date formats
        if '_' in session_id:
            date_part = session_id.split('_')[1]
        else:
            date_part = session_id

        if len(date_part) == 8:  # Format: YYYYMMDD
            return datetime.strptime(date_part, '%Y%m%d').strftime('%B %d, %Y')
        elif len(date_part) == 14:  # Format: YYYYMMDD_HHMMSS
            return datetime.strptime(date_part, '%Y%m%d%H%M%S').strftime('%B %d, %Y %I:%M %p')
        else:
            return date_part  # Return original if format unknown
    except Exception as e:
        return f"Session: {session_id}"  # Fallback display


def clean_ai_response(content):
    """Clean up AI response content and remove technical artifacts."""
    content = str(content)

    # Remove common technical artifacts
    if "content='" in content:
        content = content.split("content='")[1]
    if "additional_kwargs" in content:
        content = content.split("additional_kwargs")[0]

    # Clean up any remaining artifacts
    content = content.strip("'")
    content = content.replace('\\n', '\n')
    content = content.replace('\\t', '\t')

    return content


def format_assistant_response(content):
    """Format the assistant's response into a structured layout."""
    try:
        # Clean the content first
        content = clean_ai_response(content)

        # Identify sections and structure
        lines = [line.strip() for line in content.split('\n') if line.strip()]
        formatted_sections = []
        current_section = []

        for line in lines:
            # Handle bullet points and lists
            if line.startswith(('•', '-', '*')):
                line = f"<li>{line.lstrip('•-* ')}</li>"
                if not current_section:
                    current_section.append("<ul>")
                current_section.append(line)
            # Handle section headers
            elif line.startswith('**') and line.endswith('**'):
                if current_section:
                    if current_section[0] == "<ul>":
                        current_section.append("</ul>")
                    formatted_sections.extend(current_section)
                    current_section = []
                header = line.strip('**')
                formatted_sections.append(f'<h4 class="section-header">{header}</h4>')
            # Regular text
            else:
                if current_section and current_section[0] == "<ul>":
                    current_section.append("</ul>")
                    formatted_sections.extend(current_section)
                    current_section = []
                formatted_sections.append(f'<p>{line}</p>')

        # Add any remaining content
        if current_section:
            if current_section[0] == "<ul>":
                current_section.append("</ul>")
            formatted_sections.extend(current_section)

        # Build the final HTML
        formatted_html = f"""
        <div class="response-content">
            {''.join(formatted_sections)}
        </div>
        """

        return formatted_html
    except Exception as e:
        st.error(f"Error formatting response: {str(e)}")
        return str(content)


def display_chat_interface():
    """Display modern chat interface with clean formatting."""

    # Initialize persistence if needed
    if 'persistence' not in st.session_state:
        st.session_state.persistence = PersistenceManager()

    # Add custom CSS for modern chat styling
    st.markdown("""
    <style>
        /* Chat container */
        .chat-container {
            max-width: 800px;
            margin: auto;
        }

        /* User message */
        .user-message {
            background-color: #f0f2f6;
            padding: 1rem;
            border-radius: 10px;
            margin: 1rem 0;
            box-shadow: 0 1px 3px rgba(0,0,0,0.1);
        }

        /* Assistant message */
        .assistant-message {
            background-color: #ffffff;
            border: 1px solid #e0e0e0;
            padding: 1.5rem;
            border-radius: 10px;
            margin: 1rem 0;
            box-shadow: 0 1px 3px rgba(0,0,0,0.1);
        }

        /* Response content */
        .response-content {
            line-height: 1.6;
        }

        /* Section headers */
        .section-header {
            color: #0f52ba;
            margin: 1.5rem 0 1rem 0;
            font-size: 1.1rem;
            font-weight: 600;
            border-bottom: 2px solid #e0e0e0;
            padding-bottom: 0.5rem;
        }

        /* Lists */
        .response-content ul {
            margin: 1rem 0;
            padding-left: 1.5rem;
            list-style-type: none;
        }

        .response-content li {
            margin: 0.5rem 0;
            position: relative;
            padding-left: 1rem;
        }

        .response-content li:before {
            content: "•";
            position: absolute;
            left: -1rem;
            color: #0f52ba;
        }

        /* Paragraphs */
        .response-content p {
            margin: 1rem 0;
            color: #2c3e50;
        }

        /* Source citations */
        .source-citation {
            font-style: italic;
            color: #666;
            border-top: 1px solid #e0e0e0;
            margin-top: 1rem;
            padding-top: 0.5rem;
            font-size: 0.9rem;
        }

        /* Session selector */
        .session-selector {
            padding: 1rem;
            background-color: #f8f9fa;
            border-radius: 10px;
            margin-bottom: 1rem;
            border: 1px solid #e0e0e0;
        }

        /* Current session info */
        .session-info {
            margin-bottom: 1rem;
            padding: 0.5rem 1rem;
            background-color: #e3f2fd;
            border-radius: 5px;
            font-size: 0.9rem;
            color: #1565c0;
        }
    </style>
    """, unsafe_allow_html=True)

    try:
        # Check if QA system is initialized
        if 'qa_system' not in st.session_state or st.session_state.qa_system is None:
            # Show available sessions if any
            sessions = st.session_state.persistence.list_available_sessions()
            if sessions:
                st.markdown('<div class="session-selector">', unsafe_allow_html=True)
                st.subheader("💾 Load Previous Chat")
                selected_session = st.selectbox(
                    "Select a previous conversation:",
                    options=[s['session_id'] for s in sessions],
                    format_func=lambda x: f"Chat from {format_session_date(x)}"
                )

                if selected_session and st.button("Load Selected Chat"):
                    with st.spinner("Loading previous chat..."):
                        messages = st.session_state.persistence.load_chat_history(selected_session)
                        if messages:
                            st.session_state.messages = messages

                        # Load vector store
                        vector_store = st.session_state.persistence.load_vector_store(selected_session)
                        if vector_store:
                            st.session_state.vector_store = vector_store
                            st.session_state.qa_system = initialize_qa_system(vector_store)
                            st.session_state.current_session_id = selected_session
                            st.rerun()
                st.markdown('</div>', unsafe_allow_html=True)

            st.warning("Please upload documents or select a previous chat to begin.")
            return

        # Initialize chat history
        if 'messages' not in st.session_state:
            st.session_state.messages = []

        # Display current session info if available
        if 'current_session_id' in st.session_state:
            session_date = format_session_date(st.session_state.current_session_id)
            st.markdown(f"""
                <div class="session-info">
                    📅 Current Session: {session_date}
                </div>
            """, unsafe_allow_html=True)

        # Display chat history
        for message in st.session_state.messages:
            if isinstance(message, HumanMessage):
                st.markdown(f"""
                <div class="user-message">
                    🧑‍💼 <strong>You:</strong><br>{message.content}
                </div>
                """, unsafe_allow_html=True)
            elif isinstance(message, AIMessage):
                st.markdown(f"""
                <div class="assistant-message">
                    🤖 <strong>Assistant:</strong>
                    {format_assistant_response(message.content)}
                </div>
                """, unsafe_allow_html=True)

        # Chat input
        if prompt := st.chat_input("Ask about your documents..."):
            with st.spinner("Analyzing..."):
                # Validate input
                if not prompt.strip():
                    st.warning("Please enter a valid question.")
                    return

                try:
                    # Create and append human message
                    human_message = HumanMessage(content=prompt)
                    st.session_state.messages.append(human_message)

                    # Get response from QA system
                    response = st.session_state.qa_system.invoke({
                        "input": prompt,
                        "chat_history": []
                    })

                    if response:
                        ai_message = AIMessage(content=str(response))
                        st.session_state.messages.append(ai_message)

                        # Save chat history
                        if 'current_session_id' in st.session_state:
                            st.session_state.persistence.save_chat_history(
                                st.session_state.messages,
                                st.session_state.current_session_id,
                                metadata={
                                    'last_question': prompt,
                                    'last_updated': datetime.now().isoformat()
                                }
                            )

                        st.rerun()
                    else:
                        st.error("No valid response received. Please try again.")

                except Exception as e:
                    st.error(f"Error processing response: {str(e)}")
                    import traceback
                    st.error(traceback.format_exc())
                    # Remove the failed message attempt
                    if st.session_state.messages:
                        st.session_state.messages.pop()
    except Exception as e:
        st.error(f"An unexpected error occurred: {e}")
        import traceback
        st.error(traceback.format_exc())