import streamlit as st
import pandas as pd
from datetime import datetime
import difflib
import json

def fetch_model_versions(repo_id):
    """
    Fetch model versions from the Hugging Face API.
    In a real implementation, this would call the HF API to get version history.
    For now, we'll use demo data.
    """
    # In a production app, you would fetch this from the Hugging Face API
    # For demo purposes, create some sample version data
    versions = [
        {
            "version": "v1.0",
            "commit_id": "abc123",
            "timestamp": "2023-01-15T10:30:00Z",
            "author": st.session_state.username,
            "message": "Initial model release",
            "files_changed": 5,
            "performance": {"accuracy": 0.85, "f1": 0.82}
        },
        {
            "version": "v1.1",
            "commit_id": "def456",
            "timestamp": "2023-02-20T14:45:00Z",
            "author": st.session_state.username,
            "message": "Improved tokenization",
            "files_changed": 2,
            "performance": {"accuracy": 0.87, "f1": 0.84}
        },
        {
            "version": "v2.0",
            "commit_id": "ghi789",
            "timestamp": "2023-03-10T09:15:00Z",
            "author": st.session_state.username,
            "message": "Major model architecture upgrade",
            "files_changed": 12,
            "performance": {"accuracy": 0.92, "f1": 0.90}
        }
    ]
    return versions

def render_version_history(model_info):
    """Render the version history of a model"""
    if not model_info:
        st.error("Model information not found")
        return
    
    repo_id = model_info.modelId
    st.subheader("🔄 Version History")
    
    with st.spinner("Loading version history..."):
        versions = fetch_model_versions(repo_id)
    
    if not versions:
        st.info("No version history found for this model.")
        return
    
    # Convert to DataFrame for easier display
    df = pd.DataFrame(versions)
    
    # Format timestamp
    df["timestamp"] = pd.to_datetime(df["timestamp"]).dt.strftime("%Y-%m-%d %H:%M")
    
    # Create a cleaner display version
    display_df = df[["version", "timestamp", "author", "message", "files_changed"]]
    display_df.columns = ["Version", "Date", "Author", "Commit Message", "Files Changed"]
    
    # Show the version history
    st.dataframe(display_df, use_container_width=True)
    
    # Version comparison
    st.subheader("Compare Versions")
    col1, col2 = st.columns(2)
    
    with col1:
        base_version = st.selectbox(
            "Base Version",
            options=df["version"].tolist(),
            index=0
        )
    
    with col2:
        compare_version = st.selectbox(
            "Compare Version",
            options=[v for v in df["version"].tolist() if v != base_version],
            index=0
        )
    
    if st.button("Compare", use_container_width=True):
        with st.spinner("Generating comparison..."):
            # In a real implementation, fetch the actual data from each version
            # For demo, use the sample performance metrics
            base_data = df[df["version"] == base_version].iloc[0]
            compare_data = df[df["version"] == compare_version].iloc[0]
            
            # Display comparison
            col1, col2 = st.columns(2)
            
            with col1:
                st.markdown(f"### {base_version}")
                st.markdown(f"**Commit:** {base_data['commit_id']}")
                st.markdown(f"**Date:** {base_data['timestamp']}")
                st.markdown(f"**Author:** {base_data['author']}")
                st.markdown(f"**Message:** {base_data['message']}")
                
                # Performance metrics
                st.markdown("#### Performance Metrics")
                for metric, value in base_data["performance"].items():
                    st.markdown(f"**{metric.capitalize()}:** {value:.4f}")
            
            with col2:
                st.markdown(f"### {compare_version}")
                st.markdown(f"**Commit:** {compare_data['commit_id']}")
                st.markdown(f"**Date:** {compare_data['timestamp']}")
                st.markdown(f"**Author:** {compare_data['author']}")
                st.markdown(f"**Message:** {compare_data['message']}")
                
                # Performance metrics
                st.markdown("#### Performance Metrics")
                for metric, value in compare_data["performance"].items():
                    # Calculate change
                    base_value = base_data["performance"].get(metric, 0)
                    change = value - base_value
                    change_pct = (change / base_value * 100) if base_value != 0 else float('inf')
                    
                    # Display with change indicator
                    if change > 0:
                        st.markdown(f"**{metric.capitalize()}:** {value:.4f} 📈 **(+{change:.4f}, {change_pct:.2f}%)**")
                    elif change < 0:
                        st.markdown(f"**{metric.capitalize()}:** {value:.4f} 📉 **({change:.4f}, {change_pct:.2f}%)**")
                    else:
                        st.markdown(f"**{metric.capitalize()}:** {value:.4f} (no change)")
            
            # Show visual diff of model config
            st.subheader("Configuration Changes")
            
            # Sample configs (in a real app, you'd fetch these from the API)
            base_config = {
                "hidden_size": 768,
                "num_attention_heads": 12,
                "num_hidden_layers": 6,
                "vocab_size": 30000
            }
            
            compare_config = {
                "hidden_size": 1024,
                "num_attention_heads": 16,
                "num_hidden_layers": 8,
                "vocab_size": 30000
            }
            
            # Generate a formatted diff
            base_str = json.dumps(base_config, indent=2).splitlines()
            compare_str = json.dumps(compare_config, indent=2).splitlines()
            
            diff = difflib.unified_diff(
                base_str,
                compare_str,
                fromfile=f'config_{base_version}',
                tofile=f'config_{compare_version}',
                lineterm=''
            )
            
            diff_html = []
            for line in diff:
                if line.startswith('+'):
                    diff_html.append(f'<span style="color: green">{line}</span>')
                elif line.startswith('-'):
                    diff_html.append(f'<span style="color: red">{line}</span>')
                elif line.startswith('@@'):
                    diff_html.append(f'<span style="color: purple">{line}</span>')
                else:
                    diff_html.append(line)
            
            st.markdown('<div style="background-color: #f5f5f5; padding: 10px; border-radius: 5px; font-family: monospace; white-space: pre-wrap;">' + '<br>'.join(diff_html) + '</div>', unsafe_allow_html=True)
    
    # Rollback functionality
    st.subheader("Rollback to Previous Version")
    rollback_version = st.selectbox(
        "Select version to rollback to",
        options=df["version"].tolist(),
        index=len(df)-2  # Default to second-to-last version
    )
    
    if st.button("Rollback", use_container_width=True, type="primary"):
        with st.spinner("Rolling back to version " + rollback_version):
            # In a real implementation, this would call the HF API to perform the rollback
            st.success(f"Successfully rolled back to {rollback_version}")
            # Here you would update the model information and refresh the view