import gradio as gr
import logging
import tempfile
import os
from .db_connector import DBConnector
from .schema_inspector import SchemaInspector
from .merge_operations import MergeOperations
from .db_visualizer import DatabaseVisualizer
from .config import get_config

# Set up logging
logging.basicConfig(level=logging.INFO, 
                    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
logger = logging.getLogger(__name__)

# Initialize config but don't connect to DB yet
config = get_config()
db = None
inspector = None
merge_ops = None
visualizer = None

def connect_to_database(db_url):
    """Connect to the database with provided URL"""
    global db, inspector, merge_ops, visualizer
    
    try:
        # Initialize new connection
        db = DBConnector(db_url)
        success = db.connect()
        
        if not success:
            return "Failed to connect to database. Check the connection string and ensure the required database driver is installed.", gr.Dropdown(choices=[])
            
        inspector = SchemaInspector(db)
        merge_ops = MergeOperations(db, inspector)
        visualizer = DatabaseVisualizer(db, inspector)
        
        # Test connection by fetching tables
        tables = get_db_tables()
        if tables:
            return f"Successfully connected to database. Found {len(tables)} tables.", gr.Dropdown(choices=tables)
        else:
            return "Connected to database but found no tables.", gr.Dropdown(choices=[])
    except ImportError as e:
        error_msg = f"Database driver error: {str(e)}"
        logger.error(error_msg)
        return error_msg, gr.Dropdown(choices=[])
    except Exception as e:
        logger.error(f"Database connection error: {str(e)}")
        return f"Error connecting to database: {str(e)}", gr.Dropdown(choices=[])

def handle_merge(action, table, column, from_values, target_value, preview_only=True):
    """Handler for Gradio interface"""
    if not db:
        return "Error: Not connected to database. Please connect first.", "", ""
    
    if not table or not column:
        return "Error: Table and column must be specified", "", ""
    
    # Parse from_values as comma-separated list
    from_values_list = [v.strip() for v in from_values.split(',')]
    
    if action == "Merge Values":
        if preview_only:
            result = merge_ops.preview_merge(table, column, from_values_list, target_value)
            return result["preview"], "", ""
        else:
            result = merge_ops.run_merge(table, column, from_values_list, target_value)
            # Auto-generate visualization after successful operation
            if result.get("success", False) and visualizer:
                try:
                    text_summary = visualizer.generate_table_summary()
                    mermaid_diagram = visualizer.generate_mermaid_diagram()
                    return result["log"], text_summary, mermaid_diagram
                except Exception as e:
                    logger.error(f"Error generating visualization after merge: {str(e)}")
                    return result["log"], "Error generating visualization", ""
            return result["log"], "", ""
    else:
        return "Action not implemented yet", "", ""

def get_db_tables():
    """Get list of tables from the database for dropdown"""
    if not db:
        logger.warning("Attempted to fetch tables but database not connected")
        return []
        
    logger.info("Fetching tables from the database...")
    try:
        # Try a much simpler query first - just get tables from public schema
        query = "SELECT table_name FROM information_schema.tables WHERE table_schema = 'public' AND table_type = 'BASE TABLE'"
        result = db.execute_query(query)
        tables = [row[0] for row in result]

        logger.info(f"Found {len(tables)} tables in the database")
        return tables
    except Exception as e:
        logger.error(f"Error getting tables: {str(e)}")
        # Return an empty list as last resort
        return []

def get_columns(table):
    """Get columns for selected table"""
    if not db or not inspector:
        return gr.Dropdown(choices=[])
        
    if not table:
        return gr.Dropdown(choices=[])
    try:
        columns = inspector.get_column_info(table)
        logger.info(f"Columns for {table}: {columns}")
        return gr.Dropdown(choices=[col['column_name'] for col in columns])
    except Exception as e:
        logger.error(f"Error getting columns: {str(e)}")
        return gr.Dropdown(choices=[])

def refresh_tables():
    """Refresh the list of tables"""
    if not db:
        return "Not connected to database", gr.Dropdown(choices=[])
    
    tables = get_db_tables()
    return f"Refreshed tables. Found {len(tables)} tables.", gr.Dropdown(choices=tables)

def execute_sql_file(sql_file):
    """Execute SQL commands from uploaded file"""
    global db
    
    if not db:
        return "Error: Not connected to database. Please connect first.", "", ""
    
    if sql_file is None:
        return "Error: No SQL file provided.", "", ""
    
    try:
        # Read the uploaded file
        with open(sql_file.name, 'r', encoding='utf-8') as f:
            sql_content = f.read()
        
        if not sql_content.strip():
            return "Error: SQL file is empty.", "", ""
        
        # Split SQL content by semicolons and execute each statement
        sql_statements = [stmt.strip() for stmt in sql_content.split(';') if stmt.strip()]
        
        results = []
        session = db.get_session()
        
        try:
            for i, statement in enumerate(sql_statements, 1):
                logger.info(f"Executing SQL statement {i}: {statement[:100]}...")
                result = session.execute(statement)
                
                # Try to fetch results if it's a SELECT statement
                if statement.strip().upper().startswith('SELECT'):
                    rows = result.fetchall()
                    results.append(f"Statement {i}: Returned {len(rows)} rows")
                    if len(rows) <= 10:  # Show first 10 rows for small results
                        for row in rows:
                            results.append(f"  {row}")
                else:
                    results.append(f"Statement {i}: Executed successfully (affected rows: {result.rowcount})")
            
            session.commit()
            results.insert(0, f"Successfully executed {len(sql_statements)} SQL statements.")
            operation_log = "\n".join(results)
            
            # Auto-generate visualization after successful SQL execution
            if visualizer:
                try:
                    text_summary = visualizer.generate_table_summary()
                    mermaid_diagram = visualizer.generate_mermaid_diagram()
                    return operation_log, text_summary, mermaid_diagram
                except Exception as e:
                    logger.error(f"Error generating visualization after SQL execution: {str(e)}")
                    return operation_log, "Error generating visualization", ""
            
            return operation_log, "", ""
            
        except Exception as e:
            session.rollback()
            error_msg = f"Error executing SQL: {str(e)}"
            logger.error(error_msg)
            return error_msg, "", ""
        finally:
            session.close()
            
    except Exception as e:
        logger.error(f"Error reading SQL file: {str(e)}")
        return f"Error reading SQL file: {str(e)}", "", ""

def generate_database_visualization():
    """Generate database visualization"""
    if not visualizer:
        return "Error: Not connected to database. Please connect first.", ""
    
    try:
        # Generate both Mermaid diagram and text summary
        mermaid_diagram = visualizer.generate_mermaid_diagram()
        text_summary = visualizer.generate_table_summary()
        
        return text_summary, mermaid_diagram
        
    except Exception as e:
        error_msg = f"Error generating visualization: {str(e)}"
        logger.error(error_msg)
        return error_msg, ""

def refresh_visualization():
    """Refresh the database visualization"""
    return generate_database_visualization()

def create_ui():
    """Create and configure the Gradio UI"""
    with gr.Blocks(title="SchemaSync") as app:
        gr.Markdown("# SchemaSync - Database Schema Manipulation Tool")
        
        with gr.Row():
            with gr.Column(scale=1):
                # Database Connection Section
                gr.Markdown("## Database Connection")
                
                db_url = gr.Textbox(
                    label="Database URL",
                    placeholder="postgresql://username:password@localhost:5432/database",
                    value="",
                    type="password"
                )
                
                with gr.Row():
                    connect_btn = gr.Button("Connect to Database")
                    refresh_btn = gr.Button("Refresh Tables")
                
                connection_status = gr.Textbox(
                    label="Connection Status",
                    interactive=False
                )
                
                # SQL Import Section
                gr.Markdown("## SQL File Import")
                
                sql_file = gr.File(
                    label="Upload SQL File",
                    file_types=[".sql", ".txt"],
                    file_count="single"
                )
                
                execute_sql_btn = gr.Button("Execute SQL File")
                
                # Operations Section
                gr.Markdown("## Schema Operations")
                
                action = gr.Dropdown(
                    choices=["Merge Values"],
                    label="Action",
                    value="Merge Values"
                )
                
                table = gr.Dropdown(
                    choices=[],
                    label="Table",
                    interactive=True,
                    allow_custom_value=True
                )
                
                column = gr.Dropdown(
                    label="Column",
                    interactive=True,
                    allow_custom_value=True
                )
                
                # Update column dropdown when table changes
                table.change(fn=get_columns, inputs=table, outputs=column)
                
                from_values = gr.Textbox(
                    label="From Values (comma-separated)",
                    placeholder="value1, value2, value3"
                )
                
                target_value = gr.Textbox(
                    label="Target Value",
                    placeholder="target_value"
                )
                
                preview_checkbox = gr.Checkbox(
                    label="Preview Only (no changes will be made)",
                    value=True
                )
                
                with gr.Row():
                    preview_btn = gr.Button("Preview Changes")
                    run_btn = gr.Button("Run Operation", variant="primary")
                
                # Database Visualization Section
                gr.Markdown("## Database Visualization")
                
                visualize_btn = gr.Button("Generate Visualization", variant="secondary")
            
            with gr.Column(scale=2):
                # Operation Results
                gr.Markdown("## Operation Results")
                
                output = gr.TextArea(
                    label="Operation Log",
                    placeholder="Operation results will appear here",
                    lines=15
                )
                
                # Visualization Results
                gr.Markdown("## Database Schema")
                
                with gr.Tabs():
                    with gr.TabItem("Schema Summary"):
                        schema_summary = gr.Markdown(
                            value="Connect to a database and run operations or click 'Generate Visualization' to see the schema structure."
                        )
                    
                    with gr.TabItem("ER Diagram"):
                        gr.Markdown("Copy the code below and paste it into [Mermaid Live Editor](https://mermaid.live) to view the interactive diagram.")
                        
                        mermaid_code = gr.Code(
                            label="Mermaid Diagram Code",
                            language="markdown",
                            lines=15,
                            value="Connect to database and run operations to see diagram code here."
                        )
        
        # Connect buttons to handlers
        connect_btn.click(
            fn=connect_to_database,
            inputs=db_url,
            outputs=[connection_status, table]
        )
        
        refresh_btn.click(
            fn=refresh_tables,
            inputs=None,
            outputs=[connection_status, table]
        )
        
        execute_sql_btn.click(
            fn=execute_sql_file,
            inputs=sql_file,
            outputs=[output, schema_summary, mermaid_code]
        )
        
        preview_btn.click(
            fn=handle_merge,
            inputs=[action, table, column, from_values, target_value, preview_checkbox],
            outputs=[output, schema_summary, mermaid_code]
        )
        
        run_btn.click(
            fn=handle_merge,
            inputs=[action, table, column, from_values, target_value, gr.Checkbox(value=False, visible=False)],
            outputs=[output, schema_summary, mermaid_code]
        )
        
        # Manual visualization generation
        visualize_btn.click(
            fn=generate_database_visualization,
            inputs=None,
            outputs=[schema_summary, mermaid_code]
        )
        
    return app

def main():
    """Main entry point for the application"""
    app = create_ui()
    app.launch(
        server_name=config.get('HOST', '0.0.0.0'),
        server_port=int(config.get('PORT', 7860)),
        share=False,
        debug=True,
    )
    # Don't return anything from this function