import os
import json
import psycopg2
from psycopg2 import pool
import sqlite3
from dotenv import load_dotenv
import logging
import csv

# Load environment variables
load_dotenv()

# Initialize logging
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')

# PostgreSQL connection pool setup
db_pool = psycopg2.pool.SimpleConnectionPool(
    minconn=1,
    maxconn=5,
    user=os.getenv("db_user"),
    password=os.getenv("db_password"),
    host=os.getenv("db_host"),
    dbname=os.getenv("db_name"),
    port=os.getenv("db_port", 5432)
)

# SQLite DB path
db_path = os.getenv("DB_PATH", "./query_logs.db")

# PostgreSQL: Function to fetch schema and save to schema.json
def fetch_and_save_schema():
    try:
        logging.info("Fetching schema from the database...")

        conn = db_pool.getconn()
        cursor = conn.cursor()

        # Query to retrieve all table names and their comments
        cursor.execute("""
        SELECT table_name, obj_description(('public.' || table_name)::regclass) as table_comment
        FROM information_schema.tables
        WHERE table_schema = 'public';
        """)
        tables = cursor.fetchall()

        # Build the schema information in JSON format
        schema_info = {}

        for table_name, table_comment in tables:
            schema_info[table_name] = {
                "comment": table_comment,
                "columns": [],
                "foreign_keys": []
            }

            # Fetch column details and comments for each table
            cursor.execute(f"""
            SELECT 
                c.column_name, 
                c.data_type, 
                col_description(('public.' || c.table_name)::regclass, ordinal_position) as column_comment
            FROM information_schema.columns c
            WHERE c.table_name = '{table_name}';
            """)
            columns = cursor.fetchall()

            for column_name, data_type, column_comment in columns:
                schema_info[table_name]["columns"].append({
                    "name": column_name,
                    "data_type": data_type,
                    "comment": column_comment
                })

            # Fetch foreign key relationships for each table
            cursor.execute(f"""
            SELECT 
                kcu.column_name, 
                ccu.table_name AS foreign_table_name, 
                ccu.column_name AS foreign_column_name
            FROM information_schema.table_constraints AS tc
            JOIN information_schema.key_column_usage AS kcu
              ON tc.constraint_name = kcu.constraint_name
              AND tc.table_schema = kcu.table_schema
            JOIN information_schema.constraint_column_usage AS ccu
              ON ccu.constraint_name = tc.constraint_name
            WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name = '{table_name}';
            """)
            foreign_keys = cursor.fetchall()

            for column_name, foreign_table_name, foreign_column_name in foreign_keys:
                schema_info[table_name]["foreign_keys"].append({
                    "column": column_name,
                    "references": {
                        "table": foreign_table_name,
                        "column": foreign_column_name
                    }
                })

        cursor.close()
        db_pool.putconn(conn)

        # Save the schema to a JSON file
        with open("schema.json", "w") as schema_file:
            json.dump(schema_info, schema_file, indent=2)

        logging.info("Schema fetched and saved to schema.json.")
        return schema_info
    except Exception as e:
        logging.error(f"Error fetching schema: {e}")
        return {"error": str(e)}

# PostgreSQL: Function to execute SQL query
def execute_sql_query(sql_query):
    try:
        conn = db_pool.getconn()
        cursor = conn.cursor()
        cursor.execute(sql_query)  # Execute the query
        result = cursor.fetchall()  # Fetch all results

        # Get column names from the cursor description
        column_names = [desc[0] for desc in cursor.description]

        cursor.close()
        db_pool.putconn(conn)

        # Format the result as a list of lists for Gradio Dataframe
        return [column_names] + result
    except Exception as e:
        logging.error(f"Error executing SQL query: {e}")
        return str(e)

# SQLite: Initialize the local SQLite database
def initialize_local_db():
    conn = sqlite3.connect(db_path)
    cursor = conn.cursor()

    # Create table if it doesn't exist
    cursor.execute('''
    CREATE TABLE IF NOT EXISTS query_logs (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        natural_language_query TEXT,
        reformulated_query TEXT,
        generated_sql TEXT,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
    );
    ''')
    conn.commit()
    cursor.close()
    conn.close()

# SQLite: Function to save the query to the local database
def save_query_to_local_db(nl_query, reformulated_query, sql_query):
    try:
        conn = sqlite3.connect(db_path)
        cursor = conn.cursor()
        insert_query = '''
        INSERT INTO query_logs (natural_language_query, reformulated_query, generated_sql)
        VALUES (?, ?, ?);
        '''
        cursor.execute(insert_query, (nl_query, reformulated_query, sql_query))
        conn.commit()
        cursor.close()
        conn.close()
    except Exception as e:
        logging.error(f"Error saving query: {e}")

# SQLite: Function to get the last 50 saved queries
def get_last_50_saved_queries():
    try:
        conn = sqlite3.connect(db_path)
        cursor = conn.cursor()
        query = "SELECT natural_language_query, reformulated_query, generated_sql, created_at FROM query_logs ORDER BY created_at DESC LIMIT 50;"
        cursor.execute(query)
        rows = cursor.fetchall()
        cursor.close()
        conn.close()
        return rows
    except Exception as e:
        logging.error(f"Error retrieving saved queries: {e}")
        return str(e)

# SQLite: Function to export saved queries to a CSV file
def export_saved_queries_to_csv(file_path="./saved_queries.csv"):
    try:
        conn = sqlite3.connect(db_path)
        cursor = conn.cursor()

        # Fetch all saved queries
        cursor.execute("SELECT natural_language_query, reformulated_query, generated_sql, created_at FROM query_logs ORDER BY created_at DESC;")
        rows = cursor.fetchall()

        # Write the results to a CSV file
        with open(file_path, 'w', newline='') as csvfile:
            csv_writer = csv.writer(csvfile)
            csv_writer.writerow(['Natural Language Query', 'Reformulated Query', 'Generated SQL', 'Timestamp'])
            csv_writer.writerows(rows)

        cursor.close()
        conn.close()

        return file_path
    except Exception as e:
        logging.error(f"Error exporting queries to CSV: {e}")
        return str(e)

def show_last_50_saved_queries():
    try:
        conn = sqlite3.connect(db_path)
        cursor = conn.cursor()
        query = "SELECT natural_language_query, reformulated_query, generated_sql, created_at FROM query_logs ORDER BY created_at DESC LIMIT 50;"
        cursor.execute(query)
        rows = cursor.fetchall()
        cursor.close()
        conn.close()
        return rows
    except Exception as e:
        logging.error(f"Error retrieving saved queries: {e}")
        return str(e)


# Function to reset (drop all tables) and recreate the schema
def reset_sqlite_db():
    conn = sqlite3.connect(db_path)
    cursor = conn.cursor()

    # Drop the query_logs table
    cursor.execute("DROP TABLE IF EXISTS query_logs;")
    print("Dropped query_logs table")

    # Recreate the query_logs table
    cursor.execute('''CREATE TABLE query_logs (
                        id INTEGER PRIMARY KEY AUTOINCREMENT,
                        natural_language_query TEXT,
                        reformulated_query TEXT,
                        generated_sql TEXT,
                        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
                      );''')
    print("Recreated the query_logs table.")

    conn.commit()
    cursor.close()
    conn.close()

# Uncomment the following line to reset the SQLite database when you run this script
# reset_sqlite_db()

def fetch_schema_info():
    try:
        with open("schema.json", "r") as schema_file:
            schema_info = json.load(schema_file)
        logging.info("Schema loaded from schema.json")
        return schema_info
    except Exception as e:
        logging.error(f"Error loading schema from schema.json: {e}")
        return {}