'''
  ____   ___  _     _ _
 / ___| / _ \| |   (_) |_ ___
 \___ \| | | | |   | | __/ _ \
  ___) | |_| | |___| | ||  __/
 |____/ \__\_\_____|_|\__\___|

Script to empty (delete all data from) sensor tables in the SQLite database
This script empties sensor data tables but preserves:
- timestamp_table
- config_table
- envea_sondes_table
- config_scripts_table

/usr/bin/python3 /var/www/nebuleair_pro_4g/sqlite/empty_sensor_tables.py
'''

import sqlite3
import sys
import json

def table_exists(cursor, table_name):
    """Check if a table exists in the database"""
    try:
        cursor.execute("SELECT name FROM sqlite_master WHERE type='table' AND name=?", (table_name,))
        return cursor.fetchone() is not None
    except sqlite3.Error as e:
        print(f"[ERROR] Failed to check if table '{table_name}' exists: {e}")
        return False


def get_table_count(cursor, table_name):
    """Get the number of records in a table"""
    try:
        cursor.execute(f"SELECT COUNT(*) FROM {table_name}")
        return cursor.fetchone()[0]
    except sqlite3.Error as e:
        print(f"[WARNING] Could not get count for table '{table_name}': {e}")
        return 0


def empty_table(cursor, table_name):
    """Delete all records from a specific table"""
    try:
        # Get record count before deletion
        initial_count = get_table_count(cursor, table_name)

        if initial_count == 0:
            print(f"[INFO] Table '{table_name}' is already empty")
            return True, 0

        # Delete all records
        cursor.execute(f"DELETE FROM {table_name}")
        deleted_count = cursor.rowcount

        print(f"[SUCCESS] Deleted {deleted_count} records from '{table_name}'")
        return True, deleted_count

    except sqlite3.Error as e:
        print(f"[ERROR] Failed to empty table '{table_name}': {e}")
        return False, 0


def main():
    result = {
        'success': False,
        'message': '',
        'tables_processed': [],
        'total_deleted': 0
    }

    try:
        # Connect to the SQLite database
        print("[INFO] Connecting to database...")
        conn = sqlite3.connect("/var/www/nebuleair_pro_4g/sqlite/sensors.db")
        cursor = conn.cursor()

        # Check database connection
        cursor.execute("SELECT sqlite_version()")
        version = cursor.fetchone()[0]
        print(f"[INFO] Connected to SQLite version: {version}")

        # List of sensor tables to empty (EXCLUDING timestamp_table and config tables)
        sensor_tables = [
            "data_NPM",
            "data_NPM_5channels",
            "data_BME280",
            "data_envea",
            "data_WIND",
            "data_MPPT",
            "data_NOISE",
            "modem_status"
        ]

        # Tables to PRESERVE (not empty)
        preserved_tables = [
            "timestamp_table",
            "config_table",
            "envea_sondes_table",
            "config_scripts_table"
        ]

        print(f"[INFO] Will empty the following sensor tables: {', '.join(sensor_tables)}")
        print(f"[INFO] Will preserve the following tables: {', '.join(preserved_tables)}")

        # Check which tables actually exist
        existing_tables = []
        missing_tables = []

        for table in sensor_tables:
            if table_exists(cursor, table):
                existing_tables.append(table)
                record_count = get_table_count(cursor, table)
                print(f"[INFO] Table '{table}' exists with {record_count} records")
            else:
                missing_tables.append(table)
                print(f"[WARNING] Table '{table}' does not exist - skipping")

        if missing_tables:
            print(f"[INFO] Missing tables: {', '.join(missing_tables)}")

        if not existing_tables:
            result['success'] = True
            result['message'] = "No sensor tables found to empty"
            print("[WARNING] No sensor tables found to empty!")
            print(json.dumps(result))
            return True

        # Loop through existing tables and empty them
        successful_operations = 0
        failed_operations = 0
        total_deleted = 0

        for table in existing_tables:
            success, deleted = empty_table(cursor, table)
            if success:
                successful_operations += 1
                total_deleted += deleted
                result['tables_processed'].append({
                    'name': table,
                    'deleted': deleted
                })
            else:
                failed_operations += 1

        # Commit changes
        print("[INFO] Committing changes...")
        conn.commit()
        print("[SUCCESS] Changes committed successfully!")

        # Run VACUUM to optimize database space
        if total_deleted > 0:
            print("[INFO] Running VACUUM to optimize database space...")
            try:
                cursor.execute("VACUUM")
                print("[SUCCESS] Database optimized successfully!")
            except sqlite3.Error as e:
                print(f"[WARNING] VACUUM failed: {e}")

        # Summary
        print(f"\n[SUMMARY]")
        print(f"Tables emptied successfully: {successful_operations}")
        print(f"Tables with errors: {failed_operations}")
        print(f"Tables skipped (missing): {len(missing_tables)}")
        print(f"Total records deleted: {total_deleted}")

        result['success'] = True
        result['message'] = f"Successfully emptied {successful_operations} sensor tables. Total records deleted: {total_deleted}"
        result['total_deleted'] = total_deleted

        if failed_operations == 0:
            print("[SUCCESS] All sensor tables emptied successfully!")
        else:
            result['message'] = f"Partial success: {successful_operations} tables emptied, {failed_operations} failed"
            print("[WARNING] Some operations failed - check logs above")

        # Output JSON result for web interface
        print("\n[JSON_RESULT]")
        print(json.dumps(result))

        return failed_operations == 0

    except sqlite3.Error as e:
        result['message'] = f"Database error: {e}"
        print(f"[ERROR] Database error: {e}")
        print("\n[JSON_RESULT]")
        print(json.dumps(result))
        return False
    except Exception as e:
        result['message'] = f"Unexpected error: {e}"
        print(f"[ERROR] Unexpected error: {e}")
        print("\n[JSON_RESULT]")
        print(json.dumps(result))
        return False
    finally:
        # Always close the database connection
        if 'conn' in locals():
            conn.close()
            print("[INFO] Database connection closed")


if __name__ == "__main__":
    success = main()
    sys.exit(0 if success else 1)