import mysql.connector
from mysql.connector import Error
from typing import List, Tuple, Optional
import json
import os
import sys

# When frozen by PyInstaller, __file__ points to a temp folder that is deleted on exit.
# sys.executable points to the .exe location, which is persistent.
if getattr(sys, 'frozen', False):
    _BASE_DIR = os.path.dirname(sys.executable)
else:
    _BASE_DIR = os.path.dirname(os.path.abspath(__file__))

CONFIG_FILE = os.path.join(_BASE_DIR, 'config.json')

class DatabaseManager:
    """
    Database manager class for handling MariaDB operations.
    Connects to MariaDB server with table offsystemsCounting containing id (VARCHAR(20)) and mass (REAL).
    """
    
    def __init__(self):
        self.host = self._load_host()
        self.database = "cantare_injectie"
        self.user = "omron"
        self.password = "Initial01!"
        self.connection = None
        # init_database() is called asynchronously from the UI layer to avoid blocking

    def _load_host(self) -> str:
        """Load the database host from the config file, falling back to localhost."""
        try:
            if os.path.exists(CONFIG_FILE):
                with open(CONFIG_FILE, 'r') as f:
                    data = json.load(f)
                    return data.get('host', 'localhost')
        except Exception as e:
            print(f"Could not read config file: {e}")
        return 'localhost'

    def save_host(self, host: str):
        """Persist the database host to the config file."""
        try:
            data = {}
            if os.path.exists(CONFIG_FILE):
                with open(CONFIG_FILE, 'r') as f:
                    data = json.load(f)
            data['host'] = host
            with open(CONFIG_FILE, 'w') as f:
                json.dump(data, f, indent=2)
        except Exception as e:
            print(f"Could not save config file: {e}")

    def test_connection(self, host: str) -> tuple:
        """Test connectivity to the database using the given host. Returns (success: bool, message: str)."""
        try:
            test_conn = mysql.connector.connect(
                host=host,
                database=self.database,
                user=self.user,
                password=self.password,
                connection_timeout=5,
                use_pure=True
            )
            if test_conn.is_connected():
                test_conn.close()
                return True, f"Connected successfully to '{host}'"
        except Error as e:
            return False, str(e)
        return False, "Connection failed"
    
    def get_connection(self):
        """Get a database connection."""
        try:
            if self.connection is None or not self.connection.is_connected():
                self.connection = mysql.connector.connect(
                    host=self.host,
                    database=self.database,
                    user=self.user,
                    password=self.password,
                    connection_timeout=5,
                    use_pure=True
                )
            return self.connection
        except Error as e:
            print(f"Database connection error: {e}")
            return None
    
    def init_database(self):
        """Initialize the database connection and create the table if it doesn't exist."""
        try:
            conn = self.get_connection()
            if conn and conn.is_connected():
                cursor = conn.cursor()
                cursor.execute('''
                    CREATE TABLE IF NOT EXISTS offsystemsCounting (
                        id VARCHAR(20) PRIMARY KEY,
                        mass REAL NOT NULL
                    )
                ''')
                conn.commit()
                print(f"Connected to MariaDB database: {self.database}")
                print("Table 'offsystemsCounting' ready")
        except Error as e:
            print(f"Database initialization error: {e}")
    
    def read_all_data(self) -> List[Tuple[str, float]]:
        """Read all data from the database."""
        try:
            conn = self.get_connection()
            if conn and conn.is_connected():
                cursor = conn.cursor()
                cursor.execute("SELECT id, mass FROM offsystemsCounting ORDER BY id")
                return cursor.fetchall()
        except Error as e:
            print(f"Error reading data: {e}")
        return []
    
    def search_by_id(self, record_id: str) -> Optional[Tuple[str, float]]:
        """Search for a record by ID."""
        try:
            conn = self.get_connection()
            if conn and conn.is_connected():
                cursor = conn.cursor()
                cursor.execute("SELECT id, mass FROM offsystemsCounting WHERE id = %s", (record_id,))
                return cursor.fetchone()
        except Error as e:
            print(f"Error searching data: {e}")
        return None
    
    def add_or_update_record(self, record_id: str, mass: float) -> bool:
        """Add a new record or update existing one if ID already exists."""
        try:
            conn = self.get_connection()
            if conn and conn.is_connected():
                cursor = conn.cursor()
                
                # Check if record exists
                existing = self.search_by_id(record_id)
                
                if existing:
                    # Update existing record
                    cursor.execute(
                        "UPDATE offsystemsCounting SET mass = %s WHERE id = %s",
                        (mass, record_id)
                    )
                    print(f"Updated record: {record_id} = {mass}")
                else:
                    # Insert new record
                    cursor.execute(
                        "INSERT INTO offsystemsCounting (id, mass) VALUES (%s, %s)",
                        (record_id, mass)
                    )
                    print(f"Added new record: {record_id} = {mass}")
                
                conn.commit()
                return True
        except Error as e:
            print(f"Error adding/updating record: {e}")
        return False
    
    def delete_record(self, record_id: str) -> bool:
        """Delete a record by ID."""
        try:
            conn = self.get_connection()
            if conn and conn.is_connected():
                cursor = conn.cursor()
                cursor.execute("DELETE FROM offsystemsCounting WHERE id = %s", (record_id,))
                
                if cursor.rowcount > 0:
                    conn.commit()
                    print(f"Deleted record: {record_id}")
                    return True
                else:
                    print(f"No record found with ID: {record_id}")
                    return False
        except Error as e:
            print(f"Error deleting record: {e}")
        return False
    
    def get_record_count(self) -> int:
        """Get the total number of records in the database."""
        try:
            conn = self.get_connection()
            if conn and conn.is_connected():
                cursor = conn.cursor()
                cursor.execute("SELECT COUNT(*) FROM offsystemsCounting")
                return cursor.fetchone()[0]
        except Error as e:
            print(f"Error getting record count: {e}")
        return 0
    
    def close_connection(self):
        """Close the database connection."""
        try:
            if self.connection and self.connection.is_connected():
                self.connection.close()
                print("MariaDB connection closed")
        except Error as e:
            print(f"Error closing connection: {e}")
    
    def __del__(self):
        """Destructor to ensure connection is closed."""
        self.close_connection()