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

# 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')
LOG_FILE        = os.path.join(_BASE_DIR, 'db_debug.log')
ACTION_LOG_FILE = os.path.join(_BASE_DIR, 'app_actions.log')

# ---- Action log helpers (module-level, no class dependency) ----

def _log_action(action: str, record_id: str = '', detail: str = '') -> None:
    """Append one structured line to app_actions.log."""
    ts = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    line = f"{ts} | {action:<18} | id={record_id:<20} | {detail}\n"
    try:
        with open(ACTION_LOG_FILE, 'a', encoding='utf-8') as f:
            f.write(line)
    except Exception as e:
        print(f"Action log write error: {e}")


def purge_old_action_logs(days: int = 30) -> None:
    """Remove lines older than *days* from app_actions.log."""
    if not os.path.exists(ACTION_LOG_FILE):
        return
    cutoff = datetime.now() - timedelta(days=days)
    kept = []
    removed = 0
    try:
        with open(ACTION_LOG_FILE, 'r', encoding='utf-8') as f:
            for line in f:
                # Every valid line starts with YYYY-MM-DD HH:MM:SS
                try:
                    ts = datetime.strptime(line[:19], '%Y-%m-%d %H:%M:%S')
                    if ts >= cutoff:
                        kept.append(line)
                    else:
                        removed += 1
                except ValueError:
                    kept.append(line)   # malformed line — keep it
        with open(ACTION_LOG_FILE, 'w', encoding='utf-8') as f:
            f.writelines(kept)
        if removed:
            _log_action('LOG_PURGE', '', f'removed {removed} entries older than {days} days')
            print(f"Action log purged: {removed} old entries removed")
    except Exception as e:
        print(f"Action log purge error: {e}")

# File logger – appends on every run so history is preserved
logging.basicConfig(
    filename=LOG_FILE,
    level=logging.DEBUG,
    format='%(asctime)s [%(levelname)s] %(message)s',
    datefmt='%Y-%m-%d %H:%M:%S',
)
log = logging.getLogger('db_manager')
log.info('=== DatabaseManager module loaded ===')

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,
                autocommit=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 _new_conn(self):
        """Open and return a fresh connection. Caller must close it."""
        return mysql.connector.connect(
            host=self.host,
            database=self.database,
            user=self.user,
            password=self.password,
            connection_timeout=5,
            use_pure=True,
            autocommit=True
        )

    def get_connection(self):
        """Get a reusable connection (kept for test_connection compatibility)."""
        try:
            if self.connection is None or not self.connection.is_connected():
                log.info(f'Opening persistent connection to {self.host}/{self.database}')
                self.connection = self._new_conn()
                log.info('Connection opened OK')
            return self.connection
        except Error as e:
            log.error(f'Connection error: {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."""
        # Purge action log entries older than 30 days on every startup
        purge_old_action_logs(30)
        _log_action('APP_START', '', f'host={self.host}')
        try:
            conn = self._new_conn()
            cursor = conn.cursor(buffered=True)
            cursor.execute('''
                CREATE TABLE IF NOT EXISTS offsystemsCounting (
                    id VARCHAR(20) PRIMARY KEY,
                    mass REAL NOT NULL
                )
            ''')
            # Add t_update column if it doesn't exist yet (MySQL-compatible check)
            cursor.execute("""
                SELECT COUNT(*) FROM information_schema.COLUMNS
                WHERE TABLE_SCHEMA = %s
                  AND TABLE_NAME   = 'offsystemsCounting'
                  AND COLUMN_NAME  = 't_update'
            """, (self.database,))
            col_exists = cursor.fetchone()[0]
            cursor.close()
            if not col_exists:
                log.info("Adding t_update column to offsystemsCounting")
                c2 = conn.cursor()
                c2.execute("ALTER TABLE offsystemsCounting ADD COLUMN t_update DATETIME DEFAULT NULL")
                c2.close()
                log.info("t_update column added")
            conn.close()
            log.info("init_database complete")
            print(f"Connected to MariaDB database: {self.database}")
            print("Table 'offsystemsCounting' ready")
        except Error as e:
            log.error(f"Database initialization error: {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._new_conn()
            cursor = conn.cursor(buffered=True)
            cursor.execute("SELECT id, mass FROM offsystemsCounting ORDER BY id")
            rows = cursor.fetchall()
            cursor.close()
            conn.close()
            return rows
        except Error as e:
            log.error(f"read_all_data error: {e}")
            print(f"Error reading data: {e}")
        return []

    def search_by_id(self, record_id: str) -> Optional[Tuple]:
        """Search for a record by ID. Returns (id, mass, t_update) or None."""
        log.info(f'search_by_id: looking up id={record_id!r}')
        try:
            conn = self._new_conn()
            cursor = conn.cursor(buffered=True)
            cursor.execute("SELECT id, mass, t_update FROM offsystemsCounting WHERE id = %s", (record_id,))
            row = cursor.fetchone()
            # buffered=True already fetched the full result; no extra drain needed
            cursor.close()
            conn.close()
            log.info(f'search_by_id: result={row}')
            if row:
                _log_action('SEARCH_FOUND', record_id, f'mass={row[1]}, t_update={row[2]}')
            else:
                _log_action('SEARCH_NOT_FOUND', record_id, '')
            return row
        except Error as e:
            log.error(f'search_by_id error: {e}')
            _log_action('SEARCH_ERROR', record_id, str(e))
            print(f"Error searching data: {e}")
        return None

    def add_or_update_record(self, record_id: str, mass: float) -> bool:
        """Update mass/t_update for an existing record, or INSERT if it doesn't exist yet."""
        log.info(f'add_or_update_record: id={record_id!r}  mass={mass}')
        try:
            conn = self._new_conn()
            cursor = conn.cursor(buffered=True)

            # Try UPDATE first
            update_sql = (
                "UPDATE offsystemsCounting "
                "SET mass = %s, t_update = NOW() "
                "WHERE id = %s"
            )
            log.debug(f'Executing SQL: {update_sql} | params=({mass}, {record_id!r})')
            cursor.execute(update_sql, (mass, record_id))
            affected = cursor.rowcount

            if affected == 0:
                # Record does not exist yet — INSERT it
                insert_sql = (
                    "INSERT INTO offsystemsCounting (id, mass, t_update) "
                    "VALUES (%s, %s, NOW())"
                )
                log.debug(f'Executing SQL: {insert_sql} | params=({record_id!r}, {mass})')
                cursor.execute(insert_sql, (record_id, mass))
                affected = cursor.rowcount
                log.info(f'add_or_update_record: inserted new record, rowcount={affected}')
                _log_action('INSERT', record_id, f'mass={mass}')
                print(f"Inserted new record: {record_id} = {mass}")
            else:
                log.info(f'add_or_update_record: updated existing record, rowcount={affected}')
                _log_action('UPDATE', record_id, f'mass={mass}')
                print(f"Updated record: {record_id} = {mass}  (rowcount={affected})")

            cursor.close()
            conn.close()
            return True
        except Error as e:
            log.error(f'add_or_update_record error: {e}')
            _log_action('UPDATE_ERROR', record_id, str(e))
            print(f"Error adding/updating record: {e}")
        return False
    
    def delete_record(self, record_id: str) -> bool:
        """Delete a record by ID."""
        log.info(f'delete_record: id={record_id!r}')
        try:
            conn = self._new_conn()
            cursor = conn.cursor(buffered=True)
            cursor.execute("DELETE FROM offsystemsCounting WHERE id = %s", (record_id,))
            deleted = cursor.rowcount
            # DML produces no result set — do NOT fetchall()
            cursor.close()
            conn.close()
            if deleted > 0:
                log.info(f'delete_record: deleted {deleted} row(s)')
                _log_action('DELETE', record_id, f'rows_deleted={deleted}')
                print(f"Deleted record: {record_id}")
                return True
            else:
                log.info(f'delete_record: no row found for id={record_id!r}')
                _log_action('DELETE_NOT_FOUND', record_id, '')
                print(f"No record found with ID: {record_id}")
                return False
        except Error as e:
            log.error(f'delete_record error: {e}')
            _log_action('DELETE_ERROR', record_id, str(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._new_conn()
            cursor = conn.cursor(buffered=True)
            cursor.execute("SELECT COUNT(*) FROM offsystemsCounting")
            count = cursor.fetchone()[0]
            # fetchone() on a buffered cursor is fully consumed — no drain needed
            cursor.close()
            conn.close()
            return count
        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()