import os
import logging
from dataclasses import dataclass, field
from typing import List, Optional

try:
    from dotenv import load_dotenv
except ImportError:
    def load_dotenv(path: str = '.env'):
        """Минимальный fallback для локального .env, если python-dotenv еще не установлен."""
        if not os.path.exists(path):
            return False
        with open(path, encoding='utf-8') as env_file:
            for raw_line in env_file:
                line = raw_line.strip()
                if not line or line.startswith('#') or '=' not in line:
                    continue
                key, value = line.split('=', 1)
                key = key.strip()
                value = value.strip().strip('"').strip("'")
                os.environ.setdefault(key, value)
        return True


load_dotenv()


@dataclass
class TableMigrationConfig:
    """Настройки миграции одной таблицы."""
    source_table: str
    target_table: Optional[str] = None
    mode: str = "full"
    initial_load_mode: str = "full_then_incremental"
    life_table: Optional[str] = None
    datetime_column: str = "x_DateTime"
    sequence_column: Optional[str] = None
    order_columns: List[str] = field(default_factory=list)
    operation_column: Optional[str] = None
    delete_operations: List[str] = field(default_factory=lambda: ['d'])
    upsert_operations: List[str] = field(default_factory=lambda: ['i', 'u'])
    primary_key: List[str] = field(default_factory=list)
    exclude_columns: List[str] = field(default_factory=list)
    timescale: bool = False
    timescale_time_column: Optional[str] = None
    enabled: bool = True

    @property
    def pg_table(self) -> str:
        return (self.target_table or self.source_table).lower()

    @property
    def read_table(self) -> str:
        return self.life_table or self.source_table

    @property
    def incremental_order_columns(self) -> List[str]:
        if self.order_columns:
            return self.order_columns
        columns = [self.datetime_column]
        if self.sequence_column:
            columns.append(self.sequence_column)
        return columns

# ============================================================================
# КОНФИГУРАЦИЯ
# ============================================================================
class Config:
    """Конфигурация приложения"""
    # Настройки MSSQL
    MSSQL_CONNECTION_STRING = os.getenv('MSSQL_CONNECTION_STRING')
    MSSQL_CHARSET = os.getenv('MSSQL_CHARSET', 'cp1251')
    MSSQL_POOL_RECYCLE = int(os.getenv('MSSQL_POOL_RECYCLE', '1800'))
    MSSQL_CONNECT_TIMEOUT = int(os.getenv('MSSQL_CONNECT_TIMEOUT', '30'))
    MSSQL_TABLE_RETRIES = int(os.getenv('MSSQL_TABLE_RETRIES', '2'))
    MSSQL_POOL_SIZE = int(os.getenv('MSSQL_POOL_SIZE', '1'))
    MSSQL_MAX_OVERFLOW = int(os.getenv('MSSQL_MAX_OVERFLOW', '0'))
    
    # Настройки PostgreSQL
    POSTGRES_CONNECTION_STRING = os.getenv('POSTGRES_CONNECTION_STRING')
    
    # Настройки email
    EMAIL_HOST = os.getenv('EMAIL_HOST')
    EMAIL_PORT = int(os.getenv('EMAIL_PORT', '465'))
    EMAIL_USER = os.getenv('EMAIL_USER')
    EMAIL_PASSWORD = os.getenv('EMAIL_PASSWORD')
    EMAIL_FROM = os.getenv('EMAIL_FROM')
    EMAIL_TO = [
        email.strip()
        for email in os.getenv('EMAIL_TO', '').split(',')
        if email.strip()
    ]
    EMAIL_SUBJECT = os.getenv('EMAIL_SUBJECT', 'Результат миграции данных MSSQL → PostgreSQL')
    
    # Настройки логирования
    LOG_DIR = 'logs'
    LOG_FILE = 'migration_log_{timestamp}.log'
    LOG_LEVEL = logging.INFO
    
    # Настройки миграции
    CHUNK_SIZE = int(os.getenv('CHUNK_SIZE', '5000'))
    WRITE_CHUNK_SIZE = int(os.getenv('WRITE_CHUNK_SIZE', str(CHUNK_SIZE)))
    BATCH_SIZE = 10  # Через сколько чанков выводить прогресс
    REPLICATOR_SCHEMA = os.getenv('REPLICATOR_SCHEMA', 'replicator')
    STATE_TABLE = 'migration_state'
    TABLE_CONFIGS_TABLE = 'migration_tables'
    ENABLE_TIMESCALE = os.getenv('ENABLE_TIMESCALE', 'false').lower() == 'true'
    DRY_RUN = os.getenv('DRY_RUN', 'false').lower() == 'true'
    READ_LIMIT = int(os.getenv('READ_LIMIT', '0')) or None
    QUEUE_POLL_SECONDS = float(os.getenv('QUEUE_POLL_SECONDS', '1'))
    SCHEDULE_GRACE_SECONDS = int(os.getenv('SCHEDULE_GRACE_SECONDS', '60'))
    START_API_WORKER = os.getenv('START_API_WORKER', 'true').lower() == 'true'
    CREATE_FOREIGN_KEYS = os.getenv('CREATE_FOREIGN_KEYS', 'true').lower() == 'true'
    
    # Настройки таблиц. Для инкрементальной миграции заполните life_table
    # primary_key и exclude_columns, чтобы запись можно было делать идемпотентно.
    DEFAULT_TABLE_MIGRATIONS = [
        TableMigrationConfig(
            source_table='Oms_LPU',
            target_table='Oms_LPU',
            mode='incremental',
            initial_load_mode='full_then_incremental',
            life_table='Life_oms_LPU',
            datetime_column='x_DateTime',
            sequence_column='LPULifeID',
            order_columns=['x_DateTime', 'LPULifeID'],
            operation_column='x_Operation',
            primary_key=['LPUID'],
            exclude_columns=[
                'LPULifeID',
                'x_Operation',
                'x_DateTime',
                'x_Seance',
                'x_User',
            ],
            timescale=False,
            enabled=True,
        ),
        # TableMigrationConfig(
        #     source_table='stt_MigrationPatient',
        #     target_table='stt_MigrationPatient',
        #     mode='incremental',
        #     initial_load_mode='full_then_incremental',
        #     life_table='Life_stt_MigrationPatient',
        #     datetime_column='x_DateTime',
        #     sequence_column='MigrationPatientLifeID',
        #     order_columns=['x_DateTime', 'MigrationPatientLifeID'],
        #     operation_column='x_Operation',
        #     primary_key=['Id'],
        #     exclude_columns=['MigrationPatientLifeID', 'x_Operation', 'x_DateTime', 'x_Seance', 'x_User'],
        #     timescale=True,
        #     timescale_time_column='x_DateTime',
        # ),
    ]
    TABLE_MIGRATIONS = list(DEFAULT_TABLE_MIGRATIONS)
    TABLES_TO_COPY = [table.source_table for table in TABLE_MIGRATIONS]