"""Configuration management for Sneaky Klaus application.

This module defines configuration classes for different environments
(development, production, testing) with environment variable support.
"""

import os
from datetime import timedelta
from pathlib import Path


class Config:
    """Base configuration class with common settings."""

    # Base paths
    BASE_DIR = Path(__file__).parent.parent
    DATA_DIR = BASE_DIR / "data"

    # Security
    SECRET_KEY = os.environ.get("SECRET_KEY") or "dev-secret-key-change-in-production"

    # Database
    SQLALCHEMY_DATABASE_URI = os.environ.get(
        "DATABASE_URL", f"sqlite:///{DATA_DIR / 'sneaky-klaus.db'}"
    )
    SQLALCHEMY_TRACK_MODIFICATIONS = False

    # Session management
    SESSION_TYPE = "sqlalchemy"
    SESSION_PERMANENT = True
    SESSION_USE_SIGNER = True
    SESSION_KEY_PREFIX = "sk:"
    PERMANENT_SESSION_LIFETIME = timedelta(days=7)
    SESSION_COOKIE_SECURE = True  # HTTPS only
    SESSION_COOKIE_HTTPONLY = True
    SESSION_COOKIE_SAMESITE = "Lax"

    # Flask-WTF CSRF Protection
    WTF_CSRF_ENABLED = True
    WTF_CSRF_TIME_LIMIT = None  # No time limit for CSRF tokens

    # Email service (Resend)
    RESEND_API_KEY = os.environ.get("RESEND_API_KEY")
    EMAIL_FROM = os.environ.get("EMAIL_FROM", "noreply@sneaky-klaus.com")

    # Application URLs
    APP_URL = os.environ.get("APP_URL", "http://localhost:5000")

    # Timezone
    TIMEZONE = os.environ.get("TZ", "UTC")

    # Password requirements
    MIN_PASSWORD_LENGTH = 12


class DevelopmentConfig(Config):
    """Development environment configuration."""

    DEBUG = True
    TESTING = False
    SESSION_COOKIE_SECURE = False  # Allow HTTP in development
    SQLALCHEMY_ECHO = True  # Log SQL queries


class ProductionConfig(Config):
    """Production environment configuration."""

    DEBUG = False
    TESTING = False

    # Ensure critical environment variables are set
    @classmethod
    def validate(cls):
        """Validate that required production configuration is present."""
        required_vars = ["SECRET_KEY", "RESEND_API_KEY", "APP_URL"]
        missing_vars = [var for var in required_vars if not os.environ.get(var)]
        if missing_vars:
            raise ValueError(
                f"Missing required environment variables: {', '.join(missing_vars)}"
            )


class TestConfig(Config):
    """Test environment configuration."""

    TESTING = True
    DEBUG = True
    SESSION_COOKIE_SECURE = False

    # Use in-memory database for tests
    SQLALCHEMY_DATABASE_URI = "sqlite:///:memory:"

    # Disable CSRF for easier testing
    WTF_CSRF_ENABLED = False

    # Use a predictable secret key for tests
    SECRET_KEY = "test-secret-key"


# Configuration dictionary for easy access
config = {
    "development": DevelopmentConfig,
    "production": ProductionConfig,
    "testing": TestConfig,
    "default": DevelopmentConfig,
}


def get_config(env: str | None = None) -> type[Config]:
    """Get configuration class based on environment.

    Args:
        env: Environment name (development, production, testing).
             If None, uses FLASK_ENV environment variable.

    Returns:
        Configuration class for the specified environment.
    """
    if env is None:
        env = os.environ.get("FLASK_ENV", "development")
    return config.get(env, config["default"])