"""Application configuration via Pydantic Settings."""

from __future__ import annotations

from functools import lru_cache
from typing import Literal

from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """Application settings loaded from environment variables."""

    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        case_sensitive=False,
        extra="ignore",
    )

    # Environment
    environment: Literal["development", "production", "testing"] = "development"
    log_level: str = "INFO"

    # Database — separate connections for auth, API, worker, and migrations
    database_url: str = "postgresql+asyncpg://leocrm:leocrm@localhost:5432/leocrm_test"
    auth_database_url: str = ""  # Falls back to database_url if empty
    worker_database_url: str = ""  # Falls back to database_url if empty
    migration_database_url: str = ""  # Falls back to database_url if empty
    db_pool_size: int = 20
    db_max_overflow: int = 30
    db_echo: bool = False

    # Redis
    redis_url: str = "redis://localhost:6379/0"
    session_ttl_seconds: int = 28800  # 8 hours

    # Auth
    bcrypt_rounds: int = 12
    session_cookie_name: str = "leocrm_session"
    session_cookie_secure: bool = True  # Secure by default — set to False only for local HTTP development
    session_cookie_samesite: str = "lax"  # Lax allows WebSocket cookies while preventing CSRF on top-level navigations
    session_cookie_httponly: bool = True
    password_reset_expiry_hours: int = 1

    # Storage
    storage_path: str = "/data/storage"

    # SMTP
    smtp_host: str = "localhost"
    smtp_port: int = 587
    smtp_username: str | None = None
    smtp_password: str | None = None
    smtp_from_email: str = "noreply@leocrm.local"
    smtp_use_tls: bool = True

    # Secret Key (for signing, sessions, etc.)
    secret_key: str = "change-me-in-production-use-a-secure-random-string"

    # CORS
    cors_origins: str = "http://localhost:5173,http://localhost:3000"

    # Frontend URL for email links (password reset, invitations, etc.)
    frontend_url: str = "http://localhost:5173"

    # Trusted proxy CIDRs (comma-separated) — only these proxies can set X-Forwarded-For
    trusted_proxy_cidrs: str = ""

    # Rate Limiting
    rate_limit_login_max: int = 5
    rate_limit_login_window: int = 900  # 15 min
    rate_limit_reset_max: int = 3
    rate_limit_reset_window: int = 3600  # 1 hour
    rate_limit_reset_confirm_max: int = 5
    rate_limit_reset_confirm_window: int = 3600  # 1 hour
    rate_limit_general_max: int = 300
    rate_limit_general_window: int = 60  # 1 min

    @property
    def cors_origin_list(self) -> list[str]:
        """Parse comma-separated CORS origins into a list."""
        return [o.strip() for o in self.cors_origins.split(",") if o.strip()]


@lru_cache
def get_settings() -> Settings:
    """Get cached settings instance."""
    s = Settings()
    # Safety checks — always validate critical settings
    _DEFAULT_KEY = "change-me-in-production-use-a-secure-random-string"
    if s.secret_key == _DEFAULT_KEY:
        raise RuntimeError("SECRET_KEY must be changed from default value")
    if len(s.secret_key) < 32:
        raise RuntimeError("SECRET_KEY must be at least 32 characters long")
    # Production-only checks
    if s.environment == "production":
        if not s.session_cookie_secure:
            raise RuntimeError("SESSION_COOKIE_SECURE must be True in production")
        if s.storage_path == "/tmp":
            raise RuntimeError("STORAGE_PATH must not be /tmp in production")
    return s


# Module-level singleton for backward-compatible imports
settings = get_settings()