"""
DataVision — Centralized Configuration Module
Uses Pydantic Settings v2 for type-safe, environment-driven configuration.

All settings are loaded from environment variables or .env files.
Required variables will raise validation errors on startup if missing.
"""

import os
from typing import Optional, Literal
from pydantic_settings import BaseSettings, SettingsConfigDict
from pydantic import Field


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

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

    # ── Environment ─────────────────────────────────────────────────
    ENVIRONMENT: Literal["development", "testing", "production"] = "development"
    DEBUG: bool = False
    APP_NAME: str = "DataVision AI"
    APP_VERSION: str = "1.0.0"

    # ── Database ────────────────────────────────────────────────────
    DATABASE_URL: str = Field(
        default="postgresql+asyncpg://datavision:datavision_dev@localhost:5433/datavision",
        description="PostgreSQL async connection URL (postgresql+asyncpg://...)"
    )
    DB_POOL_SIZE: int = 5
    DB_MAX_OVERFLOW: int = 10
    DB_POOL_PRE_PING: bool = True
    DB_POOL_RECYCLE: int = 3600
    DB_ECHO: bool = False

    # ── JWT Auth ────────────────────────────────────────────────────
    JWT_SECRET: str = Field(
        default=os.environ.get("JWT_SECRET") or os.environ.get("JWT_SECRET_KEY") or "datavision-production-jwt-secret-key-32bytes-long!",
        description="Secret key for signing JWT tokens. Must be kept secret."
    )
    JWT_ALGORITHM: str = "HS256"
    ACCESS_TOKEN_EXPIRE_MINUTES: int = 30
    REFRESH_TOKEN_EXPIRE_DAYS: int = 7

    # ── Security ────────────────────────────────────────────────────
    CORS_ORIGINS: str = "*"
    ALLOWED_HOSTS: str = "*"
    BCRYPT_ROUNDS: int = 12

    # ── Redis (Optional) ────────────────────────────────────────────
    REDIS_URL: Optional[str] = None

    # ── LLM Providers ───────────────────────────────────────────────
    GROQ_API_KEY: Optional[str] = None
    GROQ_KEY_1: Optional[str] = None
    GROQ_KEY_2: Optional[str] = None
    GROQ_KEY_3: Optional[str] = None
    OPENAI_API_KEY: Optional[str] = None
    GOOGLE_API_KEY: Optional[str] = None
    ANTHROPIC_API_KEY: Optional[str] = None
    OPENROUTER_API_KEY: Optional[str] = None

    # ── Email ───────────────────────────────────────────────────────
    RESEND_API_KEY: Optional[str] = None
    FROM_EMAIL: str = "noreply@datavision.ai"

    # ── OAuth ───────────────────────────────────────────────────────
    GOOGLE_CLIENT_ID: Optional[str] = None
    GOOGLE_CLIENT_SECRET: Optional[str] = None
    GITHUB_CLIENT_ID: Optional[str] = None
    GITHUB_CLIENT_SECRET: Optional[str] = None

    @property
    def cors_origins_list(self) -> list[str]:
        """Parse CORS_ORIGINS from comma-separated string to list."""
        if self.CORS_ORIGINS == "*":
            return ["*"]
        return [origin.strip() for origin in self.CORS_ORIGINS.split(",") if origin.strip()]

    @property
    def is_production(self) -> bool:
        return self.ENVIRONMENT == "production"

    @property
    def is_development(self) -> bool:
        return self.ENVIRONMENT == "development"


# Singleton settings instance
_settings: Optional[Settings] = None


def get_settings() -> Settings:
    """Get or create the global Settings singleton."""
    global _settings
    if _settings is None:
        _settings = Settings()
    return _settings