"""
shared/config.py
────────────────
Application configuration loaded from environment variables.
Uses Pydantic Settings so every variable is validated + type-safe.

Supabase support:
  • DATABASE_URL should point to Supabase PostgreSQL (port 5432 direct, or
    port 6543 for the Connection Pooler in Transaction mode).
  • SUPABASE_URL / SUPABASE_ANON_KEY are optional — only needed if you use
    the Supabase Python client SDK for storage, auth, or realtime features.
"""
from __future__ import annotations

from functools import lru_cache
import os

# Detect Kaggle environment and auto-load secrets into environment variables
if "KAGGLE_KERNEL_RUN_TYPE" in os.environ or os.path.exists("/kaggle"):
    try:
        from kaggle_secrets import UserSecretsClient
        user_secrets = UserSecretsClient()
        for key in ["DATABASE_URL", "RABBITMQ_URL", "USE_MOCK_MODEL"]:
            try:
                val = user_secrets.get_secret(key)
                if val:
                    os.environ[key] = val
            except Exception:
                pass
    except ImportError:
        pass

from pathlib import Path
from pydantic import Field, field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict

# Resolve absolute path to the .env file in the project root
_ROOT_DIR = Path(__file__).resolve().parent.parent.parent
_ENV_FILE = _ROOT_DIR / ".env"


class Settings(BaseSettings):
    """
    Central configuration object.

    Priority order (highest → lowest):
      1. OS environment variables
      2. .env file in the project root
      3. Default values defined here
    """

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

    # ── Database ──────────────────────────────────────────────────────────────
    database_url: str = Field(
        default="sqlite+aiosqlite:///./bp_monitoring.db",
        description=(
            "Async database connection string. "
            "• postgresql+asyncpg://postgres.[ref]:[pw]@[host]:5432/postgres  (Supabase direct) "
            "• postgresql+asyncpg://postgres.[ref]:[pw]@[host]:6543/postgres  (Supabase pooler) "
            "• sqlite+aiosqlite:///./bp_monitoring.db                          (local dev)"
        ),
    )

    # Connection pool tuning (ignored for SQLite)
    db_pool_size: int = Field(
        default=5,
        description=(
            "SQLAlchemy connection pool size. "
            "Supabase free tier allows up to 60 connections; keep this ≤ 10."
        ),
    )
    db_max_overflow: int = Field(
        default=10,
        description="Extra connections allowed above pool_size during peak load.",
    )
    db_pool_recycle: int = Field(
        default=1800,
        description="Recycle idle connections after N seconds (30 min default).",
    )

    # ── Supabase (optional — for SDK features beyond raw SQL) ─────────────────
    supabase_url: str = Field(
        default="",
        description="Supabase project URL (https://[project-ref].supabase.co). Optional.",
    )
    supabase_anon_key: str = Field(
        default="",
        description="Supabase anonymous/public API key. Optional.",
    )

    # ── Message Broker ────────────────────────────────────────────────────────
    rabbitmq_url: str = Field(
        default="amqp://guest:guest@localhost:5672/",
        description="RabbitMQ connection URL. Use amqps:// for CloudAMQP (SSL).",
    )

    # ── FastAPI Server ────────────────────────────────────────────────────────
    app_host: str = Field(default="0.0.0.0", description="Bind host.")
    app_port: int = Field(default=7860, description="Bind port (7860 for HF Spaces).")

    # ── Application ───────────────────────────────────────────────────────────
    debug: bool = Field(default=False, description="Enable debug mode.")
    log_level: str = Field(default="INFO", description="Logging level.")

    # ── AI Model ──────────────────────────────────────────────────────────────
    gan_checkpoint_path: str = Field(
        default="./models/gan_checkpoint.pt",
        description="Path to GAN model checkpoint.",
    )
    vgtlnet_checkpoint_path: str = Field(
        default="./models/vgtlnet_checkpoint.pt",
        description="Path to VGTL-Net model checkpoint.",
    )
    use_mock_model: bool = Field(
        default=True,
        description=(
            "Use MockModelService instead of real GAN+VGTL-Net. "
            "Set to false only when checkpoints are available."
        ),
    )

    # ── Validators ────────────────────────────────────────────────────────────
    @field_validator("log_level")
    @classmethod
    def validate_log_level(cls, v: str) -> str:
        valid = {"DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"}
        upper = v.upper()
        if upper not in valid:
            raise ValueError(f"log_level must be one of {valid}")
        return upper

    @field_validator("app_port")
    @classmethod
    def validate_port(cls, v: int) -> int:
        if not (1 <= v <= 65535):
            raise ValueError("app_port must be between 1 and 65535")
        return v

    @field_validator("db_pool_size")
    @classmethod
    def validate_pool_size(cls, v: int) -> int:
        if v < 1:
            raise ValueError("db_pool_size must be at least 1")
        return v

    # ── Computed Helpers ──────────────────────────────────────────────────────
    @property
    def is_supabase(self) -> bool:
        """True when DATABASE_URL points to Supabase (supabase.co host)."""
        return "supabase.co" in self.database_url

    @property
    def is_sqlite(self) -> bool:
        """True when DATABASE_URL uses SQLite (local dev)."""
        return self.database_url.startswith("sqlite")

    @property
    def uses_pooler(self) -> bool:
        """True when connecting via Supabase's pgBouncer pooler (port 6543)."""
        return ":6543/" in self.database_url


@lru_cache(maxsize=1)
def get_settings() -> Settings:
    """
    Return a cached singleton Settings instance.
    """
    return Settings()