from __future__ import annotations

from functools import lru_cache

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        extra="ignore",
    )

    app_name: str = "otel-bi-backend"
    app_env: str = "dev"
    log_level: str = "INFO"

    api_host: str = "0.0.0.0"
    api_port: int = 8000

    cors_origins: str = "http://localhost:5173"

    # Go analytics service
    analytics_service_url: str = "http://localhost:8080"

    # PostgreSQL — write store for derived data
    postgres_host: str = "localhost"
    postgres_port: int = 5432
    postgres_database: str = "otel_bi"
    postgres_username: str = "otel_bi"
    postgres_password: str = "otel_bi"
    postgres_sslmode: str = "prefer"
    postgres_connection_string: str | None = None

    # Frontend OIDC JWT validation
    require_frontend_auth: bool = True
    frontend_jwt_issuer_url: str = ""
    frontend_jwt_audience: str = ""
    frontend_jwt_jwks_url: str | None = None
    frontend_jwt_algorithm: str = "RS256"
    frontend_required_scopes: str = ""
    frontend_clock_skew_seconds: int = Field(default=30, ge=0, le=300)

    # Frontend OIDC client config (served via /api/config)
    frontend_oidc_client_id: str = ""
    frontend_oidc_scope: str = "openid profile email"

    # OpenTelemetry
    otel_service_name: str = "otel-bi-backend"
    otel_service_namespace: str = "final-thesis"
    otel_collector_endpoint: str = "http://localhost:4318"
    otel_export_timeout_ms: int = 10000

    # Browser-reachable OTLP endpoint — served to the SPA via GET /api/config.
    # Distinct from otel_collector_endpoint, which is the backend's own
    # in-cluster collector address.
    frontend_otel_collector_endpoint: str = "/otel"
    frontend_otel_service_name: str = "otel-bi-frontend"
    frontend_otel_service_namespace: str = "final-thesis"
    frontend_deployment_environment: str = "production"

    # Report output — points at the K8s CSI / SMB mountpoint in production
    report_output_dir: str = "/tmp/otel-bi-reports"

    # Analytics defaults (forwarded to Go service as query params)
    forecast_horizon_days: int = Field(default=30, ge=7, le=180)
    default_history_days: int = Field(default=365, ge=30, le=1460)
    ranking_default_top_n: int = Field(default=10, ge=3, le=100)
    storage_default_limit: int = Field(default=50, ge=10, le=500)

    @property
    def cors_origins_list(self) -> list[str]:
        return [o.strip() for o in self.cors_origins.split(",") if o.strip()]

    @property
    def frontend_required_scopes_list(self) -> list[str]:
        return [s.strip() for s in self.frontend_required_scopes.split(" ") if s.strip()]

    @property
    def postgres_connection_url(self) -> str:
        if self.postgres_connection_string:
            return self.postgres_connection_string
        from urllib.parse import quote_plus
        user = quote_plus(self.postgres_username)
        password = quote_plus(self.postgres_password)
        return (
            f"postgresql+psycopg://{user}:{password}@{self.postgres_host}:{self.postgres_port}"
            f"/{self.postgres_database}?sslmode={self.postgres_sslmode}"
        )


@lru_cache
def get_settings() -> Settings:
    return Settings()


settings = get_settings()