"""Application settings (env-driven). Model slugs are configuration, not code."""

from __future__ import annotations

from functools import lru_cache
from pathlib import Path

from pydantic import SecretStr, field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict

BASE_DIR = Path(__file__).resolve().parents[2]  # backend/
REPO_DIR = BASE_DIR.parent


class Settings(BaseSettings):
    model_config = SettingsConfigDict(env_file=(REPO_DIR / ".env", BASE_DIR / ".env"), extra="ignore")

    # --- App ---
    APP_ENV: str = "development"
    APP_NAME: str = "UQO-Chat"
    APP_URL: str = "https://www.uqo-chat.app"
    CORS_ORIGINS: str = "https://www.uqo-chat.app,http://localhost:5173,http://localhost:8190"
    LOG_LEVEL: str = "INFO"
    PORT: int = 8190
    DATA_DIR: Path = REPO_DIR / "data"
    FRONTEND_DIST: Path = REPO_DIR / "frontend" / "dist"
    COURSES: str = "IMM1003,IMM1033"
    TERM_LABEL: str = "Automne 2026"

    # --- LLM (OpenRouter) ---
    OPENROUTER_API_KEY: SecretStr = SecretStr("")
    OPENROUTER_BASE_URL: str = "https://openrouter.ai/api/v1"
    OPENROUTER_APP_NAME: str = "UQO-Chat"
    OPENROUTER_APP_URL: str = "https://www.uqo-chat.app"
    # Slugs — verify on https://openrouter.ai/models before changing (checked 2026-09-05).
    MODEL_TUTOR_PRIMARY: str = "anthropic/claude-fable-5.1"
    MODEL_TUTOR_FALLBACK: str = "openai/gpt-5.5"
    MODEL_REASONING: str = "anthropic/claude-opus-4.6"
    MODEL_FAST: str = "openai/gpt-5.4-nano"
    MODEL_VISION: str = "anthropic/claude-sonnet-4.6"
    # OpenRouter exposes no embedding model (2026-09): optional OpenAI-compatible endpoint.
    EMBEDDINGS_BASE_URL: str = ""
    EMBEDDINGS_API_KEY: SecretStr = SecretStr("")
    MODEL_EMBEDDINGS: str = ""
    LLM_MAX_TOOL_ITERATIONS: int = 12
    LLM_TIMEOUT_SECONDS: int = 120
    LLM_MAX_OUTPUT_TOKENS: int = 16000
    LLM_MONTHLY_BUDGET_USD: float = 2000.0
    LLM_TURN_TIMEOUT_SECONDS: int = 300

    # --- Web search ---
    FIRECRAWL_API_KEY: SecretStr = SecretStr("")
    FIRECRAWL_BASE_URL: str = "https://api.firecrawl.dev/v1"
    WEB_SEARCH_CACHE_TTL_S: int = 6 * 3600

    # --- Data ---
    DATABASE_URL: str = ""  # default: sqlite in DATA_DIR
    REDIS_URL: str = ""  # optional; in-memory fallback

    # --- Sandbox ---
    SANDBOX_URL: str = "http://127.0.0.1:8191"
    SANDBOX_TIMEOUT_S: int = 30
    SANDBOX_HEAVY_TIMEOUT_S: int = 60
    SANDBOX_TOKEN: SecretStr = SecretStr("")

    # --- Auth ---
    JWT_SECRET: SecretStr = SecretStr("change-me-in-production")
    JWT_TTL_HOURS: int = 24
    REFRESH_TTL_DAYS: int = 30
    ALLOWED_EMAIL_DOMAINS: str = "uqo.ca"
    INVITED_EMAILS: str = ""
    PROFESSOR_EMAILS: str = ""
    ADMIN_EMAILS: str = ""
    INVITE_TTL_DAYS: int = 14  # "choose your password" link sent to newly added students
    RESET_TTL_MINUTES: int = 60  # "forgot my password" link
    # --- Mail (Resend first; SMTP kept as fallback) ---
    RESEND_API_KEY: SecretStr = SecretStr("")
    RESEND_BASE_URL: str = "https://api.resend.com"
    MAIL_FROM: str = "UQO-Chat <no-reply@uqo-chat.app>"
    MAIL_REPLY_TO: str = ""
    SMTP_HOST: str = ""
    SMTP_PORT: int = 587
    SMTP_USER: str = ""
    SMTP_PASSWORD: SecretStr = SecretStr("")
    SMTP_FROM: str = "no-reply@uqo-chat.app"

    # --- Limits ---
    RATE_MESSAGES_PER_HOUR: int = 60
    RATE_MESSAGES_PER_DAY: int = 400
    RATE_SANDBOX_PER_HOUR: int = 10
    RATE_WEBSEARCH_PER_DAY: int = 30
    RATE_UPLOADS_PER_DAY: int = 20
    UPLOAD_MAX_MB: int = 20
    FILE_TTL_DAYS: int = 7
    FILE_PINNED_TTL_DAYS: int = 30
    MESSAGE_RETENTION_MONTHS: int = 12

    @field_validator("DATA_DIR", mode="before")
    @classmethod
    def _expand(cls, v: object) -> object:
        if isinstance(v, str):
            return Path(v).expanduser()
        return v

    @property
    def database_url(self) -> str:
        if self.DATABASE_URL:
            return self.DATABASE_URL
        return f"sqlite+aiosqlite:///{self.DATA_DIR / 'uqochat.db'}"

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

    @property
    def courses(self) -> list[str]:
        return [c.strip().upper() for c in self.COURSES.split(",") if c.strip()]

    def _csv_lower(self, value: str) -> set[str]:
        return {e.strip().lower() for e in value.split(",") if e.strip()}

    @property
    def allowed_domains(self) -> set[str]:
        return self._csv_lower(self.ALLOWED_EMAIL_DOMAINS)

    @property
    def invited_emails(self) -> set[str]:
        return self._csv_lower(self.INVITED_EMAILS)

    @property
    def professor_emails(self) -> set[str]:
        return self._csv_lower(self.PROFESSOR_EMAILS)

    @property
    def admin_emails(self) -> set[str]:
        return self._csv_lower(self.ADMIN_EMAILS)

    @property
    def smtp_enabled(self) -> bool:
        return bool(self.SMTP_HOST)

    @property
    def resend_enabled(self) -> bool:
        return bool(self.RESEND_API_KEY.get_secret_value())

    @property
    def mail_enabled(self) -> bool:
        return self.resend_enabled or self.smtp_enabled

    @property
    def is_dev(self) -> bool:
        return self.APP_ENV != "production"


@lru_cache
def get_settings() -> Settings:
    s = Settings()
    s.DATA_DIR.mkdir(parents=True, exist_ok=True)
    (s.DATA_DIR / "files").mkdir(exist_ok=True)
    return s