"""Application configuration loaded from environment variables / settings DB.

Settings are layered:
1. Defaults defined in this module.
2. Overrides from environment variables (or `.env` file).
3. Runtime overrides from the `settings` table (loaded on startup and cached).

The Settings class below is a Pydantic-Settings model — it only handles (1) and (2).
The runtime DB overrides are managed by `app.core.settings_service`.
"""

from __future__ import annotations

from functools import lru_cache
from pathlib import Path

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """Layered configuration for the AI-RPG backend."""

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

    # === Application ===
    app_name: str = "AI-RPG"
    app_version: str = "1.0.0"
    debug: bool = False
    log_level: str = "INFO"
    secret_key: str = "change-me-in-production-please-32-bytes-long"
    jwt_algorithm: str = "HS256"
    access_token_expire_minutes: int = 60 * 24  # 24 hours
    refresh_token_expire_minutes: int = 60 * 24 * 7  # 7 days
    # Comma-separated list of allowed CORS origins, e.g.
    #   CORS_ORIGINS=http://localhost:8080,http://localhost:5173
    # Special value "*" allows all origins.
    # Use `settings.cors_origins_list` to access the parsed list.
    cors_origins: str = "*"

    # === Admin setup ===
    admin_setup_token: str = ""  # if empty, will be auto-generated and stored in DB

    # === Database ===
    database_url: str = "postgresql+asyncpg://airpg:airpg@localhost:5432/airpg"
    database_url_sync: str = "postgresql+psycopg2://airpg:airpg@localhost:5432/airpg"
    db_pool_size: int = 10
    db_max_overflow: int = 20
    db_echo: bool = False

    # === Qdrant ===
    qdrant_url: str = "http://localhost:6333"
    qdrant_api_key: str = ""
    qdrant_collection_prefix: str = ""
    qdrant_timeout: float = 30.0

    # === LLM (defaults; runtime overrides in `settings` table) ===
    llm_api_url: str = "http://localhost:11434/v1"
    llm_api_key: str = ""
    llm_model: str = "qwen2.5-7b-instruct"
    llm_temperature_orchestrator: float = 0.7
    llm_temperature_writer: float = 0.85
    llm_max_tokens: int = 2048
    llm_timeout_seconds: int = 60

    # === Embeddings ===
    embeddings_provider: str = "offline_hash"  # "offline_hash" | "openai"
    embeddings_api_url: str = ""
    embeddings_api_key: str = ""
    embeddings_model: str = "text-embedding-3-small"
    embeddings_dimension: int = 256  # for offline_hash; will be probed for openai
    embeddings_timeout_seconds: int = 30
    embeddings_batch_size: int = 32
    embeddings_cache_ttl_seconds: int = 300
    embeddings_max_text_chars: int = 4000

    # === Context manager ===
    context_guaranteed_messages: int = 10
    context_compression_threshold_messages: int = 20
    context_compression_threshold_tokens: int = 6000
    context_scene_text_truncate_tokens: int = 500
    context_auto_rag_on_entity_mention: bool = False
    context_safety_margin_tokens: int = 500
    llm_context_window_tokens: int = 8192  # for tokenizer-based budgeting

    # === Game ===
    game_deferred_triggers_enabled: bool = True
    game_max_substeps_per_iteration: int = 8
    game_max_suggested_actions: int = 3

    # === UI ===
    ui_page_title: str = "AI-RPG"
    ui_favicon_url: str = "/icon.png"
    ui_logo_url: str = "/icon.png"
    ui_og_image_url: str = ""

    # === Storage ===
    data_dir: str = "/home/z/my-project/ai-rpg/data"
    assets_dir: str = ""  # computed in __init__
    max_upload_size_bytes: int = 1024 * 1024  # 1 MB

    def __init__(self, **values):
        super().__init__(**values)
        if not self.assets_dir:
            self.assets_dir = str(Path(self.data_dir) / "assets")

    @property
    def cors_origins_list(self) -> list[str]:
        """Parse `cors_origins` (comma-separated string) into a list.

        Whitespace is stripped from each entry, empty entries are dropped.
        Returns `["*"]` if the field is empty or just whitespace.
        """
        if not self.cors_origins or not self.cors_origins.strip():
            return ["*"]
        return [o.strip() for o in self.cors_origins.split(",") if o.strip()]


@lru_cache(maxsize=1)
def get_settings() -> Settings:
    """Cached settings instance. Use as the single source of truth for env config."""
    return Settings()


def reload_settings() -> Settings:
    """Force reload settings (used in tests)."""
    get_settings.cache_clear()
    return get_settings()