"""Settings read/write helpers for the ``app_settings`` KV table.

Provides a typed ``LLMConfig`` dataclass and two helpers:

- ``get_app_settings(db) -> LLMConfig`` — reads KV rows (or returns defaults).
- ``save_app_settings(db, ...) -> None`` — writes KV rows; API key left blank
  means "keep the old value".
"""

from __future__ import annotations

from dataclasses import dataclass

from sqlalchemy.orm import Session

from app.models import AppSetting


@dataclass
class LLMConfig:
    """All settings consumed by the LLM client and settings UI."""

    enabled: bool = False
    base_url: str = "https://api.openai.com/v1"
    model: str = ""
    api_key: str = ""
    ai_search_enabled: bool = False


def _get_value(rows: dict[str, str], key: str, default: str) -> str:
    return rows.get(key, default)


def _get_bool(rows: dict[str, str], key: str, default: bool) -> bool:
    return rows.get(key, str(default).lower()) == "true"


def get_app_settings(db: Session) -> LLMConfig:
    """Read all settings from ``app_settings`` and return an ``LLMConfig``."""
    rows: dict[str, str] = {}
    for row in db.query(AppSetting).all():
        if row.value is not None:
            rows[row.key] = row.value

    return LLMConfig(
        enabled=_get_bool(rows, "llm_enabled", False),
        base_url=_get_value(rows, "llm_base_url", "https://api.openai.com/v1"),
        model=_get_value(rows, "llm_model", ""),
        api_key=_get_value(rows, "llm_api_key", ""),
        ai_search_enabled=_get_bool(rows, "ai_search_enabled", False),
    )


def save_app_settings(
    db: Session,
    *,
    enabled: bool | None = None,
    base_url: str | None = None,
    model: str | None = None,
    api_key: str | None = None,
    ai_search_enabled: bool | None = None,
) -> None:
    """Write settings to ``app_settings``.

    If ``api_key`` is ``None`` (form field left blank), the existing key is
    preserved.  All other fields are written as-is.
    """
    updates: dict[str, str | None] = {}

    if enabled is not None:
        updates["llm_enabled"] = str(enabled).lower()
    if base_url is not None:
        updates["llm_base_url"] = base_url
    if model is not None:
        updates["llm_model"] = model
    if api_key is not None:
        updates["llm_api_key"] = api_key
    if ai_search_enabled is not None:
        updates["ai_search_enabled"] = str(ai_search_enabled).lower()

    for key, value in updates.items():
        existing = db.get(AppSetting, key)
        if existing is not None:
            existing.value = value
        else:
            db.add(AppSetting(key=key, value=value))

    db.commit()