"""Pydantic models for backend services (Semgrep: BaseModel lives in models.py)."""
from __future__ import annotations

import json
from pathlib import Path
from typing import Literal

from pydantic import BaseModel, Field, field_validator

RecsysSource = Literal["graph", "ots", "hybrid"]


class RecsysSettings(BaseModel):
    """Production and tests configure recommender behavior explicitly or via optional JSON."""

    source: RecsysSource = Field(default="graph", description="graph | ots | hybrid")
    candidates_path: Path | None = Field(
        default=None,
        description=(
            "Override path to OTS candidate JSON; default is "
            "<store_dir>/recsys/candidates.json"
        ),
    )

    @field_validator("source", mode="before")
    @classmethod
    def normalize_source_aliases(cls, value: str | int | float | bool | None) -> str:
        if value is None:
            return "graph"
        raw = str(value).strip().lower()
        if raw in {"", "graph", "current"}:
            return "graph"
        if raw in {"ots", "cornac", "recbole"}:
            return "ots"
        if raw == "hybrid":
            return "hybrid"
        return "graph"


def load_recsys_settings_from_store(
    store_path: Path,
    override: RecsysSettings | None,
) -> RecsysSettings:
    """Load typed settings from disk (no process environment)."""
    if override is not None:
        return override.model_copy(deep=True)
    config_path = store_path.parent / "recsys" / "settings.json"
    if not config_path.is_file():
        base = RecsysSettings()
    else:
        text = config_path.read_text(encoding="utf-8")
        data = json.loads(text)
        base = RecsysSettings.model_validate(data)
        if base.candidates_path is not None and not base.candidates_path.is_absolute():
            rel = base.candidates_path
            base = base.model_copy(
                update={
                    "candidates_path": config_path.parent / rel,
                },
            )
    return base