"""Configuration loading with paths resolved relative to the config file."""

from __future__ import annotations

from pathlib import Path
from typing import Any

import yaml


PATH_KEYS = {
    "Calibration_table_path",
    "save_dir",
    "radar_path_cappi",
    "radar_path_hsr",
    "radar_path_hsp",
    "radar_latlon_file",
    "gk2a_ea020_latlon_file",
    "gk2a_base_dir",
    "gk2a_l2_base_dir",
    "input_root",
    "region_root",
    "bt_root",
    "hsr_root",
    "label_root",
    "links_root",
    "log_file",
    "log_path",
    "root",
    "output_root",
    "output_dir",
    "catalog_path",
    "checkpoint_path",
    "config",
    "dataset_config",
    "stats_path",
    "physics_formula_path",
    "validation_json_template",
    "temporal_overlapping_dir",
    "mature_cloud_dir",
    "prediction_dir",
    "all_targets_json",
    "model_available_json",
    "mask_root",
}


def _resolve(value: Any, base: Path) -> Any:
    if isinstance(value, str):
        path = Path(value).expanduser()
        return str(path if path.is_absolute() else (base / path).resolve())
    if isinstance(value, list):
        return [_resolve(item, base) for item in value]
    return value


def resolve_paths(config: dict[str, Any], config_path: str | Path) -> dict[str, Any]:
    """Return a copy with known filesystem fields made absolute."""
    base = Path(config_path).resolve().parent

    def walk(value: Any) -> Any:
        if isinstance(value, dict):
            out: dict[str, Any] = {}
            for key, item in value.items():
                if key in PATH_KEYS and item not in (None, ""):
                    out[key] = _resolve(item, base)
                elif key == "model_output_dirs" and isinstance(item, dict):
                    out[key] = {
                        provider: _resolve(provider_path, base)
                        for provider, provider_path in item.items()
                    }
                else:
                    out[key] = walk(item)
            return out
        if isinstance(value, list):
            return [walk(item) for item in value]
        return value

    return walk(config)


def load_config(path: str | Path) -> dict[str, Any]:
    path = Path(path).resolve()
    with path.open("r", encoding="utf-8") as stream:
        config = yaml.safe_load(stream)
    if not isinstance(config, dict):
        raise ValueError(f"config must be a mapping: {path}")
    config = resolve_paths(config, path)
    config["_config_path"] = str(path)
    return config