from __future__ import annotations

import importlib.util
import os
from pathlib import Path
from types import ModuleType


def _user_config_path() -> Path | None:
    explicit = os.environ.get("COPIENATOR_CONFIG", "").strip()
    if explicit:
        return Path(explicit).expanduser().resolve()
    local = Path.cwd() / "config.py"
    return local.resolve() if local.is_file() else None


def _load_user_config(path: Path) -> ModuleType:
    if not path.is_file():
        raise FileNotFoundError(f"Copienator configuration not found: {path}")
    spec = importlib.util.spec_from_file_location("_copienator_user_config", path)
    if spec is None or spec.loader is None:
        raise ImportError(f"Could not load Copienator configuration: {path}")
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    return module


def _settings(path: Path | None) -> dict[str, object]:
    import default_config

    values = {
        name: getattr(default_config, name)
        for name in dir(default_config)
        if not name.startswith("_")
    }
    if path is not None:
        # Preserve compatibility defaults for older personal configurations.
        values.update(THINKING_LEVEL_FOR_LABEL="medium", THINKING_LEVEL_PRO="high")
        module = _load_user_config(path)
        values.update({
            name: getattr(module, name)
            for name in dir(module)
            if not name.startswith("_")
        })
        # Historically the name recognizer inherited the label model when omitted.
        if not hasattr(module, "MODEL_FOR_NAME_ID"):
            values["MODEL_FOR_NAME_ID"] = values["MODEL_FOR_LABEL_ID"]
    values["PAGE_SPLITTER_KB"] = {
        "reverse_pages": "i",
        "add_secondary_splitter": "<Insert>",
        "delete_secondary_splitter": "<Delete>",
        **values["PAGE_SPLITTER_KB"],
    }
    return values


CONFIG_PATH = _user_config_path()
_global_settings = _settings(CONFIG_PATH)
globals().update(_global_settings)
LOCAL_CONFIG_PATH: Path | None = None
_evaluation_overrides: set[str] = set()


def use_evaluation(root: str | Path | None) -> None:
    """Apply selected evaluation settings, resetting any previous overrides."""
    global LOCAL_CONFIG_PATH, _evaluation_overrides
    path = Path(root).expanduser().resolve() / "config.py" if root is not None else None
    values = dict(_global_settings)
    overrides = {}
    if path is not None and path.is_file() and path != CONFIG_PATH:
        module = _load_user_config(path)
        overrides = {
            name: getattr(module, name)
            for name in dir(module)
            if name.isupper() and name in _global_settings
        }
        values.update(overrides)
    else:
        path = None
    for name in ("ANNOTATION_MAX_HEIGHT_PX", "ANNOTATION_MAX_PIXELS"):
        if type(values[name]) is not int or values[name] <= 0:
            raise ValueError(f"{name} must be a positive integer (pixels)")
    values["PAGE_SPLITTER_KB"] = {
        "reverse_pages": "i",
        "add_secondary_splitter": "<Insert>",
        "delete_secondary_splitter": "<Delete>",
        **values["PAGE_SPLITTER_KB"],
    }
    for name in _evaluation_overrides | overrides.keys():
        globals()[name] = values[name]
    _evaluation_overrides = set(overrides)
    LOCAL_CONFIG_PATH = path