"""Read-only SaraTag Book-sidecar support, mirroring SaraView's Backend/BookReader.py
so all three Sara* apps talk to SaraTag the same way (dynamically loaded, opt-in via
Config.toml's [SaraTag] section, since SaraTag isn't an installable package)."""

import fnmatch
import importlib.util
import tomllib
from pathlib import Path
from types import ModuleType
from typing import Any, Optional

from Core import AppConfig

_CachedSaraTagCore: Optional[ModuleType] = None
_CachedSaraTagCoreLoaded = False


def ClearSaraTagCache() -> None:
    """Called after Options is saved so an Enabled/CoreModulePath change takes
    effect on the next Book read, instead of needing a restart."""
    global _CachedSaraTagCore, _CachedSaraTagCoreLoaded
    _CachedSaraTagCore = None
    _CachedSaraTagCoreLoaded = False


def GetSaraTagCore(Config: AppConfig) -> Optional[ModuleType]:
    global _CachedSaraTagCore, _CachedSaraTagCoreLoaded

    if _CachedSaraTagCoreLoaded:
        return _CachedSaraTagCore

    _CachedSaraTagCoreLoaded = True

    if not Config.SaraTag.Enabled or not Config.SaraTag.CoreModulePath:
        return None

    CoreFilePath = Path(Config.SaraTag.CoreModulePath).expanduser().resolve() / "Core.py"
    if not CoreFilePath.is_file():
        return None

    ModuleSpec = importlib.util.spec_from_file_location("SaraTagCore", CoreFilePath)
    if ModuleSpec is None or ModuleSpec.loader is None:
        return None

    SaraTagCoreModule = importlib.util.module_from_spec(ModuleSpec)
    ModuleSpec.loader.exec_module(SaraTagCoreModule)

    _CachedSaraTagCore = SaraTagCoreModule
    return _CachedSaraTagCore


def IsInternalSaraTagFile(EntryPath: Path, Config: AppConfig) -> bool:
    """Whether this entry is SaraTag plumbing (a Book sidecar, its data dir, ...)
    that should stay out of the file listing, matching SaraView's HideInternalFiles."""
    if not Config.SaraTag.Enabled or not Config.SaraTag.HideInternalFiles:
        return False
    return any(fnmatch.fnmatch(EntryPath.name, Pattern) for Pattern in Config.SaraTag.InternalPatterns)


def ReadBookForFile(FilePath: Path, Config: AppConfig) -> Optional[dict[str, Any]]:
    """Return {"Parent": ..., "Tags": {...}, "Definitions": {...}} or None."""
    SaraTagCore = GetSaraTagCore(Config)
    if SaraTagCore is None:
        return None

    BookPath = SaraTagCore.GetBookPath(FilePath)
    if not BookPath.is_file():
        return None

    with BookPath.open("rb") as BookFile:
        Metadata = tomllib.load(BookFile)

    ParentValue = Metadata.get("Parent")
    Definitions: dict[str, Any] = {}
    if isinstance(ParentValue, str):
        try:
            LexiconPath = SaraTagCore.ResolveBookLexiconPath(FilePath.parent, ParentValue)
            Definitions = SaraTagCore.ResolveLexiconTags(LexiconPath)
        except Exception:
            Definitions = {}

    Tags = {Key: Value for Key, Value in Metadata.items() if Key != "Parent"}
    return {"Parent": ParentValue, "Tags": Tags, "Definitions": Definitions}