"""
This module provides the GriffeLoader, which uses the 'griffe' library to
introspect Python source code and populate the doc-forge Project models.
"""

import logging
from pathlib import Path
from typing import List, Optional

from griffe import (
    GriffeLoader as _GriffeLoader,
    ModulesCollection,
    LinesCollection,
    Object,
    AliasResolutionError,
)

from docforge.models import Module, Project, DocObject

logger = logging.getLogger(__name__)


def discover_module_paths(
    module_name: str,
    project_root: Path | None = None,
) -> List[str]:
    """
    Discover all Python modules under a package via filesystem traversal.

    Rules:
    - Directory with __init__.py is treated as a package.
    - Any .py file is treated as a module.
    - All paths are converted to dotted module paths.

    Args:
        module_name: The name of the package to discover.
        project_root: The root directory of the project. Defaults to current working directory.

    Returns:
        A sorted list of dotted module paths.
    """

    if project_root is None:
        project_root = Path.cwd()

    pkg_dir = project_root / module_name
    if not pkg_dir.exists():
        raise FileNotFoundError(f"Package not found: {pkg_dir}")

    module_paths: List[str] = []

    for path in pkg_dir.rglob("*.py"):
        if path.name == "__init__.py":
            module_path = path.parent
        else:
            module_path = path

        rel = module_path.relative_to(project_root)
        dotted = ".".join(rel.with_suffix("").parts)
        module_paths.append(dotted)

    return sorted(set(module_paths))


class GriffeLoader:
    """
    Loads Python modules and extracts documentation using the Griffe introspection engine.
    """

    def __init__(self) -> None:
        """
        Initialize the GriffeLoader.
        """
        self._loader = _GriffeLoader(
            modules_collection=ModulesCollection(),
            lines_collection=LinesCollection(),
        )

    def load_project(
        self,
        module_paths: List[str],
        project_name: Optional[str] = None,
        skip_import_errors: bool = None,
    ) -> Project:
        """
        Load multiple modules and combine them into a single Project models.

        Args:
            module_paths: A list of dotted paths to the modules to load.
            project_name: Optional name for the project. Defaults to the first module name.
            skip_import_errors: If True, modules that fail to import will be skipped.

        Returns:
            A Project instance containing the loaded modules.
        """
        if not module_paths:
            raise ValueError("At least one module path must be provided")

        if project_name is None:
            project_name = module_paths[0].split(".")[0]

        project = Project(name=project_name)

        for module_path in module_paths:
            try:
                module = self.load_module(module_path)
            except ImportError as import_error:
                if skip_import_errors:
                    logger.debug("Could not load %s: %s", module_path, import_error)
                    continue
                else:
                    raise import_error
            project.add_module(module)

        return project

    def load_module(self, path: str) -> Module:
        """
        Load a single module and convert its introspection data into the docforge models.

        Args:
            path: The dotted path of the module to load.

        Returns:
            A Module instance.
        """
        self._loader.load(path)
        griffe_module = self._loader.modules_collection[path]

        return self._convert_module(griffe_module)

    # -------------------------
    # Conversion helpers
    # -------------------------

    def _convert_module(self, obj: Object) -> Module:
        """
        Convert a Griffe Object (module) into a docforge Module.

        Args:
            obj: The Griffe Object representing the module.

        Returns:
            A populated Module instance.
        """
        module = Module(
            path=obj.path,
            docstring=self._safe_docstring(obj),
        )

        for name, member in obj.members.items():
            if name.startswith("_"):
                continue

            module.add_object(self._convert_object(member))

        return module

    def _convert_object(self, obj: Object) -> DocObject:
        """
        Recursively convert a Griffe Object into a DocObject hierarchy.

        Args:
            obj: The Griffe Object to convert.

        Returns:
            A DocObject instance.
        """
        kind = obj.kind.value
        signature = self._safe_signature(obj)

        doc_obj = DocObject(
            name=obj.name,
            kind=kind,
            path=obj.path,
            signature=signature,
            docstring=self._safe_docstring(obj),
        )

        try:
            for name, member in obj.members.items():
                if name.startswith("_"):
                    continue
                doc_obj.add_member(self._convert_object(member))
        except AliasResolutionError:
            pass

        return doc_obj

    # -------------------------
    # Safe extractors
    # -------------------------

    def _safe_docstring(self, obj: Object) -> Optional[str]:
        """
        Safely retrieve the docstring value from a Griffe object.

        Args:
            obj: The Griffe Object to inspect.

        Returns:
            The raw docstring string, or None if missing or unresolvable.
        """
        try:
            return obj.docstring.value if obj.docstring else None
        except AliasResolutionError:
            return None

    def _safe_signature(self, obj: Object) -> Optional[str]:
        """
        Safely retrieve the signature string from a Griffe object.

        Args:
            obj: The Griffe Object to inspect.

        Returns:
            The string representation of the signature, or None.
        """
        try:
            if hasattr(obj, "signature") and obj.signature:
                return str(obj.signature)
        except AliasResolutionError:
            return None
        return None