import email.message
import importlib.metadata
import os
import pathlib
import zipfile
from typing import (
    Collection,
    Dict,
    Iterable,
    Iterator,
    Mapping,
    Optional,
    Sequence,
    cast,
)

from pip._vendor.packaging.requirements import Requirement
from pip._vendor.packaging.utils import NormalizedName, canonicalize_name
from pip._vendor.packaging.version import parse as parse_version

from pip._internal.exceptions import InvalidWheel, UnsupportedWheel
from pip._internal.metadata.base import (
    BaseDistribution,
    BaseEntryPoint,
    DistributionVersion,
    InfoPath,
    Wheel,
)
from pip._internal.utils.misc import normalize_path
from pip._internal.utils.packaging import safe_extra
from pip._internal.utils.wheel import parse_wheel, read_wheel_metadata_file

from ._compat import BasePath, get_dist_name


class WheelDistribution(importlib.metadata.Distribution):
    """An ``importlib.metadata.Distribution`` read from a wheel.

    Although ``importlib.metadata.PathDistribution`` accepts ``zipfile.Path``,
    its implementation is too "lazy" for pip's needs (we can't keep the ZipFile
    handle open for the entire lifetime of the distribution object).

    This implementation eagerly reads the entire metadata directory into the
    memory instead, and operates from that.
    """

    def __init__(
        self,
        files: Mapping[pathlib.PurePosixPath, bytes],
        info_location: pathlib.PurePosixPath,
    ) -> None:
        self._files = files
        self.info_location = info_location

    @classmethod
    def from_zipfile(
        cls,
        zf: zipfile.ZipFile,
        name: str,
        location: str,
    ) -> "WheelDistribution":
        info_dir, _ = parse_wheel(zf, name)
        paths = (
            (name, pathlib.PurePosixPath(name.split("/", 1)[-1]))
            for name in zf.namelist()
            if name.startswith(f"{info_dir}/")
        )
        files = {
            relpath: read_wheel_metadata_file(zf, fullpath)
            for fullpath, relpath in paths
        }
        info_location = pathlib.PurePosixPath(location, info_dir)
        return cls(files, info_location)

    def iterdir(self, path: InfoPath) -> Iterator[pathlib.PurePosixPath]:
        # Only allow iterating through the metadata directory.
        if pathlib.PurePosixPath(str(path)) in self._files:
            return iter(self._files)
        raise FileNotFoundError(path)

    def read_text(self, filename: str) -> Optional[str]:
        try:
            data = self._files[pathlib.PurePosixPath(filename)]
        except KeyError:
            return None
        try:
            text = data.decode("utf-8")
        except UnicodeDecodeError as e:
            wheel = self.info_location.parent
            error = f"Error decoding metadata for {wheel}: {e} in {filename} file"
            raise UnsupportedWheel(error)
        return text


class Distribution(BaseDistribution):
    def __init__(
        self,
        dist: importlib.metadata.Distribution,
        info_location: Optional[BasePath],
        installed_location: Optional[BasePath],
    ) -> None:
        self._dist = dist
        self._info_location = info_location
        self._installed_location = installed_location

    @classmethod
    def from_directory(cls, directory: str) -> BaseDistribution:
        info_location = pathlib.Path(directory)
        dist = importlib.metadata.Distribution.at(info_location)
        return cls(dist, info_location, info_location.parent)

    @classmethod
    def from_wheel(cls, wheel: Wheel, name: str) -> BaseDistribution:
        try:
            with wheel.as_zipfile() as zf:
                dist = WheelDistribution.from_zipfile(zf, name, wheel.location)
        except zipfile.BadZipFile as e:
            raise InvalidWheel(wheel.location, name) from e
        except UnsupportedWheel as e:
            raise UnsupportedWheel(f"{name} has an invalid wheel, {e}")
        return cls(dist, dist.info_location, pathlib.PurePosixPath(wheel.location))

    @property
    def location(self) -> Optional[str]:
        if self._info_location is None:
            return None
        return str(self._info_location.parent)

    @property
    def info_location(self) -> Optional[str]:
        if self._info_location is None:
            return None
        return str(self._info_location)

    @property
    def installed_location(self) -> Optional[str]:
        if self._installed_location is None:
            return None
        return normalize_path(str(self._installed_location))

    def _get_dist_name_from_location(self) -> Optional[str]:
        """Try to get the name from the metadata directory name.

        This is much faster than reading metadata.
        """
        if self._info_location is None:
            return None
        stem, suffix = os.path.splitext(self._info_location.name)
        if suffix not in (".dist-info", ".egg-info"):
            return None
        return stem.split("-", 1)[0]

    @property
    def canonical_name(self) -> NormalizedName:
        name = self._get_dist_name_from_location() or get_dist_name(self._dist)
        return canonicalize_name(name)

    @property
    def version(self) -> DistributionVersion:
        return parse_version(self._dist.version)

    def is_file(self, path: InfoPath) -> bool:
        return self._dist.read_text(str(path)) is not None

    def iter_distutils_script_names(self) -> Iterator[str]:
        # A distutils installation is always "flat" (not in e.g. egg form), so
        # if this distribution's info location is NOT a pathlib.Path (but e.g.
        # zipfile.Path), it can never contain any distutils scripts.
        if not isinstance(self._info_location, pathlib.Path):
            return
        for child in self._info_location.joinpath("scripts").iterdir():
            yield child.name

    def read_text(self, path: InfoPath) -> str:
        content = self._dist.read_text(str(path))
        if content is None:
            raise FileNotFoundError(path)
        return content

    def iter_entry_points(self) -> Iterable[BaseEntryPoint]:
        # importlib.metadata's EntryPoint structure sasitfies BaseEntryPoint.
        return self._dist.entry_points

    def _metadata_impl(self) -> email.message.Message:
        # From Python 3.10+, importlib.metadata declares PackageMetadata as the
        # return type. This protocol is unfortunately a disaster now and misses
        # a ton of fields that we need, including get() and get_payload(). We
        # rely on the implementation that the object is actually a Message now,
        # until upstream can improve the protocol. (python/cpython#94952)
        return cast(email.message.Message, self._dist.metadata)

    def iter_provided_extras(self) -> Iterable[str]:
        return (
            safe_extra(extra) for extra in self.metadata.get_all("Provides-Extra", [])
        )

    def iter_dependencies(self, extras: Collection[str] = ()) -> Iterable[Requirement]:
        contexts: Sequence[Dict[str, str]] = [{"extra": safe_extra(e)} for e in extras]
        for req_string in self.metadata.get_all("Requires-Dist", []):
            req = Requirement(req_string)
            if not req.marker:
                yield req
            elif not extras and req.marker.evaluate({"extra": ""}):
                yield req
            elif any(req.marker.evaluate(context) for context in contexts):
                yield req
