"""Prepares a distribution for installation
"""

# The following comment should be removed at some point in the future.
# mypy: strict-optional=False

import logging
import mimetypes
import os
import shutil

from pip._vendor import requests
from pip._vendor.six import PY2

from pip._internal.distributions import (
    make_distribution_for_install_requirement,
)
from pip._internal.distributions.installed import InstalledDistribution
from pip._internal.exceptions import (
    DirectoryUrlHashUnsupported,
    HashMismatch,
    HashUnpinned,
    InstallationError,
    PreviousBuildDirError,
    VcsHashUnsupported,
)
from pip._internal.utils.filesystem import copy2_fixed
from pip._internal.utils.hashes import MissingHashes
from pip._internal.utils.logging import indent_log
from pip._internal.utils.misc import (
    display_path,
    hide_url,
    path_to_display,
    rmtree,
)
from pip._internal.utils.temp_dir import TempDirectory
from pip._internal.utils.typing import MYPY_CHECK_RUNNING
from pip._internal.utils.unpacking import unpack_file
from pip._internal.vcs import vcs

if MYPY_CHECK_RUNNING:
    from typing import (
        Callable, List, Optional, Tuple,
    )

    from mypy_extensions import TypedDict

    from pip._internal.distributions import AbstractDistribution
    from pip._internal.index.package_finder import PackageFinder
    from pip._internal.models.link import Link
    from pip._internal.network.download import Downloader
    from pip._internal.req.req_install import InstallRequirement
    from pip._internal.req.req_tracker import RequirementTracker
    from pip._internal.utils.hashes import Hashes

    if PY2:
        CopytreeKwargs = TypedDict(
            'CopytreeKwargs',
            {
                'ignore': Callable[[str, List[str]], List[str]],
                'symlinks': bool,
            },
            total=False,
        )
    else:
        CopytreeKwargs = TypedDict(
            'CopytreeKwargs',
            {
                'copy_function': Callable[[str, str], None],
                'ignore': Callable[[str, List[str]], List[str]],
                'ignore_dangling_symlinks': bool,
                'symlinks': bool,
            },
            total=False,
        )

logger = logging.getLogger(__name__)


def _get_prepared_distribution(
        req,  # type: InstallRequirement
        req_tracker,  # type: RequirementTracker
        finder,  # type: PackageFinder
        build_isolation  # type: bool
):
    # type: (...) -> AbstractDistribution
    """Prepare a distribution for installation.
    """
    abstract_dist = make_distribution_for_install_requirement(req)
    with req_tracker.track(req):
        abstract_dist.prepare_distribution_metadata(finder, build_isolation)
    return abstract_dist


def unpack_vcs_link(link, location):
    # type: (Link, str) -> None
    vcs_backend = vcs.get_backend_for_scheme(link.scheme)
    assert vcs_backend is not None
    vcs_backend.unpack(location, url=hide_url(link.url))


class File(object):
    def __init__(self, path, content_type):
        # type: (str, str) -> None
        self.path = path
        self.content_type = content_type


def get_http_url(
    link,  # type: Link
    downloader,  # type: Downloader
    download_dir=None,  # type: Optional[str]
    hashes=None,  # type: Optional[Hashes]
):
    # type: (...) -> File
    temp_dir = TempDirectory(kind="unpack", globally_managed=True)
    # If a download dir is specified, is the file already downloaded there?
    already_downloaded_path = None
    if download_dir:
        already_downloaded_path = _check_download_dir(
            link, download_dir, hashes
        )

    if already_downloaded_path:
        from_path = already_downloaded_path
        content_type = mimetypes.guess_type(from_path)[0]
    else:
        # let's download to a tmp dir
        from_path, content_type = _download_http_url(
            link, downloader, temp_dir.path, hashes
        )

    return File(from_path, content_type)


def _copy2_ignoring_special_files(src, dest):
    # type: (str, str) -> None
    """Copying special files is not supported, but as a convenience to users
    we skip errors copying them. This supports tools that may create e.g.
    socket files in the project source directory.
    """
    try:
        copy2_fixed(src, dest)
    except shutil.SpecialFileError as e:
        # SpecialFileError may be raised due to either the source or
        # destination. If the destination was the cause then we would actually
        # care, but since the destination directory is deleted prior to
        # copy we ignore all of them assuming it is caused by the source.
        logger.warning(
            "Ignoring special file error '%s' encountered copying %s to %s.",
            str(e),
            path_to_display(src),
            path_to_display(dest),
        )


def _copy_source_tree(source, target):
    # type: (str, str) -> None
    def ignore(d, names):
        # type: (str, List[str]) -> List[str]
        # Pulling in those directories can potentially be very slow,
        # exclude the following directories if they appear in the top
        # level dir (and only it).
        # See discussion at https://github.com/pypa/pip/pull/6770
        return ['.tox', '.nox'] if d == source else []

    kwargs = dict(ignore=ignore, symlinks=True)  # type: CopytreeKwargs

    if not PY2:
        # Python 2 does not support copy_function, so we only ignore
        # errors on special file copy in Python 3.
        kwargs['copy_function'] = _copy2_ignoring_special_files

    shutil.copytree(source, target, **kwargs)


def get_file_url(
    link,  # type: Link
    download_dir=None,  # type: Optional[str]
    hashes=None  # type: Optional[Hashes]
):
    # type: (...) -> File
    """Get file and optionally check its hash.
    """
    # If a download dir is specified, is the file already there and valid?
    already_downloaded_path = None
    if download_dir:
        already_downloaded_path = _check_download_dir(
            link, download_dir, hashes
        )

    if already_downloaded_path:
        from_path = already_downloaded_path
    else:
        from_path = link.file_path

    # If --require-hashes is off, `hashes` is either empty, the
    # link's embedded hash, or MissingHashes; it is required to
    # match. If --require-hashes is on, we are satisfied by any
    # hash in `hashes` matching: a URL-based or an option-based
    # one; no internet-sourced hash will be in `hashes`.
    if hashes:
        hashes.check_against_path(from_path)

    content_type = mimetypes.guess_type(from_path)[0]

    return File(from_path, content_type)


def unpack_url(
    link,  # type: Link
    location,  # type: str
    downloader,  # type: Downloader
    download_dir=None,  # type: Optional[str]
    hashes=None,  # type: Optional[Hashes]
):
    # type: (...) -> Optional[File]
    """Unpack link into location, downloading if required.

    :param hashes: A Hashes object, one of whose embedded hashes must match,
        or HashMismatch will be raised. If the Hashes is empty, no matches are
        required, and unhashable types of requirements (like VCS ones, which
        would ordinarily raise HashUnsupported) are allowed.
    """
    # non-editable vcs urls
    if link.is_vcs:
        unpack_vcs_link(link, location)
        return None

    # If it's a url to a local directory
    if link.is_existing_dir():
        if os.path.isdir(location):
            rmtree(location)
        _copy_source_tree(link.file_path, location)
        return None

    # file urls
    if link.is_file:
        file = get_file_url(link, download_dir, hashes=hashes)

    # http urls
    else:
        file = get_http_url(
            link,
            downloader,
            download_dir,
            hashes=hashes,
        )

    # unpack the archive to the build dir location. even when only downloading
    # archives, they have to be unpacked to parse dependencies
    unpack_file(file.path, location, file.content_type)

    return file


def _download_http_url(
    link,  # type: Link
    downloader,  # type: Downloader
    temp_dir,  # type: str
    hashes,  # type: Optional[Hashes]
):
    # type: (...) -> Tuple[str, str]
    """Download link url into temp_dir using provided session"""
    download = downloader(link)

    file_path = os.path.join(temp_dir, download.filename)
    with open(file_path, 'wb') as content_file:
        for chunk in download.chunks:
            content_file.write(chunk)

    if hashes:
        hashes.check_against_path(file_path)

    return file_path, download.response.headers.get('content-type', '')


def _check_download_dir(link, download_dir, hashes):
    # type: (Link, str, Optional[Hashes]) -> Optional[str]
    """ Check download_dir for previously downloaded file with correct hash
        If a correct file is found return its path else None
    """
    download_path = os.path.join(download_dir, link.filename)

    if not os.path.exists(download_path):
        return None

    # If already downloaded, does its hash match?
    logger.info('File was already downloaded %s', download_path)
    if hashes:
        try:
            hashes.check_against_path(download_path)
        except HashMismatch:
            logger.warning(
                'Previously-downloaded file %s has bad hash. '
                'Re-downloading.',
                download_path
            )
            os.unlink(download_path)
            return None
    return download_path


class RequirementPreparer(object):
    """Prepares a Requirement
    """

    def __init__(
        self,
        build_dir,  # type: str
        download_dir,  # type: Optional[str]
        src_dir,  # type: str
        wheel_download_dir,  # type: Optional[str]
        build_isolation,  # type: bool
        req_tracker,  # type: RequirementTracker
        downloader,  # type: Downloader
        finder,  # type: PackageFinder
        require_hashes,  # type: bool
        use_user_site,  # type: bool
    ):
        # type: (...) -> None
        super(RequirementPreparer, self).__init__()

        self.src_dir = src_dir
        self.build_dir = build_dir
        self.req_tracker = req_tracker
        self.downloader = downloader
        self.finder = finder

        # Where still-packed archives should be written to. If None, they are
        # not saved, and are deleted immediately after unpacking.
        self.download_dir = download_dir

        # Where still-packed .whl files should be written to. If None, they are
        # written to the download_dir parameter. Separate to download_dir to
        # permit only keeping wheel archives for pip wheel.
        self.wheel_download_dir = wheel_download_dir

        # NOTE
        # download_dir and wheel_download_dir overlap semantically and may
        # be combined if we're willing to have non-wheel archives present in
        # the wheelhouse output by 'pip wheel'.

        # Is build isolation allowed?
        self.build_isolation = build_isolation

        # Should hash-checking be required?
        self.require_hashes = require_hashes

        # Should install in user site-packages?
        self.use_user_site = use_user_site

    @property
    def _download_should_save(self):
        # type: () -> bool
        if not self.download_dir:
            return False

        if os.path.exists(self.download_dir):
            return True

        logger.critical('Could not find download directory')
        raise InstallationError(
            "Could not find or access download directory '{}'"
            .format(self.download_dir))

    def prepare_linked_requirement(
        self,
        req,  # type: InstallRequirement
    ):
        # type: (...) -> AbstractDistribution
        """Prepare a requirement that would be obtained from req.link
        """
        assert req.link
        link = req.link

        # TODO: Breakup into smaller functions
        if link.scheme == 'file':
            path = link.file_path
            logger.info('Processing %s', display_path(path))
        else:
            logger.info('Collecting %s', req.req or req)

        download_dir = self.download_dir
        if link.is_wheel and self.wheel_download_dir:
            # when doing 'pip wheel` we download wheels to a
            # dedicated dir.
            download_dir = self.wheel_download_dir

        if link.is_wheel:
            if download_dir:
                # When downloading, we only unpack wheels to get
                # metadata.
                autodelete_unpacked = True
            else:
                # When installing a wheel, we use the unpacked
                # wheel.
                autodelete_unpacked = False
        else:
            # We always delete unpacked sdists after pip runs.
            autodelete_unpacked = True

        with indent_log():
            # Since source_dir is only set for editable requirements.
            assert req.source_dir is None
            req.ensure_has_source_dir(self.build_dir, autodelete_unpacked)
            # If a checkout exists, it's unwise to keep going.  version
            # inconsistencies are logged later, but do not fail the
            # installation.
            # FIXME: this won't upgrade when there's an existing
            # package unpacked in `req.source_dir`
            if os.path.exists(os.path.join(req.source_dir, 'setup.py')):
                raise PreviousBuildDirError(
                    "pip can't proceed with requirements '{}' due to a"
                    " pre-existing build directory ({}). This is "
                    "likely due to a previous installation that failed"
                    ". pip is being responsible and not assuming it "
                    "can delete this. Please delete it and try again."
                    .format(req, req.source_dir)
                )

            # Now that we have the real link, we can tell what kind of
            # requirements we have and raise some more informative errors
            # than otherwise. (For example, we can raise VcsHashUnsupported
            # for a VCS URL rather than HashMissing.)
            if self.require_hashes:
                # We could check these first 2 conditions inside
                # unpack_url and save repetition of conditions, but then
                # we would report less-useful error messages for
                # unhashable requirements, complaining that there's no
                # hash provided.
                if link.is_vcs:
                    raise VcsHashUnsupported()
                elif link.is_existing_dir():
                    raise DirectoryUrlHashUnsupported()
                if not req.original_link and not req.is_pinned:
                    # Unpinned packages are asking for trouble when a new
                    # version is uploaded. This isn't a security check, but
                    # it saves users a surprising hash mismatch in the
                    # future.
                    #
                    # file:/// URLs aren't pinnable, so don't complain
                    # about them not being pinned.
                    raise HashUnpinned()

            hashes = req.hashes(trust_internet=not self.require_hashes)
            if self.require_hashes and not hashes:
                # Known-good hashes are missing for this requirement, so
                # shim it with a facade object that will provoke hash
                # computation and then raise a HashMissing exception
                # showing the user what the hash should be.
                hashes = MissingHashes()

            try:
                local_file = unpack_url(
                    link, req.source_dir, self.downloader, download_dir,
                    hashes=hashes,
                )
            except requests.HTTPError as exc:
                logger.critical(
                    'Could not install requirement %s because of error %s',
                    req,
                    exc,
                )
                raise InstallationError(
                    'Could not install requirement {} because of HTTP '
                    'error {} for URL {}'.format(req, exc, link)
                )

            # For use in later processing, preserve the file path on the
            # requirement.
            if local_file:
                req.local_file_path = local_file.path

            abstract_dist = _get_prepared_distribution(
                req, self.req_tracker, self.finder, self.build_isolation,
            )

            if download_dir:
                if link.is_existing_dir():
                    logger.info('Link is a directory, ignoring download_dir')
                elif local_file:
                    download_location = os.path.join(
                        download_dir, link.filename
                    )
                    if not os.path.exists(download_location):
                        shutil.copy(local_file.path, download_location)
                        logger.info(
                            'Saved %s', display_path(download_location)
                        )

            if self._download_should_save:
                # Make a .zip of the source_dir we already created.
                if link.is_vcs:
                    req.archive(self.download_dir)
        return abstract_dist

    def prepare_editable_requirement(
        self,
        req,  # type: InstallRequirement
    ):
        # type: (...) -> AbstractDistribution
        """Prepare an editable requirement
        """
        assert req.editable, "cannot prepare a non-editable req as editable"

        logger.info('Obtaining %s', req)

        with indent_log():
            if self.require_hashes:
                raise InstallationError(
                    'The editable requirement {} cannot be installed when '
                    'requiring hashes, because there is no single file to '
                    'hash.'.format(req)
                )
            req.ensure_has_source_dir(self.src_dir)
            req.update_editable(not self._download_should_save)

            abstract_dist = _get_prepared_distribution(
                req, self.req_tracker, self.finder, self.build_isolation,
            )

            if self._download_should_save:
                req.archive(self.download_dir)
            req.check_if_exists(self.use_user_site)

        return abstract_dist

    def prepare_installed_requirement(
        self,
        req,  # type: InstallRequirement
        skip_reason  # type: str
    ):
        # type: (...) -> AbstractDistribution
        """Prepare an already-installed requirement
        """
        assert req.satisfied_by, "req should have been satisfied but isn't"
        assert skip_reason is not None, (
            "did not get skip reason skipped but req.satisfied_by "
            "is set to {}".format(req.satisfied_by)
        )
        logger.info(
            'Requirement %s: %s (%s)',
            skip_reason, req, req.satisfied_by.version
        )
        with indent_log():
            if self.require_hashes:
                logger.debug(
                    'Since it is already installed, we are trusting this '
                    'package without checking its hash. To ensure a '
                    'completely repeatable environment, install into an '
                    'empty virtualenv.'
                )
            abstract_dist = InstalledDistribution(req)

        return abstract_dist
