"""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 typing import Dict, Iterable, List, Optional

from pip._vendor.packaging.utils import canonicalize_name

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,
    NetworkConnectionError,
    PreviousBuildDirError,
    VcsHashUnsupported,
)
from pip._internal.index.package_finder import PackageFinder
from pip._internal.metadata import BaseDistribution
from pip._internal.models.link import Link
from pip._internal.models.wheel import Wheel
from pip._internal.network.download import BatchDownloader, Downloader
from pip._internal.network.lazy_wheel import (
    HTTPRangeRequestUnsupported,
    dist_from_wheel_url,
)
from pip._internal.network.session import PipSession
from pip._internal.req.req_install import InstallRequirement
from pip._internal.req.req_tracker import RequirementTracker
from pip._internal.utils.filesystem import copy2_fixed
from pip._internal.utils.hashes import Hashes, MissingHashes
from pip._internal.utils.logging import indent_log
from pip._internal.utils.misc import display_path, hide_url, is_installable_dir, rmtree
from pip._internal.utils.temp_dir import TempDirectory
from pip._internal.utils.unpacking import unpack_file
from pip._internal.vcs import vcs

logger = logging.getLogger(__name__)


def _get_prepared_distribution(
    req: InstallRequirement,
    req_tracker: RequirementTracker,
    finder: PackageFinder,
    build_isolation: bool,
) -> BaseDistribution:
    """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.get_metadata_distribution()


def unpack_vcs_link(link: Link, location: 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:
    def __init__(self, path: str, content_type: Optional[str]) -> None:
        self.path = path
        if content_type is None:
            self.content_type = mimetypes.guess_type(path)[0]
        else:
            self.content_type = content_type


def get_http_url(
    link: Link,
    download: Downloader,
    download_dir: Optional[str] = None,
    hashes: Optional[Hashes] = None,
) -> 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 = None
    else:
        # let's download to a tmp dir
        from_path, content_type = download(link, temp_dir.path)
        if hashes:
            hashes.check_against_path(from_path)

    return File(from_path, content_type)


def _copy2_ignoring_special_files(src: str, dest: 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),
            src,
            dest,
        )


def _copy_source_tree(source: str, target: str) -> None:
    target_abspath = os.path.abspath(target)
    target_basename = os.path.basename(target_abspath)
    target_dirname = os.path.dirname(target_abspath)

    def ignore(d: str, names: List[str]) -> List[str]:
        skipped: List[str] = []
        if d == source:
            # 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
            skipped += [".tox", ".nox"]
        if os.path.abspath(d) == target_dirname:
            # Prevent an infinite recursion if the target is in source.
            # This can happen when TMPDIR is set to ${PWD}/...
            # and we copy PWD to TMPDIR.
            skipped += [target_basename]
        return skipped

    shutil.copytree(
        source,
        target,
        ignore=ignore,
        symlinks=True,
        copy_function=_copy2_ignoring_special_files,
    )


def get_file_url(
    link: Link, download_dir: Optional[str] = None, hashes: Optional[Hashes] = None
) -> 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)
    return File(from_path, None)


def unpack_url(
    link: Link,
    location: str,
    download: Downloader,
    download_dir: Optional[str] = None,
    hashes: Optional[Hashes] = None,
) -> 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

    # Once out-of-tree-builds are no longer supported, could potentially
    # replace the below condition with `assert not link.is_existing_dir`
    # - unpack_url does not need to be called for in-tree-builds.
    #
    # As further cleanup, _copy_source_tree and accompanying tests can
    # be removed.
    #
    # TODO when use-deprecated=out-of-tree-build is removed
    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,
            download,
            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, except wheels
    if not link.is_wheel:
        unpack_file(file.path, location, file.content_type)

    return file


def _check_download_dir(
    link: Link, download_dir: str, hashes: 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:
    """Prepares a Requirement"""

    def __init__(
        self,
        build_dir: str,
        download_dir: Optional[str],
        src_dir: str,
        build_isolation: bool,
        req_tracker: RequirementTracker,
        session: PipSession,
        progress_bar: str,
        finder: PackageFinder,
        require_hashes: bool,
        use_user_site: bool,
        lazy_wheel: bool,
        in_tree_build: bool,
    ) -> None:
        super().__init__()

        self.src_dir = src_dir
        self.build_dir = build_dir
        self.req_tracker = req_tracker
        self._session = session
        self._download = Downloader(session, progress_bar)
        self._batch_download = BatchDownloader(session, progress_bar)
        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

        # 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

        # Should wheels be downloaded lazily?
        self.use_lazy_wheel = lazy_wheel

        # Should in-tree builds be used for local paths?
        self.in_tree_build = in_tree_build

        # Memoized downloaded files, as mapping of url: path.
        self._downloaded: Dict[str, str] = {}

        # Previous "header" printed for a link-based InstallRequirement
        self._previous_requirement_header = ("", "")

    def _log_preparing_link(self, req: InstallRequirement) -> None:
        """Provide context for the requirement being prepared."""
        if req.link.is_file and not req.original_link_is_in_wheel_cache:
            message = "Processing %s"
            information = str(display_path(req.link.file_path))
        else:
            message = "Collecting %s"
            information = str(req.req or req)

        if (message, information) != self._previous_requirement_header:
            self._previous_requirement_header = (message, information)
            logger.info(message, information)

        if req.original_link_is_in_wheel_cache:
            with indent_log():
                logger.info("Using cached %s", req.link.filename)

    def _ensure_link_req_src_dir(
        self, req: InstallRequirement, parallel_builds: bool
    ) -> None:
        """Ensure source_dir of a linked InstallRequirement."""
        # Since source_dir is only set for editable requirements.
        if req.link.is_wheel:
            # We don't need to unpack wheels, so no need for a source
            # directory.
            return
        assert req.source_dir is None
        if req.link.is_existing_dir() and self.in_tree_build:
            # build local directories in-tree
            req.source_dir = req.link.file_path
            return

        # We always delete unpacked sdists after pip runs.
        req.ensure_has_source_dir(
            self.build_dir,
            autodelete=True,
            parallel_builds=parallel_builds,
        )

        # 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`
        # TODO: this check is now probably dead code
        if is_installable_dir(req.source_dir):
            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)
            )

    def _get_linked_req_hashes(self, req: InstallRequirement) -> Hashes:
        # By the time this is called, the requirement's link should have
        # been checked so we can tell what kind of requirements req is
        # and raise some more informative errors than otherwise.
        # (For example, we can raise VcsHashUnsupported for a VCS URL
        # rather than HashMissing.)
        if not self.require_hashes:
            return req.hashes(trust_internet=True)

        # 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 req.link.is_vcs:
            raise VcsHashUnsupported()
        if req.link.is_existing_dir():
            raise DirectoryUrlHashUnsupported()

        # 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.
        if req.original_link is None and not req.is_pinned:
            raise HashUnpinned()

        # If known-good hashes are missing for this requirement,
        # 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.
        return req.hashes(trust_internet=False) or MissingHashes()

    def _fetch_metadata_using_lazy_wheel(
        self,
        link: Link,
    ) -> Optional[BaseDistribution]:
        """Fetch metadata using lazy wheel, if possible."""
        if not self.use_lazy_wheel:
            return None
        if self.require_hashes:
            logger.debug("Lazy wheel is not used as hash checking is required")
            return None
        if link.is_file or not link.is_wheel:
            logger.debug(
                "Lazy wheel is not used as %r does not points to a remote wheel",
                link,
            )
            return None

        wheel = Wheel(link.filename)
        name = canonicalize_name(wheel.name)
        logger.info(
            "Obtaining dependency information from %s %s",
            name,
            wheel.version,
        )
        url = link.url.split("#", 1)[0]
        try:
            return dist_from_wheel_url(name, url, self._session)
        except HTTPRangeRequestUnsupported:
            logger.debug("%s does not support range requests", url)
            return None

    def _complete_partial_requirements(
        self,
        partially_downloaded_reqs: Iterable[InstallRequirement],
        parallel_builds: bool = False,
    ) -> None:
        """Download any requirements which were only fetched by metadata."""
        # Download to a temporary directory. These will be copied over as
        # needed for downstream 'download', 'wheel', and 'install' commands.
        temp_dir = TempDirectory(kind="unpack", globally_managed=True).path

        # Map each link to the requirement that owns it. This allows us to set
        # `req.local_file_path` on the appropriate requirement after passing
        # all the links at once into BatchDownloader.
        links_to_fully_download: Dict[Link, InstallRequirement] = {}
        for req in partially_downloaded_reqs:
            assert req.link
            links_to_fully_download[req.link] = req

        batch_download = self._batch_download(
            links_to_fully_download.keys(),
            temp_dir,
        )
        for link, (filepath, _) in batch_download:
            logger.debug("Downloading link %s to %s", link, filepath)
            req = links_to_fully_download[link]
            req.local_file_path = filepath

        # This step is necessary to ensure all lazy wheels are processed
        # successfully by the 'download', 'wheel', and 'install' commands.
        for req in partially_downloaded_reqs:
            self._prepare_linked_requirement(req, parallel_builds)

    def prepare_linked_requirement(
        self, req: InstallRequirement, parallel_builds: bool = False
    ) -> BaseDistribution:
        """Prepare a requirement to be obtained from req.link."""
        assert req.link
        link = req.link
        self._log_preparing_link(req)
        with indent_log():
            # Check if the relevant file is already available
            # in the download directory
            file_path = None
            if self.download_dir is not None and link.is_wheel:
                hashes = self._get_linked_req_hashes(req)
                file_path = _check_download_dir(req.link, self.download_dir, hashes)

            if file_path is not None:
                # The file is already available, so mark it as downloaded
                self._downloaded[req.link.url] = file_path
            else:
                # The file is not available, attempt to fetch only metadata
                wheel_dist = self._fetch_metadata_using_lazy_wheel(link)
                if wheel_dist is not None:
                    req.needs_more_preparation = True
                    return wheel_dist

            # None of the optimizations worked, fully prepare the requirement
            return self._prepare_linked_requirement(req, parallel_builds)

    def prepare_linked_requirements_more(
        self, reqs: Iterable[InstallRequirement], parallel_builds: bool = False
    ) -> None:
        """Prepare linked requirements more, if needed."""
        reqs = [req for req in reqs if req.needs_more_preparation]
        for req in reqs:
            # Determine if any of these requirements were already downloaded.
            if self.download_dir is not None and req.link.is_wheel:
                hashes = self._get_linked_req_hashes(req)
                file_path = _check_download_dir(req.link, self.download_dir, hashes)
                if file_path is not None:
                    self._downloaded[req.link.url] = file_path
                    req.needs_more_preparation = False

        # Prepare requirements we found were already downloaded for some
        # reason. The other downloads will be completed separately.
        partially_downloaded_reqs: List[InstallRequirement] = []
        for req in reqs:
            if req.needs_more_preparation:
                partially_downloaded_reqs.append(req)
            else:
                self._prepare_linked_requirement(req, parallel_builds)

        # TODO: separate this part out from RequirementPreparer when the v1
        # resolver can be removed!
        self._complete_partial_requirements(
            partially_downloaded_reqs,
            parallel_builds=parallel_builds,
        )

    def _prepare_linked_requirement(
        self, req: InstallRequirement, parallel_builds: bool
    ) -> BaseDistribution:
        assert req.link
        link = req.link

        self._ensure_link_req_src_dir(req, parallel_builds)
        hashes = self._get_linked_req_hashes(req)

        if link.is_existing_dir() and self.in_tree_build:
            local_file = None
        elif link.url not in self._downloaded:
            try:
                local_file = unpack_url(
                    link, req.source_dir, self._download, self.download_dir, hashes
                )
            except NetworkConnectionError as exc:
                raise InstallationError(
                    "Could not install requirement {} because of HTTP "
                    "error {} for URL {}".format(req, exc, link)
                )
        else:
            file_path = self._downloaded[link.url]
            if hashes:
                hashes.check_against_path(file_path)
            local_file = File(file_path, content_type=None)

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

        dist = _get_prepared_distribution(
            req,
            self.req_tracker,
            self.finder,
            self.build_isolation,
        )
        return dist

    def save_linked_requirement(self, req: InstallRequirement) -> None:
        assert self.download_dir is not None
        assert req.link is not None
        link = req.link
        if link.is_vcs or (link.is_existing_dir() and req.editable):
            # Make a .zip of the source_dir we already created.
            req.archive(self.download_dir)
            return

        if link.is_existing_dir():
            logger.debug(
                "Not copying link to destination directory "
                "since it is a directory: %s",
                link,
            )
            return
        if req.local_file_path is None:
            # No distribution was downloaded for this requirement.
            return

        download_location = os.path.join(self.download_dir, link.filename)
        if not os.path.exists(download_location):
            shutil.copy(req.local_file_path, download_location)
            download_path = display_path(download_location)
            logger.info("Saved %s", download_path)

    def prepare_editable_requirement(
        self,
        req: InstallRequirement,
    ) -> BaseDistribution:
        """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()

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

            req.check_if_exists(self.use_user_site)

        return dist

    def prepare_installed_requirement(
        self,
        req: InstallRequirement,
        skip_reason: str,
    ) -> BaseDistribution:
        """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."
                )
            return InstalledDistribution(req).get_metadata_distribution()