import functools
import os
import sys
import sysconfig
from importlib.util import cache_from_source
from typing import Any, Callable, Dict, Generator, Iterable, List, Optional, Set, Tuple

from pip._internal.exceptions import UninstallationError
from pip._internal.locations import get_bin_prefix, get_bin_user
from pip._internal.metadata import BaseDistribution
from pip._internal.utils.compat import WINDOWS
from pip._internal.utils.egg_link import egg_link_path_from_location
from pip._internal.utils.logging import getLogger, indent_log
from pip._internal.utils.misc import ask, normalize_path, renames, rmtree
from pip._internal.utils.temp_dir import AdjacentTempDirectory, TempDirectory
from pip._internal.utils.virtualenv import running_under_virtualenv

logger = getLogger(__name__)


def _script_names(
    bin_dir: str, script_name: str, is_gui: bool
) -> Generator[str, None, None]:
    """Create the fully qualified name of the files created by
    {console,gui}_scripts for the given ``dist``.
    Returns the list of file names
    """
    exe_name = os.path.join(bin_dir, script_name)
    yield exe_name
    if not WINDOWS:
        return
    yield f"{exe_name}.exe"
    yield f"{exe_name}.exe.manifest"
    if is_gui:
        yield f"{exe_name}-script.pyw"
    else:
        yield f"{exe_name}-script.py"


def _unique(
    fn: Callable[..., Generator[Any, None, None]]
) -> Callable[..., Generator[Any, None, None]]:
    @functools.wraps(fn)
    def unique(*args: Any, **kw: Any) -> Generator[Any, None, None]:
        seen: Set[Any] = set()
        for item in fn(*args, **kw):
            if item not in seen:
                seen.add(item)
                yield item

    return unique


@_unique
def uninstallation_paths(dist: BaseDistribution) -> Generator[str, None, None]:
    """
    Yield all the uninstallation paths for dist based on RECORD-without-.py[co]

    Yield paths to all the files in RECORD. For each .py file in RECORD, add
    the .pyc and .pyo in the same directory.

    UninstallPathSet.add() takes care of the __pycache__ .py[co].

    If RECORD is not found, raises UninstallationError,
    with possible information from the INSTALLER file.

    https://packaging.python.org/specifications/recording-installed-packages/
    """
    location = dist.location
    assert location is not None, "not installed"

    entries = dist.iter_declared_entries()
    if entries is None:
        msg = f"Cannot uninstall {dist}, RECORD file not found."
        installer = dist.installer
        if not installer or installer == "pip":
            dep = f"{dist.raw_name}=={dist.version}"
            msg += (
                " You might be able to recover from this via: "
                f"'pip install --force-reinstall --no-deps {dep}'."
            )
        else:
            msg += f" Hint: The package was installed by {installer}."
        raise UninstallationError(msg)

    for entry in entries:
        path = os.path.join(location, entry)
        yield path
        if path.endswith(".py"):
            dn, fn = os.path.split(path)
            base = fn[:-3]
            path = os.path.join(dn, base + ".pyc")
            yield path
            path = os.path.join(dn, base + ".pyo")
            yield path


def compact(paths: Iterable[str]) -> Set[str]:
    """Compact a path set to contain the minimal number of paths
    necessary to contain all paths in the set. If /a/path/ and
    /a/path/to/a/file.txt are both in the set, leave only the
    shorter path."""

    sep = os.path.sep
    short_paths: Set[str] = set()
    for path in sorted(paths, key=len):
        should_skip = any(
            path.startswith(shortpath.rstrip("*"))
            and path[len(shortpath.rstrip("*").rstrip(sep))] == sep
            for shortpath in short_paths
        )
        if not should_skip:
            short_paths.add(path)
    return short_paths


def compress_for_rename(paths: Iterable[str]) -> Set[str]:
    """Returns a set containing the paths that need to be renamed.

    This set may include directories when the original sequence of paths
    included every file on disk.
    """
    case_map = {os.path.normcase(p): p for p in paths}
    remaining = set(case_map)
    unchecked = sorted({os.path.split(p)[0] for p in case_map.values()}, key=len)
    wildcards: Set[str] = set()

    def norm_join(*a: str) -> str:
        return os.path.normcase(os.path.join(*a))

    for root in unchecked:
        if any(os.path.normcase(root).startswith(w) for w in wildcards):
            # This directory has already been handled.
            continue

        all_files: Set[str] = set()
        all_subdirs: Set[str] = set()
        for dirname, subdirs, files in os.walk(root):
            all_subdirs.update(norm_join(root, dirname, d) for d in subdirs)
            all_files.update(norm_join(root, dirname, f) for f in files)
        # If all the files we found are in our remaining set of files to
        # remove, then remove them from the latter set and add a wildcard
        # for the directory.
        if not (all_files - remaining):
            remaining.difference_update(all_files)
            wildcards.add(root + os.sep)

    return set(map(case_map.__getitem__, remaining)) | wildcards


def compress_for_output_listing(paths: Iterable[str]) -> Tuple[Set[str], Set[str]]:
    """Returns a tuple of 2 sets of which paths to display to user

    The first set contains paths that would be deleted. Files of a package
    are not added and the top-level directory of the package has a '*' added
    at the end - to signify that all it's contents are removed.

    The second set contains files that would have been skipped in the above
    folders.
    """

    will_remove = set(paths)
    will_skip = set()

    # Determine folders and files
    folders = set()
    files = set()
    for path in will_remove:
        if path.endswith(".pyc"):
            continue
        if path.endswith("__init__.py") or ".dist-info" in path:
            folders.add(os.path.dirname(path))
        files.add(path)

    _normcased_files = set(map(os.path.normcase, files))

    folders = compact(folders)

    # This walks the tree using os.walk to not miss extra folders
    # that might get added.
    for folder in folders:
        for dirpath, _, dirfiles in os.walk(folder):
            for fname in dirfiles:
                if fname.endswith(".pyc"):
                    continue

                file_ = os.path.join(dirpath, fname)
                if (
                    os.path.isfile(file_)
                    and os.path.normcase(file_) not in _normcased_files
                ):
                    # We are skipping this file. Add it to the set.
                    will_skip.add(file_)

    will_remove = files | {os.path.join(folder, "*") for folder in folders}

    return will_remove, will_skip


class StashedUninstallPathSet:
    """A set of file rename operations to stash files while
    tentatively uninstalling them."""

    def __init__(self) -> None:
        # Mapping from source file root to [Adjacent]TempDirectory
        # for files under that directory.
        self._save_dirs: Dict[str, TempDirectory] = {}
        # (old path, new path) tuples for each move that may need
        # to be undone.
        self._moves: List[Tuple[str, str]] = []

    def _get_directory_stash(self, path: str) -> str:
        """Stashes a directory.

        Directories are stashed adjacent to their original location if
        possible, or else moved/copied into the user's temp dir."""

        try:
            save_dir: TempDirectory = AdjacentTempDirectory(path)
        except OSError:
            save_dir = TempDirectory(kind="uninstall")
        self._save_dirs[os.path.normcase(path)] = save_dir

        return save_dir.path

    def _get_file_stash(self, path: str) -> str:
        """Stashes a file.

        If no root has been provided, one will be created for the directory
        in the user's temp directory."""
        path = os.path.normcase(path)
        head, old_head = os.path.dirname(path), None
        save_dir = None

        while head != old_head:
            try:
                save_dir = self._save_dirs[head]
                break
            except KeyError:
                pass
            head, old_head = os.path.dirname(head), head
        else:
            # Did not find any suitable root
            head = os.path.dirname(path)
            save_dir = TempDirectory(kind="uninstall")
            self._save_dirs[head] = save_dir

        relpath = os.path.relpath(path, head)
        if relpath and relpath != os.path.curdir:
            return os.path.join(save_dir.path, relpath)
        return save_dir.path

    def stash(self, path: str) -> str:
        """Stashes the directory or file and returns its new location.
        Handle symlinks as files to avoid modifying the symlink targets.
        """
        path_is_dir = os.path.isdir(path) and not os.path.islink(path)
        if path_is_dir:
            new_path = self._get_directory_stash(path)
        else:
            new_path = self._get_file_stash(path)

        self._moves.append((path, new_path))
        if path_is_dir and os.path.isdir(new_path):
            # If we're moving a directory, we need to
            # remove the destination first or else it will be
            # moved to inside the existing directory.
            # We just created new_path ourselves, so it will
            # be removable.
            os.rmdir(new_path)
        renames(path, new_path)
        return new_path

    def commit(self) -> None:
        """Commits the uninstall by removing stashed files."""
        for save_dir in self._save_dirs.values():
            save_dir.cleanup()
        self._moves = []
        self._save_dirs = {}

    def rollback(self) -> None:
        """Undoes the uninstall by moving stashed files back."""
        for p in self._moves:
            logger.info("Moving to %s\n from %s", *p)

        for new_path, path in self._moves:
            try:
                logger.debug("Replacing %s from %s", new_path, path)
                if os.path.isfile(new_path) or os.path.islink(new_path):
                    os.unlink(new_path)
                elif os.path.isdir(new_path):
                    rmtree(new_path)
                renames(path, new_path)
            except OSError as ex:
                logger.error("Failed to restore %s", new_path)
                logger.debug("Exception: %s", ex)

        self.commit()

    @property
    def can_rollback(self) -> bool:
        return bool(self._moves)


class UninstallPathSet:
    """A set of file paths to be removed in the uninstallation of a
    requirement."""

    def __init__(self, dist: BaseDistribution) -> None:
        self._paths: Set[str] = set()
        self._refuse: Set[str] = set()
        self._pth: Dict[str, UninstallPthEntries] = {}
        self._dist = dist
        self._moved_paths = StashedUninstallPathSet()
        # Create local cache of normalize_path results. Creating an UninstallPathSet
        # can result in hundreds/thousands of redundant calls to normalize_path with
        # the same args, which hurts performance.
        self._normalize_path_cached = functools.lru_cache()(normalize_path)

    def _permitted(self, path: str) -> bool:
        """
        Return True if the given path is one we are permitted to
        remove/modify, False otherwise.

        """
        # aka is_local, but caching normalized sys.prefix
        if not running_under_virtualenv():
            return True
        return path.startswith(self._normalize_path_cached(sys.prefix))

    def add(self, path: str) -> None:
        head, tail = os.path.split(path)

        # we normalize the head to resolve parent directory symlinks, but not
        # the tail, since we only want to uninstall symlinks, not their targets
        path = os.path.join(self._normalize_path_cached(head), os.path.normcase(tail))

        if not os.path.exists(path):
            return
        if self._permitted(path):
            self._paths.add(path)
        else:
            self._refuse.add(path)

        # __pycache__ files can show up after 'installed-files.txt' is created,
        # due to imports
        if os.path.splitext(path)[1] == ".py":
            self.add(cache_from_source(path))

    def add_pth(self, pth_file: str, entry: str) -> None:
        pth_file = self._normalize_path_cached(pth_file)
        if self._permitted(pth_file):
            if pth_file not in self._pth:
                self._pth[pth_file] = UninstallPthEntries(pth_file)
            self._pth[pth_file].add(entry)
        else:
            self._refuse.add(pth_file)

    def remove(self, auto_confirm: bool = False, verbose: bool = False) -> None:
        """Remove paths in ``self._paths`` with confirmation (unless
        ``auto_confirm`` is True)."""

        if not self._paths:
            logger.info(
                "Can't uninstall '%s'. No files were found to uninstall.",
                self._dist.raw_name,
            )
            return

        dist_name_version = f"{self._dist.raw_name}-{self._dist.version}"
        logger.info("Uninstalling %s:", dist_name_version)

        with indent_log():
            if auto_confirm or self._allowed_to_proceed(verbose):
                moved = self._moved_paths

                for_rename = compress_for_rename(self._paths)

                for path in sorted(compact(for_rename)):
                    moved.stash(path)
                    logger.verbose("Removing file or directory %s", path)

                for pth in self._pth.values():
                    pth.remove()

                logger.info("Successfully uninstalled %s", dist_name_version)

    def _allowed_to_proceed(self, verbose: bool) -> bool:
        """Display which files would be deleted and prompt for confirmation"""

        def _display(msg: str, paths: Iterable[str]) -> None:
            if not paths:
                return

            logger.info(msg)
            with indent_log():
                for path in sorted(compact(paths)):
                    logger.info(path)

        if not verbose:
            will_remove, will_skip = compress_for_output_listing(self._paths)
        else:
            # In verbose mode, display all the files that are going to be
            # deleted.
            will_remove = set(self._paths)
            will_skip = set()

        _display("Would remove:", will_remove)
        _display("Would not remove (might be manually added):", will_skip)
        _display("Would not remove (outside of prefix):", self._refuse)
        if verbose:
            _display("Will actually move:", compress_for_rename(self._paths))

        return ask("Proceed (Y/n)? ", ("y", "n", "")) != "n"

    def rollback(self) -> None:
        """Rollback the changes previously made by remove()."""
        if not self._moved_paths.can_rollback:
            logger.error(
                "Can't roll back %s; was not uninstalled",
                self._dist.raw_name,
            )
            return
        logger.info("Rolling back uninstall of %s", self._dist.raw_name)
        self._moved_paths.rollback()
        for pth in self._pth.values():
            pth.rollback()

    def commit(self) -> None:
        """Remove temporary save dir: rollback will no longer be possible."""
        self._moved_paths.commit()

    @classmethod
    def from_dist(cls, dist: BaseDistribution) -> "UninstallPathSet":
        dist_location = dist.location
        info_location = dist.info_location
        if dist_location is None:
            logger.info(
                "Not uninstalling %s since it is not installed",
                dist.canonical_name,
            )
            return cls(dist)

        normalized_dist_location = normalize_path(dist_location)
        if not dist.local:
            logger.info(
                "Not uninstalling %s at %s, outside environment %s",
                dist.canonical_name,
                normalized_dist_location,
                sys.prefix,
            )
            return cls(dist)

        if normalized_dist_location in {
            p
            for p in {sysconfig.get_path("stdlib"), sysconfig.get_path("platstdlib")}
            if p
        }:
            logger.info(
                "Not uninstalling %s at %s, as it is in the standard library.",
                dist.canonical_name,
                normalized_dist_location,
            )
            return cls(dist)

        paths_to_remove = cls(dist)
        develop_egg_link = egg_link_path_from_location(dist.raw_name)

        # Distribution is installed with metadata in a "flat" .egg-info
        # directory. This means it is not a modern .dist-info installation, an
        # egg, or legacy editable.
        setuptools_flat_installation = (
            dist.installed_with_setuptools_egg_info
            and info_location is not None
            and os.path.exists(info_location)
            # If dist is editable and the location points to a ``.egg-info``,
            # we are in fact in the legacy editable case.
            and not info_location.endswith(f"{dist.setuptools_filename}.egg-info")
        )

        # Uninstall cases order do matter as in the case of 2 installs of the
        # same package, pip needs to uninstall the currently detected version
        if setuptools_flat_installation:
            if info_location is not None:
                paths_to_remove.add(info_location)
            installed_files = dist.iter_declared_entries()
            if installed_files is not None:
                for installed_file in installed_files:
                    paths_to_remove.add(os.path.join(dist_location, installed_file))
            # FIXME: need a test for this elif block
            # occurs with --single-version-externally-managed/--record outside
            # of pip
            elif dist.is_file("top_level.txt"):
                try:
                    namespace_packages = dist.read_text("namespace_packages.txt")
                except FileNotFoundError:
                    namespaces = []
                else:
                    namespaces = namespace_packages.splitlines(keepends=False)
                for top_level_pkg in [
                    p
                    for p in dist.read_text("top_level.txt").splitlines()
                    if p and p not in namespaces
                ]:
                    path = os.path.join(dist_location, top_level_pkg)
                    paths_to_remove.add(path)
                    paths_to_remove.add(f"{path}.py")
                    paths_to_remove.add(f"{path}.pyc")
                    paths_to_remove.add(f"{path}.pyo")

        elif dist.installed_by_distutils:
            raise UninstallationError(
                "Cannot uninstall {!r}. It is a distutils installed project "
                "and thus we cannot accurately determine which files belong "
                "to it which would lead to only a partial uninstall.".format(
                    dist.raw_name,
                )
            )

        elif dist.installed_as_egg:
            # package installed by easy_install
            # We cannot match on dist.egg_name because it can slightly vary
            # i.e. setuptools-0.6c11-py2.6.egg vs setuptools-0.6rc11-py2.6.egg
            paths_to_remove.add(dist_location)
            easy_install_egg = os.path.split(dist_location)[1]
            easy_install_pth = os.path.join(
                os.path.dirname(dist_location),
                "easy-install.pth",
            )
            paths_to_remove.add_pth(easy_install_pth, "./" + easy_install_egg)

        elif dist.installed_with_dist_info:
            for path in uninstallation_paths(dist):
                paths_to_remove.add(path)

        elif develop_egg_link:
            # PEP 660 modern editable is handled in the ``.dist-info`` case
            # above, so this only covers the setuptools-style editable.
            with open(develop_egg_link) as fh:
                link_pointer = os.path.normcase(fh.readline().strip())
                normalized_link_pointer = paths_to_remove._normalize_path_cached(
                    link_pointer
                )
            assert os.path.samefile(
                normalized_link_pointer, normalized_dist_location
            ), (
                f"Egg-link {develop_egg_link} (to {link_pointer}) does not match "
                f"installed location of {dist.raw_name} (at {dist_location})"
            )
            paths_to_remove.add(develop_egg_link)
            easy_install_pth = os.path.join(
                os.path.dirname(develop_egg_link), "easy-install.pth"
            )
            paths_to_remove.add_pth(easy_install_pth, dist_location)

        else:
            logger.debug(
                "Not sure how to uninstall: %s - Check: %s",
                dist,
                dist_location,
            )

        if dist.in_usersite:
            bin_dir = get_bin_user()
        else:
            bin_dir = get_bin_prefix()

        # find distutils scripts= scripts
        try:
            for script in dist.iter_distutils_script_names():
                paths_to_remove.add(os.path.join(bin_dir, script))
                if WINDOWS:
                    paths_to_remove.add(os.path.join(bin_dir, f"{script}.bat"))
        except (FileNotFoundError, NotADirectoryError):
            pass

        # find console_scripts and gui_scripts
        def iter_scripts_to_remove(
            dist: BaseDistribution,
            bin_dir: str,
        ) -> Generator[str, None, None]:
            for entry_point in dist.iter_entry_points():
                if entry_point.group == "console_scripts":
                    yield from _script_names(bin_dir, entry_point.name, False)
                elif entry_point.group == "gui_scripts":
                    yield from _script_names(bin_dir, entry_point.name, True)

        for s in iter_scripts_to_remove(dist, bin_dir):
            paths_to_remove.add(s)

        return paths_to_remove


class UninstallPthEntries:
    def __init__(self, pth_file: str) -> None:
        self.file = pth_file
        self.entries: Set[str] = set()
        self._saved_lines: Optional[List[bytes]] = None

    def add(self, entry: str) -> None:
        entry = os.path.normcase(entry)
        # On Windows, os.path.normcase converts the entry to use
        # backslashes.  This is correct for entries that describe absolute
        # paths outside of site-packages, but all the others use forward
        # slashes.
        # os.path.splitdrive is used instead of os.path.isabs because isabs
        # treats non-absolute paths with drive letter markings like c:foo\bar
        # as absolute paths. It also does not recognize UNC paths if they don't
        # have more than "\\sever\share". Valid examples: "\\server\share\" or
        # "\\server\share\folder".
        if WINDOWS and not os.path.splitdrive(entry)[0]:
            entry = entry.replace("\\", "/")
        self.entries.add(entry)

    def remove(self) -> None:
        logger.verbose("Removing pth entries from %s:", self.file)

        # If the file doesn't exist, log a warning and return
        if not os.path.isfile(self.file):
            logger.warning("Cannot remove entries from nonexistent file %s", self.file)
            return
        with open(self.file, "rb") as fh:
            # windows uses '\r\n' with py3k, but uses '\n' with py2.x
            lines = fh.readlines()
            self._saved_lines = lines
        if any(b"\r\n" in line for line in lines):
            endline = "\r\n"
        else:
            endline = "\n"
        # handle missing trailing newline
        if lines and not lines[-1].endswith(endline.encode("utf-8")):
            lines[-1] = lines[-1] + endline.encode("utf-8")
        for entry in self.entries:
            try:
                logger.verbose("Removing entry: %s", entry)
                lines.remove((entry + endline).encode("utf-8"))
            except ValueError:
                pass
        with open(self.file, "wb") as fh:
            fh.writelines(lines)

    def rollback(self) -> bool:
        if self._saved_lines is None:
            logger.error("Cannot roll back changes to %s, none were made", self.file)
            return False
        logger.debug("Rolling %s back to previous state", self.file)
        with open(self.file, "wb") as fh:
            fh.writelines(self._saved_lines)
        return True
