import csv
import logging
import pathlib
from optparse import Values
from typing import Iterator, List, NamedTuple, Optional, Tuple

from pip._vendor.packaging.utils import canonicalize_name

from pip._internal.cli.base_command import Command
from pip._internal.cli.status_codes import ERROR, SUCCESS
from pip._internal.metadata import BaseDistribution, get_default_environment
from pip._internal.utils.misc import write_output

logger = logging.getLogger(__name__)


class ShowCommand(Command):
    """
    Show information about one or more installed packages.

    The output is in RFC-compliant mail header format.
    """

    usage = """
      %prog [options] <package> ..."""
    ignore_require_venv = True

    def add_options(self) -> None:
        self.cmd_opts.add_option(
            '-f', '--files',
            dest='files',
            action='store_true',
            default=False,
            help='Show the full list of installed files for each package.')

        self.parser.insert_option_group(0, self.cmd_opts)

    def run(self, options: Values, args: List[str]) -> int:
        if not args:
            logger.warning('ERROR: Please provide a package name or names.')
            return ERROR
        query = args

        results = search_packages_info(query)
        if not print_results(
                results, list_files=options.files, verbose=options.verbose):
            return ERROR
        return SUCCESS


class _PackageInfo(NamedTuple):
    name: str
    version: str
    location: str
    requires: List[str]
    required_by: List[str]
    installer: str
    metadata_version: str
    classifiers: List[str]
    summary: str
    homepage: str
    author: str
    author_email: str
    license: str
    entry_points: List[str]
    files: Optional[List[str]]


def _covert_legacy_entry(entry: Tuple[str, ...], info: Tuple[str, ...]) -> str:
    """Convert a legacy installed-files.txt path into modern RECORD path.

    The legacy format stores paths relative to the info directory, while the
    modern format stores paths relative to the package root, e.g. the
    site-packages directory.

    :param entry: Path parts of the installed-files.txt entry.
    :param info: Path parts of the egg-info directory relative to package root.
    :returns: The converted entry.

    For best compatibility with symlinks, this does not use ``abspath()`` or
    ``Path.resolve()``, but tries to work with path parts:

    1. While ``entry`` starts with ``..``, remove the equal amounts of parts
       from ``info``; if ``info`` is empty, start appending ``..`` instead.
    2. Join the two directly.
    """
    while entry and entry[0] == "..":
        if not info or info[-1] == "..":
            info += ("..",)
        else:
            info = info[:-1]
        entry = entry[1:]
    return str(pathlib.Path(*info, *entry))


def search_packages_info(query: List[str]) -> Iterator[_PackageInfo]: