"""
A module that implements tooling to enable easy warnings about deprecations.
"""

import logging
import warnings
from typing import Any, Optional, TextIO, Type, Union

from pip._vendor.packaging.version import parse

from pip import __version__ as current_version  # NOTE: tests patch this name.

DEPRECATION_MSG_PREFIX = "DEPRECATION: "


class PipDeprecationWarning(Warning):
    pass


_original_showwarning: Any = None


# Warnings <-> Logging Integration
def _showwarning(
    message: Union[Warning, str],
    category: Type[Warning],
    filename: str,
    lineno: int,
    file: Optional[TextIO] = None,
    line: Optional[str] = None,
) -> None:
    if file is not None:
        if _original_showwarning is not None:
            _original_showwarning(message, category, filename, lineno, file, line)
    elif issubclass(category, PipDeprecationWarning):
        # We use a specially named logger which will handle all of the
        # deprecation messages for pip.
        logger = logging.getLogger("pip._internal.deprecations")
        logger.warning(message)
    else:
        _original_showwarning(message, category, filename, lineno, file, line)


def install_warning_logger() -> None:
    # Enable our Deprecation Warnings
    warnings.simplefilter("default", PipDeprecationWarning, append=True)

    global _original_showwarning

    if _original_showwarning is None:
        _original_showwarning = warnings.showwarning
        warnings.showwarning = _showwarning


def deprecated(
    *,
    reason: str,
    replacement: Optional[str],
    gone_in: Optional[str],
    feature_flag: Optional[str] = None,
    issue: Optional[int] = None,
) -> None:
    """Helper to deprecate existing functionality.

    reason:
        Textual reason shown to the user about why this functionality has
        been deprecated. Should be a complete sentence.
    replacement:
        Textual suggestion shown to the user about what alternative
        functionality they can use.
    gone_in:
        The version of pip does this functionality should get removed in.
        Raises an error if pip's current version is greater than or equal to
        this.
    feature_flag:
        Command-line flag of the form --use-feature={feature_flag} for testing
        upcoming functionality.
    issue:
        Issue number on the tracker that would serve as a useful place for
        users to find related discussion and provide feedback.
    """

    # Determine whether or not the feature is already gone in this version.
    is_gone = gone_in is not None and parse(current_version) >= parse(gone_in)

    message_parts = [
        (reason, f"{DEPRECATION_MSG_PREFIX}{{}}"),
        (
            gone_in,
            (
                "pip {} will enforce this behaviour change."
                if not is_gone
                else "Since pip {}, this is no longer supported."
            ),
        ),
        (
            replacement,
            "A possible replacement is {}.",
        ),
        (
            feature_flag,
            (
                "You can use the flag --use-feature={} to test the upcoming behaviour."
                if not is_gone
                else None
            ),
        ),
        (
            issue,
            "Discussion can be found at https://github.com/pypa/pip/issues/{}",
        ),
    ]

    message = " ".join(
        format_str.format(value)
        for value, format_str in message_parts
        if format_str is not None and value is not None
    )

    # Raise as an error if this behaviour is deprecated.
    if is_gone:
        raise PipDeprecationWarning(message)

    warnings.warn(message, category=PipDeprecationWarning, stacklevel=2)

"""
Package containing all pip commands
"""

import importlib
from collections import namedtuple
from typing import Any, Dict, Optional

from pip._internal.cli.base_command import Command

CommandInfo = namedtuple("CommandInfo", "module_path, class_name, summary")

# This dictionary does a bunch of heavy lifting for help output:
# - Enables avoiding additional (costly) imports for presenting `--help`.
# - The ordering matters for help display.
#
# Even though the module path starts with the same "pip._internal.commands"
# prefix, the full path makes testing easier (specifically when modifying
# `commands_dict` in test setup / teardown).
commands_dict: Dict[str, CommandInfo] = {
    "install": CommandInfo(
        "pip._internal.commands.install",
        "InstallCommand",
        "Install packages.",
    ),
    "download": CommandInfo(
        "pip._internal.commands.download",
        "DownloadCommand",
        "Download packages.",
    ),
    "uninstall": CommandInfo(
        "pip._internal.commands.uninstall",
        "UninstallCommand",
        "Uninstall packages.",
    ),
    "freeze": CommandInfo(
        "pip._internal.commands.freeze",
        "FreezeCommand",
        "Output installed packages in requirements format.",
    ),
    "inspect": CommandInfo(
        "pip._internal.commands.inspect",
        "InspectCommand",
        "Inspect the python environment.",
    ),
    "list": CommandInfo(
        "pip._internal.commands.list",
        "ListCommand",
        "List installed packages.",
    ),
    "show": CommandInfo(
        "pip._internal.commands.show",
        "ShowCommand",
        "Show information about installed packages.",
    ),
    "check": CommandInfo(
        "pip._internal.commands.check",
        "CheckCommand",
        "Verify installed packages have compatible dependencies.",
    ),
    "config": CommandInfo(
        "pip._internal.commands.configuration",
        "ConfigurationCommand",
        "Manage local and global configuration.",
    ),
    "search": CommandInfo(
        "pip._internal.commands.search",
        "SearchCommand",
        "Search PyPI for packages.",
    ),
    "cache": CommandInfo(
        "pip._internal.commands.cache",
        "CacheCommand",
        "Inspect and manage pip's wheel cache.",
    ),
    "index": CommandInfo(
        "pip._internal.commands.index",
        "IndexCommand",
        "Inspect information available from package indexes.",
    ),
    "wheel": CommandInfo(
        "pip._internal.commands.wheel",
        "WheelCommand",
        "Build wheels from your requirements.",
    ),
    "hash": CommandInfo(
        "pip._internal.commands.hash",
        "HashCommand",
        "Compute hashes of package archives.",
    ),
    "completion": CommandInfo(
        "pip._internal.commands.completion",
        "CompletionCommand",
        "A helper command used for command completion.",
    ),
    "debug": CommandInfo(
        "pip._internal.commands.debug",
        "DebugCommand",
        "Show information useful for debugging.",
    ),
    "help": CommandInfo(
        "pip._internal.commands.help",
        "HelpCommand",
        "Show help for commands.",
    ),
}


def create_command(name: str, **kwargs: Any) -> Command:
    """
    Create an instance of the Command class with the given name.
    """
    module_path, class_name, summary = commands_dict[name]
    module = importlib.import_module(module_path)
    command_class = getattr(module, class_name)
    command = command_class(name=name, summary=summary, **kwargs)

    return command


def get_similar_commands(name: str) -> Optional[str]:
    """Command name auto-correct."""
    from difflib import get_close_matches

    name = name.lower()

    close_commands = get_close_matches(name, commands_dict.keys())

    if close_commands:
        return close_commands[0]
    else:
        return None

"""
For types associated with installation schemes.

For a general overview of available schemes and their context, see
https://docs.python.org/3/install/index.html#alternate-installation.
"""

from dataclasses import dataclass

SCHEME_KEYS = ["platlib", "purelib", "headers", "scripts", "data"]


@dataclass(frozen=True)
class Scheme:
    """A Scheme holds paths which are used as the base directories for
    artifacts associated with a Python package.
    """

    __slots__ = SCHEME_KEYS

    platlib: str
    purelib: str
    headers: str
    scripts: str
    data: str