import shutil
import sys
from enum import Enum
from io import StringIO
from itertools import chain
from pathlib import Path
from typing import Iterator, Optional, Set, TextIO, Union, cast
from warnings import warn

from isort import core

from . import files, identify, io
from .exceptions import (
    ExistingSyntaxErrors,
    FileSkipComment,
    FileSkipSetting,
    IntroducedSyntaxErrors,
)
from .format import ask_whether_to_apply_changes_to_file, create_terminal_printer, show_unified_diff
from .io import Empty
from .place import module as place_module  # noqa: F401
from .place import module_with_reason as place_module_with_reason  # noqa: F401
from .settings import DEFAULT_CONFIG, Config


class ImportKey(Enum):
    """Defines how to key an individual import, generally for deduping.

    Import keys are defined from less to more specific:

    from x.y import z as a
    ______| |        |    |
       |    |        |    |
    PACKAGE |        |    |
    ________|        |    |
          |          |    |
        MODULE       |    |
    _________________|    |
              |           |
           ATTRIBUTE      |
    ______________________|
                  |
                ALIAS
    """

    PACKAGE = 1
    MODULE = 2
    ATTRIBUTE = 3
    ALIAS = 4


def sort_code_string(
    code: str,
    extension: Optional[str] = None,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    disregard_skip: bool = False,
    show_diff: Union[bool, TextIO] = False,
    **config_kwargs,
):
    """Sorts any imports within the provided code string, returning a new string with them sorted.

    - **code**: The string of code with imports that need to be sorted.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **disregard_skip**: set to `True` if you want to ignore a skip set in config for this file.
    - **show_diff**: If `True` the changes that need to be done will be printed to stdout, if a
    TextIO stream is provided results will be written to it, otherwise no diff will be computed.
    - ****config_kwargs**: Any config modifications.
    """
    input_stream = StringIO(code)
    output_stream = StringIO()
    config = _config(path=file_path, config=config, **config_kwargs)
    sort_stream(
        input_stream,
        output_stream,
        extension=extension,
        config=config,
        file_path=file_path,
        disregard_skip=disregard_skip,
        show_diff=show_diff,
    )
    output_stream.seek(0)
    return output_stream.read()


def check_code_string(
    code: str,
    show_diff: Union[bool, TextIO] = False,
    extension: Optional[str] = None,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    disregard_skip: bool = False,
    **config_kwargs,
) -> bool:
    """Checks the order, format, and categorization of imports within the provided code string.
    Returns `True` if everything is correct, otherwise `False`.

    - **code**: The string of code with imports that need to be sorted.
    - **show_diff**: If `True` the changes that need to be done will be printed to stdout, if a
    TextIO stream is provided results will be written to it, otherwise no diff will be computed.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **disregard_skip**: set to `True` if you want to ignore a skip set in config for this file.
    - ****config_kwargs**: Any config modifications.
    """
    config = _config(path=file_path, config=config, **config_kwargs)
    return check_stream(
        StringIO(code),
        show_diff=show_diff,
        extension=extension,
        config=config,
        file_path=file_path,
        disregard_skip=disregard_skip,
    )


def sort_stream(
    input_stream: TextIO,
    output_stream: TextIO,
    extension: Optional[str] = None,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    disregard_skip: bool = False,
    show_diff: Union[bool, TextIO] = False,
    **config_kwargs,
) -> bool:
    """Sorts any imports within the provided code stream, outputs to the provided output stream.
     Returns `True` if anything is modified from the original input stream, otherwise `False`.

    - **input_stream**: The stream of code with imports that need to be sorted.
    - **output_stream**: The stream where sorted imports should be written to.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **disregard_skip**: set to `True` if you want to ignore a skip set in config for this file.
    - **show_diff**: If `True` the changes that need to be done will be printed to stdout, if a
    TextIO stream is provided results will be written to it, otherwise no diff will be computed.
    - ****config_kwargs**: Any config modifications.
    """
    if show_diff:
        _output_stream = StringIO()
        _input_stream = StringIO(input_stream.read())
        changed = sort_stream(
            input_stream=_input_stream,
            output_stream=_output_stream,
            extension=extension,
            config=config,
            file_path=file_path,
            disregard_skip=disregard_skip,
            **config_kwargs,
        )
        _output_stream.seek(0)
        _input_stream.seek(0)
        show_unified_diff(
            file_input=_input_stream.read(),
            file_output=_output_stream.read(),
            file_path=file_path,
            output=output_stream if show_diff is True else cast(TextIO, show_diff),
            color_output=config.color_output,
        )
        return changed

    config = _config(path=file_path, config=config, **config_kwargs)
    content_source = str(file_path or "Passed in content")
    if not disregard_skip:
        if file_path and config.is_skipped(file_path):
            raise FileSkipSetting(content_source)

    _internal_output = output_stream

    if config.atomic:
        try:
            file_content = input_stream.read()
            compile(file_content, content_source, "exec", 0, 1)
            input_stream = StringIO(file_content)
        except SyntaxError:
            raise ExistingSyntaxErrors(content_source)

        if not output_stream.readable():
            _internal_output = StringIO()

    try:
        changed = core.process(
            input_stream,
            _internal_output,
            extension=extension or (file_path and file_path.suffix.lstrip(".")) or "py",
            config=config,
        )
    except FileSkipComment:
        raise FileSkipComment(content_source)

    if config.atomic:
        _internal_output.seek(0)
        try:
            compile(_internal_output.read(), content_source, "exec", 0, 1)
            _internal_output.seek(0)
            if _internal_output != output_stream:
                output_stream.write(_internal_output.read())
        except SyntaxError:  # pragma: no cover
            raise IntroducedSyntaxErrors(content_source)

    return changed


def check_stream(
    input_stream: TextIO,
    show_diff: Union[bool, TextIO] = False,
    extension: Optional[str] = None,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    disregard_skip: bool = False,
    **config_kwargs,
) -> bool:
    """Checks any imports within the provided code stream, returning `False` if any unsorted or
    incorrectly imports are found or `True` if no problems are identified.

    - **input_stream**: The stream of code with imports that need to be sorted.
    - **show_diff**: If `True` the changes that need to be done will be printed to stdout, if a
    TextIO stream is provided results will be written to it, otherwise no diff will be computed.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **disregard_skip**: set to `True` if you want to ignore a skip set in config for this file.
    - ****config_kwargs**: Any config modifications.
    """
    config = _config(path=file_path, config=config, **config_kwargs)

    if show_diff:
        input_stream = StringIO(input_stream.read())

    changed: bool = sort_stream(
        input_stream=input_stream,
        output_stream=Empty,
        extension=extension,
        config=config,
        file_path=file_path,
        disregard_skip=disregard_skip,
    )
    printer = create_terminal_printer(color=config.color_output)
    if not changed:
        if config.verbose and not config.only_modified:
            printer.success(f"{file_path or ''} Everything Looks Good!")
        return True

    printer.error(f"{file_path or ''} Imports are incorrectly sorted and/or formatted.")
    if show_diff:
        output_stream = StringIO()
        input_stream.seek(0)
        file_contents = input_stream.read()
        sort_stream(
            input_stream=StringIO(file_contents),
            output_stream=output_stream,
            extension=extension,
            config=config,
            file_path=file_path,
            disregard_skip=disregard_skip,
        )
        output_stream.seek(0)

        show_unified_diff(
            file_input=file_contents,
            file_output=output_stream.read(),
            file_path=file_path,
            output=None if show_diff is True else cast(TextIO, show_diff),
            color_output=config.color_output,
        )
    return False


def check_file(
    filename: Union[str, Path],
    show_diff: Union[bool, TextIO] = False,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    disregard_skip: bool = True,
    extension: Optional[str] = None,
    **config_kwargs,
) -> bool:
    """Checks any imports within the provided file, returning `False` if any unsorted or
    incorrectly imports are found or `True` if no problems are identified.

    - **filename**: The name or Path of the file to check.
    - **show_diff**: If `True` the changes that need to be done will be printed to stdout, if a
    TextIO stream is provided results will be written to it, otherwise no diff will be computed.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **disregard_skip**: set to `True` if you want to ignore a skip set in config for this file.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - ****config_kwargs**: Any config modifications.
    """
    with io.File.read(filename) as source_file:
        return check_stream(
            source_file.stream,
            show_diff=show_diff,
            extension=extension,
            config=config,
            file_path=file_path or source_file.path,
            disregard_skip=disregard_skip,
            **config_kwargs,
        )


def sort_file(
    filename: Union[str, Path],
    extension: Optional[str] = None,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    disregard_skip: bool = True,
    ask_to_apply: bool = False,
    show_diff: Union[bool, TextIO] = False,
    write_to_stdout: bool = False,
    output: Optional[TextIO] = None,
    **config_kwargs,
) -> bool:
    """Sorts and formats any groups of imports imports within the provided file or Path.
     Returns `True` if the file has been changed, otherwise `False`.

    - **filename**: The name or Path of the file to format.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **disregard_skip**: set to `True` if you want to ignore a skip set in config for this file.
    - **ask_to_apply**: If `True`, prompt before applying any changes.
    - **show_diff**: If `True` the changes that need to be done will be printed to stdout, if a
    TextIO stream is provided results will be written to it, otherwise no diff will be computed.
    - **write_to_stdout**: If `True`, write to stdout instead of the input file.
    - **output**: If a TextIO is provided, results will be written there rather than replacing
    the original file content.
    - ****config_kwargs**: Any config modifications.
    """
    with io.File.read(filename) as source_file:
        actual_file_path = file_path or source_file.path
        config = _config(path=actual_file_path, config=config, **config_kwargs)
        changed: bool = False
        try:
            if write_to_stdout:
                changed = sort_stream(
                    input_stream=source_file.stream,
                    output_stream=sys.stdout,
                    config=config,
                    file_path=actual_file_path,
                    disregard_skip=disregard_skip,
                    extension=extension,
                )
            else:
                if output is None:
                    tmp_file = source_file.path.with_suffix(source_file.path.suffix + ".isorted")
                    try:
                        with tmp_file.open(
                            "w", encoding=source_file.encoding, newline=""
                        ) as output_stream:
                            shutil.copymode(filename, tmp_file)
                            changed = sort_stream(
                                input_stream=source_file.stream,
                                output_stream=output_stream,
                                config=config,
                                file_path=actual_file_path,
                                disregard_skip=disregard_skip,
                                extension=extension,
                            )
                        if changed:
                            if show_diff or ask_to_apply:
                                source_file.stream.seek(0)
                                with tmp_file.open(
                                    encoding=source_file.encoding, newline=""
                                ) as tmp_out:
                                    show_unified_diff(
                                        file_input=source_file.stream.read(),
                                        file_output=tmp_out.read(),
                                        file_path=actual_file_path,
                                        output=None
                                        if show_diff is True
                                        else cast(TextIO, show_diff),
                                        color_output=config.color_output,
                                    )
                                    if show_diff or (
                                        ask_to_apply
                                        and not ask_whether_to_apply_changes_to_file(
                                            str(source_file.path)
                                        )
                                    ):
                                        return False
                            source_file.stream.close()
                            tmp_file.replace(source_file.path)
                            if not config.quiet:
                                print(f"Fixing {source_file.path}")
                    finally:
                        try:  # Python 3.8+: use `missing_ok=True` instead of try except.
                            tmp_file.unlink()
                        except FileNotFoundError:
                            pass  # pragma: no cover
                else:
                    changed = sort_stream(
                        input_stream=source_file.stream,
                        output_stream=output,
                        config=config,
                        file_path=actual_file_path,
                        disregard_skip=disregard_skip,
                        extension=extension,
                    )
                    if changed:
                        if show_diff:
                            source_file.stream.seek(0)
                            output.seek(0)
                            show_unified_diff(
                                file_input=source_file.stream.read(),
                                file_output=output.read(),
                                file_path=actual_file_path,
                                output=None if show_diff is True else cast(TextIO, show_diff),
                                color_output=config.color_output,
                            )
                    source_file.stream.close()

        except ExistingSyntaxErrors:
            warn(f"{actual_file_path} unable to sort due to existing syntax errors")
        except IntroducedSyntaxErrors:  # pragma: no cover
            warn(f"{actual_file_path} unable to sort as isort introduces new syntax errors")

        return changed


def find_imports_in_code(
    code: str,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    unique: Union[bool, ImportKey] = False,
    top_only: bool = False,
    **config_kwargs,
) -> Iterator[identify.Import]:
    """Finds and returns all imports within the provided code string.

    - **code**: The string of code with imports that need to be sorted.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **unique**: If True, only the first instance of an import is returned.
    - **top_only**: If True, only return imports that occur before the first function or class.
    - ****config_kwargs**: Any config modifications.
    """
    yield from find_imports_in_stream(
        input_stream=StringIO(code),
        config=config,
        file_path=file_path,
        unique=unique,
        top_only=top_only,
        **config_kwargs,
    )


def find_imports_in_stream(
    input_stream: TextIO,
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    unique: Union[bool, ImportKey] = False,
    top_only: bool = False,
    _seen: Optional[Set[str]] = None,
    **config_kwargs,
) -> Iterator[identify.Import]:
    """Finds and returns all imports within the provided code stream.

    - **input_stream**: The stream of code with imports that need to be sorted.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **unique**: If True, only the first instance of an import is returned.
    - **top_only**: If True, only return imports that occur before the first function or class.
    - **_seen**: An optional set of imports already seen. Generally meant only for internal use.
    - ****config_kwargs**: Any config modifications.
    """
    config = _config(config=config, **config_kwargs)
    identified_imports = identify.imports(
        input_stream, config=config, file_path=file_path, top_only=top_only
    )
    if not unique:
        yield from identified_imports

    seen: Set[str] = set() if _seen is None else _seen
    for identified_import in identified_imports:
        if unique in (True, ImportKey.ALIAS):
            key = identified_import.statement()
        elif unique == ImportKey.ATTRIBUTE:
            key = f"{identified_import.module}.{identified_import.attribute}"
        elif unique == ImportKey.MODULE:
            key = identified_import.module
        elif unique == ImportKey.PACKAGE:
            key = identified_import.module.split(".")[0]

        if key and key not in seen:
            seen.add(key)
            yield identified_import


def find_imports_in_file(
    filename: Union[str, Path],
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    unique: Union[bool, ImportKey] = False,
    top_only: bool = False,
    **config_kwargs,
) -> Iterator[identify.Import]:
    """Finds and returns all imports within the provided source file.

    - **filename**: The name or Path of the file to look for imports in.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **unique**: If True, only the first instance of an import is returned.
    - **top_only**: If True, only return imports that occur before the first function or class.
    - ****config_kwargs**: Any config modifications.
    """
    with io.File.read(filename) as source_file:
        yield from find_imports_in_stream(
            input_stream=source_file.stream,
            config=config,
            file_path=file_path or source_file.path,
            unique=unique,
            top_only=top_only,
            **config_kwargs,
        )


def find_imports_in_paths(
    paths: Iterator[Union[str, Path]],
    config: Config = DEFAULT_CONFIG,
    file_path: Optional[Path] = None,
    unique: Union[bool, ImportKey] = False,
    top_only: bool = False,
    **config_kwargs,
) -> Iterator[identify.Import]:
    """Finds and returns all imports within the provided source paths.

    - **paths**: A collection of paths to recursively look for imports within.
    - **extension**: The file extension that contains imports. Defaults to filename extension or py.
    - **config**: The config object to use when sorting imports.
    - **file_path**: The disk location where the code string was pulled from.
    - **unique**: If True, only the first instance of an import is returned.
    - **top_only**: If True, only return imports that occur before the first function or class.
    - ****config_kwargs**: Any config modifications.
    """
    config = _config(config=config, **config_kwargs)
    seen: Optional[Set[str]] = set() if unique else None
    yield from chain(
        *(
            find_imports_in_file(
                file_name, unique=unique, config=config, top_only=top_only, _seen=seen
            )
            for file_name in files.find(map(str, paths), config, [], [])
        )
    )


def _config(
    path: Optional[Path] = None, config: Config = DEFAULT_CONFIG, **config_kwargs
) -> Config:
    if path:
        if (
            config is DEFAULT_CONFIG
            and "settings_path" not in config_kwargs
            and "settings_file" not in config_kwargs
        ):
            config_kwargs["settings_path"] = path

    if config_kwargs:
        if config is not DEFAULT_CONFIG:
            raise ValueError(
                "You can either specify custom configuration options using kwargs or "
                "passing in a Config object. Not Both!"
            )

        config = Config(**config_kwargs)

    return config
