"""Pycln regex utility."""
import os
import re
import tokenize
from pathlib import Path
from typing import List, Pattern

import typer
from pathspec import PathSpec
from pathspec.patterns import GitWildMatchPattern

from .. import ISWIN

# Constants.
INCLUDE = "include"
EXCLUDE = "exclude"
GITIGNORE = ".gitignore"
SKIP_FILE_REGEX = r"# *(nopycln *: *file).*"
SKIP_IMPORT_REGEX = r"# *((noqa *:*)|(nopycln *: *import)).*"
INIT_FILE_REGEX = r"^__init__.pyi?$"
STUB_FILE_REGEX = r".*\.pyi$"
EMPTY_REGEX = r"^$"
INCLUDE_REGEX = r".*\.pyi?$"
EXCLUDE_REGEX = (
    r"(\.eggs|\.git|\.hg|\.mypy_cache|__pycache__|\.nox|"
    + r"\.tox|\.venv|\.svn|buck-out|build|dist)/"
)


def safe_compile(pattern: str, type_: str) -> Pattern[str]:
    """Safely compile [--include, --exclude] options regex.

    :param pattern: an str regex to be complied.
    :param type_: 'include' OR 'exclude'.
    :returns: complied regex.
    """
    try:
        if isinstance(pattern, str):
            compiled: Pattern[str] = re.compile(pattern, re.IGNORECASE)
            return compiled
        return pattern  # type: ignore
    except re.error as err:
        typer.secho(
            f"Invalid regular expression for {type_} given: {pattern!r} ⛔",
            fg=typer.colors.RED,
            err=True,
        )
        raise typer.Exit(1) from err


def strpath(path: Path) -> str:
    """Custom `Path` to `str` casting.

    :param path: file-system path.
    :returns: stringified path.
    """
    if ISWIN:
        path_str = str(path).replace("\\", "/")
        return path_str if path.is_file() else f"{path_str}/"
    else:
        return f"{path}" if path.is_file() else f"{path}/"


def is_init_file(path: Path) -> bool:
    """Check if the file name is `__init__.py(i)`.

    :param path: file-system path to check.
    :returns: True if the file is `__init__.py(i)` else False.
    """
    regex: Pattern[str] = safe_compile(INIT_FILE_REGEX, INCLUDE)
    return bool(regex.match(path.name))


def is_stub_file(path: Path) -> bool:
    """Check if the file extension is `.pyi`.

    :param path: file-system path to check.
    :returns: True if the file extension is `.pyi` else False.
    """
    regex: Pattern[str] = safe_compile(STUB_FILE_REGEX, INCLUDE)
    return bool(regex.search(path.name))


def is_included(path: Path, regex: Pattern[str]) -> bool:
    """Check if the file/directory name match include pattern.

    :param path: file-system path to check.
    :param regex: include regex pattern.
    :returns: True if the name match else False.
    """
    return bool(regex.search(strpath(path)))


def is_excluded(path: Path, regex: Pattern[str]) -> bool:
    """Check if the file/directory name match exclude pattern.

    :param path: file-system path to check.
    :param regex: exclude regex pattern.
    :returns: True if the name match else False.
    """
    return bool(regex.search(strpath(path)))


def get_gitignore(root: Path, no_gitignore: bool = False) -> PathSpec:
    """Return a PathSpec matching gitignore content, if present.

    :param root: root path to search for `.gitignore`.
    :param no_gitignore: `config.no_gitignore` value (default=False).
    :returns: PathSpec matching gitignore content, if present.
    """
    lines: List[str] = []
    if not no_gitignore:
        path = os.path.join(root, GITIGNORE)
        if os.path.isfile(path):
            if os.access(path, os.R_OK):
                with tokenize.open(path) as ignore_file:
                    lines = ignore_file.readlines()
    return PathSpec.from_lines(GitWildMatchPattern, lines)


def skip_import(line: str) -> bool:
    """Check if the lines has `# noqa` or `# nopycln: import` to skip.

    :param line: a line to check.
    :returns: True if it matches else False.
    """
    return bool(re.search(SKIP_IMPORT_REGEX, line, re.IGNORECASE))


def skip_file(src_code: str) -> bool:
    """Check if the src_code code has `nopycln: file` comment to skip.

    :param src_code: string source code to check.
    :returns: True if it matches else False.
    """
    return bool(re.search(SKIP_FILE_REGEX, src_code, re.IGNORECASE))