replace-cased-names

#!/usr/bin/env python3
# SPDX-License-Identifier: WTFPL

import argparse
import enum
import os
import re
import sys
import tempfile


def to_camel(snake):
    parts = snake.split("_")
    return "".join([parts[0], *[part.capitalize() for part in parts[1:]]])


def to_kebab(snake):
    return snake.replace("_", "-")


def to_caps(snake):
    return snake.upper()


def to_pascal(snake):
    parts = snake.split("_")
    return "".join([part.capitalize() for part in parts])


def to_snake(snake):
    return snake


class Case(str, enum.Enum):
    camel = "camel"
    kebab = "kebab"
    snake = "snake"
    upper = "upper"
    pascal = "pascal"


VARIANTS = {
    Case.camel: to_camel,
    Case.kebab: to_kebab,
    Case.snake: to_snake,
    Case.upper: to_caps,
    Case.pascal: to_pascal,
}


def build_replaces():
    replaces = []
    for name, func in VARIANTS.items():
        from_ = getattr(args, f"{name}_from", None)
        if from_ is None:
            from_ = func(args.old_name)
        to = getattr(args, f"{name}_to", None)
        if to is None:
            to = func(args.new_name)

        replaces.append((from_, to))

    return replaces


def replace_line(line):
    for pair in replacements:
        line = line.replace(*pair)
    return line


def replace_file(filename):
    with (
        open(filename) as infp,
        tempfile.NamedTemporaryFile("w+", dir=os.path.dirname(filename), delete=False) as outfp
    ):
        for line in infp:
            print(replace_line(line), end="", file=outfp)
        os.replace(outfp.name, filename)


def replace_stdin():
    for line in sys.stdin:
        print(replace_line(line), end="")


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("old_name", metavar="old_name")
    parser.add_argument("new_name", metavar="new_name")
    parser.add_argument("--snake-from")
    parser.add_argument("--snake-to")
    parser.add_argument("--kebab-from")
    parser.add_argument("--kebab-to")
    parser.add_argument("--camel-from")
    parser.add_argument("--camel-to")
    parser.add_argument("--pascal-from")
    parser.add_argument("--pascal-to")
    parser.add_argument("files", nargs="+")
    args = parser.parse_args()

    validate_re = re.compile("[a-z_0-9]+")
    if not validate_re.fullmatch(args.old_name):
        parser.error(f"old_name should be in lower snake case: {args.old_name!r}")
    if not validate_re.fullmatch(args.new_name):
        parser.error(f"new_name should be in lower snake case: {args.new_name!r}")

    replacements = build_replaces()

    for filename in args.files:
        if filename == "-":
            replace_stdin()
        else:
            replace_file(filename)