import os
import re
import argparse
from pathlib import Path
from tempfile import mkstemp

VERSION_HEADER = re.compile(r"\[\d+.\d+.\d+\]")


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("version")
    args = parser.parse_args()

    changelog = get_changelog(args.version)
    outfilename = save_changelog(args.version, changelog)

    print(outfilename)


def get_changelog(version: str) -> list[str]:
    script_dir = Path(__file__).absolute().parent.parent
    changelog = script_dir / "CHANGELOG.md"

    with changelog.open("r") as infile:
        lines = infile.readlines()

    start = -1
    end = -1

    for i, line in enumerate(lines):
        if start == -1:
            match = re.search(version, line)
            if match is None:
                continue
            start = i
        else:
            match = VERSION_HEADER.search(line)
            if match is not None:
                end = i
                break

    if start == -1:
        exit(1)

    return lines[start:end] if end > -1 else lines[start:]


def save_changelog(version: str, lines: list[str]) -> str:
    fd, name = mkstemp(prefix=f"wapp-changelog-{version}-", text=True)
    os.write(fd, "".join(lines).encode("utf-8"))
    os.close(fd)
    return name


if __name__ == "__main__":
    main()