#!/usr/bin/env python3
"""
Extract changelog for a specified version (or __NEXT__ if no version
specified).
"""
from pathlib import Path
from sys import argv, exit, stdout, stderr


CHANGELOG = Path(__file__).parent / "../CHANGES.md"


def main(version = "__NEXT__"):
    with CHANGELOG.open(encoding = "utf-8") as file:
        for line in file:
            # Find the heading for this version
            if line.rstrip("\n") == f"## {version}" or line.startswith(f"## {version} "):

                # Print subsequent lines until we reach the next version heading
                for line in file:
                    if line.startswith("## "):
                        break
                    stdout.write(line)
                return 0

        print(f"No changes found for {version!r}.", file = stderr)
        return 1


if __name__ == "__main__":
    exit(main(*argv[1:]))
