import argparse
import json
import re
from pathlib import Path

BODY_LIMIT = 125000


def release_body(notes):
    if len(notes) <= BODY_LIMIT:
        return notes
    return re.sub(
        r"^## What's Changed[^\S\r\n]*\r?\n.*?(?=^#{1,2} |^\*\*Full Changelog\*\*:|\Z)",
        "",
        notes,
        count=1,
        flags=re.MULTILINE | re.DOTALL,
    )


def prepare_notes(source, body, full):
    paths = (source, body, full)
    for index, first in enumerate(paths):
        for second in paths[index + 1:]:
            if first.resolve() == second.resolve() or (first.exists() and second.exists() and first.samefile(second)):
                raise ValueError("Release note input and outputs must be distinct files")
    notes = json.loads(source.read_text(encoding="utf-8"))["body"]
    if not isinstance(notes, str):
        raise ValueError("Generated release notes body must be a string")
    full.parent.mkdir(parents=True, exist_ok=True)
    full.write_bytes(notes.encode("utf-8"))
    body.write_bytes(release_body(notes).encode("utf-8"))


def main():
    parser = argparse.ArgumentParser(description="Prepare size-safe GitHub release notes")
    parser.add_argument("--input", type=Path, required=True)
    parser.add_argument("--body", type=Path, required=True)
    parser.add_argument("--full", type=Path, required=True)
    args = parser.parse_args()
    prepare_notes(args.input, args.body, args.full)


if __name__ == "__main__":
    main()