#!/usr/bin/env python3
import re
import sys
from pathlib import Path

VERSION_FILE = Path("version.txt")
TOP_V_FILE = Path("top.v")
VERSION_FIELD_LEN = 9

def main():
    if not VERSION_FILE.exists():
        sys.exit("Error: version.txt not found")
    if not TOP_V_FILE.exists():
        sys.exit("Error: top.v not found")

    old_version = VERSION_FILE.read_text(encoding='utf-8').strip()
    parts = old_version.split(".")
    if len(parts) != 3 or not all(p.isdigit() for p in parts):
        sys.exit(f"Error: unexpected version format '{old_version}'")
    new_version = f"{parts[0]}.{parts[1]}.{int(parts[2])+1}"
    padded = new_version.ljust(VERSION_FIELD_LEN)

    content = TOP_V_FILE.read_text(encoding='utf-8-sig', newline='\n')

    m = re.search(r'version chars at indices (\d+)', content)
    if not m:
        sys.exit("Error: could not find 'version chars at indices' comment in top.v")
    start_idx = int(m.group(1))

    for offset, ch in enumerate(padded):
        idx = start_idx + offset
        pattern = rf"(9'd{idx}:\s+banner_char\s*=\s*)[^\n]+;"
        new_content, n = re.subn(pattern, lambda mo, c=ch: mo.group(1) + f'"{c}";', content)
        if n == 0:
            sys.exit(f"Error: could not find banner_char entry for index {idx}")
        content = new_content

    TOP_V_FILE.write_text(content, encoding='utf-8', newline='\n')
    VERSION_FILE.write_text(new_version + "\n", encoding='utf-8')
    print(f"Version bumped to {new_version}")

if __name__ == "__main__":
    main()