#!/usr/bin/env python3
"""Increment the PATCH component of version.txt and update banner_char in top.v."""

import re
import sys
from pathlib import Path

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

# Fixed 9-character field in banner_char; indices 343-351.
VERSION_FIELD_LEN = 9
VERSION_START_IDX = 343


def read_version():
    if not VERSION_FILE.exists():
        sys.exit(f"Error: {VERSION_FILE} not found")
    return VERSION_FILE.read_text().strip()


def bump_patch(version):
    parts = version.split(".")
    if len(parts) != 3 or not all(p.isdigit() for p in parts):
        sys.exit(f"Error: unexpected version format '{version}'")
    major, minor, patch = int(parts[0]), int(parts[1]), int(parts[2])
    return f"{major}.{minor}.{patch + 1}"


def update_top_v(new_version):
    if not TOP_V_FILE.exists():
        sys.exit(f"Error: {TOP_V_FILE} not found")

    padded = new_version.ljust(VERSION_FIELD_LEN)
    if len(padded) > VERSION_FIELD_LEN:
        sys.exit(f"Error: version '{new_version}' exceeds {VERSION_FIELD_LEN} characters")

    content = TOP_V_FILE.read_text()

    for offset, ch in enumerate(padded):
        idx = VERSION_START_IDX + offset
        pattern = rf"(9'd{idx}:\s+banner_char\s*=\s*)[^\n]+;"
        replacement = rf'\g<1>"{ch}";'
        new_content = re.sub(pattern, replacement, content)
        if new_content == content:
            sys.exit(f"Error: could not find banner_char entry for index {idx} in {TOP_V_FILE}")
        content = new_content

    TOP_V_FILE.write_text(content)


def main():
    old_version = read_version()
    new_version = bump_patch(old_version)
    update_top_v(new_version)
    VERSION_FILE.write_text(new_version + "\n")
    print(f"Version bumped to {new_version}")


if __name__ == "__main__":
    main()