import re
import csv
from pathlib import Path

def parse_can_log(input_path: str | Path, out_bus1: str | Path, out_bus2: str | Path) -> None:
    """
    Parses a CAN bus log file and saves valid frames to separate CSV files for Bus 1 and Bus 2.
    Corrupted, incomplete, or debug frames are silently discarded.
    """
    input_file = Path(input_path)
    out1_file = Path(out_bus1)
    out2_file = Path(out_bus2)

    # Group 1: Bus (C1 or C2)
    # Group 2: ID (1 to 8 hex chars)
    # Group 3: DLC (1 to 2 hex chars)
    start_pattern = re.compile(r'(C[12]):([0-9A-Fa-f]{1,8})\s+([0-9A-Fa-f]{1,2})\s+')

    byte_pattern = re.compile(r'^[0-9A-Fa-f]{2}$')

    with input_file.open('r', encoding='utf-8') as f_in, \
         out1_file.open('w', newline='', encoding='utf-8') as f_out1, \
         out2_file.open('w', newline='', encoding='utf-8') as f_out2:

        writer1 = csv.writer(f_out1)
        writer2 = csv.writer(f_out2)

        writer1.writerow(['ID', 'DLC', 'Data'])
        writer2.writerow(['ID', 'DLC', 'Data'])

        for line in f_in:
            for match in start_pattern.finditer(line):
                bus = match.group(1)
                can_id = match.group(2).upper()
                dlc_str = match.group(3)

                try:
                    dlc = int(dlc_str, 16)
                except ValueError:
                    continue

                if dlc > 8:
                    continue

                remaining = line[match.end():]
                tokens = remaining.split()

                data_bytes = []
                for token in tokens:
                    if byte_pattern.match(token):
                        data_bytes.append(token.upper())
                    else:
                        break

                if len(data_bytes) == dlc:
                    data_str = ' '.join(data_bytes)
                    row = [can_id, dlc, data_str]

                    if bus == 'C1':
                        writer1.writerow(row)
                    elif bus == 'C2':
                        writer2.writerow(row)

if __name__ == '__main__':
    # Example usage:
    # parse_can_log('can_traffic.txt', 'bus1_output.csv', 'bus2_output.csv')
    # or on CLI:
    # python3 can_parser.py your_log.txt bus1_output.csv bus2_output.csv
    pass