OrcaSlicer M106 bug workaround

cleanup_m106.py

## License: GPLv2
## Author: quantumfrost
## This is a post-processing speed to workaround the OrcaSlicer but that causes unnecessary fan speed changes
## See here for more info: https://github.com/SoftFever/OrcaSlicer/issues/1330
## Add this at the bottom of the "Others" tab under "Process" like so:
## "path/to/python" "path/to/script"

import re
import sys, os

m106_pattern = re.compile('[Mm]106\s+[Ss]([0-9]{1,3})')
m107_pattern = re.compile('[Mm]107')


def sanitize(line: str) -> str:
    return line.split(';')[0].strip()


def is_command(sanitized_line: str) -> bool:
    return sanitized_line and not sanitized_line.startswith(';')


def is_fan_command(sanitized_line: str) -> bool:
    s = sanitized_line.lower()
    return s.startswith('m106') or s.startswith('m107')


def get_fan_speed(fan_command: str) -> int:
    m106 = m106_pattern.fullmatch(fan_command)
    m107 = m107_pattern.fullmatch(fan_command)
    if m106:
        assert m107 is None
        return int(m106.group(1))
    if m107:
        return 0
    assert False, 'unexpected fan speed syntax: {0}'.format(fan_command)


def cleanup_fan_speeds(input_file, output_file):
    with open(input_file, 'r') as inp, open(output_file, 'w') as out:
        last_fan_speed = -1
        it = iter(inp)
        num_removed = 0
        for original_line in it:
            s = sanitize(original_line)
            # If it's not a fan command, write it as-is
            if not is_fan_command(s):
                out.write(original_line)
                continue
            # Look for back-to-back fan speed changes in adjacent lines
            while True:
                if s is None:   # EOF
                    break
                if is_fan_command(s):   # update values
                    speed = get_fan_speed(s)
                    cmd = original_line
                    num_removed += 1
                elif is_command(s): # non-fan command
                    break
                else:   # non-command statement, whitespace or comment
                    out.write(original_line)    # write it but continue looking for more fan cmds
                original_line = next(it, None)
                s = sanitize(original_line)
            # Write the last encountered fan command, if it would change the speed
            if speed != last_fan_speed:
                out.write(cmd)
                last_fan_speed = speed
            # Write the line that made us break out of the loop
            if original_line:
                out.write(original_line)
        out.write('; {0} unnecessary fan speed commands removed by cleanup_m106.py\n'.format(num_removed))


def main():
    input_file = sys.argv[1]
    output_file = input_file + '.temp'
    cleanup_fan_speeds(input_file, output_file)
    os.replace(output_file, input_file)


if __name__ == '__main__':
    main()