hcat

#!/usr/bin/env python3
"Horizontally concatenate files."

import argparse
from sys import stdin
from typing import Iterable, Optional

parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument(
    'file', nargs='+',
    help="Accepts - for stdin (noninteractive)")
parser.add_argument(
    '--no-color', dest='skip_color_codes', action='store_true',
    help="Do not ignore invisible color codes, and count all characters."
    " This may affect column length, and has negligible speedup.")
parser.add_argument(
    '--sep', default=' ',
    help="Column separator. Default is a single space.")
parser.add_argument(
    '--widths', '-w', nargs='+', default=[],
    help="Widths of each file (useful if you're using color styling etc)."
    " Accepts - to automatically determine."
    " Does not have to match nunber of files.")

def visible_char_count(string: str) -> int:
    '''Number of visible characters in a string, Terminal color codes notwithstanding.'''
    # This has been tested with `viu` and `lolcat`.
    # Hopefully it catches other fanciful formatting
    ESC = chr(27)
    ESC_FINISH_COL_CODE = 'm'
    n = 0
    is_visible = 1
    for c in string:
        if c == ESC:
            is_visible = 0
            continue
        elif not is_visible and c == ESC_FINISH_COL_CODE:
            is_visible = 1
            continue
        n += is_visible
    return n

def horizontal_concat(
    strings: Iterable[str],
    col_widths: Iterable[Optional[int]],
    skip_color_codes: bool = True,
    sep=' ',
) -> str:
    length = len if skip_color_codes else visible_char_count
    # split (and remove trailing newline)
    col_rows = [s.removesuffix('\n').split('\n') for s in strings]  # list[column]

    # get lengths for filling blanks:
    # zip(*x) is only good on rectangular transpose!
    max_row_count = max(map(len, col_rows))
    actual_col_widths = list(map(
        lambda col: max(map(length, col)),
        col_rows))
    # (args override)
    for i, w in enumerate(col_widths):
        if w is not None:
            actual_col_widths[i] = w

    # fill with blanks
    col_rows = [
        [row.ljust(width) for row in rows]
        + [' '*width] * (max_row_count - len(rows))
        for rows, width in zip(col_rows, actual_col_widths)
    ]

    row_cols = zip(*col_rows)  # transpile

    return '\n'.join(
        sep.join(row)
        for row in row_cols
    )

if __name__ == '__main__':
    args = parser.parse_args()
    print(horizontal_concat(
        [(stdin if path == '-' else open(path)).read() for path in args.file],
        col_widths=[None if width == '-' else int(width) for width in args.widths],
        skip_color_codes=args.skip_color_codes,
        sep=args.sep,
    ))