#!/usr/bin/python3.8
#
# USAGE: ./compare-links.py DIR1 DIR2
#
# Recursively compare DIR1 and DIR2 for matching symlinks. Report
# missing subdirs, missing links, and unequal link targets.
#

import sys
import os.path
import stat


def compare(dir1, dir2):
    files1 = set(os.listdir(dir1))
    files2 = set(os.listdir(dir2))
    report_diffs(dir1, files1, dir2, files2)
    both = files1.intersection(files2)
    #print(f'BOTH: {list(both)[:10]}...')
    for f in both:
        p1 = os.path.join(dir1, f)
        p2 = os.path.join(dir2, f)
        s1 = os.stat(p1, follow_symlinks=False)
        s2 = os.stat(p2, follow_symlinks=False)
        t1 = stat.S_IFMT(s1.st_mode)
        t2 = stat.S_IFMT(s2.st_mode)
        if t1 != t2:
            print(f'TYPE DIFFERS:\n  {p1}: {t1}\n  {p2}: {t2}')
        elif stat.S_ISDIR(s1.st_mode):
            # Recurse on the subdirs
            compare(p1, p2)
        elif stat.S_ISLNK(s1.st_mode):
            pass
        else:
            print(f'UNKNOWN TYPE: {p1}')


def report_diffs(dir1, files1, dir2, files2):
    only_dir1 = files1 - files2
    if only_dir1:
        print(f'ONLY IN: {dir1}\n  {", ".join(sorted(only_dir1))}')
    only_dir2 = files2 - files1
    if only_dir2:
        print(f'ONLY IN: {dir2}\n  {", ".join(sorted(only_dir2))}')


if __name__ == '__main__':
    compare(sys.argv[1], sys.argv[2])