#!/usr/bin/python
# Copyright 2020 (c) Anna Schumaker
#
# Use Mutagen to generate a list of common tag names for
# all music files in the requested directory
import mutagen
import os
import pathlib
import sys

if len(sys.argv) != 2 or not os.path.isdir(sys.argv[1]):
    print(f"Usage: {sys.argv[0]} DIRECTORY")
    sys.exit(1)

print()
print(f"Reading directory {sys.argv[1]}:")

files  = [ ]
for entry in pathlib.Path(sys.argv[1]).rglob("*"):
    if os.path.isfile(entry):
        files += [ entry ]

print(f"  Found {len(files)} files")

read = 0
skip = 0
unique = None
for f in files:
    try:
        keys = set(mutagen.File(f).keys())
        if unique == None:
            unique = keys
        else:
            unique = unique.intersection(keys)
        read += 1
    except Exception as e:
        #print(e)
        skip += 1

print(f"  Read {read} files, skipped {skip}")

tags = list(unique)
tags.sort()
print(f"  There are {len(tags)} common tags:")
for t in tags:
    print(f"    {t}")
print()