'''
--------------COMPARE TWO FOLDERS----------------------------------------------

Ref: askubuntu.com/questions/421712/comparing-the-contents-of-two-directories
Syntax: python3 Py/compareFolders.py ../folder1 ../folder2. The first folder is
        called source folder and second is called target folder.  The aim is to
        modify the code for in-place copy/deletion of files in target folder.
It doesn't compare contents of the files. Also it doesn't travel inside sub-
directories which are missing in one of the directories. 
'''
#!/usr/bin/env python3

import os, sys, shutil
def compare_dirs(d1: "Source directory name", d2: "Target directory name"):
    
    def print_local(t, a, msg):
        print(t, 'DIR--- ' if a[2] else 'FILE--', a[1], msg)
    
    # Ensure validity: check that both arguments are valid folder names
    for d in [d1,d2]:
        if not os.path.isdir(d):
            raise ValueError("not a directory: " + d)
    
    # Get relative path: array of file names for two folders
    # Create a List of Tuples (file_name, relative_path)
    l1 = [(x,os.path.join(d1,x)) for x in os.listdir(d1)]
    #print(l1)
    l2 = [(x,os.path.join(d2,x)) for x in os.listdir(d2)]
    
    # Determine type: directory or file?
    # Sort the tuples by adding Boolean for folders (True). The new list formed
    # are List of Tuples like (file_name, relative_path, True). They are sorted
    # in ascending older: files first and then folders
    l1 = sorted([(x,y,os.path.isdir(y)) for x,y in l1])
    l2 = sorted([(x,y,os.path.isdir(y)) for x,y in l2])
    
    #Set file counters to ZERO
    i1 = i2 = 0
    
    common_dirs = []
    while i1<len(l1) and i2<len(l2):
        if l1[i1][0] == l2[i2][0]:      # Same name - First item of the Tuple
            if l1[i1][2] == l2[i2][2]:  # Same type - TRUE or FALSE in the Tuple 
                if l1[i1][2]:           # If TRUE, Remember folder for recursion
                    common_dirs.append((l1[i1][1], l2[i2][1]))
            else:                       #Name remains same but file type changed
                print_local('\t',l1[i1],'type changed')
            i1 = i1 + 1
            i2 = i2 + 1
        elif l1[i1][0]<l2[i2][0]:       #Files found in source but not in target
            print_local('\t',l1[i1],'\t-[removed from source]')
            i1 = i1 + 1
        elif l1[i1][0]>l2[i2][0]:       #Files NOT found in source but in target
            print_local('\t\t',l2[i2],'\t-[added in target]')
            i2 = i2 + 1
    while i1<len(l1):
    #File present in folder-1 (d1) but not in folder-2 (d2)
        print_local('\t',l1[i1],'\t-[removed from source]')
        i1 = i1 + 1
    print('\n')
    while i2<len(l2):
    #File present in folder-2 (d2) but not in folder-1 (d1)
        print_local('\t\t',l2[i2],'\t-[added in target]')
        i2 = i2 + 1
    # Compare subfolders recursively (compare_dir is called recursively)
    for sd1,sd2 in common_dirs:
        compare_dirs(sd1, sd2)

if __name__=="__main__":
    compare_dirs(sys.argv[1], sys.argv[2])