import pygit2 # using version 1.15.1 in this example
import sys
import os

def walk_repo_files(repo, branch):
    tree = repo.revparse_single(branch).tree   
    trees_and_paths = [(tree, [])]    
    # keep going until there is no more data
    while len(trees_and_paths) != 0:
        tree, path = trees_and_paths.pop() # take the last entry        
        
        new_trees = []
        for entry in tree:
            if entry.filemode == pygit2.GIT_FILEMODE_TREE:
                next_tree = repo.get(entry.id)
                next_path = list(path)
                next_path.append(entry.name)
                new_trees.append((next_tree, next_path, entry.name))
            else:
                yield path, entry
                
        # sort by the last element in the tuples, the name
        new_trees.sort(key = lambda x: x[2].lower())
        trees_and_paths.extend( (a,b) for a, b, _ in new_trees)


def walk_repo_files_reverse_sorted(repo, branch):
    walker = walk_repo_files(repo, branch)
    try:
        prev_path, entry = next(walker)
    except StopIteration:
        return # repo is empty    
    accum = [entry]
    for path, entry in walker:
        if prev_path != path:
            # sort elements in reverse order by name
            accum.sort(key = lambda x: x.name.lower(), reverse=True)
            for i in accum:
                yield prev_path, i 
            prev_path = path
            accum.clear()
            
        accum.append(entry)
            

repo_path = sys.argv[1] 
branch_name = sys.argv[2]

repo = pygit2.Repository(repo_path)

all_files = list(walk_repo_files_reverse_sorted(repo, branch_name))
all_files.reverse()
for path, entry in all_files:
    sys.stdout.write(os.path.join(*path, entry.name))
    sys.stdout.write("\n")