#!/usr/bin/env python

import argparse
from pathlib import Path
from progress.bar import Bar
import shutil
import subprocess

def files_and_dirs_for_directory(path):
    filepaths = []
    dirpaths = []

    for dirpath, dirnames, filenames in path.walk():
        dirpaths.append(dirpath)

        for filename in filenames:
            filepath = dirpath / filename
            filepaths.append(filepath)

    return set(filepaths), set(dirpaths)

def make_paths_relative(paths, relative_to_path):
    return set(path.relative_to(relative_to_path) for path in paths)

def replace_suffix(path, suffix):
    return path.with_name(path.stem + suffix)

def convert_filepath(path):
    if path.suffix == ".flac":
        return replace_suffix(path, ".mp3")

    return path

def ffmpeg_flac_to_mp3(in_path, out_path):
    print("")
    subprocess.run(["ffmpeg", "-hide_banner", "-loglevel", "warning", "-stats", "-i", in_path, "-ab", "320k", "-map_metadata", "0", "-id3v2_version", "3", out_path], check=True)
    print("")

if __name__ == "__main__":

    parser = argparse.ArgumentParser(prog="convert-flac-dir-to-mp3")
    parser.add_argument("from_dir", type=Path)
    parser.add_argument("to_dir", type=Path)

    args = parser.parse_args()

    from_path = args.from_dir.absolute()
    to_path = args.to_dir.absolute()

    if not from_path.exists():
        raise Exception("from_path does not exist")

    if not to_path.exists():
        raise Exception("to_path does not exist")

    if not from_path.is_dir():
        raise Exception("from_path is not a directory")

    if not to_path.is_dir():
        raise Exception("to_path is not a directory")

    print(f"Converting {from_path} to {to_path}…")

    from_filepaths, from_dirpaths = files_and_dirs_for_directory(from_path)
    to_filepaths, to_dirpaths = files_and_dirs_for_directory(to_path)


    relative_from_filepaths = make_paths_relative(from_filepaths, from_path)
    relative_to_filepaths = make_paths_relative(to_filepaths, to_path)

    converted_from_filepaths = set(convert_filepath(filepath) for filepath in relative_from_filepaths)

    filepaths_missing_in_to_path = converted_from_filepaths - relative_to_filepaths


    relative_from_dirpaths = make_paths_relative(from_dirpaths, from_path)
    relative_to_dirpaths = make_paths_relative(to_dirpaths, to_path)

    dirpaths_missing_in_to_path = relative_from_dirpaths - relative_to_dirpaths

    print(f"Missing {len(filepaths_missing_in_to_path)} files and {len(dirpaths_missing_in_to_path)} directories")

    if len(dirpaths_missing_in_to_path) > 0:
        for dirpath in Bar("Creating directories").iter(dirpaths_missing_in_to_path):
            (to_path / dirpath).mkdir(parents=True, exist_ok=True)

    if len(filepaths_missing_in_to_path) > 0:
        for filepath in Bar("Creating files").iter(filepaths_missing_in_to_path):
            if filepath in relative_from_filepaths:
                # Just copy the file
                shutil.copy(from_path / filepath, to_path / filepath)
            elif filepath.suffix == ".mp3" and replace_suffix(filepath, ".flac") in relative_from_filepaths:
                # Convert from flac
                print("")
                print(f"Converting {to_path / filepath}…")

                # Tempfile for ffmpeg
                tmpfilepath = filepath.with_name(".~" + filepath.name)
                (to_path / tmpfilepath).unlink(missing_ok=True)

                print(f"Using tempfile for ffmpeg {to_path / tmpfilepath}…")

                # Convert
                ffmpeg_flac_to_mp3(from_path / replace_suffix(filepath, ".flac"), to_path / tmpfilepath)

                # Rename tempfile
                (to_path / tmpfilepath).rename(to_path / filepath)
            else:
                raise Exception("Unable to figure out how to get {to_path / filepath} from {from_path}")