"""Docstring."""

import csv
import os
import sys


def main():
    """Entrypoint."""
    upc = sys.argv[1]
    qa_dir = f'data/qa/{upc}'
    prod_dir = f'data/prod/{upc}'

    qa_files = load_media_dir(qa_dir)
    prod_files = load_media_dir(prod_dir)

    results = {}
    for filename in set(list(qa_files.keys()) + list(prod_files.keys())):
        data = {
            'error_msg': '',
            'diffs': None
        }
        if filename not in qa_files:
            data['error_msg'] = 'qa file does not exist'
        elif filename not in prod_files:
            data['error_msg'] = 'prod file does not exist'
        else:
            data['diffs'] = diff_dicts(
                load_media_info(qa_files[filename]),
                load_media_info(prod_files[filename]),
                [
                    'Writing library'
                ]
            )
        results[filename] = data

    with open(f'{upc}.csv', 'w', newline='') as csvfile:
        fieldnames = ['filename', 'error_msg', 'key', 'qa_val', 'prod_val']
        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
        writer.writeheader()

        for filename, value in results.items():
            row = {
                'filename': filename,
                'error_msg': value['error_msg'],
                'key': '',
                'qa_val': '',
                'prod_val': ''
            }
            if not value['diffs']:
                writer.writerow(row)
            else:
                for key, values in value['diffs'].items():
                    row['key'] = key
                    row['qa_val'] = values[0],
                    row['prod_val'] = values[1]
                    writer.writerow(row)


def diff_dicts(left, right, ignore_keys):
    """Compare two dicts, return diff."""
    results = {}
    for key in set(list(left.keys()) + list(right.keys())):
        if key in ignore_keys:
            continue
        left_val = left.get(key)
        right_val = right.get(key)
        if left_val != right_val:
            results[key] = (left.get(key), right.get(key))
    return results


def load_media_info(path):
    """Read metadata into dict."""
    sep = ':'
    with open(f'{path}.txt', 'rb') as f:
        raw_data = f.read()

    try:
        data = raw_data.decode('ascii')
    except UnicodeDecodeError:
        data = raw_data.decode('utf-8')

    results = {}
    for line in data.splitlines():
        if sep not in line:
            continue
        parts = line.split(sep)
        key = parts[0].strip()
        value = parts[1].strip()
        results[key] = value
    return results


def load_media_dir(path):
    """Read files in dir into dict."""
    return {
        x.name: x.path
        for x in os.scandir(path)
        if x.is_file() and not x.name.endswith('.txt')
    }


if __name__ == '__main__':
    main()