#!/usr/bin/env python3

# Usage:
#     envcheck source/.env.template source/.env

import sys


def main():
    variables_sets_list = _get_variables_set_list()
    file_paths = sys.argv[1:]
    reference_file_variables = variables_sets_list[0]

    compared_sets_list = variables_sets_list[1:]
    missing = False
    for compared_file_variables_index in range(0, len(compared_sets_list)):
        compared_file_variables = \
            compared_sets_list[compared_file_variables_index]
        relevant_file_path = file_paths[compared_file_variables_index + 1]
        missing_variables_message = _get_missing_variables_message(
            reference_file_variables, compared_file_variables,
            relevant_file_path)

        if missing_variables_message is None:
            continue
        missing = True
        print(missing_variables_message)

    return_code = {True: 1, False: 0}[missing]
    sys.exit(return_code)


def _get_variables_set_list():
    variables_sets_list = []
    file_paths = sys.argv[1:]
    for file_path in file_paths:
        variables_sets_list.append(_get_file_variables_from_file(file_path))

    if len(variables_sets_list) == 0:
        raise Exception('Missing target files')

    if len(variables_sets_list) == 1:
        raise Exception('Missing files to compare with reference')

    return variables_sets_list


def _get_file_variables_from_file(file_path):
    handle = open(file_path, 'r')

    variables = []
    for line in handle.readlines():
        parts = line.split('=')
        if len(parts) < 2:
            continue
        variables.append(parts[0])

    handle.close()

    return set(variables)


def _get_missing_variables_message(reference_set, compared_set, compared_path):
    missing_variables_set = reference_set - compared_set

    if len(missing_variables_set) == 0:
        return None
    missing_variables = list(missing_variables_set)
    missing_variables.sort()

    message = compared_path + ' is missing: \n\t' + "\n\t".join(
        missing_variables)
    return message


if __name__ == '__main__':
    main()