import copy
import json
import os
import random


def create_pairs_dict(lst: list[str]) -> dict[str, str]:
    result = {}
    lst_len = len(lst)

    if lst_len < 2:
        print("\033[1;31mList length should be at least 2!\033[0m")
        raise RuntimeError

    for i in range(lst_len - 1):
        result[lst[i]] = lst[i+1]
    result[lst[lst_len-1]] = lst[0]

    return result


# Main
input_file = "participants.json"
output_file = "pairs.json"


if os.path.isfile(input_file):
    print(f"\033[1;33mReading from {input_file}.\033[0m")
    with open(input_file, "r", encoding="utf-8") as f:
        participants_list = json.load(f)
else:
    print("\033[1;31mNo input file found! Please create participants.json file.\033[0m")
    participants_list: list[str] = ["1", "2", "3", "4"]

shuffled_list = copy.copy(participants_list)
random.shuffle(shuffled_list)
pairs = create_pairs_dict(shuffled_list)

print(f"\033[1;33mWriting to {output_file}.\033[0m")
with open(output_file, 'w', encoding='utf-8') as f:
    json.dump(pairs, f, ensure_ascii=False, indent=4)

print("\033[1;32mFinished!\033[0m")

print("\nResults:")
for giver, receiver in pairs.items():
    print(f"{giver} → {receiver}")