#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <map>
#include <iomanip>
#include <fstream>
#include <cctype>
#include "json.hpp"

using namespace std;
using json = nlohmann::json;

struct Transaction {
    string from;
    string to;
    double value;
};

struct Block {
    int index;
    string hash;
    int64_t timestamp;
    string miner;
    double reward;
    vector<Transaction> transactions;
    string secret_info;
    int nonce;
};

vector<Block> blocks;


bool loadBlocksFromFile(const string& filename) {
    ifstream input_file(filename);
    if (!input_file.is_open()) {
        cerr << "Error: Cannot open file " << filename << endl;  //Ошибка: не удалось открыть файл
        return false;
    }

    try {
        json j;
        input_file >> j;
        blocks.clear();

        for (const auto& item : j) {
            Block block;
            block.index = item["index"];
            block.hash = item["hash"];
            block.timestamp = item["timestamp"];
            block.miner = item["miner"];
            block.reward = item["reward"];
            block.secret_info = item.value("secret_info", "");
            block.nonce = item["nonce"];

            for (const auto& tx_item : item["transactions"]) {
                Transaction tx;
                tx.from = tx_item["from"];
                tx.to = tx_item["to"];
                tx.value = tx_item["value"];
                block.transactions.push_back(tx);
            }

            blocks.push_back(block);
        }

                 //Успешно загружено                         //блоков из файла
        cout << "Successfully loaded " << blocks.size() << " blocks from " << filename << endl;
        return true;
    }
    catch (const exception& e) {
        cerr << "JSON parsing error: " << e.what() << endl;  //Ошибка при чтении JSON:
        return false;
    }
}

bool saveBlocksToFile(const string& filename) {
    json j;

    for (const auto& block : blocks) {
        json block_json;
        block_json["index"] = block.index;
        block_json["hash"] = block.hash;
        block_json["timestamp"] = block.timestamp;
        block_json["miner"] = block.miner;
        block_json["reward"] = block.reward;
        block_json["secret_info"] = block.secret_info;
        block_json["nonce"] = block.nonce;

        for (const auto& tx : block.transactions) {
            json tx_json;
            tx_json["from"] = tx.from;
            tx_json["to"] = tx.to;
            tx_json["value"] = tx.value;
            block_json["transactions"].push_back(tx_json);
        }

        j.push_back(block_json);
    }

    ofstream output_file(filename);
    if (!output_file.is_open()) {
        cerr << "Error: Cannot create file " << filename << endl;  //Ошибка: не удалось создать файл
        return false;
    }

    output_file << setw(4) << j << endl;
    cout << "Successfully saved " << blocks.size() << " blocks to " << filename << endl;  //Успешно сохранено  //блоков в файл
    return true;
}

void printBlock(const Block& block) {
    cout << "index: " << block.index << "\n"
        << "hash: " << block.hash << "\n"
        << "timestamp: " << block.timestamp << "\n"
        << "miner: " << block.miner << "\n"
        << "reward: " << fixed << setprecision(2) << block.reward << "\n"
        << "secret_info: " << block.secret_info << "\n"
        << "nonce: " << block.nonce << "\n"
        << "Transactions (" << block.transactions.size() << "):\n";

    for (const auto& tx : block.transactions) {
        cout << "  " << tx.from << " -> " << tx.to << ": " << tx.value << "\n";
    }
    cout << "----------------------------\n";
}

void printAllBlocks() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks.Download them first." << endl;   //Нет данных о блоках. Загрузите их сначала.
        return;
    }

    for (const auto& block : blocks) {
        printBlock(block);
    }
}

void filterByMiner() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks. Download them first." << endl;  //Нет данных о блоках. Загрузите их сначала.
        return;
    }

    string minerName;
    cout << "Enter the miner's name: "; //Введите имя майнера:
    cin >> minerName;

    bool found = false;
    for (const auto& block : blocks) {
        if (block.miner == minerName) {
            printBlock(block);
            found = true;
        }
    }

    if (!found) {
        cout << "Blocks with a miner " << minerName << " not found." << endl; //Блоки с майнером ...  не найдены
    }
}

void printTransactionsCount() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks. Download them first." << endl;  //Нет данных о блоках. Загрузите их сначала.
        return;
    }

    cout << "Number of transactions in blocks: " << endl;   //Количество транзакций в блоках:
    for (const auto& block : blocks) {
        cout << "block " << block.index << ": "
            << block.transactions.size() << " transactions" << endl;
    }
}

void calculateBalances() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks. Download them first." << endl;  //Нет данных о блоках. Загрузите их сначала.
        return;
    }

    map<string, double> balances;

    for (const auto& block : blocks) {
        for (const auto& tx : block.transactions) {
            if (tx.from != "SYSTEM") {
                balances[tx.from] -= tx.value;
            }
            balances[tx.to] += tx.value;
        }
    }

    cout << "User balances:" << endl; //Балансы пользователей:
    for (const auto& entry : balances) {
        cout << entry.first << ": " << fixed << setprecision(2) << entry.second << endl;
    }
}

void sortBlocksByIndex() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks. Download them first." << endl;
        return;
    }

    for (size_t i = 0; i < blocks.size(); ++i) {
        for (size_t j = 0; j < blocks.size() - i - 1; ++j) {
            if (blocks[j].index > blocks[j + 1].index) {
                swap(blocks[j], blocks[j + 1]);
            }
        }
    }
    cout << "The blocks are sorted by index." << endl;   //Блоки отсортированы по индексу.
}

void printEvenIndexBlocks() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks. Download them first." << endl;
        return;
    }

    cout << "Blocks with an even index:" << endl; //Блоки с четным индексом:
    for (const auto& block : blocks) {
        if (block.index % 2 == 0) {
            printBlock(block);
        }
    }
}

void printVowelMinerBlocks() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks. Download them first." << endl;
        return;
    }

    const string vowels = "AEIOUaeiou";
    cout << "Blocks where the miner starts with a vowel:" << endl; //Блоки, где майнер начинается с гласной:

    for (const auto& block : blocks) {
        if (!block.miner.empty() && vowels.find(block.miner[0]) != string::npos) {
            printBlock(block);
        }
    }
}

void printFourDigitNonceBlocks() {
    if (blocks.empty()) {
        cout << "There is no data about the blocks. Download them first." << endl;
        return;
    }

    cout << "Blocks with a 4-digit nonce (1000-9999):" << endl; //Блоки с 4-значным nonce (1000-9999):
    for (const auto& block : blocks) {
        if (block.nonce >= 1000 && block.nonce <= 9999) {
            printBlock(block);
        }
    }
}

void showMenu() {
    cout << "\n=== Menu ===" << endl  //Загрузить блоки из файла
        << "1. Load blocks from file" << endl  //Загрузить блоки из файла
        << "2. Save blocks to file" << endl  //Сохранить блоки в файл
        << "3. Print all blocks" << endl  //Вывести все блоки
        << "4. Filter by miner" << endl  //Фильтр по майнеру
        << "5. Transaction count" << endl  //Количество транзакций
        << "6. User balances" << endl   //Балансы пользователей
        << "7. Sort by index" << endl  //Сортировать по индексу
        << "8. Blocks with even index" << endl  //Блоки с четным индексом
        << "9. Blocks where miner starts with a vowel" << endl  //Блоки, где майнер начинается с гласной
        << "10. Blocks with 4-digit nonce" << endl  //Блоки с 4-значным nonce
        << "0. Exit" << endl  //Выход
        << "Enter choice: "; //Введите номер
}

int main() {
    int choice;
    do {
        showMenu();
        cin >> choice;

        switch (choice) {
        case 1: {
            string filename;
            cout << "Enter the file name to download: "; //Введите имя файла для загрузки:
            cin >> filename;
            if (!loadBlocksFromFile(filename)) {
                cout << "File upload error!" << endl; //Ошибка загрузки файла!
            }
            break;
        }
        case 2: {
            string filename;
            cout << "Enter the file name to save: "; //Введите имя файла для сохранения:
            cin >> filename;
            if (!saveBlocksToFile(filename)) {
                cout << "File upload error!" << endl;
            }
            break;
        }
        case 3:
            printAllBlocks();
            break;
        case 4:
            filterByMiner();
            break;
        case 5:
            printTransactionsCount();
            break;
        case 6:
            calculateBalances();
            break;
        case 7:
            sortBlocksByIndex();
            break;
        case 8:
            printEvenIndexBlocks();
            break;
        case 9:
            printVowelMinerBlocks();
            break;
        case 10:
            printFourDigitNonceBlocks();
            break;
        case 0:
            cout << "Exit the program..." << endl;
            break;
        default:
            cout << "Wrong choice! Try again." << endl; //Неверный выбор! Попробуйте снова.
        }
    } while (choice != 0);

    return 0;
}