#include <iostream>
#include <string>
#include <curl/curl.h>
#include <ncurses.h>

static size_t WriteCallback(void *contents, size_t size, size_t nmemb, std::string *userp) {
    userp->append(static_cast<char*>(contents), size * nmemb);
    return size * nmemb;
}

double getConversionRate() {
    CURL *curl;
    CURLcode res;
    std::string readBuffer;
    double rate = 0.0;

    curl = curl_easy_init();
    if(curl) {
        curl_easy_setopt(curl, CURLOPT_URL, "https://api.coingecko.com/api/v3/simple/price?ids=solana&vs_currencies=usd");
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);
        res = curl_easy_perform(curl);
        curl_easy_cleanup(curl);

        if(res == CURLE_OK) {
            std::size_t usdPos = readBuffer.find("\"usd\":");
            if (usdPos != std::string::npos) {
                std::size_t start = readBuffer.find(':', usdPos) + 1;
                std::size_t end = readBuffer.find_first_of("},", start);
                if(start < end) {
                    std::string usdValue = readBuffer.substr(start, end - start);
                    usdValue.erase(0, usdValue.find_first_not_of(" \n\r\t"));
                    usdValue.erase(usdValue.find_last_not_of(" \n\r\t") + 1);
                    try {
                        rate = std::stod(usdValue);
                    } catch (const std::invalid_argument& ia) {
                        std::cerr << "Invalid argument: " << ia.what() << '\n';
                    } catch (const std::out_of_range& oor) {
                        std::cerr << "Out of Range error: " << oor.what() << '\n';
                    }
                }
            } else {
                std::cerr << "USD rate not found in response." << std::endl;
            }
        } else {
            std::cerr << "CURL failed with error code: " << res << std::endl;
        }
    }
    return rate;
}

void displayMenu(WINDOW *menu_win, int highlight, const std::string choices[], int n_choices, double solRate) {
    int x = 2, y = 2;
    box(menu_win, 0, 0);
    if(solRate == 0.0) {
        mvwprintw(menu_win, 1, 1, "Fetching SOL price...");
    } else {
        mvwprintw(menu_win, 1, 1, "1 SOL = $%.2f          ", solRate);
    }
    for(int i = 0; i < n_choices; ++i) {
        if(highlight == i + 1) {
            wattron(menu_win, A_REVERSE);
            mvwprintw(menu_win, y + 1, x, "%s", choices[i].c_str());
            wattroff(menu_win, A_REVERSE);
        } else
            mvwprintw(menu_win, y + 1, x, "%s", choices[i].c_str());
        ++y;
    }
    wrefresh(menu_win);
}

void processChoice(int choice, double rate) {
    echo();
    if (choice == 1) {
        printw("Enter amount in SOL: ");
        double sol;
        scanw("%lf", &sol);
        printw("%.2f SOL is approximately %.2f USD.\n", sol, sol * rate);
    } else if (choice == 2) {
        printw("Enter amount in USD: ");
        double usd;
        scanw("%lf", &usd);
        printw("%.2f USD is approximately %.2f SOL.\n", usd, usd / rate);
    }
    noecho();
}

int main() {
    initscr();
    clear();
    noecho();
    cbreak();

    start_color();
    init_pair(1, COLOR_CYAN, COLOR_BLACK);

    double rate = 0.0;

    WINDOW *menu_win = newwin(7, 60, 4, 4);
    keypad(menu_win, TRUE);
    refresh();

    const std::string choices[] = {"Convert SOL to USD", "Convert USD to SOL", "Exit"};
    int n_choices = sizeof(choices) / sizeof(std::string);

    int highlight = 1;

    bool needsFetch = true;

    displayMenu(menu_win, highlight, choices, n_choices, rate);

    int choice = 0;
    int c;

    while(1) {
        if (needsFetch) {
            refresh();
            rate = getConversionRate();
            needsFetch = false;
            clear();
            displayMenu(menu_win, highlight, choices, n_choices, rate);
        }
        c = wgetch(menu_win);
        switch(c) {
            case KEY_UP:
                if(highlight == 1)
                    highlight = n_choices;
                else
                    --highlight;
                break;
            case KEY_DOWN:
                if(highlight == n_choices)
                    highlight = 1;
                else
                    ++highlight;
                break;
            case 10: {
                choice = highlight;
                clear();
                refresh();
                if (choice == 3) {
                    endwin();
                    return 0;
                }
                rate = getConversionRate();
                if (rate == 0.0) {
                    printw("Failed to fetch conversion rate. Please try again later.\n");
                } else {
                    processChoice(choice, rate);
                }
                printw("Press any key to return to the menu.");
                getch();
                clear();
                displayMenu(menu_win, highlight, choices, n_choices, rate);
                break;
            }
            default:
                break;
        }
        displayMenu(menu_win, highlight, choices, n_choices, rate);
    }
    endwin();
    return 0;
}