//  _____         _  _____
// |_   _|____  _| ||_   _|_   __
//   | |/ _ \ \/ / __|| | \ \ / /
//   | |  __/>  <| |_ | |  \ V /
//   |_|\___/_/\_\\__||_|   \_/
// Author: Love Billenius <lovebillenius@disroot.org>
// License: GPL-3

#include "Tui.hpp"

#include <iostream>
#include <optional>
#include <ostream>
#include <utility>

#include "Command.hpp"
#include "Pager.hpp"

Tui::Tui(Pager pager) : m_pager(std::move(pager)) {
}

std::optional<int> get_page_number(const std::string_view line) {
    const size_t space = line.find_first_of(' ');
    if (space == std::string::npos)
        return std::nullopt;

    int number = 0;
    const size_t size = line.size();
    for (size_t i = space; i < size; i++) {
        const char c = line[i];
        if (!std::isdigit(c))
            return std::nullopt;

        number = number * 10 + (c - '0');
    }

    return number;
}

void printHelp() {
    std::cout
            << "Available Commands:\n"
            << "  r, refresh                : Refresh the current view.\n"
            << "  n, >, next                : Move to the next item.\n"
            << "  p, <, previous            : Move to the previous item.\n"
            << "  x, exit, q, quit          : Exit the application.\n"
            << "  seek <number>, s <number> : Seek to the specified number.\n"
            << "  help, h, ?                : Display this help message."
            << std::endl;
}

void Tui::run() {
    clear_console();
    std::cout << m_pager->str_pretty() << std::endl;
    for (;;) {
        std::cout << "Enter a command: ";
        std::flush(std::cout);
        Command::Command command;
        try {
            command = Command::readCommand();
        } catch (const Command::NoNumberException &e) {
            std::cout << e.what() << std::endl;
            continue;
        }

        bool should_exit = false;
        bool should_output = false;
        auto visitor = [this, &should_exit, &should_output]<typename T0>(T0 &&arg) {
            using T = std::decay_t<T0>;

            if constexpr (std::is_same_v<T, Command::None>) {
                std::cout << "Invalid command!" << std::endl;
            } else if constexpr (std::is_same_v<T, Command::Next>) {
                try {
                    std::cout << "Fetching..." << std::endl;
                    m_pager += 1;
                } catch (const std::runtime_error &e) {
                    std::cout << e.what() << std::endl;
                    return;
                }
                should_output = true;
            } else if constexpr (std::is_same_v<T, Command::Previous>) {
                try {
                    std::cout << "Fetching..." << std::endl;
                    m_pager -= 1;
                } catch (const std::runtime_error &e) {
                    std::cout << e.what() << std::endl;
                    return;
                }
                should_output = true;
            } else if constexpr (std::is_same_v<T, Command::Refresh>) {
                m_pager.clear();
                should_output = true;
            } else if constexpr (std::is_same_v<T, Command::Exit>) {
                should_exit = true;
            } else if constexpr (std::is_same_v<T, Command::Help>) {
                printHelp();
            } else if constexpr (std::is_same_v<T, Command::Seek>) {
                const Command::Seek &seek = arg;
                const int number = seek.number;
                try {
                    std::cout << "Fetching..." << std::endl;
                    m_pager.seek(number);
                } catch (const std::runtime_error &e) {
                    std::cout << e.what() << std::endl;
                    return;
                }
                should_output = true;
            }
        };
        std::visit(visitor, command);
        if (should_exit)
            return;

        clear_console();
        if (should_output)
            std::cout << m_pager->str_pretty() << std::endl;
    }
}

void Tui::clear_console() {
    const auto CMD =
#ifdef _WIN32 || _WIN64
             "cls";
#else
            "clear";
#endif

    system(CMD);
}