#include "TestManager.hpp"
#include "MinecraftServer.hpp"

#include <catch2/catch_test_case_info.hpp>

#include <protocolCraft/Types/NBT/NBT.hpp>

#include <botcraft/Network/NetworkManager.hpp>
#include <botcraft/Game/Entities/EntityManager.hpp>
#include <botcraft/Game/Entities/LocalPlayer.hpp>
#include <botcraft/Utilities/Logger.hpp>

#include <fstream>
#include <sstream>
#include <regex>

std::string ReplaceCharacters(const std::string& in, const std::vector<std::pair<char, std::string>>& replacements = { {'"', "\\\""}, {'\n', "\\n"} });

TestManager::TestManager()
{
    current_offset = {spacing_x, 2, 2 * spacing_z };
    current_test_index = 0;
    bot_index = 0;
}

TestManager::~TestManager()
{

}

TestManager& TestManager::GetInstance()
{
    static TestManager instance;
    return instance;
}

const Botcraft::Position& TestManager::GetCurrentOffset() const
{
    return current_offset;
}

#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
void TestManager::SetBlock(const std::string& name, const Botcraft::Position& pos, const std::map<std::string, std::string>& blockstates, const std::map<std::string, std::string>& metadata, const bool escape_metadata) const
#else
void TestManager::SetBlock(const std::string& name, const Botcraft::Position& pos, const int block_variant, const std::map<std::string, std::string>& metadata, const bool escape_metadata) const
#endif
{
    MakeSureLoaded(pos);
    std::stringstream command;
    command
        << "setblock" << " "
        << pos.x << " "
        << pos.y << " "
        << pos.z << " "
        << ((name.size() > 10 && name.substr(0, 10) == "minecraft:") ? "" : "minecraft:") << name;
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
    if (!blockstates.empty())
    {
        command << "[";
        int index = 0;
        for (const auto& [k, v] : blockstates)
        {
            command << k << "=";
            if (v.find(' ') != std::string::npos ||
                v.find(',') != std::string::npos ||
                v.find(':') != std::string::npos)
            {
                // Make sure the whole string is between quotes and all internal quotes are escaped
                command << "\"" << ReplaceCharacters(v) << "\"";
            }
            else
            {
                command << v;
            }
            command << (index == blockstates.size() - 1 ? "" : ",");
            index += 1;
        }
        command << "]";
    }
#else
    command << " "
        << block_variant << " "
        << "replace" << " ";
#endif
    if (!metadata.empty())
    {
        command << "{";
        int index = 0;
        for (const auto& [k, v] : metadata)
        {
            command << k << ":";
            if (escape_metadata &&
                (v.find(' ') != std::string::npos ||
                 v.find(',') != std::string::npos ||
                 v.find(':') != std::string::npos)
                )
            {
                // Make sure the whole string is between quotes and all internal quotes are escaped
                command << "\"" << ReplaceCharacters(v) << "\"";
            }
            else
            {
                command << v;
            }
            command << (index == metadata.size() - 1 ? "" : ",");
            index += 1;
        }
        command << "}";
    }
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
    command << " replace";
#endif
    MinecraftServer::GetInstance().SendLine(command.str());
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
    MinecraftServer::GetInstance().WaitLine(
        ".*: Changed the block at "
        + std::to_string(pos.x) + ", "
        + std::to_string(pos.y) + ", "
        + std::to_string(pos.z) + ".*", 5000);
#else
    MinecraftServer::GetInstance().WaitLine(".*: Block placed.*", 5000);
#endif
}

void TestManager::CreateBook(const Botcraft::Position& pos, const std::vector<std::string>& pages, const std::string& facing, const std::string& title, const std::string& author, const std::vector<std::string>& description)
{
    int facing_id = 0;
    if (facing == "south")
    {
        facing_id = 0;
    }
    else if (facing == "west")
    {
        facing_id = 1;
    }
    else if (facing == "north")
    {
        facing_id = 2;
    }
    else if (facing == "east")
    {
        facing_id = 3;
    }

    std::stringstream command;

    command
#if PROTOCOL_VERSION < 477 /* < 1.14 */
        << "summon" << " "
        << "minecraft:item_frame" << " "
#else
        << "setblock" << " "
#endif
        << pos.x << " "
        << pos.y << " "
        << pos.z << " "
#if PROTOCOL_VERSION < 477 /* < 1.14 */
        << "{Facing:" << facing_id << ","
        << "Item:{"
#else
        << "minecraft:lectern"
        << "[facing=" << facing << ",has_book=true]"
        << "{"
        << "Book:{"
#endif
            << "id:\"written_book\"" << ","
            << "Count:1" << ","
            << "tag:{"
                << "pages:[";
    for (size_t i = 0; i < pages.size(); ++i)
    {
        command
            << "\"{"
            << "\\\"text\\\"" << ":" << "\\\"" << ReplaceCharacters(pages[i], { {'\n', "\\\\n"}, {'"', "\\\\\\\""} }) << "\\\""
            << "}\"" << ((i < pages.size() - 1) ? "," : "");
    }
    command << "]";
    if (!title.empty())
    {
        command << ","
            << "title" << ":" << "\"" << ReplaceCharacters(title) << "\"";
    }
    if (!author.empty())
    {
        command << ","
            << "author" << ":" << "\"" << ReplaceCharacters(author) << "\"";
    }
    if (!description.empty())
    {
        command << "," << "display" << ":"
            << "{Lore:[";
        for (size_t i = 0; i < description.size(); ++i)
        {
            command
                << "\""
#if PROTOCOL_VERSION < 735 /* < 1.16 */
                // Just a list of strings is working before 1.16(?)
                << ReplaceCharacters(description[i])
#else
                // After, a JSON text element is required
                << "{" << "\\\"text\\\"" << ":" << "\\\"" << ReplaceCharacters(description[i], { { '\n', "\\\\n"}, { '"', "\\\\\\\"" } }) << "\\\"" << "}"
#endif
                << "\"" << ((i < description.size() - 1) ? "," : "");
        }
        command << "]}";
    }
    command
        << "}" // tag
        << "}" // Item
        << "}"; // Main

    MinecraftServer::GetInstance().SendLine(command.str());
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */ && PROTOCOL_VERSION < 477 /* < 1.14 */
    MinecraftServer::GetInstance().WaitLine(".*?: Summoned new Item Frame.*", 5000);
#elif PROTOCOL_VERSION == 340 /* 1.12.2 */
    MinecraftServer::GetInstance().WaitLine(".*?: Object successfully summoned.*", 5000);
#else
    MinecraftServer::GetInstance().WaitLine(
        ".*: Changed the block at "
        + std::to_string(pos.x) + ", "
        + std::to_string(pos.y) + ", "
        + std::to_string(pos.z) + ".*", 5000);
#endif
}

void TestManager::Teleport(const std::string& name, const Botcraft::Vector3<double>& pos, const float yaw, const float pitch) const
{
    std::stringstream command;
    command
        << "teleport" << " "
        << name << " "
        << pos.x << " "
        << pos.y << " "
        << pos.z << " "
        << yaw << " "
        << pitch;
    MinecraftServer::GetInstance().SendLine(command.str());
    MinecraftServer::GetInstance().WaitLine(".*?Teleported " + name + " to.*", 5000);
}

Botcraft::Position TestManager::GetStructureSize(const std::string& filename) const
{
    std::string no_space_filename = ReplaceCharacters(filename, { {' ', "_"} });
    // If there is a # in the file name, only use what's before (useful to have multiple tests sharing the same structure file)
    size_t split_index = no_space_filename.find('#');
    if (split_index != std::string::npos)
    {
        no_space_filename = no_space_filename.substr(0, split_index);
    }
    const std::filesystem::path filepath = MinecraftServer::GetInstance().GetStructurePath() / (no_space_filename + ".nbt");

    if (!std::filesystem::exists(filepath))
    {
        return GetStructureSize("_default");
    }
    std::ifstream file(filepath.string(), std::ios::in | std::ios::binary);
    file.unsetf(std::ios::skipws);

    ProtocolCraft::NBT::Value nbt;
    file >> nbt;
    file.close();

    // TODO: deal with recursive structures (structures containing structure blocks) ?
    return nbt["size"].as_list_of<int>();
}

void TestManager::CreateTPSign(const Botcraft::Position& src, const Botcraft::Vector3<double>& dst, const std::vector<std::string>& texts, const std::string& facing, const TestSucess success) const
{
    Botcraft::Position offset_target;
    int block_rotation = 0;
    if (facing == "north")
    {
        block_rotation = 0;
        offset_target = dst + Botcraft::Position(0, 0, -1);
    }
    else if (facing == "south")
    {
        block_rotation = 8;
        offset_target = dst + Botcraft::Position(0, 0, 1);
    }
    else if (facing == "east")
    {
        block_rotation = 12;
        offset_target = dst + Botcraft::Position(-1, 0, 0);
    }
    else if (facing == "west")
    {
        block_rotation = 4;
        offset_target = dst + Botcraft::Position(1, 0, 0);
    }
    std::string text_color;
    switch (success)
    {
    case TestSucess::None:
        text_color = "black";
        break;
    case TestSucess::Success:
        text_color = "dark_green";
        break;
    case TestSucess::Failure:
        text_color = "red";
        break;
    case TestSucess::ExpectedFailure:
        text_color = "gold";
        break;
    }
#if PROTOCOL_VERSION < 763 /* < 1.20 */
    std::map<std::string, std::string> lines;
#else
    std::vector<std::string> lines;
    lines.reserve(4);
#endif
    for (size_t i = 0; i < std::min(texts.size(), static_cast<size_t>(4)); ++i)
    {
        std::stringstream line;
        line
            << "{"
            << "\"text\":\"" << texts[i] << "\"" << ",";
        if (i == 0)
        {
            line
                << "\"underlined\"" << ":" << "false" << ","
                << "\"color\"" << ":" << "\"" << "black" << "\"" << ","
                << "\"clickEvent\"" << ":" << "{"
                    << "\"action\"" << ":" << "\"run_command\"" << ","
                    << "\"value\"" << ":" << "\""
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
                    << "teleport @s" << " " << offset_target.x << " " << offset_target.y << " " << offset_target.z
                    << " " << "facing" << " " << dst.x << " " << dst.y << " " << dst.z
#else
                    << "teleport @s" << " " << dst.x << " " << dst.y << " " << dst.z
#endif
                    << "\""
                << "}";
        }
        else
        {
            line
                << "\"underlined\"" << ":" << "true" << ","
                << "\"color\"" << ":" << "\"" << text_color << "\"";
        }
        line << "}";
#if PROTOCOL_VERSION < 763 /* < 1.20 */
        lines.insert({ "Text" + std::to_string(i + 1), line.str() });
#else
        lines.push_back(line.str());
#endif
    }
    // There is a bug in version 1.14 (and prereleases) that requires all 4 lines
    // to be specified or the server can't read the text. See: https://bugs.mojang.com/browse/MC-144316
#if PROTOCOL_VERSION > 459 /* > 1.13.2 */ && PROTOCOL_VERSION < 478 /* < 1.14.1 */
    for (size_t i = texts.size(); i < 4ULL; ++i)
    {
        lines.insert({ "Text" + std::to_string(i + 1), "{\"text\":\"\"}" });
    }
#endif
#if PROTOCOL_VERSION > 762 /* > 1.19.4 */ // In 1.20 texts are sent as a list with exactly 4 elements
    std::stringstream text_content;
    text_content << "{\"messages\":[";
    for (size_t i = 0; i < 4ULL; ++i)
    {
        if (i < lines.size())
        {
            text_content << "\"" << ReplaceCharacters(lines[i]) << "\"";
        }
        else
        {
            text_content << "\"" << ReplaceCharacters("{\"text\":\"\"}") << "\"";
        }
        if (i != 3ULL)
        {
            text_content << ",";
        }
    }
    text_content << "]}";
    const std::string text_content_str = text_content.str();
#endif

    SetBlock(
#if PROTOCOL_VERSION < 393 /* < 1.13 */
        "standing_sign",
#elif PROTOCOL_VERSION < 477 /* < 1.14 */
        "sign",
#else
        "oak_sign",
#endif
        src,
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
        {
            { "rotation", std::to_string(block_rotation) }
        },
#else
        block_rotation,
#endif
#if PROTOCOL_VERSION < 763 /* < 1.20 */
        lines
#else
        {
            { "is_waxed", "true" },
            { "front_text", text_content_str },
            { "back_text", text_content_str },
        },
        false
#endif
    );
}

void TestManager::LoadStructure(const std::string& filename, const Botcraft::Position& pos, const Botcraft::Position& load_offset) const
{
    std::string no_space_filename = ReplaceCharacters(filename, { {' ', "_"} });
    // If there is a # in the file name, only use what's before (useful to have multiple tests sharing the same structure file)
    size_t split_index = no_space_filename.find('#');
    if (split_index != std::string::npos)
    {
        no_space_filename = no_space_filename.substr(0, split_index);
    }
    const std::string& loaded = std::filesystem::exists(MinecraftServer::GetInstance().GetStructurePath() / (no_space_filename + ".nbt")) ?
        no_space_filename :
        "_default";

    SetBlock(
        "structure_block",
        pos,
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
        {},
#else
        0,
#endif
        {
            {"mode", "LOAD"},
            {"name", loaded},
            {"posX", std::to_string(load_offset.x)},
            {"posY", std::to_string(load_offset.y)},
            {"posZ", std::to_string(load_offset.z)},
            {"showboundingbox", "1"}
        }
    );
    SetBlock("redstone_block", pos + Botcraft::Position(0, 1, 0));
}

void TestManager::MakeSureLoaded(const Botcraft::Position& pos) const
{
    std::shared_ptr<Botcraft::World> world = chunk_loader->GetWorld();
    if (chunk_loader->GetWorld()->IsLoaded(pos))
    {
        return;
    }

    Teleport(chunk_loader_name, pos);

    // Wait for bot to load center and corner view_distance blocks
    const int chunk_x = static_cast<int>(std::floor(pos.x / static_cast<double>(Botcraft::CHUNK_WIDTH)));
    const int chunk_z = static_cast<int>(std::floor(pos.z / static_cast<double>(Botcraft::CHUNK_WIDTH)));
    // -1 because sometimes corner chunks are not sent
    const int view_distance = MinecraftServer::options.view_distance - 1;
    std::vector<std::pair<int, int>> wait_loaded = {
        {chunk_x * Botcraft::CHUNK_WIDTH, chunk_z * Botcraft::CHUNK_WIDTH},
        {(chunk_x + view_distance) * Botcraft::CHUNK_WIDTH - 1, (chunk_z + view_distance) * Botcraft::CHUNK_WIDTH - 1},
        {(chunk_x - view_distance) * Botcraft::CHUNK_WIDTH, (chunk_z + view_distance) * Botcraft::CHUNK_WIDTH - 1},
        {(chunk_x + view_distance) * Botcraft::CHUNK_WIDTH - 1, (chunk_z - view_distance) * Botcraft::CHUNK_WIDTH},
        {(chunk_x - view_distance) * Botcraft::CHUNK_WIDTH, (chunk_z - view_distance) * Botcraft::CHUNK_WIDTH}
    };

    if (!Botcraft::Utilities::WaitForCondition([&]()
        {
            for (size_t i = 0; i < wait_loaded.size(); ++i)
            {
                if (!world->IsLoaded(Botcraft::Position(wait_loaded[i].first, pos.y, wait_loaded[i].second)))
                {
                    return false;
                }
            }
            return true;
        }, 15000))
    {
        LOG_ERROR("Timeout waiting " << chunk_loader_name << " to load surroundings from " << chunk_loader->GetLocalPlayer()->GetPosition());
        for (size_t i = 0; i < wait_loaded.size(); ++i)
        {
            const Botcraft::Position pos(wait_loaded[i].first, pos.y, wait_loaded[i].second);
            LOG_ERROR(pos << " is" << (world->IsLoaded(pos) ? "" : " not") << " loaded");
        }
        std::stringstream loaded;
        loaded << "\n";
        for (const auto& c : *world->GetChunks())
        {
            loaded << c.first.first << "\t" << c.first.second << ";";
        }
        LOG_ERROR("Loaded chunks: " << loaded.str());
        throw std::runtime_error("Timeout waiting " + chunk_loader_name + " to load surroundings");
    }
}

void TestManager::SetGameMode(const std::string& name, const Botcraft::GameType gamemode) const
{
    std::string gamemode_string;
    switch (gamemode)
    {
    case Botcraft::GameType::Survival:
        gamemode_string = "survival";
        break;
    case Botcraft::GameType::Creative:
        gamemode_string = "creative";
        break;
    case Botcraft::GameType::Adventure:
        gamemode_string = "adventure";
        break;
    case Botcraft::GameType::Spectator:
        gamemode_string = "spectator";
        break;
    default:
        return;
    }
    std::stringstream command;
    command
        << "gamemode" << " "
        << gamemode_string << " "
        << name;
    MinecraftServer::GetInstance().SendLine(command.str());
    MinecraftServer::GetInstance().WaitLine(".*? Set " + name + "'s game mode to.*", 5000);
}


void TestManager::testRunStarting(Catch::TestRunInfo const& test_run_info)
{
    // Make sure the server is running and ready before the first test run
    MinecraftServer::GetInstance().Initialize();
    // Retrieve header size
    header_size = GetStructureSize("_header_running");
    chunk_loader = GetBot(chunk_loader_name, Botcraft::GameType::Spectator);
}

void TestManager::testCaseStarting(Catch::TestCaseInfo const& test_info)
{
    // Retrieve test structure size
    current_test_size = GetStructureSize(test_info.name);
    LoadStructure("_header_running", Botcraft::Position(current_offset.x, 0, spacing_z - header_size.z));
    current_offset.z = 2 * spacing_z;
}

void TestManager::testCasePartialStarting(Catch::TestCaseInfo const& test_info, uint64_t part_number)
{
    // Load header
    current_header_position = current_offset - Botcraft::Position(0, 2, 0);
    LoadStructure("_header_running", current_header_position);
    current_offset.z += header_size.z;
    // Load test structure
    LoadStructure(test_info.name, current_offset + Botcraft::Position(0, -1, 0), Botcraft::Position(0, 1, 0));
    current_test_case_failures.clear();
    section_stack = { std::filesystem::path(test_info.lineInfo.file).stem().string() };
}

void TestManager::sectionStarting(Catch::SectionInfo const& section_info)
{
    section_stack.push_back(section_info.name);
}

void TestManager::assertionEnded(Catch::AssertionStats const& assertion_stats)
{
    if (!assertion_stats.assertionResult.succeeded())
    {
        const std::filesystem::path file_path = std::filesystem::relative(assertion_stats.assertionResult.getSourceInfo().file, BASE_SOURCE_DIR);
        current_test_case_failures.push_back(
            ReplaceCharacters(file_path.string(), {{'\\', "/"}}) + ":" +
            std::to_string(assertion_stats.assertionResult.getSourceInfo().line) + "\n\n" +
            assertion_stats.assertionResult.getExpressionInMacro() + "\n\n"
            "with expansion:" + "\n" +
            assertion_stats.assertionResult.getExpandedExpression()
        );
    }
}

void TestManager::testCasePartialEnded(Catch::TestCaseStats const& test_case_stats, uint64_t part_number)
{
    const bool passed = test_case_stats.totals.assertions.allPassed();
    // Replace header with proper test result
    LoadStructure(passed ? "_header_success" : (test_case_stats.testInfo->okToFail() ? "_header_expected_fail" : "_header_fail"), current_header_position);
    // Create TP sign for the partial that just ended
    CreateTPSign(
        Botcraft::Position(-2 * (current_test_index + 1), 2, -2 * part_number - 5),
        Botcraft::Vector3(current_offset.x, 2, current_offset.z - 1),
        section_stack, "north", passed ? TestSucess::Success : (test_case_stats.testInfo->okToFail() ? TestSucess::ExpectedFailure : TestSucess::Failure)
    );
    // Create back to spawn sign for the section that just ended
    CreateTPSign(
        Botcraft::Position(current_offset.x, 2, current_offset.z - 1),
        Botcraft::Vector3(-2 * (current_test_index + 1), 2, -2 * static_cast<int>(part_number) - 5),
        section_stack, "south", passed ? TestSucess::Success : (test_case_stats.testInfo->okToFail() ? TestSucess::ExpectedFailure : TestSucess::Failure)
    );
    if (!passed)
    {
        CreateBook(
            Botcraft::Position(current_offset.x + 1, 2, current_offset.z - header_size.z),
            current_test_case_failures,
            "north",
            test_case_stats.testInfo->name + "#" + std::to_string(part_number),
            "Botcraft Test Framework",
            section_stack
        );
    }
    current_offset.z += current_test_size.z + spacing_z;

    // Kill all items that could exist on the floor
    MinecraftServer::GetInstance().SendLine("kill @e[type=item]");
#if PROTOCOL_VERSION > 340 /* > 1.12.2 */
    // In 1.12.2 server sends one line per entity killed so we can't wait without knowing
    // how many there were. Just assume the command worked
    MinecraftServer::GetInstance().WaitLine(".*?: (?:Killed|No entity was found).*", 5000);
#endif
}

void TestManager::testCaseEnded(Catch::TestCaseStats const& test_case_stats)
{
    const bool passed = test_case_stats.totals.assertions.allPassed();
    LoadStructure(passed ? "_header_success" : (test_case_stats.testInfo->okToFail() ? "_header_expected_fail" : "_header_fail"), Botcraft::Position(current_offset.x, 0, spacing_z - header_size.z));
    // Create Sign to TP to current test
    CreateTPSign(
        Botcraft::Position(-2 * (current_test_index + 1), 2, -2),
        Botcraft::Vector3(current_offset.x, 2, spacing_z - 1),
        { std::filesystem::path(test_case_stats.testInfo->lineInfo.file).stem().string(), test_case_stats.testInfo->name },
        "north", passed ? TestSucess::Success : (test_case_stats.testInfo->okToFail() ? TestSucess::ExpectedFailure : TestSucess::Failure)
    );
    // Create sign to TP to TP back to spawn
    CreateTPSign(
        Botcraft::Position(current_offset.x, 2, spacing_z - 1),
        Botcraft::Vector3(-2 * (current_test_index + 1), 2, -2),
        { std::filesystem::path(test_case_stats.testInfo->lineInfo.file).stem().string(), test_case_stats.testInfo->name },
        "south", passed ? TestSucess::Success : (test_case_stats.testInfo->okToFail() ? TestSucess::ExpectedFailure : TestSucess::Failure)
    );
    current_test_index += 1;
    current_offset.x += std::max(current_test_size.x, header_size.x) + spacing_x;
}

void TestManager::testRunEnded(Catch::TestRunStats const& test_run_info)
{
    if (chunk_loader)
    {
        chunk_loader->Disconnect();
    }
}




void TestManagerListener::testRunStarting(Catch::TestRunInfo const& test_run_info)
{
    TestManager::GetInstance().testRunStarting(test_run_info);
}

void TestManagerListener::testCaseStarting(Catch::TestCaseInfo const& test_info)
{
    TestManager::GetInstance().testCaseStarting(test_info);
}

void TestManagerListener::testCasePartialStarting(Catch::TestCaseInfo const& test_info, uint64_t part_number)
{
    TestManager::GetInstance().testCasePartialStarting(test_info, part_number);
}

void TestManagerListener::sectionStarting(Catch::SectionInfo const& section_info)
{
    TestManager::GetInstance().sectionStarting(section_info);
}

void TestManagerListener::assertionEnded(Catch::AssertionStats const& assertion_stats)
{
    TestManager::GetInstance().assertionEnded(assertion_stats);
}

void TestManagerListener::testCasePartialEnded(Catch::TestCaseStats const& test_case_stats, uint64_t part_number)
{
    TestManager::GetInstance().testCasePartialEnded(test_case_stats, part_number);
}

void TestManagerListener::testCaseEnded(Catch::TestCaseStats const& test_case_stats)
{
    TestManager::GetInstance().testCaseEnded(test_case_stats);
}

void TestManagerListener::testRunEnded(Catch::TestRunStats const& test_run_info)
{
    TestManager::GetInstance().testRunEnded(test_run_info);
}
CATCH_REGISTER_LISTENER(TestManagerListener)

std::string ReplaceCharacters(const std::string& in, const std::vector<std::pair<char, std::string>>& replacements)
{
    std::string output;
    output.reserve(in.size());

    for (size_t i = 0; i < in.size(); ++i)
    {
        bool found = false;
        for (size_t j = 0; j < replacements.size(); ++j)
        {
            if (replacements[j].first == in[i])
            {
                output += replacements[j].second;
                found = true;
                break;
            }
        }
        if (!found)
        {
            output += in[i];
        }
    }

    return output;
}