#include "client.hh"

namespace {
std::queue<proto::chunk> received_chunks;

} // namespace

namespace client {

static shared::net::connection make_connection(const std::string_view address,
                                               const std::string_view port) {
    constexpr addrinfo hints = {.ai_flags = AI_PASSIVE,
                                .ai_family = AF_INET,
                                .ai_socktype = SOCK_STREAM};
    const auto info = shared::net::get_addr_info(address, port, &hints);
    const auto sock = shared::net::make_socket(info.get());
    shared::net::connect_socket(sock, info.get());
    return shared::net::connection(sock);
}

static proto::packet
make_request_chunk_packet(const shared::math::coords& coords) noexcept {
    proto::packet packet;

    const auto chunk_packet = packet.mutable_request_chunk_packet();
    shared::net::set_coords(chunk_packet->mutable_chunk_pos(), coords);

    return packet;
}

static proto::packet make_auth_packet(const std::string& username,
                                      const std::string& password) noexcept {
    proto::packet packet;

    const auto auth_packet = packet.mutable_auth_packet();
    auth_packet->set_username(username);
    auth_packet->set_password(password);

    return packet;
}

static proto::packet
make_add_block_packet(const shared::math::coords& coords, const glm::ivec3& pos,
                      const std::uint32_t& active) noexcept {
    proto::packet packet;

    const auto add_block_packet = packet.mutable_add_block_packet();
    shared::net::set_coords(add_block_packet->mutable_chunk_pos(), coords);
    shared::net::set_ivec3(add_block_packet->mutable_block_pos(), pos);

    add_block_packet->set_active_item(active);

    return packet;
}

static proto::packet
make_remove_block_packet(const shared::math::coords& coords,
                         const glm::ivec3& pos) noexcept {
    proto::packet packet;

    const auto remove_block_packet = packet.mutable_remove_block_packet();
    shared::net::set_coords(remove_block_packet->mutable_chunk_pos(), coords);
    shared::net::set_ivec3(remove_block_packet->mutable_block_pos(), pos);

    return packet;
}

[[maybe_unused]] // [[actually_used]]
static proto::packet
make_remove_chunk_packet(const shared::math::coords& coords) noexcept {
    proto::packet packet;

    const auto remove_chunk_packet = packet.mutable_remove_chunk_packet();
    shared::net::set_coords(remove_chunk_packet->mutable_chunk_pos(), coords);

    return packet;
}

static proto::packet
make_move_packet(const client::moveable& localplayer) noexcept {
    proto::packet packet;

    const auto move_packet = packet.mutable_move_packet();
    move_packet->set_commands(localplayer.get_commands());
    shared::net::set_angles(move_packet->mutable_viewangles(),
                            localplayer.get_angles());
    move_packet->set_active_item(localplayer.get_active_item());
    move_packet->set_sequence(localplayer.get_latest_sequence());

    return packet;
}

static void handle_init_packet(const proto::init& packet) noexcept {

    // Draw distance is the std::min, but we make it more verbose.
    if (const auto& wanted = state::draw_distance =
            settings::get({"video", "draw_distance"}, 32);
        wanted != packet.draw_distance()) {

        if (wanted < packet.draw_distance()) {
            state::draw_distance = wanted;
        } else {
            shared::print::warn << shared::print::time
                                << "client: server supported draw_distance ("
                                << packet.draw_distance()
                                << ") less than requested (" << wanted << ")\n";
            state::draw_distance = packet.draw_distance();
        }
    }

    state::seed = packet.seed();
    state::tickrate = packet.tickrate();
    state::tick = packet.tick();
    state::delta_ticks = 0.0f; // amount of time passed (in ticks)

    const auto& localplayer = packet.localplayer();
    const auto& index = localplayer.animate().entity().index();

    state::localplayer_index = index;
    state::entities.emplace(index, std::make_unique<player>(localplayer));
}

static void
handle_animate_update_packet(const proto::animate_update& packet) noexcept {
    const auto& animate = packet.animate();
    const auto& index = animate.entity().index();

    const auto entity_it = get_entity_it(index);
    if (entity_it == std::end(state::entities)) {
        state::entities.emplace(index, std::make_unique<player>(animate));
        return;
    }

    const auto animate_ptr = dynamic_cast<class animate*>(&*entity_it->second);
    if (animate_ptr == nullptr) {
        return;
    }

    const shared::tick_t tick = packet.tick();

    // Localplayer updates time factor and is update is called with the sequence
    // number instead of the tick.
    if (packet.has_sequence()) {
        const shared::tick_t sequence = packet.sequence();
        animate_ptr->update_time_factor(sequence, tick);
        animate_ptr->notify(animate, sequence, true);
        return;
    }

    animate_ptr->notify(animate, tick, true);
}

// Remove the client whose element is equal to pkt.index.
static void
handle_remove_entity_packet(const proto::remove_entity& packet) noexcept {
    const auto entity_it = get_entity_it(packet.index());
    if (entity_it == std::end(state::entities)) {
        return;
    }

    state::entities.erase(entity_it);
}

static void handle_hear_packet(const proto::hear_player& packet) noexcept {
    const auto entity_it = get_entity_it(packet.index());
    if (entity_it == std::end(state::entities)) {
        return;
    }

    const auto player_ptr = dynamic_cast<player*>(&*entity_it->second);
    if (player_ptr == nullptr) {
        return;
    }

    player_ptr->message.emplace(packet.text());
}

static void handle_chunk_packet(proto::chunk& packet) noexcept {
    // Ratelimited parsing, moved into a vector.
    ::received_chunks.push(std::move(packet));
}

static void
handle_server_message_packet(const proto::server_message& packet) noexcept {
    const bool fatal = packet.fatal();
    const std::string message =
        "client: received " + std::string{fatal ? "fatal" : ""} +
        " message from the server \"" + packet.message() + "\"\n";
    if (!fatal) {
        shared::print::notify << shared::print::time << message;
        return;
    }

    shared::print::warn << shared::print::time << message;
    shared::should_exit = true;
}

static void parse_packet(proto::packet&& packet) noexcept {
    if (packet.has_init_packet()) {
        handle_init_packet(packet.init_packet());
    } else if (packet.has_animate_update_packet()) {
        handle_animate_update_packet(packet.animate_update_packet());
    } else if (packet.has_remove_entity_packet()) {
        handle_remove_entity_packet(packet.remove_entity_packet());
    } else if (packet.has_hear_player_packet()) {
        handle_hear_packet(packet.hear_player_packet());
    } else if (packet.has_chunk_packet()) {
        handle_chunk_packet(*packet.mutable_chunk_packet());
    } else if (packet.has_server_message_packet()) {
        handle_server_message_packet(packet.server_message_packet());
    }
#ifndef NDEBUG
    else {
        shared::print::warn << shared::print::time
                            << "client: unhandled packet type\n";
    }
#endif
}

static void regenerate_surrounding_chunks(const shared::math::coords& pos) {
    // Force the surrounding chunks to regenerate their vbos.
    // It's possible we could only generate the ones that we actually need
    // to generate, but that's not really a priority atm.
    for (auto x = -1; x <= 1; ++x) {
        for (auto z = -1; z <= 1; ++z) {
            if (std::abs(x) == 1 && std::abs(z) == 1) {
                continue;
            }
            const auto find_update_it =
                state::chunks.find(pos + shared::math::coords{x, z});
            if (find_update_it == std::end(state::chunks)) {
                continue;
            }
            if (!find_update_it->second.has_value()) {
                continue;
            }
            find_update_it->second->should_regenerate_vbo = true;
        }
    }
}

static void parse_new_chunks() {
    // Add new chunks. We have to ratelimit these because the server responds
    // so quickly that our frametime dives as it parses these new chunk packets.
    constexpr int CHUNKS_PER_FRAME = 1;
    for (int i = 0; i < CHUNKS_PER_FRAME && !::received_chunks.empty();
         ++i, ::received_chunks.pop()) {

        const proto::chunk& packet = ::received_chunks.front();
        const shared::math::coords pos{packet.chunk_pos().x(),
                                       packet.chunk_pos().z()};

        const auto find_it = state::chunks.find(pos);
        if (find_it == std::end(state::chunks)) {
            continue;
        }
        find_it->second.emplace(state::seed, packet);
        regenerate_surrounding_chunks(pos);
    }
}

static void erase_bad_chunks(const shared::math::coords& lp_pos) {
    const auto draw_distance = state::draw_distance;
    std::erase_if(state::chunks, [&](const auto& chunk) {
        const bool should_erase = !shared::math::coords::is_inside_draw(
            chunk.first, lp_pos, draw_distance);
        if (should_erase) {
            state::connection->rsend_packet(
                make_remove_chunk_packet(chunk.first));
        }
        return should_erase;
    });
}

static void request_new_chunks(const shared::math::coords& lp_pos) {
    for (int dist = 0; dist <= state::draw_distance; ++dist) {

        const auto draw_distance = state::draw_distance;
        const auto maybe_add_chunk = [&](const int x, const int z) -> bool {
            const auto pos = shared::math::coords{x + lp_pos.x, z + lp_pos.z};
            if (!shared::math::coords::is_inside_draw(pos, lp_pos,
                                                      draw_distance)) {
                return false;
            }
            if (state::chunks.contains(pos)) {
                return false;
            }
            state::connection->rsend_packet(make_request_chunk_packet(pos));
            state::chunks.emplace(pos, std::nullopt);
            return true;
        };

        int x = -dist;
        int z = dist;
        for (int i = 0; i < dist * 2 + 1; ++i) {
            if (maybe_add_chunk(x, z)) {
                return;
            }
            x += (i < dist * 2);
        }
        for (int i = 0; i < dist * 2; ++i) {
            --z;
            if (maybe_add_chunk(x, z)) {
                return;
            }
        }
        for (int i = 0; i < dist * 2; ++i) {
            --x;
            if (maybe_add_chunk(x, z)) {
                return;
            }
        }
        for (int i = 0; i < dist * 2 - 1; ++i) {
            ++z;
            if (maybe_add_chunk(x, z)) {
                return;
            }
        }
    }
}

static void update_chunks() {
    parse_new_chunks();

    const shared::math::coords& lp_pos = get_localplayer().get_chunk_pos();
    erase_bad_chunks(lp_pos);
    request_new_chunks(lp_pos);
}

static void handle_button_input() noexcept {

    // Don't build our movement commands if we're inputting text.
    if (input::state.typing) {
        return;
    }

    using spm = shared::player::mask;
    auto& commands = get_localplayer().get_mutable_commands();
    commands |= spm::forward * input::is_key_pressed(SDLK_w);
    commands |= spm::left * input::is_key_pressed(SDLK_a);
    commands |= spm::backward * input::is_key_pressed(SDLK_s);
    commands |= spm::right * input::is_key_pressed(SDLK_d);
    commands |= spm::jump * input::is_key_pressed(SDLK_SPACE);
    commands |= spm::crouch * input::is_key_pressed(SDLK_LCTRL);
    commands |= spm::sprint * input::is_key_pressed(SDLK_LSHIFT);
    commands |= spm::attack * input::is_key_pressed(SDL_BUTTON_LEFT);
}

static void update_input() noexcept {
    input::update();

    if (input::is_key_pressed(SDLK_z)) {
        render::camera::get_xfov() = 30.0f;
    } else {
        render::camera::get_xfov() = settings::get({"gameplay", "fov"}, 100.0f);
    }

    if (!window::is_open()) {
        handle_button_input();
    }

    if (input::state.quit) {
        shared::should_exit = true;
    }
}

static void update_delta_ticks() noexcept {
    static shared::time_point_t last = std::chrono::steady_clock::now();

    const auto now = std::chrono::steady_clock::now();
    const auto delta_ticks =
        shared::get_duration_seconds(now - last) /
        shared::get_duration_seconds(state::get_time_per_tick());

    state::delta_ticks += state::time_factor * delta_ticks;

    last = now;
}

static void update_pre_move() {
    state::player_count = state::entities.size();
    state::requested_chunk_count = static_cast<std::uint32_t>(
        std::ranges::count_if(state::chunks, [](const auto& c) {
            return !c.second.has_value();
        }));
    state::networked_chunk_count =
        std::size(state::chunks) - state::requested_chunk_count;
    update_delta_ticks();
    update_input();
    update_chunks();
}

static void interp_entities() {
    for (auto& [index, entity] : state::entities) {
        const auto animate_ptr = dynamic_cast<animate*>(&*entity);
        if (animate_ptr == nullptr) {
            continue;
        }
        animate_ptr->interpolate();
    }
}

static void remove_bad_entities() {
    const auto lp_index = *state::localplayer_index;
    // pvs, remove clients outside of chunks we own
    std::erase_if(state::entities, [&](const auto& pair) {
        const auto& [idx, entity] = pair;

        const auto player_ptr = dynamic_cast<const player*>(&*entity);
        if (player_ptr == nullptr) {
            return false;
        }

        if (player_ptr->get_index() == lp_index) {
            return false;
        }

        // Players should be removed if the chunk can't draw.
        const auto chunk_it = state::chunks.find(player_ptr->get_chunk_pos());
        if (chunk_it == std::end(state::chunks)) {
            return true;
        }
        const auto& chunk = chunk_it->second;
        if (chunk.has_value() && !chunk->can_draw()) {
            return true;
        }
        return false;
    });
}

static void update_entities() noexcept {
    interp_entities();
    remove_bad_entities();
}

static void update_post_move() { update_entities(); }

static void maybe_send_move() noexcept {

    // An unknown amount of time has passed since we last rendered and this may
    // be more than one tick. We do nothing if it's less than one tick.
    const auto num_ticks_passed = static_cast<unsigned>(state::delta_ticks);

    if (num_ticks_passed <= 0) {
        return;
    }

    // Extrapolate for the number of ticks passed.
    auto& localplayer = get_localplayer();
    for (auto i = 0u; i < num_ticks_passed; ++i) {
        ++state::tick; // possibly after?
        state::delta_ticks -= 1.0f;
        localplayer.extrapolate();
        ++localplayer.get_mutable_latest_sequence();
        state::connection->usend_packet(make_move_packet(localplayer));
    }

    // reset all commands except for flying, more later probably
    const auto retained = shared::animate::flying;
    localplayer.get_mutable_commands() &= retained;
}

// requires SDL_MOUSEMOTION
static void handle_mousemotion(const SDL_Event& event) noexcept {
    const float sens =
        settings::get<float>({"gameplay", "mouse_sensitivity"}, 0.0235f);

    auto& lp = get_localplayer();
    auto& angles = lp.get_mutable_angles();

    const float pitch_offset = static_cast<float>(event.motion.yrel) * sens;
    const float yaw_offset = static_cast<float>(event.motion.xrel) * sens;

    angles.pitch -= glm::radians(pitch_offset);
    angles.yaw += glm::radians(yaw_offset);
    angles.normalise();
    angles.clamp();
}

// requires SDL_MOUSEBUTTONDOWN
static void handle_mousebuttons(const SDL_Event& event) noexcept {
    if (event.button.button != SDL_BUTTON_LEFT &&
        event.button.button != SDL_BUTTON_RIGHT) {
        return;
    }

    auto& lp = get_localplayer();
    const auto mode = event.button.button == SDL_BUTTON_LEFT
                          ? movement::interact_mode::remove
                          : movement::interact_mode::add;
    const auto position = movement::interact(lp, mode, state::chunks);
    if (!position.has_value()) {
        return;
    }

    const auto& [chunk_pos, block_pos] = *position;
    auto& block = state::chunks.find(chunk_pos)->second->get_block(block_pos);

    if (mode == movement::interact_mode::remove) {
        lp.inventory.maybe_add(shared::item::block::get_type(block.type), 1,
                               client::item::make_item);
        block.type = shared::world::block::type::air;

        state::connection->rsend_packet(
            make_remove_block_packet(chunk_pos, block_pos));
    } else {
        // Adding is more complicated, needs the active item.
        const auto& active = lp.get_active_item();
        auto& item = lp.inventory.contents[active];
        if (item == nullptr) {
            return;
        }

        const auto block_ptr = dynamic_cast<const shared::item::block*>(&*item);
        if (block_ptr == nullptr) {
            return;
        }
        lp.inventory.decrement(active);
        block.type = block_ptr->type;

        state::connection->rsend_packet(
            make_add_block_packet(chunk_pos, block_pos, active));
    }

    regenerate_surrounding_chunks(chunk_pos);
}

static void handle_space(const SDL_Event& event) noexcept {
    if (event.type == SDL_KEYUP) {
        return;
    }
    auto& commands = get_localplayer().get_mutable_commands();
    commands |= shared::animate::mask::jump;

    if (event.key.repeat) {
        return;
    }
    constexpr auto JUMP_FLY_DELAY = std::chrono::milliseconds(250);

    static std::optional<shared::time_point_t> prev = std::nullopt;
    const auto now = std::chrono::steady_clock::now();
    if (prev.has_value() && now < *prev + JUMP_FLY_DELAY) {
        commands ^= shared::animate::mask::flying;
        prev.reset();
        return;
    }

    prev.emplace(now);
}

static void handle_keys(const SDL_Event& event) noexcept {
    switch (event.key.keysym.sym) {
    case SDLK_SPACE:
        handle_space(event);
        break;
    default:
        break;
    }
}

static void handle_events(const SDL_Event& event) noexcept {
    if (window::is_open()) {
        return;
    }
    if (!state::localplayer_index.has_value()) {
        return;
    }

    switch (event.type) {
    case SDL_KEYDOWN:
    case SDL_KEYUP:
        handle_keys(event);
        break;
    case SDL_MOUSEBUTTONDOWN:
        handle_mousebuttons(event);
        break;
    case SDL_MOUSEMOTION:
        handle_mousemotion(event);
        break;
    default:
        break;
    }
}

static std::string get_username() {
    const settings::setting_pair_t loc = {"gameplay", "username"};
    if (const auto username = settings::maybe_get_setting_str(loc);
        username.has_value()) {
        return *username;
    }

    shared::print::notify << shared::print::time
                          << "first launch detected, username required\n";
    std::string ret;
    while (ret.empty() || !std::ranges::all_of(ret, isalnum)) {
        std::cin.clear();
        std::cout << "enter a valid username: ";
        std::getline(std::cin, ret);
    }
    settings::set_setting_str(loc, ret);
    return ret;
}

static std::string get_password(const std::string_view& address) {
    const settings::setting_pair_t loc = {
        "auth", std::string{address == "0.0.0.0" ? "localhost" : address}};
    if (const auto password = settings::maybe_get_setting_str(loc);
        password.has_value()) {
        return *password;
    }

    // We generate a random string as our password. Our password has decent
    // complexitity but considering we don't use any encryption it is worthless 
    // to any real attacker and just basic authentication.
    std::string ret;
    std::random_device rand{};
    std::uniform_int_distribution<char> uniform{'a', 'z'};
    for (int i = 0; i < 256; ++i) {
        const char random_char = uniform(rand);
        ret.push_back(random_char);
    }
    settings::set_setting_str(loc, ret);
    return ret;
}

static void send_auth_packet(const std::string_view& address,
                             shared::net::connection& connection) {
    const std::string username = get_username();
    const std::string password = get_password(address);

    connection.rsend_packet(make_auth_packet(username, password));
}

static bool should_do_loop(shared::net::connection& connection) noexcept {
    if (shared::should_exit) {
        return false;
    }

    if (!connection.good()) {
        shared::print::notify << shared::print::time
                              << "client: disconnected for \""
                              << connection.get_bad_reason() << "\"\n";
        shared::should_exit = true; // cleanup server if necessary
        return false;
    }

    return true;
}

static void do_client_loop(shared::net::connection& connection) {
    while (should_do_loop(connection)) {
        connection.poll();
        while (auto packet = connection.recv_packet()) {
            parse_packet(std::move(*packet));
        }

        if (!state::has_initialised()) {
            continue;
        }

        update_pre_move();
        maybe_send_move();
        update_post_move();

        render::draw(state::entities, state::chunks);
    }
}

static void init_client(const std::string_view& address,
                        const std::string_view& port,
                        shared::net::connection& connection) {
    // Setup client state, some vars should be cleaned up later (raii lol).
    state::address = address;
    state::port = port;
    state::connection = &connection;

    input::register_event_handler(&handle_events);
    send_auth_packet(address, connection);

    render::init();
}

static void cleanup_client() {
    state::connection = nullptr;
    state::localplayer_index.reset();
    state::chunks.clear();
    state::entities.clear();
    render::quit();
    settings::save();
}

void main(const std::string_view address, const std::string_view port) {
    shared::net::connection connection = make_connection(address, port);
    init_client(address, port, connection);
    shared::print::notify << shared::print::time << "client: connected to "
                          << address << ':' << port << '\n';

    do_client_loop(connection);

    shared::print::notify << shared::print::time
                          << "client: disconnecting from server\n";
    cleanup_client();
}

} // namespace client