#include "client/render/draw.hh"

namespace client {
namespace render {

static void draw_state_info(const shared::player& lp) noexcept {

    constexpr auto nstr = [](const auto d) -> std::string {
        auto str = std::to_string(d);
        str.erase(std::prev(std::end(str), 4), std::end(str));
        return str;
    };

    const auto make_position = [&]() -> std::string {
        const auto chunk_x = lp.get_chunk_pos().x;
        const auto chunk_z = lp.get_chunk_pos().z;
        const auto x = static_cast<double>(lp.get_local_pos().x);
        const auto y = static_cast<double>(lp.get_local_pos().y);
        const auto z = static_cast<double>(lp.get_local_pos().z);
        constexpr auto WIDTH = shared::world::chunk::WIDTH;
        const auto abs_x =
            static_cast<double>(lp.get_chunk_pos().x) * WIDTH + x;
        const auto abs_z =
            static_cast<double>(lp.get_chunk_pos().z) * WIDTH + z;

        constexpr auto nstr = [](const double d) -> std::string {
            auto str = std::to_string(d);
            str.erase(std::prev(std::end(str), 4), std::end(str));
            return str;
        };
        const std::string chk_str = '[' + std::to_string(chunk_x) + ", " +
                                    std::to_string(chunk_z) + ']';
        const std::string abs_str =
            '(' + nstr(abs_x) + ", " + nstr(y) + ", " + nstr(abs_z) + ')';
        return "position: " + abs_str + chk_str;
    };

    const auto make_direction = [&]() -> std::string {
        const float yaw = glm::degrees(lp.get_angles().yaw);
        const float pitch = glm::degrees(lp.get_angles().pitch);

        const std::string bearing = [&]() -> std::string {
            if (yaw > 135.0f || yaw < -135.0f) {
                return "South";
            } else if (yaw > 45.0f) {
                return "East";
            } else if (yaw > -45.0f) {
                return "North";
            } else {
                return "West";
            }
        }();
        const std::string face_str = '(' + nstr(pitch) + ", " + nstr(yaw) + ')';
        // Yaw is between 0 and 360.
        return "perspective: " + face_str + " -> " + bearing;
    };

    const auto make_address = []() -> std::string {
        const std::string address = std::string(client::state::address);
        const std::string port = std::string(client::state::port);
        return "address: " + address + ":" + port;
    };

    const auto make_tickrate = [&]() -> std::string {
        return "tickrate: " + std::to_string(state::tickrate);
    };

    const auto make_seed = []() -> std::string {
        return "seed: " + std::to_string(client::state::seed);
    };

    const auto make_entities = []() -> std::string {
        const auto index = std::to_string(*client::state::localplayer_index);
        return "index: " + index;
    };

    const auto make_chunks = []() -> std::string {
        return "chunks: " +
               std::to_string(client::state::requested_chunk_count) + ", " +
               std::to_string(client::state::networked_chunk_count) + " @ " +
               std::to_string(client::state::draw_distance) + " draw distance";
    };

    const auto make_speed = [&]() -> std::string {
        return "speed: " + nstr(glm::length(lp.get_velocity())) + " b/s";
    };

    const auto make_velocity = [&]() -> std::string {
        return "velocity: (" + nstr(lp.get_velocity().x) + ", " +
               nstr(lp.get_velocity().y) + ", " + nstr(lp.get_velocity().z) +
               ")";
    };

    const auto make_msg = [&]() -> std::string {
        const auto& message = get_localplayer().get_message();
        return "message: " + (message.has_value() ? message->text : "");
    };

    const auto make_biome = [&]() -> std::string {
        const int x = static_cast<int>(lp.get_local_pos().x);
        const int z = static_cast<int>(lp.get_local_pos().z);
        const auto is_inside = [](const int val) {
            return std::clamp(val, 0, shared::world::chunk::WIDTH) == val;
        };
        if (!is_inside(x) || !is_inside(z)) {
            return "?";
        }

        const auto find_it = client::state::chunks.find(lp.get_chunk_pos());
        if (find_it == std::end(client::state::chunks)) {
            return "?";
        }
        const auto& chunk = find_it->second;
        if (!chunk.has_value()) {
            return "?";
        }
        return std::string{"biome: "} + chunk->get_biome(x, z);
    };

    // Draws all of our strings and works its way down the top of the screen.
    text_args args{.pos = {.extent = {0.0f, 1.0f - 0.015f}},
                   .extent_height = 0.0165f,
                   .colour = {1.0f, 1.0f, 1.0f, 1.0f},
                   .has_backing = true};
    const auto draw_str_trail = [&args](const std::string& str) {
        draw_text(str, args);
        args.pos.extent.y -= 0.02f;
    };
    draw_str_trail("blockgame_linux v0.22");
    draw_str_trail(make_address());
    draw_str_trail(make_tickrate());
    draw_str_trail(make_seed());
    draw_str_trail(make_entities());
    draw_str_trail(make_chunks());
    draw_str_trail(make_position());
    draw_str_trail(make_direction());
    draw_str_trail(make_speed());
    draw_str_trail(make_velocity());
    draw_str_trail(make_biome());
    draw_str_trail(make_msg());
}

static void draw_fps() noexcept {
    const auto get_fps_colour = [](const int fps) -> glm::vec4 {
        if (fps == 0) {
            return {1.0f, 1.0f, 1.0f, 1.0f};
        } else if (fps < 30) {
            return {1.0f, 0.0f, 0.0f, 1.0f};
        } else if (fps < 60) {
            return {1.0f, 0.5f, 0.0f, 1.0f};
        } else if (fps < 120) {
            return {0.0f, 1.0f, 0.0f, 1.0f};
        }
        return {0.0f, 1.0f, 1.0f, 1.0f};
    };

    const int fps = client::render::get_fps();
    const std::string fps_str = fps != 0 ? std::to_string(fps) : "~";
    draw_text("FPS: " + fps_str, {.pos = relative_arg{.offset = {0.0f, 2.0f}},
                                  .extent_height = 0.0165f,
                                  .colour = get_fps_colour(fps),
                                  .has_backing = true});
}

// Player position, version, fps etc
// Just don't read past this point, doing this is unbelievably ugly.
// I don't know why I write this like someone else will read it.
static void draw_overlay(const shared::player& lp) noexcept {
    draw_state_info(lp);
    draw_fps();
}

static void draw_main_pass(const client::player& localplayer,
                           client::entities_t& entities,
                           client::world::chunks_t& chunks) noexcept {

    {
        // zero means no limit
        const unsigned chunks_per_frame =
            client::settings::get<unsigned>({"video", "chunks_per_frame"}, 0u);
        unsigned chunks_regenerated = 0u;
        for (auto& chunk : chunks) {
            if (!chunk.second.has_value()) {
                continue;
            }

            const bool skip = chunks_per_frame == 0
                                  ? false
                                  : chunks_regenerated >= chunks_per_frame;
            chunks_regenerated += chunk.second->draw(
                chunks, localplayer, world::chunk::pass::solid, skip);
        }
    }

    for (const auto& [index, entity_ptr] : entities) {
        if (index == localplayer.get_index()) {
            continue;
        }
        entity_ptr->draw(localplayer);
    }
}

static void draw_water_pass(const client::player& localplayer,
                            client::world::chunks_t& chunks) noexcept {
    for (auto& chunk : chunks) {
        if (!chunk.second.has_value()) {
            continue;
        }
        chunk.second->draw(chunks, localplayer,
                           client::world::chunk::pass::water);
    }
}

static void draw_wts_text(const client::player& localplayer,
                          client::entities_t& entities) noexcept {
    for (const auto& [index, entity_ptr] : entities) {
        if (index == localplayer.get_index()) {
            continue;
        }
        entity_ptr->draw_wts(localplayer);
    }
}

static void draw_hud(const client::player& localplayer,
                     const client::world::chunks_t& chunks) noexcept {
    const auto should_draw_hud = !client::input::is_key_toggled(SDLK_F1);
    if (client::input::is_key_toggled(SDLK_F3) && should_draw_hud) {
        draw_overlay(localplayer);
    }

    if (client::window::is_open()) {
        return;
    }

    if (!should_draw_hud) {
        return;
    }

    // crosshair
    client::render::draw_rectangle(
        {.pos = {.extent = {0.5f, 0.5f}, .offset = {-3.0f, -3.0f}},
         .size = {.offset = {6.0f, 6.0f}},
         .colour = {1.0f, 1.0f, 1.0f, 1.0f}});

    // Draw the outline of the block we're aiming at.
    if (const auto interact = client::movement::interact(
            localplayer, movement::interact_mode::remove, chunks);
        interact.has_value()) {

        const auto [world_x, world_z] = [&]() -> std::pair<float, float> {
            const float offset_x = static_cast<float>(
                interact->first.x - localplayer.get_chunk_pos().x);
            const float offset_z = static_cast<float>(
                interact->first.z - localplayer.get_chunk_pos().z);
            return {offset_x * shared::world::chunk::WIDTH,
                    offset_z * shared::world::chunk::WIDTH};
        }();

        const glm::vec3 render_pos = {
            world_x + static_cast<float>(interact->second.x),
            interact->second.y,
            world_z + static_cast<float>(interact->second.z)};

        client::render::render_cube_outline(render_pos + 0.5f,
                                            {0.8f, 0.8f, 0.8f, 1.0f});
    }
}

static void update_camera(const shared::player& localplayer) noexcept {
    // approximately encompasses everything we could possibly see

    // if our zfar is too low, our fog breaks
    // bit of maths for calculating the max distance we could can see
    client::render::camera::get_zfar() = std::hypot(
        static_cast<float>(world::chunk::HEIGHT),
        float(client::state::draw_distance) * std::hypot(16.0f, 16.0f));
    client::render::camera::get_pos() =
        localplayer.get_local_pos() +
        glm::vec3{0.0f, shared::player::EYE_HEIGHT, 0.0f};
    client::render::camera::get_front() = localplayer.get_angles().to_dir();
    client::render::camera::update();
}

// We create framebuffer here to enable postprocessing and solve some
// rendering problems.
static void draw_buffers(const client::player& localplayer,
                         client::entities_t& entities,
                         client::world::chunks_t& chunks) noexcept {
    const auto make_vbo = [](const auto& vertices) -> GLuint {
        GLuint vbo = 0;
        glGenBuffers(1, &vbo);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), std::data(vertices),
                     GL_STATIC_DRAW);
        return vbo;
    };
    const auto make_vao = []() -> GLuint {
        GLuint vao = 0;
        glGenVertexArrays(1, &vao);
        glBindVertexArray(vao);
        // position
        glVertexAttribPointer(0, sizeof(glm::vec2) / sizeof(float), GL_FLOAT,
                              GL_FALSE, sizeof(glm::vec2), nullptr);
        glEnableVertexAttribArray(0);
        return vao;
    };
    const auto make_ebo = [](const auto& indices) -> GLuint {
        GLuint ebo = 0;
        glGenBuffers(1, &ebo);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), &indices,
                     GL_STATIC_DRAW);
        return ebo;
    };
    const auto make_fbo = []() -> GLuint {
        GLuint fbo;
        glGenFramebuffers(1, &fbo);
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
        return fbo;
    };
    const auto make_texture = [](const auto& internal_format,
                                 const auto& format,
                                 const int texture_offset) -> GLuint {
        GLuint texture;
        glGenTextures(1, &texture);
        glActiveTexture(GL_TEXTURE2 + texture_offset);
        glBindTexture(GL_TEXTURE_2D, texture);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);

        const glm::vec2& window = client::render::get_window_size();
        glTexImage2D(GL_TEXTURE_2D, 0, internal_format, window.x, window.y, 0,
                     internal_format, GL_UNSIGNED_BYTE, nullptr);
        glFramebufferTexture2D(GL_FRAMEBUFFER, format, GL_TEXTURE_2D, texture,
                               0);
        return texture;
    };

    static constexpr std::array<glm::vec2, 4> vertices = {
        glm::vec2{-1.0f, -1.0f}, glm::vec2{1.0f, -1.0f}, glm::vec2{1.0f, 1.0f},
        glm::vec2{-1.0f, 1.0f}};
    static constexpr std::array<unsigned, 6> indices = {0, 1, 2, 2, 3, 0};
    static const client::render::program framebuffer_program{
        "res/shaders/framebuffer.vs", "res/shaders/framebuffer.fs"};
    static const GLuint vbo [[maybe_unused]] = make_vbo(vertices);
    static const GLuint vao = make_vao();
    static const GLuint ebo [[maybe_unused]] = make_ebo(indices);
    // Main frame buffer object.
    static const GLuint fbo_main = make_fbo();
    static const GLuint main_colour [[maybe_unused]] =
        make_texture(GL_RGB, GL_COLOR_ATTACHMENT0, 0);
    static const GLuint main_depth [[maybe_unused]] =
        make_texture(GL_DEPTH_COMPONENT, GL_DEPTH_ATTACHMENT, 1);
    // Water frame buffer object.
    static const GLuint fbo_water = make_fbo();
    static const GLuint water_colour [[maybe_unused]] =
        make_texture(GL_RGB, GL_COLOR_ATTACHMENT0, 2);
    static const GLuint water_depth [[maybe_unused]] =
        make_texture(GL_DEPTH_COMPONENT, GL_DEPTH_ATTACHMENT, 3);
    static const GLint u_is_underwater =
        glGetUniformLocation(framebuffer_program, "_u_is_underwater");

    // We render our main scene on the main framebuffer.
    glBindFramebuffer(GL_FRAMEBUFFER, fbo_main);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    draw_main_pass(localplayer, entities, chunks);

    // We render our water scene on the water framebuffer.
    glBindFramebuffer(GL_FRAMEBUFFER, fbo_water);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    const bool is_underwater = [&]() -> bool {
        const glm::ivec3 pos{client::render::camera::get_pos()};

        const auto find_it = chunks.find(localplayer.get_chunk_pos());
        if (find_it == std::end(chunks) || !find_it->second.has_value()) {
            return false;
        }
        if (shared::world::chunk::is_outside_chunk(pos)) {
            return false;
        }

        const auto block = find_it->second->get_block(pos);
        return block.type == shared::world::block::type::water;
    }();
    if (is_underwater) {
        glFrontFace(GL_CW);
        draw_water_pass(localplayer, chunks);
        glFrontFace(GL_CCW);
    } else {
        draw_water_pass(localplayer, chunks);
    }

    glBindFramebuffer(GL_FRAMEBUFFER, main_colour);
    glDisable(GL_DEPTH_TEST);
    glUseProgram(framebuffer_program);
    glBindVertexArray(vao);

    glUniform1i(u_is_underwater, is_underwater);

    glDrawElements(GL_TRIANGLES, std::size(indices), GL_UNSIGNED_INT, nullptr);

    static client::render::program postprocess_program{
        "res/shaders/framebuffer.vs", "res/shaders/postprocess.fs"};
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    glUseProgram(postprocess_program);
    glDrawElements(GL_TRIANGLES, std::size(indices), GL_UNSIGNED_INT, nullptr);

    glEnable(GL_DEPTH_TEST);
}

void draw(entities_t& entities, world::chunks_t& chunks) noexcept {
    const auto& localplayer = get_localplayer();

    update_camera(localplayer);
    client::render::update_uniforms();

    draw_buffers(localplayer, entities, chunks);
    draw_hud(localplayer, chunks);
    draw_wts_text(localplayer, entities);

    client::window::draw();

    client::render::swap_window();
}

} // namespace render
} // namespace client