#include "engine.hpp"

#include <backends/imgui_impl_glfw.h>
#include <exception>
#include <game/components.hpp>
#include <glm/trigonometric.hpp>
#include <imgui.h>
#include <limits>
#include <ranges>
#include <vuk/extra/ImGuiIntegration.hpp>

#include "GLFW/glfw3.h"
#include "glm/ext/matrix_clip_space.hpp"
#include "glm/ext/matrix_transform.hpp"
#include <glm/gtc/matrix_transform.hpp>

namespace {
[[nodiscard]] auto load_scene_to_renderer(trb::render::renderer &renderer,
                                          trb::game::scene &scene) {
  const auto upload_mesh_node = [&](const auto &mesh) {
    return renderer.register_mesh(
        mesh,
        scene.textures[scene.materials[mesh.material_index].albedo_texture]);
  };

  return scene.meshes | std::views::transform(upload_mesh_node) |
         std::ranges::to<std::vector<std::uint32_t>>();
}

[[nodiscard]] std::pair<glm::vec3, glm::vec3>
bounds_of(const trb::game::scene &scene) {
  auto min = glm::vec3(std::numeric_limits<float>::infinity());
  auto max = glm::vec3(-std::numeric_limits<float>::infinity());

  for (const auto &mesh : scene.meshes) {
    const auto transform = [mesh](glm::vec3 p) {
      return glm::vec3(mesh.transform * glm::vec4(p, 1.0f));
    };
    for (const auto [position, normal, uv] : mesh.vertices) {
      min = glm::min(min, transform(position));
      max = glm::max(max, transform(position));
    }
  }

  return std::make_pair(min, max);
}

struct level_view {
  glm::mat4 view;
  glm::mat4 projection;
};
[[nodiscard]] level_view calculate_camera_matrices(glm::vec3 min, glm::vec3 max,
                                                   float aspectRatio,
                                                   float zoom = 1.0f,
                                                   bool debug = false,
                                                   float timeSeconds = 0.0f) {
  glm::vec3 center = glm::vec3((min.x + max.x) * 0.5f, (min.y + max.y) * 0.5f,
                               (min.z + max.z) * 0.5f);

  glm::mat4 view;
  glm::mat4 projection;

  if (debug) {
    float bboxSize = glm::length(max - min);
    float baseDistance = bboxSize * 1.5f * 0.1f;

    float orbitSpeed = 0.2f;
    float bobSpeed = 1.0f;
    float bobAmount = bboxSize * 0.08f;

    float angle = timeSeconds * orbitSpeed;

    glm::vec3 offset =
        glm::vec3(glm::cos(angle) * baseDistance * 1.05f,
                  glm::sin(timeSeconds * bobSpeed) * bobAmount +
                      baseDistance * 0.9f, // up/down bob + base height
                  glm::sin(angle) * baseDistance * 1.15f);

    glm::vec3 cameraPos = center + offset;

    glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f);

    view = glm::lookAt(cameraPos, center, up);

    float fov = 45.0f;
    float nearPlane = baseDistance * 0.1f;
    float farPlane = baseDistance * 4.0f;

    projection =
        glm::perspective(glm::radians(fov), aspectRatio, nearPlane, farPlane);
  } else {
    glm::vec3 cameraPos = center + glm::vec3(0.0f, 100.0f, 100.0f);
    view = glm::lookAt(cameraPos, center, glm::vec3(0.0f, 1.0f, 0.0f));

    glm::vec3 corners[8] = {{min.x, min.y, min.z}, {max.x, min.y, min.z},
                            {min.x, max.y, min.z}, {max.x, max.y, min.z},
                            {min.x, min.y, max.z}, {max.x, min.y, max.z},
                            {min.x, max.y, max.z}, {max.x, max.y, max.z}};

    float vMinX = FLT_MAX, vMaxX = -FLT_MAX;
    float vMinY = FLT_MAX, vMaxY = -FLT_MAX;

    for (const auto &corner : corners) {
      glm::vec4 vSpace = view * glm::vec4(corner, 1.0f);
      vMinX = glm::min(vMinX, vSpace.x);
      vMaxX = glm::max(vMaxX, vSpace.x);
      vMinY = glm::min(vMinY, vSpace.y);
      vMaxY = glm::max(vMaxY, vSpace.y);
    }

    float width = (vMaxX - vMinX) / zoom;
    float height = (vMaxY - vMinY) / zoom;
    float midX = (vMinX + vMaxX) * 0.5f;
    float midY = (vMinY + vMaxY) * 0.5f;

    if (aspectRatio > (width / height)) {
      width = height * aspectRatio;
    } else {
      height = width / aspectRatio;
    }

    projection = glm::ortho(midX - width * 0.5f, midX + width * 0.5f,
                            midY - height * 0.5f, midY + height * 0.5f,
                            -1000.0f, 1000.0f);
  }

  return {view, projection};
}

} // namespace

namespace trb::game {

engine::game_models engine::load_models(std::filesystem::path model_path) {
  return {
      .boundary = load_glb(model_path / "level_scene.glb"),
      .boxes = load_glb(model_path / "boxes.glb"),
  };
}

engine::map_boxes engine::load_boxes() {
  auto boxes = map_boxes();

  const auto upload_mesh_to_ecs =
      [this](const game::mesh_node &mesh) -> std::uint32_t {
    const auto entity = entities.create();

    const auto render_id = renderer.register_mesh(
        mesh, models.boxes.textures[models.boxes.materials[mesh.material_index]
                                        .albedo_texture]);
    entities.emplace<components::render_id>(entity,
                                            components::render_id(render_id));

    return entity;
  };

  for (const auto &mesh : models.boxes.meshes) {
    if (mesh.name == "wall.full") {
      boxes.solid_full = upload_mesh_to_ecs(mesh);
    } else if (mesh.name == "wall.half") {
      boxes.solid_half = upload_mesh_to_ecs(mesh);
    } else if (mesh.name == "explodable.full") {
      boxes.cork_full = upload_mesh_to_ecs(mesh);
    } else if (mesh.name == "explodable.half") {
      boxes.cork_half = upload_mesh_to_ecs(mesh);
    } else {
      throw std::runtime_error("unexpected mesh found in box model");
    }
  }

  return boxes;
}

std::vector<std::uint32_t> engine::load_scene_to_ecs(game::scene &scene) {
  const auto load_mesh =
      [this, &scene](const game::mesh_node &mesh) -> std::uint32_t {
    const auto entity = entities.create();

    const auto render_id = renderer.register_mesh(
        mesh,
        scene.textures[scene.materials[mesh.material_index].albedo_texture]);
    entities.emplace<components::render_id>(entity,
                                            components::render_id(render_id));

    return entity;
  };

  return scene.meshes | std::views::transform(load_mesh) |
         std::ranges::to<std::vector<std::uint32_t>>();
}

render::request
engine::add_level_bounds_to_render_request(render::request request) const {
  for (const auto eid : level_border_entity_ids) {
    const auto render_id = entities.get<components::render_id>(eid);
    request = request.add_mesh(static_cast<std::uint32_t>(render_id)).commit();
  }

  return request;
}

render::request
engine::add_playing_bounds_to_render_request(render::request request) const {
  auto lines = std::vector<glm::vec3>();
  const float xmin = area_origin.x - area_size.x;
  const float xmax = area_origin.x + area_size.x;
  const float zmin = area_origin.z - area_size.z;
  const float zmax = area_origin.z + area_size.z;

  const auto p1 = glm::vec3(xmin, 0.0f, zmin);
  const auto p2 = glm::vec3(xmax, 0.0f, zmin);
  const auto p3 = glm::vec3(xmax, 0.0f, zmax);
  const auto p4 = glm::vec3(xmin, 0.0f, zmax);

  lines.push_back(p1);
  lines.push_back(p2);
  lines.push_back(p2);
  lines.push_back(p3);
  lines.push_back(p3);
  lines.push_back(p4);
  lines.push_back(p4);
  lines.push_back(p1);

  return request.add_lines(lines);
}

render::request
engine::add_tiles_to_render_request(render::request request) const {
  auto lines = std::vector<glm::vec3>();

  const auto full_dimensions = area_size * 2.0f;
  const auto cell_size = full_dimensions.x / 22.0f;

  const auto start = area_origin - area_size;

  for (int x = 0; x < 22; x++) {
    for (int y = 0; y < 16; y++) {
      const auto min_x = start.x + (static_cast<float>(x) * cell_size);
      const auto min_y = start.z + (static_cast<float>(y) * cell_size);
      const auto max_x = start.x + (static_cast<float>(x + 1) * cell_size);
      const auto max_y = start.z + (static_cast<float>(y + 1) * cell_size);

      const auto p1 = glm::vec3(min_x, 0.0f, min_y);
      const auto p2 = glm::vec3(max_x, 0.0f, min_y);
      const auto p3 = glm::vec3(max_x, 0.0f, max_y);
      const auto p4 = glm::vec3(min_x, 0.0f, max_y);

      lines.push_back(p1);
      lines.push_back(p2);
      lines.push_back(p2);
      lines.push_back(p3);
      lines.push_back(p3);
      lines.push_back(p4);
      lines.push_back(p4);
      lines.push_back(p1);
    }
  }

  return request.add_lines(lines);
}

render::request
engine::add_single_tile_to_render_request(render::request request,
                                          glm::uvec2 tile) const {
  auto lines = std::vector<glm::vec3>();

  const auto full_dimensions = area_size * 2.0f;
  const auto cell_size = full_dimensions.x / 22.0f;

  const auto start = area_origin - area_size;

  const auto min_x = start.x + (static_cast<float>(tile.x) * cell_size);
  const auto min_y = start.z + (static_cast<float>(tile.y) * cell_size);
  const auto max_x = start.x + (static_cast<float>(tile.x + 1) * cell_size);
  const auto max_y = start.z + (static_cast<float>(tile.y + 1) * cell_size);

  const auto p1 = glm::vec3(min_x, 0.0f, min_y);
  const auto p2 = glm::vec3(max_x, 0.0f, min_y);
  const auto p3 = glm::vec3(max_x, 0.0f, max_y);
  const auto p4 = glm::vec3(min_x, 0.0f, max_y);

  lines.push_back(p1);
  lines.push_back(p2);
  lines.push_back(p2);
  lines.push_back(p3);
  lines.push_back(p3);
  lines.push_back(p4);
  lines.push_back(p4);
  lines.push_back(p1);

  return request.add_lines(lines, glm::vec3(1.0f, 1.0f, 0.0f));
}

std::optional<glm::uvec2>
engine::calculate_intersected_tile(glm::mat4 view, glm::mat4 projection,
                                   glm::vec2 mouse) const {
  const float width = static_cast<float>(display.extent().x);
  const float height = static_cast<float>(display.extent().y);

  float x = (2.0f * mouse.x) / width - 1.0f;
  float y = 1.0f - (2.0f * mouse.y) / height;

  glm::vec4 near_clip = glm::vec4(x, y, -1.0f, 1.0f);
  glm::vec4 far_clip = glm::vec4(x, y, 1.0f, 1.0f);

  glm::vec4 near_world = glm::inverse(projection * view) * near_clip;
  glm::vec4 far_world = glm::inverse(projection * view) * far_clip;

  near_world /= near_world.w;
  far_world /= far_world.w;

  glm::vec3 ray_world = glm::normalize(glm::vec3(far_world - near_world));
  glm::vec3 cam_pos = glm::vec3(near_world);

  if (std::abs(ray_world.y) < 1e-5f) {
    return std::nullopt;
  }

  float t = -cam_pos.y / ray_world.y;
  glm::vec3 hit = cam_pos + ray_world * t;

  const auto full_dimensions = area_size * 2.0f;
  const float cell_width = full_dimensions.x / 22.0f;
  const float cell_depth = full_dimensions.z / 16.0f;

  const auto start = area_origin - area_size;

  int tile_x = static_cast<int>((hit.x - start.x) / cell_width);
  int tile_y = static_cast<int>((hit.z - start.z) / cell_depth);

  tile_x = std::clamp(tile_x, 0, 21);
  tile_y = std::clamp(tile_y, 0, 15);

  return glm::uvec2(tile_x, tile_y);
}

engine::mesh_bounds engine::compute_size_of_mesh(const mesh_node &mesh) {
  auto bounds = mesh_bounds();

  const auto project = [&mesh](const glm::vec3 &v) {
    return glm::vec3(mesh.transform * glm::vec4(v, 1.0f));
  };

  auto min = glm::vec3(std::numeric_limits<float>::infinity());
  auto max = glm::vec3(-std::numeric_limits<float>::infinity());

  for (const auto &v : mesh.vertices) {
    min = glm::min(project(v.position), min);
    max = glm::max(project(v.position), max);
  }

  return {
      .min = min,
      .max = max,
      .size = max - min,
  };
}

void engine::calculate_game_plane_size() {
  const auto &game_plane_mesh = [&]() {
    for (const auto &mesh : models.boundary.meshes) {
      if (mesh.name == "Plane.001") {
        return mesh;
      }
    }

    throw std::runtime_error("couldn't find game mesh plane");
  }();
  const auto [min, max, size] = compute_size_of_mesh(game_plane_mesh);

  area_origin = min + (max - min) * 0.5f;
  area_size = (max - min) * 0.5f;
  area_size *= 0.85f;
  tile_size = area_size / glm::vec3(22.0f, 1.0f, 16.0f);
  auto normalized_ts = tile_size / glm::vec3(tile_size.x, 1.0f, tile_size.x);
  area_size.z /= normalized_ts.z;
  tile_size = area_size / glm::vec3(22.0f, 1.0f, 16.0f);
  tile_size.y = 1.0f;
}

void engine::calculate_box_size() {
  const auto &full_box = [&]() {
    for (const auto &mesh : models.boxes.meshes) {
      if (mesh.name == "wall.full") {
        return mesh;
      }
    }

    throw std::runtime_error("couldn't find game mesh plane");
  }();

  const auto &half_box = [&]() {
    for (const auto &mesh : models.boxes.meshes) {
      if (mesh.name == "wall.half") {
        return mesh;
      }
    }

    throw std::runtime_error("couldn't find game mesh plane");
  }();

  const auto [full_max, full_min, full_size] = compute_size_of_mesh(full_box);
  const auto [half_max, half_min, half_size] = compute_size_of_mesh(half_box);

  full_box_size = full_size;
  half_box_size = half_size;
  const auto scale_required = (tile_size * 1.8f) / full_box_size;
  const auto s = glm::vec3(scale_required.x, 1.0f, scale_required.z);
  box_transform = glm::scale(glm::mat4(1.0f), s);
}

render::request engine::add_level_to_render_request(render::request request,
                                                    level *level) const {

  for (const auto [eid, position, wall] :
       level->get_entities()
           ->view<components::tile_position, components::wall_definition>()
           .each()) {
    const auto coord_transform = transform_given_coordinate(position);

    auto current_height =
        (wall.heights[0] == components::wall_height::full ? full_box_size.y
                                                          : half_box_size.y) *
        0.5f;

    current_height = 0.0f;
    for (int i = 0; i < wall.wall_count; i++) {
      const auto wall_entity_id =
          wall.type == components::wall_type::cork
              ? (wall.heights[i] == components::wall_height::full
                     ? box_entities.cork_full
                     : box_entities.cork_half)
              : (wall.heights[i] == components::wall_height::full
                     ? box_entities.solid_full
                     : box_entities.solid_half);
      const auto wall_tile_render_id =
          entities.get<components::render_id>(wall_entity_id);

      const float half_extent =
          (wall.heights[i] == components::wall_height::full ? full_box_size.y
                                                            : half_box_size.y) *
          0.5f;

      const auto height = glm::translate(
          glm::mat4(1.0f), glm::vec3(0.0f, current_height + half_extent, 0.0f));

      request =
          request.add_mesh(static_cast<std::uint32_t>(wall_tile_render_id))
              .with_transform(coord_transform * height * box_transform)
              .commit();

      current_height +=
          (wall.heights[i] == components::wall_height::full ? full_box_size.y
                                                            : half_box_size.y);
    }
  }

  return request;
}

glm::mat4 engine::transform_given_coordinate(glm::uvec2 coordinate) const {
  const glm::vec3 full_dimensions = area_size * 2.0f;

  const float cell_width = full_dimensions.x / 22.0f;
  const float cell_depth = full_dimensions.z / 16.0f;

  const auto start_point = area_origin - area_size;

  float world_x = start_point.x +
                  (static_cast<float>(coordinate.x) * cell_width) +
                  (cell_width * 0.5f);
  float world_z = start_point.z +
                  (static_cast<float>(coordinate.y) * cell_depth) +
                  (cell_depth * 0.5f);

  return glm::translate(glm::mat4(1.0f), glm::vec3(world_x, 0.0f, world_z));
}

void engine::do_level_editor_ui() {
  if (!debug_drawing.level_editor) {
    return;
  }

  ImGui::Begin("Level Editor");

  ImGui::Checkbox("Enabled", &is_editing_level);

  static int wall_type = 0;
  ImGui::Combo("Wall Type", &wall_type, "cork\0solid\0\0");
  level_editing_data.type_to_write =
      static_cast<components::wall_type>(wall_type);

  static int wall_height = 0;
  ImGui::Combo("Wall Height", &wall_height, "half\0full\0\0");
  level_editing_data.height_to_write =
      static_cast<components::wall_height>(wall_height);

  if (level_editing_data.intersected_tile.has_value()) {
    // Todo: Check for validity based on same types
    if (ImGui::Button("Add Wall To Tile")) {
      auto entity = current_level->get_or_create_entity_at(
          *level_editing_data.intersected_tile);
      auto &wall = current_level->get_entities()
                       ->get_or_emplace<components::wall_definition>(entity);
      wall.type = level_editing_data.type_to_write;
      wall.heights[wall.wall_count++] = level_editing_data.height_to_write;
    }
  }

  ImGui::End();
}

void engine::do_debug_ui() {
  ImGui::Begin("Debug");

  ImGui::Checkbox("Playing Bounds", &debug_drawing.playing_bounds);
  ImGui::Checkbox("Individual Tiles", &debug_drawing.individual_tiles);
  ImGui::Checkbox("Level Editor", &debug_drawing.level_editor);

  ImGui::End();
}

engine::engine()
    : display(&input, {1920, 1080}, "Tanks Reborn"), renderer(&display),
      models(load_models("../assets/models")),
      level_border_entity_ids(load_scene_to_ecs(models.boundary)),
      box_entities(load_boxes()) {
  calculate_game_plane_size();
  calculate_box_size();
}

void engine::run() {
  while (!display.should_close()) {
    display.poll_events();

    try {
      const auto [map_min, map_max] = ::bounds_of(models.boundary);
      const auto [view, projection] = ::calculate_camera_matrices(
          map_min, map_max, 1920.0f / 1080.0f, 3.0f);

      renderer.do_ui([this] {
        do_level_editor_ui();
        do_debug_ui();
      });

      auto request = render::request();

      request = add_level_bounds_to_render_request(request);
      if (current_level.has_value()) {
        request = add_level_to_render_request(request, &(*current_level));
      }

      if (debug_drawing.playing_bounds) {
        request = add_playing_bounds_to_render_request(request);
      }

      if (debug_drawing.individual_tiles) {
        request = add_tiles_to_render_request(request);
      }

      if (debug_drawing.level_editor) {
        if (!ImGui::GetIO().WantCaptureMouse) {
          const auto mx = ImGui::GetIO().MousePos;
          if (ImGui::GetIO().MouseDown[0]) {
            level_editing_data.intersected_tile =
                calculate_intersected_tile(view, projection, {mx.x, mx.y});
          }
          if (level_editing_data.intersected_tile.has_value()) {
            request = add_single_tile_to_render_request(
                request, *level_editing_data.intersected_tile);
          }
        }
      }

      renderer.render(request, view, projection);
    } catch (const vuk::VkException &ex) {
      if (ex.what() != std::string("Out of date.")) {
        std::rethrow_exception(std::current_exception());
      }
    }
  }
}

} // namespace trb::game