#include "scene_hierarchy_panel.hpp"

#include <imgui.h>

#include <cstdio>
#include <sophia/components.hpp>
#include <string>

void SceneHierarchyPanel::onUpdate(const sophia::FrameInfo&) {
  drawSceneSelector();
  ImGui::Separator();

  if (!context.hasScene()) {
    ImGui::TextDisabled("No scene open");
    return;
  }

  sophia::Scene& scene = context.getScene();
  sophia::Entity& selected = context.selected;

  if (ImGui::Button("+ Sprite")) {
    selected = scene.createEntity("Sprite");
    selected.addComponent<sophia::SpriteComponent>();
  }
  ImGui::SameLine();
  if (ImGui::Button("+ Cube")) {
    selected = scene.createEntity("Cube");
    selected.addComponent<sophia::MeshComponent>(
        sophia::MeshComponent{.handle = cubeMesh});
  }

  ImGui::Separator();

  // Flat for now: there is no parent/child component yet.
  scene.forEachEntity([&selected](sophia::Entity entity) {
    ImGuiTreeNodeFlags flags = ImGuiTreeNodeFlags_Leaf |
                               ImGuiTreeNodeFlags_NoTreePushOnOpen |
                               ImGuiTreeNodeFlags_SpanAvailWidth;
    if (entity == selected) {
      flags |= ImGuiTreeNodeFlags_Selected;
    }

    const std::string& name = entity.getComponent<sophia::TagComponent>().tag;
    ImGui::PushID(static_cast<int>(static_cast<sophia::u32>(entity)));
    ImGui::TreeNodeEx(name.c_str(), flags);
    if (ImGui::IsItemClicked()) {
      selected = entity;
    }
    ImGui::PopID();
  });
}

namespace {
// See SceneHierarchyPanel::renameFocusFrames.
constexpr int RENAME_FOCUS_FRAMES = 2;
}  // namespace

void SceneHierarchyPanel::drawSceneSelector() {
  // Leave room for the button: its label, its padding, and the gap to it.
  constexpr const char* ADD_SCENE_LABEL = "Add Scene";
  const ImGuiStyle& style = ImGui::GetStyle();
  ImGui::SetNextItemWidth(-(ImGui::CalcTextSize(ADD_SCENE_LABEL).x +
                            style.FramePadding.x * 2.f + style.ItemSpacing.x));

  const std::string* current = context.getSceneName(context.getSceneHandle());
  bool startRename = false;

  if (renamingScene && current) {
    drawSceneRename();
  } else {
    renamingScene = false;
    if (ImGui::BeginCombo("##scene", current ? current->c_str() : "No scene")) {
      for (const EditorContext::OpenScene& open : context.getOpenScenes()) {
        ImGui::PushID(static_cast<int>(open.handle.index));
        bool isCurrent = open.handle == context.getSceneHandle();
        if (ImGui::Selectable(open.name.c_str(), isCurrent) && !isCurrent) {
          context.setScene(open.handle);
        }
        ImGui::PopID();
      }
      ImGui::EndCombo();
    }

    if (current && ImGui::BeginPopupContextItem("##sceneMenu")) {
      startRename = ImGui::MenuItem("Rename", "F2");
      ImGui::EndPopup();
    }
    startRename = startRename || (current && ImGui::IsWindowFocused() &&
                                  !ImGui::GetIO().WantTextInput &&
                                  ImGui::IsKeyPressed(ImGuiKey_F2));
  }

  ImGui::SameLine();
  if (ImGui::Button(ADD_SCENE_LABEL)) {
    std::string name = "Untitled " + std::to_string(++this->untitledSceneCount);
    context.setScene(context.createScene(std::move(name)));
    startRename = false;
  }

  if (startRename) {
    renamingScene = true;
    renameFocusFrames = RENAME_FOCUS_FRAMES;
    std::snprintf(renameBuffer.data(), renameBuffer.size(), "%s",
                  current->c_str());
  }
}

void SceneHierarchyPanel::drawSceneRename() {
  if (renameFocusFrames == RENAME_FOCUS_FRAMES) {
    ImGui::SetKeyboardFocusHere();
  }

  ImGui::InputText("##sceneName", renameBuffer.data(), renameBuffer.size(),
                   ImGuiInputTextFlags_AutoSelectAll);

  bool active = ImGui::IsItemActive();
  if (active) {
    renameFocusFrames = 0;
  } else if (renameFocusFrames > 0) {
    renameFocusFrames--;
    return;
  }

  // Escape reverts the text before deactivating, so committing whatever is
  // left when the field closes covers Enter, clicking away and Escape alike.
  if (!active) {
    std::string name = renameBuffer.data();
    // Keep the old name rather than leave the scene nameless.
    if (name.find_first_not_of(' ') != std::string::npos) {
      context.renameScene(context.getSceneHandle(), std::move(name));
    }
    renamingScene = false;
  }
}