// Copyright Epic Games, Inc. All Rights Reserved.

// Zen command line client utility
//

#include "imgui_ui.h"

#include <zencore/logging.h>

ZEN_THIRD_PARTY_INCLUDES_START
#include <imgui.h>
#include <imgui_impl_glfw.h>
#include <imgui_impl_opengl3.h>

#if defined(IMGUI_IMPL_OPENGL_ES2)
#	include <GLES2/gl2.h>
#endif
#undef GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>	 // Will drag system OpenGL headers
ZEN_THIRD_PARTY_INCLUDES_END

namespace zen {

static void
glfw_error_callback(int error, const char* description)
{
	ZEN_ERROR("Glfw Error {}: {}", error, description);
}

std::thread
OpenImGuiWindow(int													Width,
				int													Height,
				std::string_view									Title,
				std::function<void(int display_w, int display_h)>&& UICallback,
				std::function<void()>&&								OnClosed,
				std::function<bool()>&&								ShouldExit)
{
	return std::thread([Width,
						Height,
						Title	   = std::string(Title),
						UICallback = std::move(UICallback),
						OnClosed   = std::move(OnClosed),
						ShouldExit = std::move(ShouldExit)]() {
		glfwSetErrorCallback(glfw_error_callback);
		if (!glfwInit())
			return 1;

			// Decide GL+GLSL versions
#if defined(IMGUI_IMPL_OPENGL_ES2)
		// GL ES 2.0 + GLSL 100
		const char* glsl_version = "#version 100";
		glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
		glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
		glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
#elif defined(__APPLE__)
		// GL 3.2 + GLSL 150
		const char* glsl_version = "#version 150";
		glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
		glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
		glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);	// 3.2+ only
		glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);			// Required on Mac
#else
		// GL 3.0 + GLSL 130
		const char* glsl_version = "#version 130";
		glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
		glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
		// glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
		// glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);            // 3.0+ only
#endif

		// Create window with graphics context
		GLFWwindow* window = glfwCreateWindow(Width, Height, Title.c_str(), NULL, NULL);
		if (window == NULL)
			return 1;
		glfwMakeContextCurrent(window);
		glfwSwapInterval(1);  // Enable vsync

		// Setup Dear ImGui context
		IMGUI_CHECKVERSION();
		ImGui::CreateContext();
		ImGuiIO& io = ImGui::GetIO();
		(void)io;
		// io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
		// io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls

		// Setup Dear ImGui style
		ImGui::StyleColorsDark();
		// ImGui::StyleColorsClassic();

		// Setup Platform/Renderer backends
		ImGui_ImplGlfw_InitForOpenGL(window, true);
		ImGui_ImplOpenGL3_Init(glsl_version);

		// Our state
		ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

		// Main loop
		while (!ShouldExit() && !glfwWindowShouldClose(window))
		{
			// Poll and handle events (inputs, window resize, etc.)
			// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
			// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
			// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
			// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
			glfwPollEvents();

			// Start the Dear ImGui frame
			ImGui_ImplOpenGL3_NewFrame();
			ImGui_ImplGlfw_NewFrame();
			ImGui::NewFrame();

			int display_w, display_h;
			glfwGetFramebufferSize(window, &display_w, &display_h);

			UICallback(display_w, display_h);

			// Rendering
			ImGui::Render();
			glViewport(0, 0, display_w, display_h);
			glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
			glClear(GL_COLOR_BUFFER_BIT);
			ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

			glfwSwapBuffers(window);
		}

		ImGui_ImplOpenGL3_Shutdown();
		ImGui_ImplGlfw_Shutdown();
		ImGui::DestroyContext();

		glfwDestroyWindow(window);
		glfwTerminate();

		OnClosed();

		return 0;
	});
}

}  // namespace zen