#include <GL/glew.h>
#include <GLFW/glfw3.h>

#define GLM_ENABLE_EXPERIMENTAL
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtx/transform.hpp>
#include <glm/gtc/type_ptr.hpp>

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

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>

#include "scene.h"
#include "Uniforms.h"
#include "InitShader.h"         //Functions for loading shaders from text files
//#include "LoadMesh.h"           //Functions for creating OpenGL buffers from mesh files
//#include "LoadTexture.h"        //Functions for creating OpenGL textures from image files
//#include "VideoRecorder.h"      //Functions for saving videos
#include "DebugCallback.h"

static const std::string vertex_shader("shaders/vertex.glsl");
static const std::string fragment_shader("shaders/fragment.glsl");
GLuint shader_program = -1;

float angle = 0.0f;
float scale = 1.0f;

namespace Camera {
    glm::mat4 V, P;

    float Aspect = 1.0f;
    float NearZ = 0.1f;
    float FarZ = 100.0f;
    float Fov = glm::pi<float>() / 4.0f;

    void UpdateP() {
        P = glm::perspective(Fov, Aspect, NearZ, FarZ);
    }
}

void Scene::Display(GLFWwindow* window) {
    glClear(GL_COLOR_BUFFER_BIT);

    Camera::V = glm::lookAt(glm::vec3(Uniforms::SceneData.eye_w), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
    Uniforms::SceneData.PV = Camera::P * Camera::V;
    Uniforms::BufferSceneData();

    glUseProgram(shader_program);

    glm::mat4 M = glm::rotate(angle, glm::vec3(0.0f, 1.0f, 0.0f)) * glm::scale(glm::vec3(scale));
    glUniformMatrix4fv(Uniforms::UniformLocs::M, 1, false, glm::value_ptr(M));

    //glBindVertexArray(mesh_data.mVao);
    //glDrawElements(GL_TRIANGLES, mesh_data.mSubmesh[0].mNumIndices, GL_UNSIGNED_INT, 0);    

    Scene::DrawGUI(window);

    glfwSwapBuffers(window);
}

void Scene::DrawGUI(GLFWwindow* window) {
    // Begin ImGui frame
    ImGui_ImplOpenGL3_NewFrame();
    ImGui_ImplGlfw_NewFrame();

    // Enable docking
    ImGuiIO& io = ImGui::GetIO();
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;

    ImGui::NewFrame();

    static ImGuiDockNodeFlags dockspace_flags = ImGuiDockNodeFlags_PassthruCentralNode;

    // Add menu bar
    ImGuiWindowFlags window_flags = ImGuiWindowFlags_MenuBar | ImGuiWindowFlags_NoDocking;

    // Style windows
    const ImGuiViewport* viewport = ImGui::GetMainViewport();
    ImGui::SetNextWindowPos(viewport->WorkPos);
    ImGui::SetNextWindowSize(viewport->WorkSize);
    ImGui::SetNextWindowViewport(viewport->ID);
    ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
    ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 0.0f);
    window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove;
    window_flags |= ImGuiWindowFlags_NoBringToFrontOnFocus | ImGuiWindowFlags_NoNavFocus;
    window_flags |= ImGuiWindowFlags_NoBackground;

    ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0.0f, 0.0f));
    ImGui::Begin("TerraVisor", nullptr, window_flags);
    ImGui::PopStyleVar(3);

    // Submit the DockSpace
    if (io.ConfigFlags & ImGuiConfigFlags_DockingEnable)
    {
        ImGuiID dockspace_id = ImGui::GetID("MyDockSpace");
        ImGui::DockSpace(dockspace_id, ImVec2(0.0f, 0.0f), dockspace_flags);
    }

    if (ImGui::BeginMenuBar())
    {
        if (ImGui::BeginMenu("Options"))
        {
            ImGui::Text("Nothing Here Yet, Check Back Later!");

            ImGui::EndMenu();
        }

        ImGui::EndMenuBar();
    }

    ImGui::End();

    //Draw Gui
    ImGui::Begin("Terrain Controls");
    if (ImGui::Button("Quit"))
    {
        glfwSetWindowShouldClose(window, GLFW_TRUE);
    }

    ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
    ImGui::End();

    ImGui::Render();
    ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
}

void Scene::Idle() {
}

void Scene::ReloadShader()
{
   GLuint new_shader = InitShader(vertex_shader.c_str(), fragment_shader.c_str());

   if (new_shader == -1) // loading failed
   {
      DebugBreak(); //alert user by breaking and showing debugger
      glClearColor(1.0f, 0.0f, 1.0f, 0.0f); //change clear color if shader can't be compiled
   }
   else
   {
      glClearColor(0.35f, 0.35f, 0.35f, 0.0f);

      if (shader_program != -1)
      {
         glDeleteProgram(shader_program);
      }
      shader_program = new_shader;
   }
}

void Scene::Init() {
    glewInit();

    glEnable(GL_DEPTH_TEST);
    glEnable(GL_CULL_FACE);

    ReloadShader();
}