#ifndef DRAW_CPP
#define DRAW_CPP
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <cmath>
#include <filesystem>
#include "draw.hpp"
#include "renderLoop.hpp"
#include "shaders.hpp"
#include "constants.hpp"
#include "misc.hpp"
#include "shader.hpp"
#include "textures.hpp"
#include "stb_image.h"

drawFigureReturn drawFigure(const int whatToDraw)
{
    switch (whatToDraw)
    {
    case 0:
        return drawTriangleClass(constants::TRIANGLE_VERTICES, constants::TRIANGLE_VERTICES_SIZE, constants::VERTEX_SHADER_SOURCE_FILENAME, constants::FRAGMENT_SHADER_SOURCE_FILENAME);
    case 1:
        return drawSquare(constants::SQUARE_VERTICES, constants::SQUARE_VERTICES_SIZE, constants::SQUARE_INDICES, constants::SQUARE_INDICES_SIZE, constants::VERTEX_SHADER_SOURCE, constants::FRAGMENT_SHADER_SOURCE);
    case 2:
        // Try to draw 2 triangles next to each other using glDrawArrays by adding more vertices to your data.
        return drawTriangleClass(constants::TRIANGLES_VERTICES, constants::TRIANGLES_VERTICES_SIZE, constants::VERTEX_SHADER_SOURCE_FILENAME, constants::FRAGMENT_SHADER_SOURCE_FILENAME);
    case 3:
        drawTriangleClass(constants::TRIANGLE_ONE, constants::TRIANGLE_ONE_SIZE, constants::VERTEX_SHADER_SOURCE_FILENAME, constants::FRAGMENT_SHADER_SOURCE_FILENAME);
        // Now create the same 2 triangles using two different VAOs and VBOs for their data
        return drawTriangleClass(constants::TRIANGLE_TWO, constants::TRIANGLE_TWO_SIZE, constants::VERTEX_SHADER_SOURCE_FILENAME, constants::FRAGMENT_SHADER_SOURCE_FILENAME);
    case 4:
        drawTriangleClass(constants::TRIANGLE_ONE, constants::TRIANGLE_ONE_SIZE, constants::VERTEX_SHADER_SOURCE_FILENAME, constants::FRAGMENT_SHADER_SOURCE_FILENAME);
        // Create two shader programs where the second program uses a different fragment shader that outputs the color yellow; draw both triangles again where one outputs the color yellow
        return  drawTriangleClass(constants::TRIANGLE_TWO, constants::TRIANGLE_TWO_SIZE, constants::VERTEX_SHADER_SOURCE_FILENAME, constants::FRAGMENT_SHADER_SOURCE_YELLOW_FILENAME);
    case 5:
        // Get color from vertex shader to fragment shader
        return drawTriangleClass(constants::TRIANGLE_VERTICES, constants::TRIANGLE_VERTICES_SIZE, constants::VERTEX_SHADER_COLOR_FILENAME, constants::FRAGMENT_SHADER_COLOR_FROM_VERTEX_FILENAME);
    case 6:
        // set color from opengl code to uniform value in fragment shader
        return drawTriangleClass(constants::TRIANGLE_VERTICES, constants::TRIANGLE_VERTICES_SIZE, constants::VERTEX_SHADER_COLOR_FILENAME, constants::FRAGMENT_SHADER_UNIFORMS_FILENAME);
    case 7:
        // set color from opengl code to uniform value in fragment shader
        return drawTriangleClass(constants::TRIANGLE_COLORS, constants::TRIANGLE_COLORS_SIZE, constants::VERTEX_SHADER_VERTICE_COLOR_FILENAME, constants::FRAGMENT_SHADER_COLOR_FROM_VERTEX_FILENAME, true);
    case 8:
        // upside down triangle
        return drawTriangleClass(constants::TRIANGLE_VERTICES, constants::TRIANGLE_VERTICES_SIZE, constants::VERTEX_SHADER_UPSIDE_DOWN_FILENAME, constants::FRAGMENT_SHADER_SOURCE_FILENAME);
    case 9:
    {
        // offset triangle
        offsetsStruct offsets = offsetsStruct();
        offsets.xOffset = 0.5f;
        return drawTriangleClass(constants::TRIANGLE_VERTICES, constants::TRIANGLE_VERTICES_SIZE, constants::VERTEX_SHADER_OFFSET_FILENAME, constants::FRAGMENT_SHADER_SOURCE_FILENAME, false, false, offsets);
    }
    case 10:
        return drawTriangleClass(constants::TRIANGLE_VERTICES, constants::TRIANGLE_VERTICES_SIZE, constants::VERTEX_SHADER_TASK_THREE_FILENAME, constants::FRAGMENT_SHADER_TASK_THREE_FILENAME);
    case constants::MAX_DRAW_CALL: 
        return drawDebilMode(constants::VERTEX_SHADER_TEXTURE_FILENAME, constants::FRAGMENT_SHADER_TEXTURE_FILENAME, constants::TEXTURE_VERTICES, constants::TEXTURE_VERTICES_SIZE, constants::TEXTURE_INDICES, constants::TEXTURE_INDICES_SIZE);
    default:
        throw "No function for this draw call";
    }
}

unsigned int getShaderProgram(const char* vertexShaderSource, const char* fragmentShaderSource) 
{
    const std::pair<unsigned int, unsigned int> shaders = compileShaders(vertexShaderSource, fragmentShaderSource);
    if (shaders.first == 0 || shaders.second == 0)
        return 0;

    const unsigned int shaderProgram = linkShaderObjectsShaderProgram(shaders.first, shaders.second);
    if (shaderProgram == 0)
        return 0;
    return shaderProgram;
}

void setOffsets(Shader shader, const offsetsStruct offsets) {
    shader.setFloat("xOffset", offsets.xOffset);
    shader.setFloat("yOffset", offsets.yOffset);
    shader.setFloat("zOffset", offsets.zOffset);
}

drawFigureReturn drawTriangleClass(const float triangleVertices[], const size_t triangleVerticesSize, const char* vertexPath, const char* fragmentPath, const bool colorIncluded, const bool textureIncluded, const offsetsStruct offsets) 
{
    // In your CPP file:
    // ======================
    // float offset = 0.5f;

    Shader ourShader(vertexPath, fragmentPath);
    ourShader.use();
    setOffsets(ourShader, offsets);

    const unsigned int vertexBufferObject = copyVerticesMemory(triangleVertices, triangleVerticesSize, GL_ARRAY_BUFFER);
    const unsigned int vertexArrayObject = generateBindVAO();
    copyVerticesArray(vertexBufferObject, triangleVertices, triangleVerticesSize, GL_ARRAY_BUFFER);
    // set vertex attribute pointers
    configureVertexAttribute(colorIncluded, textureIncluded);
    doDrawArrays(ourShader.ID, vertexArrayObject, GL_TRIANGLES, 0, triangleVerticesSize);
    drawFigureReturn newReturn;
    newReturn.success = 0;
    newReturn.VAO = vertexArrayObject;
    newReturn.VBO = vertexBufferObject;
    newReturn.EBO = 0;
    return newReturn;
}

drawFigureReturn drawTriangle(const float triangleVertices[], const size_t triangleVerticesSize, const char* vertexShaderSource, const char* fragmentShaderSource, const bool colorIncluded, const bool textureIncluded)
{
    
    const unsigned int shaderProgram = getShaderProgram(vertexShaderSource, fragmentShaderSource);
    drawFigureReturn newReturn;
    if (shaderProgram == 0) {
        newReturn.success = -1;
        return newReturn;
    }
            
    const unsigned int vertexBufferObject = copyVerticesMemory(triangleVertices, triangleVerticesSize, GL_ARRAY_BUFFER);
    const unsigned int vertexArrayObject = generateBindVAO();
    copyVerticesArray(vertexBufferObject, triangleVertices, triangleVerticesSize, GL_ARRAY_BUFFER);

    // set vertex attribute pointers
    configureVertexAttribute(colorIncluded, textureIncluded);
    doDrawArrays(shaderProgram, vertexArrayObject, GL_TRIANGLES, 0, triangleVerticesSize);
    newReturn.success = 0;
    newReturn.VAO = vertexArrayObject;
    newReturn.VBO = vertexBufferObject;
    newReturn.EBO = 0;
    return newReturn;
}

drawFigureReturn drawSquare(const float squareVertices[], const size_t squareVerticesSize, const unsigned int squareIndices[], const size_t squareIndicesSize, const char* vertexShaderSource, const char* fragmentShaderSource, const bool colorIncluded, const bool textureIncluded, const offsetsStruct offsets)
{
    const unsigned int shaderProgram = getShaderProgram(vertexShaderSource, fragmentShaderSource);
    drawFigureReturn newReturn;
    if (shaderProgram == 0) {
        newReturn.success = -1;
        return newReturn;
    }
    const unsigned int VAO = generateBindVAO();
    copyVerticesMemory(squareVertices, squareVerticesSize, GL_ARRAY_BUFFER);
    copyVerticesMemory(squareIndices, squareIndicesSize, GL_ELEMENT_ARRAY_BUFFER);

    // set vertex attribute pointers
    configureVertexAttribute(colorIncluded, textureIncluded);

    doDrawElements(shaderProgram, VAO, GL_TRIANGLES, GL_UNSIGNED_INT, squareIndicesSize);
    newReturn.success = 0;
    newReturn.VAO = VAO;
    newReturn.VBO = 0;
    newReturn.EBO = 0;
    return newReturn;
}

drawFigureReturn drawSquareClass(const char* vertexPath, const char* fragmentPath, const bool colorIncluded, const bool textureIncluded, const offsetsStruct offsets) 
{
    Shader ourShader(vertexPath, fragmentPath);
    ourShader.use();
    const unsigned int vertexBufferObject = copyVerticesMemory(constants::SQUARE_VERTICES, constants::SQUARE_VERTICES_SIZE, GL_ARRAY_BUFFER);
    const unsigned int vertexArrayObject = generateBindVAO();
    copyVerticesArray(vertexBufferObject, constants::SQUARE_VERTICES, constants::SQUARE_VERTICES_SIZE, GL_ARRAY_BUFFER);

    // set vertex attribute pointers
    configureVertexAttribute(false, false);
    doDrawArrays(ourShader.ID, vertexArrayObject, GL_TRIANGLES, 0, constants::SQUARE_VERTICES_SIZE);
    drawFigureReturn newReturn;
    newReturn.success = 0;
    newReturn.VAO = vertexArrayObject;
    newReturn.VBO = vertexBufferObject;
    newReturn.EBO = 0;
    return newReturn;
}

drawFigureReturn drawDebilMode(const char* vertexPath, const char* fragmentPath, const float vertices[], const size_t verticesSize, const unsigned int indices[], const size_t indicesSize) {
    // https://stackoverflow.com/questions/33883609/opengl-linker-error-linking-with-uncompiled-shader
    Shader ourShader(constants::VERTEX_SHADER_TEXTURE_FILENAME, constants::FRAGMENT_SHADER_TEXTURE_FILENAME);

    unsigned int VAO = generateBindVAO();
    unsigned int VBO = copyVerticesMemory(vertices, verticesSize, GL_ARRAY_BUFFER);
    unsigned int EBO = copyVerticesMemory(indices, indicesSize, GL_ELEMENT_ARRAY_BUFFER);

    configureVertexAttribute(true, true);

    loadAndCreateTexture();

    ourShader.use(); // don't forget to activate/use the shader before setting uniforms!
    // set it via the texture class
    ourShader.setInt("texture1", 1);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
    
    drawFigureReturn newReturn;
    newReturn.success = 0;
    newReturn.VAO = VAO;
    newReturn.VBO = VBO;
    newReturn.EBO = EBO;
    return newReturn;
}

void doDrawElements(const unsigned int shaderProgram, const unsigned int vertexArrayObject, const GLenum drawArrayMode, const GLenum drawType, const int numberOfElementsToDraw)
{
    glUseProgram(shaderProgram);
    glBindVertexArray(vertexArrayObject);
    glDrawElements(drawArrayMode, numberOfElementsToDraw, drawType, 0);
    glBindVertexArray(0);
}

void updateUniformColor(const unsigned int shaderProgram, const GLchar* uniformName)
{
    // update the uniform color
    const float timeValue = glfwGetTime(); // retrieve running time
    const float greenValue = sin(timeValue) / 2.0f + 0.5f; // vary the color from 0.0 to 1.0 using sin
    const int vertexColorLocation = glGetUniformLocation(shaderProgram, uniformName); // query the location of our uniform
    if(vertexColorLocation != -1)  // if glGetUniformLocation returns -1 it could not find the location 
    { 
        glUniform4f(vertexColorLocation, 0.0f, greenValue, 0.0f, 1.0f); /* we set the uniform value using glUniform4f
        4f means that it expects 4 floats 
        few of possible postfixes:
            f: the function expects a float as its value.
            i: the function expects an int as its value.
            ui: the function expects an unsigned int as its value.
            3f: the function expects 3 floats as its value.
            fv: the function expects a float vector/array as its value.
        */
    }
}

void doDrawArrays(const unsigned int shaderProgram, const unsigned int vertexArrayObject, const GLenum drawArrayMode, const int firstIndex, const unsigned int numberOfIndicesToBeRendered)
{
    // use shader program to render an object
    glUseProgram(shaderProgram);
    updateUniformColor(shaderProgram, "ourColor");
    const unsigned int texture = generateTexture("./assets/Preview.png", 430, 288, 3);
    glBindTexture(GL_TEXTURE_2D, texture);
    glBindVertexArray(vertexArrayObject);
    // From left:
    // primitive type we want to draw
    // starting index of vertex array
    // how many vertices we want to draw
    glDrawArrays(drawArrayMode, firstIndex, numberOfIndicesToBeRendered);
}

int drawTexture() {
    // we added new vertex attribute and need to inform opengl that we done so
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);
    return -1;
}

#endif