//
// Created by saintruler on 05.05.19.
//
#include "Canvas.h"

Canvas::Canvas(int width, int height, Point *points, int nPoints)
{
    float vertices[] = {
            // positions        // colors           // texture coords
            1.f,  1.f, 0.0f,    1.0f, 0.0f, 0.0f,   1.0f, 1.0f, // top right
            1.f, -1.f, 0.0f,    0.0f, 1.0f, 0.0f,   1.0f, 0.0f, // bottom right
            -1.f, -1.f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f, // bottom left
            -1.f,  1.f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f  // top left
    };

    int indices[] = {
            0, 1, 3, // first triangle
            1, 2, 3  // second triangle
    };

    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // color attribute
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    // texture coord attribute
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);

    this->width = width;
    this->height = height;
    this->nPoints = nPoints;

    this->points = points;
    canvas = (unsigned char*) malloc(width * height * 3);
    glGenTextures(1, &texture);
}

void Canvas::SetPixel(int x, int y, Color color)
{
    canvas[y * width * 3 + x * 3 + 0] = color.r;
    canvas[y * width * 3 + x * 3 + 1] = color.g;
    canvas[y * width * 3 + x * 3 + 2] = color.b;

    UpdateTexture();
}

void Canvas::UpdateTexture()
{
    // all upcoming GL_TEXTURE_2D operations now have effect on this texture object
    glBindTexture(GL_TEXTURE_2D, texture);

    // set texture wrapping to GL_REPEAT (default wrapping method)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

    // set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    generate_canvas(width, height, canvas, points, nPoints);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, width, 0, GL_RGB, GL_UNSIGNED_BYTE, canvas);
    glGenerateMipmap(GL_TEXTURE_2D);
}

void Canvas::DrawTexture()
{
    UpdateTexture();

    glBindTexture(GL_TEXTURE_2D, texture);
    shader.use();

    glBindVertexArray(VAO);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
}

void Canvas::DeleteCanvas()
{
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);

    delete[] canvas;
}