{% extends "base.html" %}

{% block title %}Browser Random Generation{% endblock %}

{% block content %}
<div class="max-w-scree grid grid-cols-1 items-center divide-y">
  <div class="flex justify-center pt-6">
    <p class="text-2xl" id="browser-name">Detected Browser: Something</p>
  </div>
  <div class="flex justify-center pt-6">
  <canvas id="randNumCanvas" width="1000" height="1000"></canvas>
  </div>
</div>
{% endblock %}

{% block js %}
<script>
"use strict";

var vertexShaderSource = `#version 300 es

// an attribute is an input (in) to a vertex shader.
// It will receive data from a buffer
in vec2 a_position;

// Used to pass in the resolution of the canvas
uniform vec2 u_resolution;

// all shaders have a main function
void main() {

  // convert the position from pixels to 0.0 to 1.0
  vec2 zeroToOne = a_position / u_resolution;

  // convert from 0->1 to 0->2
  vec2 zeroToTwo = zeroToOne * 2.0;

  // convert from 0->2 to -1->+1 (clipspace)
  vec2 clipSpace = zeroToTwo - 1.0;

  gl_Position = vec4(clipSpace * vec2(1, -1), 0, 1);
}
`;

var fragmentShaderSource = `#version 300 es

precision highp float;

uniform vec4 u_color;

// we need to declare an output for the fragment shader
out vec4 outColor;

void main() {
  outColor = u_color;
}
`;

function main() {
  // Get A WebGL context
  var canvas = document.querySelector("#randNumCanvas");
  var gl = canvas.getContext("webgl2");
  if (!gl) {
    return;
  }

  // Use our boilerplate utils to compile the shaders and link into a program
  var program = webglUtils.createProgramFromSources(gl,
      [vertexShaderSource, fragmentShaderSource]);

  // look up where the vertex data needs to go.
  var positionAttributeLocation = gl.getAttribLocation(program, "a_position");

  // look up uniform locations
  var resolutionUniformLocation = gl.getUniformLocation(program, "u_resolution");
  var colorLocation = gl.getUniformLocation(program, "u_color");

  // Create a buffer
  var positionBuffer = gl.createBuffer();

  // Create a vertex array object (attribute state)
  var vao = gl.createVertexArray();

  // and make it the one we're currently working with
  gl.bindVertexArray(vao);

  // Turn on the attribute
  gl.enableVertexAttribArray(positionAttributeLocation);

  // Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
  gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);

  // Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
  var size = 2;          // 2 components per iteration
  var type = gl.FLOAT;   // the data is 32bit floats
  var normalize = false; // don't normalize the data
  var stride = 0;        // 0 = move forward size * sizeof(type) each iteration to get the next position
  var offset = 0;        // start at the beginning of the buffer
  gl.vertexAttribPointer(
      positionAttributeLocation, size, type, normalize, stride, offset);

  webglUtils.resizeCanvasToDisplaySize(gl.canvas);

  // Tell WebGL how to convert from clip space to pixels
  gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

  // Clear the canvas
  gl.clearColor(0, 0, 0, 0);
  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

  // Tell it to use our program (pair of shaders)
  gl.useProgram(program);

  // Bind the attribute/buffer set we want.
  gl.bindVertexArray(vao);

  // Pass in the canvas resolution so we can convert from
  // pixels to clipspace in the shader
  gl.uniform2f(resolutionUniformLocation, gl.canvas.width, gl.canvas.height);
  //const array = new Uint16Array(30_000);
  //const randNum = self.crypto.getRandomValues(array);
  // draw 50 random rectangles in random colors
  var primitiveType = gl.TRIANGLES;
  var offset = 0;
  var count = 6;
  var counter = 0;
  var array2D = [];
  var y_cnt = 0;
  var x_cnt = 0;
  for (var size = 0; size < 1000; ++size) {
    array2D[size] = self.crypto.getRandomValues(new Uint16Array(1000));
  }
  for (var y = 0; y < 2000; y = y + 2) {
    for (var x = 0; x < 2000; x = x + 2) {
      setRectangle(gl, x, y, 2, 2);
      gl.uniform4f(colorLocation, 0.0, 0.0, 0.0, normalizeUint16(array2D[y/2][x/2]));
      gl.drawArrays(primitiveType, offset, count);
      counter++;
    }
  }
}

// Returns a random integer from 0 to range - 1.
function randomInt(range) {
  return Math.floor(Math.random() * range);
}

function normalizeUint16(val) {
  return val/65535;
  
}

// Fill the buffer with the values that define a rectangle.
function setRectangle(gl, x, y, width, height) {
  var x1 = x;
  var x2 = x + width;
  var y1 = y;
  var y2 = y + height;
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
     x1, y1,
     x2, y1,
     x1, y2,
     x1, y2,
     x2, y1,
     x2, y2,
  ]), gl.STATIC_DRAW);
}

main();

</script>
<script>
// Function to detect the browser name
function detectBrowser() {
    var userAgent = navigator.userAgent;
    if (userAgent.indexOf("Edg") > -1) {
        return "Microsoft Edge";
    } else if (userAgent.indexOf("Chrome") > -1) {
        return "Chrome";
    } else if (userAgent.indexOf("Firefox") > -1) {
        return "Firefox";
    } else if (userAgent.indexOf("Safari") > -1) {
        return "Safari";
    } else if (userAgent.indexOf("Opera") > -1) {
        return "Opera";
    } else if (userAgent.indexOf("Trident") > -1 || userAgent.indexOf("MSIE") > -1) {
        return "Internet Explorer";
    }

    return "Unknown";
}

// Get the browser name and display it
var browserName = detectBrowser();
document.getElementById("browser-name").innerText = "Detected Browser: " + browserName;
</script>

{% endblock %}