//Matrix canvas
var c = document.getElementById("c");
var ctx = c.getContext("2d");
//Get client offsets
var my_height = "innerHeight" in window 
               ? window.innerHeight
               : document.documentElement.offsetHeight; ;
var my_width = "innerWidth" in window 
               ? window.innerWidth
               : document.documentElement.offsetWidth; ;

// making the canvas full screen
c.height = my_height;
c.width = my_width;

//latin characters - taken from the unicode charset
var matrix = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789@#$%^&*()*&^%+-/~{[|`]}";
//converting the string into an array of single characters
matrix = matrix.split("");

var font_size = 10;
var columns = c.width / font_size; //number of columns for the rain
//an array of drops - one per column
var drops = [];
//x below is the x coordinate
//1 = y co-ordinate of the drop(same for every drop initially)
for (var x = 0; x < columns; x++)
    drops[x] = 1;

//drawing the characters
function draw() {
    //Black BG for the canvas
    //translucent BG to show trail
    ctx.fillStyle = "rgba(0, 0, 0, 0.04)";
    ctx.fillRect(0, 0, c.width, c.height);

    ctx.fillStyle = "#5AA509"; // Gitea green
    //ctx.fillStyle = "red";
    ctx.font = font_size + "px arial";
    //looping over drops
    for (var i = 0; i < drops.length; i++) {
        //a random chinese character to print
        var text = matrix[Math.floor(Math.random() * matrix.length)];
        //x = i*font_size, y = value of drops[i]*font_size
        ctx.fillText(text, i * font_size, drops[i] * font_size);

        //sending the drop back to the top randomly after it has crossed the screen
        //adding a randomness to the reset to make the drops scattered on the Y axis

        if (drops[i] * font_size > c.height && Math.random() > 0.975) {
            drops[i] = 0;
        }


        //incrementing Y coordinate
        drops[i]++;
    }
}

setInterval(draw, 35);