// ==UserScript==
// @name         4chan Anonymouse File Names
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Changes your upload filenames to random timestamps and changes the hash of images
// @author       Some Anon
// @match        https://boards.4chan.org/*
// @match        http://boards.4chan.org/*
// @match        https://boards.4channel.org/*
// @match        http://boards.4channel.org/*
// @run-at      document-start
// ==/UserScript==

//This script changes the input event of every type=file input field to an name-changing function
//it can be used on every site where the onchange event isn't used for something else already
//(if it is, you can always also hook it up to the input event or make it call the original change event after name changing)

function createFileList(a) {
    a = [].slice.call(Array.isArray(a) ? a : arguments)
    for (var c, b = c = a.length, d = !0; b-- && d;) d = a[b] instanceof File
    if (!d) throw new TypeError('expected argument to FileList is File or array of File objects')
    for (b = (new ClipboardEvent('')).clipboardData || new DataTransfer; c--;) b.items.add(a[c])
    return b.files
}

function getFilename() {
    var curtime = new Date().getTime();
    return curtime - Math.floor(Math.random() * 365 * 24 * 60 * 60 * 1000);
}

function fileNameChange() {
    var element = this;
    var mimetype = element.files[0].type;
    var filename = getFilename() + '.' + element.files[0].name.split('.')[1];
    //change name and write element first immediately because fast responding sites
    //would not catch after hash change
    var file = new File([element.files[0]], filename, {type: mimetype});
    element.files = createFileList(file);
    console.log("Change filename to " + filename);
    if (mimetype == 'image/png' || mimetype == 'image/jpeg') {
        var reader = new FileReader();
        reader.addEventListener("load", function () {
            var imgs = new Image();
            imgs.src = reader.result;
            imgs.onload = function() {
                var cvs = document.createElement('canvas');
                cvs.width = imgs.naturalWidth;
                cvs.height = imgs.naturalHeight;
                var canvas = cvs.getContext("2d");
                console.log("Change Imagehash");
                canvas.drawImage(imgs, 0, 0);
                canvas.fillStyle = "rgba(" + Math.floor(Math.random() * 255) + "," + Math.floor(Math.random() * 255) + "," + Math.floor(Math.random() * 255) + ",255)";
                canvas.fillRect(Math.floor(Math.random() * cvs.width), Math.floor(Math.random() * cvs.height), 1, 1 );
                var newImageData = cvs.toBlob(function(blob) {
                    file = new File([blob], filename, {type: mimetype});
                    element.files = createFileList(file);
                }, 'image/jpeg', 0.9);
            }
        }, false)
        reader.readAsDataURL(element.files[0]);
    }
}

function addNameChangeEvent(element) {
    element.addEventListener('change', fileNameChange);
}

function mutationChange (mutations) {
  mutations.forEach((mutation) => {
    var nodes = mutation.addedNodes;
    for(var n = 0; n < nodes.length; n++) {
        if(typeof nodes[n].type !== 'undefined' && nodes[n].type.toLowerCase() == 'file') {
            //if element itself is input=file
            addNameChangeEvent(nodes[n]);
        }
        else {
            //search child nodes for input=file
            var nodesl = nodes[n].getElementsByTagName("input");
            for(var i=0; i<nodesl.length; i++) {
                if(nodesl[i].type.toLowerCase() == 'file') {
                    addNameChangeEvent(nodesl[i]);
                }
            }
        }
    }
  });
};

window.addEventListener('load', function() {
    //add event to all already existing fileinput DOM elements
    var inputs = document.getElementsByTagName('input');
    for(var i = 0; i < inputs.length; i++) {
        if(inputs[i].type.toLowerCase() == 'file') {
            addNameChangeEvent(inputs[i]);
        }
    }
    //check for later added fileinput DOM elements and add event
    const observer = new MutationObserver(mutationChange);
    observer.observe(document.body, {childList: true});
}, false);