
// generate reandom string
getRndomString = function (length) {
    var result = '',
        chars = '!-().0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    for (var i = length; i > 0; --i)
        result += chars[Math.round(Math.random() * (chars.length - 1))];
    return result;
};


// getnerat random small alphabet
getRandomAlphabet = function (length) {
    var result = '',
        chars = 'abcdefghijklmnopqrstuvwxyz';
    for (var i = length; i > 0; --i)
        result += chars[Math.round(Math.random() * (chars.length - 1))];
    return result;
};


attachDropzoneWithForm = function (dropzoneTarget, uploadUrl, validationUrl, options) {
    var $dropzonePreviewArea = $(dropzoneTarget),
        $dropzonePreviewScrollbar = $dropzonePreviewArea.find(".post-file-dropzone-scrollbar"),
        $previews = $dropzonePreviewArea.find(".post-file-previews"),
        $postFileUploadRow = $dropzonePreviewArea.find(".post-file-upload-row"),
        $uploadFileButton = $dropzonePreviewArea.find(".upload-file-button"),
        $submitButton = $dropzonePreviewArea.find("button[type=submit]"),
        previewsContainer = getRandomAlphabet(15),
        postFileUploadRowId = getRandomAlphabet(15),
        uploadFileButtonId = getRandomAlphabet(15);

    //set random id with the previws
    $previews.attr("id", previewsContainer);
    $postFileUploadRow.attr("id", postFileUploadRowId);
    $uploadFileButton.attr("id", uploadFileButtonId);

    //get the template HTML and remove it from the doumenthe template HTML and remove it from the doument
    var previewNode = document.querySelector("#" + postFileUploadRowId);
    previewNode.id = "";
    var previewTemplate = previewNode.parentNode.innerHTML;
    previewNode.parentNode.removeChild(previewNode);

    if (!options)
        options = {};

    var postFilesDropzone = new Dropzone(dropzoneTarget, {
        url: uploadUrl,
        thumbnailWidth: 80,
        thumbnailHeight: 80,
        parallelUploads: 20,
        maxFilesize: 3000,
        previewTemplate: previewTemplate,
        dictDefaultMessage: file_upload_instruction,
        autoQueue: true,
        previewsContainer: "#" + previewsContainer,
        clickable: "#" + uploadFileButtonId,
        maxFiles: options.maxFiles ? options.maxFiles : 1000,
        init: function () {
            this.on("maxfilesexceeded", function (file) {
                this.removeAllFiles();
                this.addFile(file);
            });
        },
        accept: function (file, done) {
            if (file.name.length > 200) {
                done(filename_too_long);
            }
            $dropzonePreviewScrollbar.removeClass("hide");
            initScrollbar($dropzonePreviewScrollbar, {setHeight: 90});

            $dropzonePreviewScrollbar.parent().removeClass("hide");

            $dropzonePreviewArea.find("textarea").focus();
            //validate the file
            $.ajax({
                url: validationUrl,
                data: {file_name: file.name, file_size: file.size},
                cache: false,
                type: 'POST',
                dataType: "json",
                success: function (response) {
                    if (response.success) {
                        $(file.previewTemplate).append("<input type='hidden' name='file_names[]' value='" + file.name + "' />\n\
                                 <input type='hidden' name='file_sizes[]' value='" + file.size + "' />");
                        done();
                    } else {
                        toastr[error](response.message);
                        $(file.previewTemplate).find("input").remove();
                        done(response.message);

                    }
                }
            });
        },
        processing: function () {
            $submitButton.prop("disabled", true);
        },
        queuecomplete: function () {
            $submitButton.prop("disabled", false);
        },
        reset: function (file) {
            $dropzonePreviewScrollbar.addClass("hide");
        },
        fallback: function () {
            //add custom fallback;
            $("body").addClass("dropzone-disabled");

            $uploadFileButton.on("click", function(){
                //fallback for old browser
                $(this).html("<i class='fa fa-camera'></i> Add more");
                $dropzonePreviewScrollbar.removeClass("hide");
                initScrollbar($dropzonePreviewScrollbar, {setHeight: 90});
                $dropzonePreviewScrollbar.parent().removeClass("hide");

                $previews.prepend("<div class='clearfix p-sm file-row'><button type='button' class='btn btn-xs btn-danger pull-left mr remove-file'><i class='fa fa-times'></i></button> <input class='pull-left' type='file' name='manualFiles[]' /></div>");

            });
            $previews.on("click", ".remove-file", function () {
                $(this).parent().remove();
            });
        },
        success: function (file) {
            setTimeout(function () {
                $(file.previewElement).find(".progress-striped").removeClass("progress-striped").addClass("progress-bar-success");
            }, 1000);
        }
    });
    return postFilesDropzone;
};
