(function(global, undefined) {
    "use strict";

    var document = global.document, Alertify;

    Alertify = function() {

        var _alertify = {},
            dialogs = {},
            isopen = false,
            keys = {ENTER: 13, ESC: 27, SPACE: 32},
            queue = [],
            $, btnCancel, btnOK, btnReset, btnResetBack, btnFocus, elCallee, elCover, elDialog, elLog, form, input, getTransitionEvent;

        function getStyleRuleValue(style, selector, sheet) {
            var sheets = typeof sheet !== "undefined" ? [sheet] : document.styleSheets;
            for (var i = 0, l = sheets.length; i < l; i++) {
                sheet = sheets[i];
                if (!sheet.cssRules) {
                    continue;
                }
                for (var j = 0, k = sheet.cssRules.length; j < k; j++) {
                    var rule = sheet.cssRules[j];
                    if (rule.selectorText && rule.selectorText.split(",").indexOf(selector) !== -1) {
                        return rule.style[style];
                    }
                }
            }
            return null;
        }

        /**
         * Markup pieces
         * @type {Object}
         */
        dialogs = {
            buttons: {
                holder: "<nav class=\"alertify-buttons\">{{buttons}}</nav>",
                submit: "<button type=\"submit\" class=\"alertify-button alertify-button-ok\" id=\"alertify-ok\">{{ok}}</button>",
                ok: "<button class=\"alertify-button alertify-button-ok\" id=\"alertify-ok\">{{ok}}</button>",
                cancel: "<button class=\"alertify-button alertify-button-cancel\" id=\"alertify-cancel\">{{cancel}}</button>"
            },
            input: "<div class=\"alertify-text-wrapper\"><input type=\"text\" class=\"alertify-text\" id=\"alertify-text\"></div>",
            message: "<p class=\"alertify-message\">{{message}}</p>",
            log: "<article class=\"alertify-log{{class}}\">{{message}}</article>"
        };

        /**
         * Return the proper transitionend event
         * @return {String}    Transition type string
         */
        getTransitionEvent = function() {
            var t,
                type,
                supported = false,
                el = document.createElement("fakeelement"),
                transitions = {
                    "WebkitTransition": "webkitTransitionEnd",
                    "MozTransition": "transitionend",
                    "OTransition": "otransitionend",
                    "transition": "transitionend"
                };

            for (t in transitions) {
                if (transitions.hasOwnProperty(t)) {
                    if (el.style[t] !== undefined) {
                        type = transitions[t];
                        supported = true;
                        break;
                    }
                }
            }

            return {
                type: type,
                supported: supported
            };
        };

        /**
         * Shorthand for document.getElementById()
         *
         * @param  {String} id    A specific element ID
         * @return {Object}       HTML element
         */
        $ = function(id) {
            return document.getElementById(id);
        };

        /**
         * Alertify private object
         * @type {Object}
         */
        _alertify = {

            /**
             * Labels object
             * @type {Object}
             */
            labels: {
                ok: "OK",
                cancel: "Cancel"
            },

            /**
             * Delay number
             * @type {Number}
             */
            delay: 5000,

            /**
             * Whether buttons are reversed (default is secondary/primary)
             * @type {Boolean}
             */
            buttonReverse: false,

            /**
             * Which button should be focused by default
             * @type {String}    "ok" (default), "cancel", or "none"
             */
            buttonFocus: "ok",

            /**
             * Set the transition event on load
             * @type {[type]}
             */
            transition: undefined,

            /**
             * Track the keydown state
             * @type {boolean}
             */
            keydown: false,

            /**
             * Set the proper button click events
             *
             * @param {Function} fn    [Optional] Callback function
             *
             * @return {undefined}
             */
            addListeners: function(fn) {

                var hasOK = typeof btnOK !== "undefined",
                    hasCancel = typeof btnCancel !== "undefined",
                    hasInput = typeof input !== "undefined",
                    val = "",
                    self = this,
                    keydown,
                    ok, cancel, common, key, reset;

                // ok event handler
                ok = function(event) {
                    event.preventDefault();
                    common(event);
                    if (typeof input !== "undefined") {
                        val = input.value;
                    }
                    if (typeof fn === "function") {
                        if (typeof input !== "undefined") {
                            fn(true, val);
                        }
                        else {
                            fn(true);
                        }
                    }
                };

                // cancel event handler
                cancel = function(event) {
                    event.preventDefault();
                    common(event);
                    if (typeof fn === "function") {
                        fn(false);
                    }
                };

                // common event handler (keyup, ok and cancel)
                common = function() {
                    self.hide();
                    global.removeEventListener("keyup", key);
                    global.removeEventListener("keydown", keydown);
                    global.removeEventListener("focus", reset);
                    if (hasOK) {
                        btnOK.removeEventListener("click", ok);
                    }
                    if (hasCancel) {
                        btnCancel.removeEventListener("click", cancel);
                    }
                };

                // keyup handler
                key = function(event) {
                    var keyCode = event.keyCode;
                    self.keydown = false;
                    if ((keyCode === keys.SPACE && !hasInput) || (hasInput && keyCode === keys.ENTER)) {
                        ok(event);
                    } else if (keyCode === keys.ESC && hasCancel) {
                        cancel(event);
                    }
                };

                keydown = function() {
                    self.keydown = true;
                };

                // reset focus to first item in the dialog
                reset = function() {
                    if (hasInput) {
                        input.focus();
                    } else if (!hasCancel || self.buttonReverse) {
                        btnOK.focus();
                    } else {
                        btnCancel.focus();
                    }
                };

                // handle reset focus link
                // this ensures that the keyboard focus does not
                // ever leave the dialog box until an action has
                // been taken
                btnReset.addEventListener("focus", reset);
                btnResetBack.addEventListener("focus", reset);
                // handle OK click
                if (hasOK) {
                    btnOK.addEventListener("click", ok);
                }
                // handle Cancel click
                if (hasCancel) {
                    btnCancel.addEventListener("click", cancel);
                }
                // listen for keys, Cancel => ESC
                global.addEventListener("keyup", key);
                global.addEventListener("keydown", keydown);
                if (!this.transition.supported) {
                    this.setFocus();
                }
            },

            /**
             * Use alertify as the global error handler (using global.onerror)
             *
             * @return {boolean} success
             */
            handleErrors: function() {
                if (typeof global.onerror !== "undefined") {
                    var self = this;
                    global.onerror = function(msg, url, line) {
                        self.error("[" + msg + " on line " + line + " of " + url + "]", 0);
                    };
                    return true;
                } else {
                    return false;
                }
            },

            /**
             * Append button HTML strings
             *
             * @param {String} secondary    The secondary button HTML string
             * @param {String} primary      The primary button HTML string
             *
             * @return {String}             The appended button HTML strings
             */
            appendButtons: function(secondary, primary) {
                return this.buttonReverse ? primary + secondary : secondary + primary;
            },

            /**
             * Build the proper message box
             *
             * @param  {Object} item    Current object in the queue
             *
             * @return {String}         An HTML string of the message box
             */
            build: function(item) {
                var html = "",
                    type = item.type,
                    message = item.message,
                    css = item.cssClass || "";

                html += "<div class=\"alertify-dialog\">";
                html += "<a id=\"alertify-resetFocusBack\" class=\"alertify-resetFocus\" href=\"#\">Reset Focus</a>";

                if (_alertify.buttonFocus === "none") {
                    html += "<a href=\"#\" id=\"alertify-noneFocus\" class=\"alertify-hidden\"></a>";
                }

                // doens't require an actual form
                if (type === "prompt") {
                    html += "<div id=\"alertify-form\">";
                }

                html += "<article class=\"alertify-inner\">";
                html += dialogs.message.replace("{{message}}", message);

                if (type === "prompt") {
                    html += dialogs.input;
                }

                html += dialogs.buttons.holder;
                html += "</article>";

                if (type === "prompt") {
                    html += "</div>";
                }

                html += "<a id=\"alertify-resetFocus\" class=\"alertify-resetFocus\" href=\"#\">Reset Focus</a>";
                html += "</div>";

                switch (type) {
                    case "confirm":
                        html = html.replace("{{buttons}}", this.appendButtons(dialogs.buttons.cancel, dialogs.buttons.ok));
                        html = html.replace("{{ok}}", this.labels.ok).replace("{{cancel}}", this.labels.cancel);
                        break;
                    case "prompt":
                        html = html.replace("{{buttons}}", this.appendButtons(dialogs.buttons.cancel, dialogs.buttons.submit));
                        html = html.replace("{{ok}}", this.labels.ok).replace("{{cancel}}", this.labels.cancel);
                        break;
                    case "alert":
                        html = html.replace("{{buttons}}", dialogs.buttons.ok);
                        html = html.replace("{{ok}}", this.labels.ok);
                        break;
                    default:
                        break;
                }

                elDialog.className = "alertify alertify-" + type + " " + css;
                elCover.className = "alertify-cover";
                return html;
            },

            /**
             * Close the log messages
             *
             * @param  {Object} elem    HTML Element of log message to close
             * @param  {Number} wait    [optional] Time (in ms) to wait before automatically hiding the message, if 0 never hide
             *
             * @return {undefined}
             */
            close: function(elem, wait) {
                // Unary Plus: +"2" === 2
                var timer = (wait && !isNaN(wait)) ? +wait : this.delay,
                    self = this,
                    hideElement, transitionDone;

                // set click event on log messages
                elem.addEventListener("click", function() {
                    hideElement(elem);
                });
                // Hide the dialog box after transition
                // This ensure it doens't block any element from being clicked
                transitionDone = function(event) {
                    event.stopPropagation();
                    // unbind event so function only gets called once
                    this.removeEventListener(self.transition.type, transitionDone);
                    // remove log message
                    elLog.removeChild(this);
                    if (!elLog.hasChildNodes()) {
                        elLog.className += " alertify-logs-hidden";
                    }
                };
                // this sets the hide class to transition out
                // or removes the child if css transitions aren't supported
                hideElement = function(el) {
                    // ensure element exists
                    if (typeof el !== "undefined" && el.parentNode === elLog) {
                        // whether CSS transition exists
                        if (self.transition.supported) {

                            el.addEventListener(self.transition.type, transitionDone);
                            el.className += " alertify-log-hide";

                            // This is a "just in case" for situations where the transition doesn't fire.
                            var dur = (
                                    getStyleRuleValue("transition-duration", ".alertify-log-hide") ||
                                    getStyleRuleValue("-webkit-transition-duration", ".alertify-log-hide") ||
                                    getStyleRuleValue("-moz-transition-duration", ".alertify-log-hide") ||
                                    getStyleRuleValue("-o-transition-duration", ".alertify-log-hide") ||
                                    "0"
                                ).toLowerCase(),
                                time = parseInt(dur),
                                offset = 1;

                            if (!time || isNaN(time)) {
                                time = 500;
                            }
                            if (dur.indexOf("ms") > -1) {
                                time += offset;
                            } else if (dur.indexOf("s") > -1) {
                                time *= 1000;
                                time += offset;
                            }
                            setTimeout(function () {
                                if (typeof el !== "undefined" && el.parentNode === elLog) {
                                    elLog.removeChild(el);
                                }
                            }, time);

                        } else {
                            elLog.removeChild(el);
                            if (!elLog.hasChildNodes()) {
                                elLog.className += " alertify-logs-hidden";
                            }
                        }
                    }
                };
                // never close (until click) if wait is set to 0
                if (wait === 0) {
                    return;
                }
                // set timeout to auto close the log message
                setTimeout(function() {
                    hideElement(elem);
                }, timer);
            },

            /**
             * Create a dialog box
             *
             * @param  {String}   message        The message passed from the callee
             * @param  {String}   type           Type of dialog to create
             * @param  {Function} fn             [Optional] Callback function
             * @param  {String}   placeholder    [Optional] Default value for prompt input field
             * @param  {String}   cssClass       [Optional] Class(es) to append to dialog box
             *
             * @return {Object}
             */
            dialog: function(message, type, fn, placeholder, cssClass) {
                // set the current active element
                // this allows the keyboard focus to be reset
                // after the dialog box is closed
                elCallee = document.activeElement;
                // check to ensure the alertify dialog element
                // has been successfully created
                var check = function() {
                    if ((elLog && elLog.scrollTop !== null) && (elCover && elCover.scrollTop !== null)) {
                        return;
                    } else {
                        check();
                    }
                };
                // error catching
                if (typeof message !== "string") {
                    throw new Error("message must be a string");
                }
                if (typeof type !== "string") {
                    throw new Error("type must be a string");
                }
                if (typeof fn !== "undefined" && typeof fn !== "function") {
                    throw new Error("fn must be a function");
                }
                // initialize alertify if it hasn't already been done
                this.init();
                check();

                queue.push({type: type, message: message, callback: fn, placeholder: placeholder, cssClass: cssClass});
                if (!isopen) {
                    this.setup();
                }

                return this;
            },

            /**
             * Extend the log method to create custom methods
             *
             * @param  {String} type    Custom method name
             *
             * @return {Function}
             */
            extend: function(type) {
                if (typeof type !== "string") {
                    throw new Error("extend method must have exactly one parameter");
                }
                return function(message, wait) {
                    this.log(message, type, wait);
                    return this;
                };
            },

            /**
             * Hide the dialog and rest to defaults
             *
             * @return {undefined}
             */
            hide: function() {
                var transitionDone,
                    self = this;
                // remove reference from queue
                queue.splice(0, 1);
                // if items remaining in the queue
                if (queue.length > 0) {
                    this.setup(true);
                } else {
                    isopen = false;
                    // Hide the dialog box after transition
                    // This ensure it doens't block any element from being clicked
                    transitionDone = function(event) {
                        event.stopPropagation();
                        // unbind event so function only gets called once
                        elDialog.removeEventListener(self.transition.type, transitionDone);
                    };
                    // whether CSS transition exists
                    if (this.transition.supported) {
                        elDialog.addEventListener(this.transition.type, transitionDone);
                        elDialog.className = "alertify alertify-hide alertify-hidden";
                    } else {
                        elDialog.className = "alertify alertify-hide alertify-hidden alertify-isHidden";
                    }
                    elCover.className = "alertify-cover alertify-cover-hidden";
                    // set focus to the last element or body
                    // after the dialog is closed
                    setTimeout(function() {
                        if (! self.keydown) {
                            elCallee.focus();
                        } else {
                            document.body.focus();
                        }
                    });
                }
            },

            /**
             * Initialize Alertify
             * Create the 2 main elements
             *
             * @return {undefined}
             */
            init: function() {
                // ensure legacy browsers support html5 tags
                // cover
                if ($("alertify-cover") == null) {
                    elCover = document.createElement("div");
                    elCover.setAttribute("id", "alertify-cover");
                    elCover.className = "alertify-cover alertify-cover-hidden";
                    document.body.appendChild(elCover);
                }
                // main element
                if ($("alertify") == null) {
                    isopen = false;
                    queue = [];
                    elDialog = document.createElement("section");
                    elDialog.setAttribute("id", "alertify");
                    elDialog.className = "alertify alertify-hidden";
                    document.body.appendChild(elDialog);
                }
                // log element
                if ($("alertify-logs") == null) {
                    elLog = document.createElement("section");
                    elLog.setAttribute("id", "alertify-logs");
                    elLog.className = "alertify-logs alertify-logs-hidden";
                    document.body.appendChild(elLog);
                }
                // set tabindex attribute on body element
                // this allows script to give it focus
                // after the dialog is closed
                document.body.setAttribute("tabindex", "0");
                // set transition type
                this.transition = getTransitionEvent();
            },

            /**
             * Show a new log message box
             *
             * @param  {String} message    The message passed from the callee
             * @param  {String} type       [Optional] Optional type of log message
             * @param  {Number} wait       [Optional] Time (in ms) to wait before auto-hiding the log
             *
             * @return {Object}
             */
            log: function(message, type, wait, click) {
                // check to ensure the alertify dialog element
                // has been successfully created
                var check = function() {
                    if (elLog && elLog.scrollTop !== null) {
                        return;
                    } else {
                        check();
                    }
                };
                // initialize alertify if it hasn't already been done
                this.init();
                check();

                elLog.className = "alertify-logs";
                this.notify(message, type, wait, click);
                return this;
            },

            /**
             * Add new log message
             * If a type is passed, a class name "alertify-log-{type}" will get added.
             * This allows for custom look and feel for various types of notifications.
             *
             * @param  {String} message    The message passed from the callee
             * @param  {String} type       [Optional] Type of log message
             * @param  {Number} wait       [Optional] Time (in ms) to wait before auto-hiding
             *
             * @return {undefined}
             */
            notify: function(message, type, wait, click) {
                var log = document.createElement("article");
                log.className = "alertify-log" + ((typeof type === "string" && type !== "") ? " alertify-log-" + type : "");
                log.innerHTML = message;
                // Add the click handler, if specified.
                if ("function" === typeof click) {
                    log.addEventListener("click", click);
                }
                // append child
                elLog.appendChild(log);
                // triggers the CSS animation
                setTimeout(function() {
                    log.className = log.className + " alertify-log-show";
                }, 50);
                this.close(log, wait);
            },

            /**
             * Set properties
             *
             * @param {Object} args     Passing parameters
             *
             * @return {undefined}
             */
            set: function(args) {
                var k;
                // error catching
                if (typeof args !== "object" && args instanceof Array) {
                    throw new Error("args must be an object");
                }
                // set parameters
                for (k in args) {
                    if (args.hasOwnProperty(k)) {
                        this[k] = args[k];
                    }
                }
            },

            /**
             * Common place to set focus to proper element
             *
             * @return {undefined}
             */
            setFocus: function() {
                if (input) {
                    input.focus();
                    input.select();
                }
                else {
                    btnFocus.focus();
                }
            },

            /**
             * Initiate all the required pieces for the dialog box
             *
             * @return {undefined}
             */
            setup: function(fromQueue) {
                var item = queue[0],
                    self = this,
                    transitionDone;

                // dialog is open
                isopen = true;
                // Set button focus after transition
                transitionDone = function(event) {
                    event.stopPropagation();
                    self.setFocus();
                    // unbind event so function only gets called once
                    elDialog.removeEventListener(self.transition.type, transitionDone);
                };
                // whether CSS transition exists
                if (this.transition.supported && !fromQueue) {
                    elDialog.addEventListener(this.transition.type, transitionDone);
                }
                // build the proper dialog HTML
                elDialog.innerHTML = this.build(item);
                // assign all the common elements
                btnReset = $("alertify-resetFocus");
                btnResetBack = $("alertify-resetFocusBack");
                btnOK = $("alertify-ok") || undefined;
                btnCancel = $("alertify-cancel") || undefined;
                btnFocus = (_alertify.buttonFocus === "cancel") ? btnCancel : ((_alertify.buttonFocus === "none") ? $("alertify-noneFocus") : btnOK);
                input = $("alertify-text") || undefined;
                form = $("alertify-form") || undefined;
                // add placeholder value to the input field
                if (typeof item.placeholder === "string" && item.placeholder !== "") {
                    input.value = item.placeholder;
                }
                if (fromQueue) {
                    this.setFocus();
                }
                this.addListeners(item.callback);
            }
        };

        return {
            alert: function(message, fn, cssClass) {
                _alertify.dialog(message, "alert", fn, "", cssClass);
                return this;
            },
            confirm: function(message, fn, cssClass) {
                _alertify.dialog(message, "confirm", fn, "", cssClass);
                return this;
            },
            extend: _alertify.extend,
            init: _alertify.init,
            log: function(message, type, wait, click) {
                _alertify.log(message, type, wait, click);
                return this;
            },
            prompt: function(message, fn, placeholder, cssClass) {
                _alertify.dialog(message, "prompt", fn, placeholder, cssClass);
                return this;
            },
            success: function(message, wait, click) {
                _alertify.log(message, "success", wait, click);
                return this;
            },
            error: function(message, wait, click) {
                _alertify.log(message, "error", wait, click);
                return this;
            },
            set: function(args) {
                _alertify.set(args);
            },
            labels: _alertify.labels,
            debug: _alertify.handleErrors
        };
    };

    // AMD and window support
    if (typeof define === "function") {
        define([], function() {
            return new Alertify();
        });
    } else if (typeof global.alertify === "undefined") {
        global.alertify = new Alertify();
    }

}(window));
