<div id="speeddate">

    <h1>Communicating With Attribute Events On Speed Dates</h1>

    <div id="john">
        <button type="button" class="hi">Hi, I'm John</button>

        <span class="interests disabled">
            I enjoy: 
            <label><input type="checkbox" id="sunsets" class="interest" value="Sunsets" disabled="disabled"> Sunsets</label>
            <label><input type="checkbox" id="specs" class="interest" value="Reading Specifications" disabled="disabled"> Reading Specifications</label> 
            <label><input type="checkbox" id="whales" class="interest" value="Saving Whales" disabled="disabled"> Saving Whales</label>
            <label><input type="checkbox" id="knitting" class="interest" value="Knitting" disabled="disabled"> Knitting</label>
        </span>
        <div class="shirt"></div>
    </div>

    <div id="jane">
        <button type="button" class="hi" disabled="disabled">Hey, I'm Jane</button>
        <button type="button" class="movingOn" disabled="disabled">I'm Moving On...</button> <span class="reconsider disabled">(unless he likes whales, and avoids knitting <em class="message"></em>)</span>
        <div class="shirt"></div>
    </div>
</div>

<script type="text/javascript">

// Get a new instance of YUI and 
// load it with the required set of modules

YUI().use("collection", "event", "node", "attribute", function(Y) {

    // Setup custom class which we want to add managed attribute support to

    function SpeedDater(cfg) {
        // When constructed, setup the initial attributes for the instance, by calling the addAttrs method.
        var attrs = {
            name : {
                writeOnce:true
            },

            personality : {
                value:50
            },

            available : {
                value:true
            }, 

            interests : {
                value : []
            }
        };

        this.addAttrs(attrs, cfg);
    }

    // The HTML template representing the SpeedDater name tag.
    SpeedDater.NAMETAG = '<div class="sd-nametag"> \
                            <div class="sd-hd">Hello!</div> \
                            <div class="sd-bd"> \
                                <p>I\'m <span class="sd-name">{name}</span> and my PersonalityQuotientIndex is <span class="sd-personality">{personality}</span></p> \
                                <p>I enjoy <span class="sd-interests">{interests}</span>.</p> \
                            </div> \
                            <div class="sd-ft sd-availability">{available}</div> \
                         </div>';

    // Method used to render the visual representation of a SpeedDater object's state (in this case as a name tag)
    SpeedDater.prototype.applyNameTag = function(where) {

        var tokens = {
            name: this.get("name"),
            available: (this.get("available")) ? "" : "Sorry, moving on",
            personality: this.get("personality"),
            interests: (this.get("interests").length == 0) ? "absolutely nothing" : this.get("interests").join(", ")
        };

        this.nameTag = Y.Node.create(Y.Lang.sub(SpeedDater.NAMETAG, tokens));
        Y.one(where).appendChild(this.nameTag);

        this.listenForChanges();
    };

    // Method used to attach attribute change event listeners, so that the SpeedDater instance 
    // will react to changes in attribute state, and update what's rendered on the page
    SpeedDater.prototype.listenForChanges = function() {

        // Sync up the UI for "available", after the value of the "available" attribute has changed:
        this.after("availableChange", function(e) {
            var taken = (e.newVal) ? "" : "Oh, is that the time?";
            this.nameTag.one(".sd-availability").set("innerHTML", taken);
        });

        // Sync up the UI for "name", after the value of the "name" attribute has changed:
        this.after("nameChange", function(e) {
            var name = e.newVal;
            this.nameTag.one(".sd-name").set("innerHTML", name);
        });

        // Sync up the UI for "personality", after the value of the "personality" attribute has changed:
        this.after("personalityChange", function(e) {
            var personality = e.newVal;

            var personalityEl = this.nameTag.one(".sd-personality");
            personalityEl.set("innerHTML", personality);

            if (personality > 90) {
                personalityEl.addClass("sd-max");
            }
        });

        // Sync up the UI for "interests", after the value of the "interests" attribute has changed:
        this.after("interestsChange", function(e) {
            var interests = (e.newVal.length == 0) ? "absolutely nothing" : this.get("interests").join(", ");
            this.nameTag.one(".sd-interests").set("innerHTML", interests);
        });
    };

    // Augment custom class with Attribute
    Y.augment(SpeedDater, Y.Attribute);

    var john, jane;

    Y.on("click", function() {

        if (!john) {

            john = new SpeedDater({
                name: "John",
                personality: 78
            });
            john.applyNameTag("#john .shirt");

            Y.one("#jane .hi").set("disabled", false); 
        }

    }, "#john .hi");

    Y.on("click", function() {

        if (!jane) {

            jane = new SpeedDater({
                name: "Jane",
                personality: 82,
                interests: ["Popcorn", "Saving Whales"]
            });
            jane.applyNameTag("#jane .shirt");

            // Update Jane's interests state, after John's interests state changes...
            john.after("interestsChange", function(e) {

                var janesInterests = jane.get("interests"),
                    johnsInterests = e.newVal,

                    readingSpecs = "Reading Specifications";
    
                // If it turns out that John enjoys reading specs, then Jane can admit it too...
                if (Y.Array.indexOf(johnsInterests, readingSpecs) !== -1) {
                    if(Y.Array.indexOf(janesInterests, readingSpecs) == -1) {
                        janesInterests.push(readingSpecs);
                    }
                } else {
                    janesInterests = Y.Array.reject(janesInterests, function(item){return (item == readingSpecs);});
                }

                jane.set("interests", janesInterests);
                jane.set("available", true);

                setMessage("");
            });

            // We can also listen before an attribute changes its value, and decide if we want to
            // allow the state change to occur or not. Invoking e.preventDefault() stops the state from
            // being updated. 

            // In this case, Jane can change her mind about making herself unavailable, if John likes 
            // saving whales, as long as he doesn't dig knitting too.
 
            jane.on("availableChange", function(e) {
                var johnsInterests = john.get("interests");
                var janeAvailable = e.newVal;
                if (janeAvailable === false && Y.Array.indexOf(johnsInterests, "Saving Whales") !== -1 &&  Y.Array.indexOf(johnsInterests, "Knitting") == -1 ) {
                    // Reconsider..
                    e.preventDefault();

                    setMessage("... which he does");
                };
            });

            enableExampleUI();
        }

    }, "#jane .hi");

    Y.on("click", function() { 
        jane.set("available", false); 
    }, "#jane .movingOn");

    // A delegate DOM event listener which will update John's interests, based on the checkbox state, whenever
    // a checkbox is clicked. (Using click for IE, due to it's weirdness with requiring a blur before firing change)
    Y.delegate("click", function() {
        var interests = [];

        Y.Node.all("#john input[type=checkbox].interest").each(function(checkbox) {
            if (checkbox.get("checked")) {
                interests.push(checkbox.get("value"));
            }
        });
        john.set("interests", interests);

    }, "#john", "input[type=checkbox].interest");


    // Example helpers...
    function enableExampleUI() {
        Y.all("#jane button").set("disabled", false);
        Y.all("#john button").set("disabled", false);
        Y.all("#john input").set("disabled", false);
        Y.one("#john .interests").removeClass("disabled");
        Y.one("#jane .reconsider").removeClass("disabled");
    }
    
    function setMessage(msg) {
        Y.one("#jane .message").set("innerHTML", msg);      
    }

 });
</script>
