/**
 * Model used for metadata setting editors. This model does not do its own saving,
 * as that is done by module_edit.coffee.
 */
CMS.Models.Metadata = Backbone.Model.extend({

    defaults: {
        "field_name": null,
        "display_name": null,
        "value" : null,
        "explicitly_set": null,
        "default_value" : null,
        "options" : null,
        "type" : null
    },

    initialize: function() {
        this.original_value = this.get('value');
        this.original_explicitly_set = this.get('explicitly_set');
    },

    /**
     * Returns true if the stored value is different, or if the "explicitly_set"
     * property has changed.
     */
    isModified : function() {
        if (!this.get('explicitly_set') && !this.original_explicitly_set) {
            return false;
        }
        if (this.get('explicitly_set') && this.original_explicitly_set) {
            return this.get('value') !== this.original_value;
        }
        return true;
    },

    /**
     * Returns true if a non-default/non-inherited value has been set.
     */
    isExplicitlySet: function() {
        return this.get('explicitly_set');
    },

    /**
     * The value, as shown in the UI. This may be an inherited or default value.
     */
    getDisplayValue : function () {
        return this.get('value');
    },

    /**
     * The value, as should be returned to the server. if 'isExplicitlySet'
     * returns false, this method returns null to indicate that the value
     * is not set at this level.
     */
    getValue: function() {
        return this.get('explicitly_set') ? this.get('value') : null;
    },

    /**
     * Sets the displayed value.
     */
    setValue: function (value) {
        this.set('explicitly_set', true);
        this.set('value', value);
    },

    /**
     * Returns the field name, which should be used for persisting the metadata
     * field to the server.
     */
    getFieldName: function () {
        return this.get('field_name');
    },

    /**
     * Returns the options. This may be a array of possible values, or an object
     * with properties like "max", "min" and "step".
     */
    getOptions: function () {
        return this.get('options');
    },

    /**
     * Returns the type of this metadata field. Possible values are SELECT_TYPE,
     * INTEGER_TYPE, and FLOAT_TYPE, GENERIC_TYPE.
     */
    getType: function() {
        return this.get('type');
    },

    /**
     * Reverts the value to the default_value specified at construction, and updates the
     * explicitly_set property.
     */
    clear: function() {
        this.set('explicitly_set', false);
        this.set('value', this.get('default_value'));
    }
});

CMS.Models.Metadata.SELECT_TYPE = "Select";
CMS.Models.Metadata.INTEGER_TYPE = "Integer";
CMS.Models.Metadata.FLOAT_TYPE = "Float";
CMS.Models.Metadata.GENERIC_TYPE = "Generic";
