MattiSG/Watai

var promises = require('q');

/** Mapping from short selector types to WebDriver's fully qualified selector types.
*
*@see    {@link http://code.google.com/p/selenium/wiki/JsonWireProtocol#POST_/session/:sessionId/element|JsonWire sessionId}
*/
var WATAI_SELECTOR_TYPES_TO_WEBDRIVER_TYPES = {
    css        : 'css selector',
    xpath    : 'xpath',
    a        : 'partial link text',
    linkText: 'link text',
    id        : 'id',
    name    : 'name',
    'class'    : 'class name',
    tag        : 'tag name'
};

/** Default Watai selector type
*
*@type    {String}
*/
var DEFAULT_SELECTOR_TYPE = 'css';

/**@class    A Locator allows one to target a specific element on a web page.
* It is a wrapper around both a selector and its type (css, xpath, id…).
*
*@param    {Object}    locator    A single value-pair hash whose key may be one of `css`, `id`, or any other value of Selenium's `By` class; and whose value must be a string of the matching form.
*@param    {WebDriver}    driver    The WebDriver instance in which the described elements are to be sought.
*/
var Locator = function Locator(locator, driver) {
    if (typeof locator == 'string') {
        this.type = DEFAULT_SELECTOR_TYPE;
        this.selector = locator;
    } else {
        this.type = Object.getOwnPropertyNames(locator)[0];
        this.selector = locator[this.type];
    }

    this.driver = driver;

    /** Returns the element this locator points to in the given driver, as an object with all WebDriver methods.
    *
    *@see    {@link http://seleniumhq.org/docs/03_webdriver.html|WebDriver}
    *@private
    */
    this.toSeleniumElement = function toSeleniumElement() {
        return this.driver.element(WATAI_SELECTOR_TYPES_TO_WEBDRIVER_TYPES[this.type] || this.type, this.selector);
    };

    /** Sends the given sequence of keystrokes to the element pointed by this locator.
    *
    *@param    {String}    input    A string that will be sent to this element.
    *@returns    {QPromise}    A promise, resolved when keystrokes have been received, rejected in case of a failure.
    *@see    {@link http://seleniumhq.org/docs/03_webdriver.html#sendKeys|WebDriver.sendKeys}
    *@private
    */
    this.handleInput = function handleInput(input) {
        var element;

        return this.toSeleniumElement().then(function(elm) {
            element = elm;
            return elm.clear();
        }).then(function() {
            return element.type(input);
        }).then(function() {
            return element;    // allow easier chaining
        });
    };
};

/** Adds a getter and a setter to the given Object, allowing access to the Selenium element corresponding to the given locator description.
* The getter dynamically retrieves the Selenium element pointed at by the given selector description.
* The setter will pass the value to the `Locator.handleInput` method.
*
*@param    {Object}    target            The Object to which the getter and setter will be added.
*@param    {String}    key                The name of the property to add to the target object.
*@param    {Object}    typeAndSelector    A locator descriptor, as defined in the Locator constructor.
*@param    {WebDriver}    driver            The WebDriver instance in which the described elements are to be sought.
*/
Locator.addLocator = function addLocator(target, key, typeAndSelector, driver) {
    var locator = new Locator(typeAndSelector, driver);

    var inputHandler = function handleInputAndEmit(input) {
        target.emit('action', key, 'write', [ input ]);

        return locator.handleInput(input);
    };

    var propertyDescriptor = {};

    propertyDescriptor[key] = {
        get: function() {
            target.emit('access', key);
            return locator.toSeleniumElement(locator);
        },
        set: inputHandler    // TODO: remove in v0.7, deprecated since v0.6
    };

    Object.defineProperties(target, propertyDescriptor);

    var setterName = 'set' + key.capitalize();

    target[setterName] = function(input) {    // wrapping to allow call-like syntax in scenarios
        var setter = inputHandler.bind(null, input);

        setter.component = target;
        setter.reference = setterName;
        setter.title = setterName.humanize();
        setter.args = [ input ];

        return setter;
    };
};

module.exports = Locator;    // CommonJS export