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 * Distributed under the BSD license:
 *
 * Copyright (c) 2010, Ajax.org B.V.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of Ajax.org B.V. nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 * ***** END LICENSE BLOCK ***** */

define(function (require, exports, module) {
    "use strict";

    var oop = require("./lib/oop");
    var dom = require("./lib/dom");
    var event = require("./lib/event");
    var EventEmitter = require("./lib/event_emitter").EventEmitter;
// on ie maximal element height is smaller than what we get from 4-5K line document
// so scrollbar doesn't work, as a workaround we do not set height higher than MAX_SCROLL_H
// and rescale scrolltop
    var MAX_SCROLL_H = 0x8000;

    /**
     * An abstract class representing a native scrollbar control.
     * @class ScrollBar
     **/

    /**
     * Creates a new `ScrollBar`. `parent` is the owner of the scroll bar.
     * @param {DOMElement} parent A DOM element
     *
     * @constructor
     **/
    var ScrollBar = function (parent) {
        this.element = dom.createElement("div");
        this.element.className = "ace_scrollbar ace_scrollbar" + this.classSuffix;

        this.inner = dom.createElement("div");
        this.inner.className = "ace_scrollbar-inner";
        this.element.appendChild(this.inner);

        parent.appendChild(this.element);

        this.setVisible(false);
        this.skipEvent = false;

        event.addListener(this.element, "scroll", this.onScroll.bind(this));
        event.addListener(this.element, "mousedown", event.preventDefault);
    };

    (function () {
        oop.implement(this, EventEmitter);

        this.setVisible = function (isVisible) {
            this.element.style.display = isVisible ? "" : "none";
            this.isVisible = isVisible;
            this.coeff = 1;
        };
    }).call(ScrollBar.prototype);

    /**
     * Represents a vertical scroll bar.
     * @class VScrollBar
     **/

    /**
     * Creates a new `VScrollBar`. `parent` is the owner of the scroll bar.
     * @param {DOMElement} parent A DOM element
     * @param {Object} renderer An editor renderer
     *
     * @constructor
     **/
    var VScrollBar = function (parent, renderer) {
        ScrollBar.call(this, parent);
        this.scrollTop = 0;
        this.scrollHeight = 0;

        // in OSX lion the scrollbars appear to have no width. In this case resize the
        // element to show the scrollbar but still pretend that the scrollbar has a width
        // of 0px
        // in Firefox 6+ scrollbar is hidden if element has the same width as scrollbar
        // make element a little bit wider to retain scrollbar when page is zoomed 
        renderer.$scrollbarWidth =
            this.width = dom.scrollbarWidth(parent.ownerDocument);
        this.inner.style.width =
            this.element.style.width = (this.width || 15) + 5 + "px";
    };

    oop.inherits(VScrollBar, ScrollBar);

    (function () {

        this.classSuffix = '-v';

        /**
         * Emitted when the scroll bar, well, scrolls.
         * @event scroll
         * @param {Object} e Contains one property, `"data"`, which indicates the current scroll top position
         **/
        this.onScroll = function () {
            if (!this.skipEvent) {
                this.scrollTop = this.element.scrollTop;
                if (this.coeff != 1) {
                    var h = this.element.clientHeight / this.scrollHeight;
                    this.scrollTop = this.scrollTop * (1 - h) / (this.coeff - h);
                }
                this._emit("scroll", {data: this.scrollTop});
            }
            this.skipEvent = false;
        };

        /**
         * Returns the width of the scroll bar.
         * @returns {Number}
         **/
        this.getWidth = function () {
            return this.isVisible ? this.width : 0;
        };

        /**
         * Sets the height of the scroll bar, in pixels.
         * @param {Number} height The new height
         **/
        this.setHeight = function (height) {
            this.element.style.height = height + "px";
        };

        /**
         * Sets the inner height of the scroll bar, in pixels.
         * @param {Number} height The new inner height
         * @deprecated Use setScrollHeight instead
         **/
        this.setInnerHeight =
            /**
             * Sets the scroll height of the scroll bar, in pixels.
             * @param {Number} height The new scroll height
             **/
            this.setScrollHeight = function (height) {
                this.scrollHeight = height;
                if (height > MAX_SCROLL_H) {
                    this.coeff = MAX_SCROLL_H / height;
                    height = MAX_SCROLL_H;
                } else if (this.coeff != 1) {
                    this.coeff = 1
                }
                this.inner.style.height = height + "px";
            };

        /**
         * Sets the scroll top of the scroll bar.
         * @param {Number} scrollTop The new scroll top
         **/
        this.setScrollTop = function (scrollTop) {
            // on chrome 17+ for small zoom levels after calling this function
            // this.element.scrollTop != scrollTop which makes page to scroll up.
            if (this.scrollTop != scrollTop) {
                this.skipEvent = true;
                this.scrollTop = scrollTop;
                this.element.scrollTop = scrollTop * this.coeff;
            }
        };

    }).call(VScrollBar.prototype);

    /**
     * Represents a horisontal scroll bar.
     * @class HScrollBar
     **/

    /**
     * Creates a new `HScrollBar`. `parent` is the owner of the scroll bar.
     * @param {DOMElement} parent A DOM element
     * @param {Object} renderer An editor renderer
     *
     * @constructor
     **/
    var HScrollBar = function (parent, renderer) {
        ScrollBar.call(this, parent);
        this.scrollLeft = 0;

        // in OSX lion the scrollbars appear to have no width. In this case resize the
        // element to show the scrollbar but still pretend that the scrollbar has a width
        // of 0px
        // in Firefox 6+ scrollbar is hidden if element has the same width as scrollbar
        // make element a little bit wider to retain scrollbar when page is zoomed 
        this.height = renderer.$scrollbarWidth;
        this.inner.style.height =
            this.element.style.height = (this.height || 15) + 5 + "px";
    };

    oop.inherits(HScrollBar, ScrollBar);

    (function () {

        this.classSuffix = '-h';

        /**
         * Emitted when the scroll bar, well, scrolls.
         * @event scroll
         * @param {Object} e Contains one property, `"data"`, which indicates the current scroll left position
         **/
        this.onScroll = function () {
            if (!this.skipEvent) {
                this.scrollLeft = this.element.scrollLeft;
                this._emit("scroll", {data: this.scrollLeft});
            }
            this.skipEvent = false;
        };

        /**
         * Returns the height of the scroll bar.
         * @returns {Number}
         **/
        this.getHeight = function () {
            return this.isVisible ? this.height : 0;
        };

        /**
         * Sets the width of the scroll bar, in pixels.
         * @param {Number} width The new width
         **/
        this.setWidth = function (width) {
            this.element.style.width = width + "px";
        };

        /**
         * Sets the inner width of the scroll bar, in pixels.
         * @param {Number} width The new inner width
         * @deprecated Use setScrollWidth instead
         **/
        this.setInnerWidth = function (width) {
            this.inner.style.width = width + "px";
        };

        /**
         * Sets the scroll width of the scroll bar, in pixels.
         * @param {Number} width The new scroll width
         **/
        this.setScrollWidth = function (width) {
            this.inner.style.width = width + "px";
        };

        /**
         * Sets the scroll left of the scroll bar.
         * @param {Number} scrollTop The new scroll left
         **/
        this.setScrollLeft = function (scrollLeft) {
            // on chrome 17+ for small zoom levels after calling this function
            // this.element.scrollTop != scrollTop which makes page to scroll up.
            if (this.scrollLeft != scrollLeft) {
                this.skipEvent = true;
                this.scrollLeft = this.element.scrollLeft = scrollLeft;
            }
        };

    }).call(HScrollBar.prototype);


    exports.ScrollBar = VScrollBar; // backward compatibility
    exports.ScrollBarV = VScrollBar; // backward compatibility
    exports.ScrollBarH = HScrollBar; // backward compatibility

    exports.VScrollBar = VScrollBar;
    exports.HScrollBar = HScrollBar;
});
