define(["require", "exports", "tslib", "react", "../../Utilities", "./List.types"], function (require, exports, tslib_1, React, Utilities_1, List_types_1) {
    "use strict";
    Object.defineProperty(exports, "__esModule", { value: true });
    var RESIZE_DELAY = 16;
    var MIN_SCROLL_UPDATE_DELAY = 100;
    var MAX_SCROLL_UPDATE_DELAY = 500;
    var IDLE_DEBOUNCE_DELAY = 200;
    // The amount of time to wait before declaring that the list isn't scrolling
    var DONE_SCROLLING_WAIT = 500;
    var DEFAULT_ITEMS_PER_PAGE = 10;
    var DEFAULT_PAGE_HEIGHT = 30;
    var DEFAULT_RENDERED_WINDOWS_BEHIND = 2;
    var DEFAULT_RENDERED_WINDOWS_AHEAD = 2;
    var PAGE_KEY_PREFIX = 'page-';
    var SPACER_KEY_PREFIX = 'spacer-';
    var EMPTY_RECT = {
        top: -1,
        bottom: -1,
        left: -1,
        right: -1,
        width: 0,
        height: 0
    };
    // Naming expensive measures so that they're named in profiles.
    var _measurePageRect = function (element) { return element.getBoundingClientRect(); };
    var _measureSurfaceRect = _measurePageRect;
    var _measureScrollRect = _measurePageRect;
    /**
     * The List renders virtualized pages of items. Each page's item count is determined by the getItemCountForPage callback if
     * provided by the caller, or 10 as default. Each page's height is determined by the getPageHeight callback if provided by
     * the caller, or by cached measurements if available, or by a running average, or a default fallback.
     *
     * The algorithm for rendering pages works like this:
     *
     * 1. Predict visible pages based on "current measure data" (page heights, surface position, visible window)
     * 2. If changes are necessary, apply changes (add/remove pages)
     * 3. For pages that are added, measure the page heights if we need to using getBoundingClientRect
     * 4. If measurements don't match predictions, update measure data and goto step 1 asynchronously
     *
     * Measuring too frequently can pull performance down significantly. To compensate, we cache measured values so that
     * we can avoid re-measuring during operations that should not alter heights, like scrolling.
     *
     * To optimize glass rendering performance, onShouldVirtualize can be set. When onShouldVirtualize return false,
     * List will run in fast mode (not virtualized) to render all items without any measurements to improve page load time. And we
     * start doing measurements and rendering in virtualized mode when items grows larger than this threshold.
     *
     * However, certain operations can make measure data stale. For example, resizing the list, or passing in new props,
     * or forcing an update change cause pages to shrink/grow. When these operations occur, we increment a measureVersion
     * number, which we associate with cached measurements and use to determine if a remeasure should occur.
     */
    var List = /** @class */ (function (_super) {
        tslib_1.__extends(List, _super);
        function List(props) {
            var _this = _super.call(this, props) || this;
            _this._root = React.createRef();
            _this._surface = React.createRef();
            _this._onRenderPage = function (pageProps, defaultRender) {
                var _a = _this.props, onRenderCell = _a.onRenderCell, role = _a.role;
                var _b = pageProps.page, _c = _b.items, items = _c === void 0 ? [] : _c, startIndex = _b.startIndex, divProps = tslib_1.__rest(pageProps, ["page"]);
                // only assign list item role if no role is assigned
                var cellRole = role === undefined ? 'listitem' : 'presentation';
                var cells = [];
                for (var i = 0; i < items.length; i++) {
                    var index = startIndex + i;
                    var item = items[i];
                    var itemKey = _this.props.getKey ? _this.props.getKey(item, index) : item && item.key;
                    if (itemKey === null || itemKey === undefined) {
                        itemKey = index;
                    }
                    cells.push(React.createElement("div", { role: cellRole, className: 'ms-List-cell', key: itemKey, "data-list-index": index, "data-automationid": "ListCell" }, onRenderCell && onRenderCell(item, index, _this.state.isScrolling)));
                }
                return React.createElement("div", tslib_1.__assign({}, divProps), cells);
            };
            Utilities_1.initializeComponentRef(_this);
            _this.state = {
                pages: [],
                isScrolling: false
            };
            _this._async = new Utilities_1.Async(_this);
            _this._events = new Utilities_1.EventGroup(_this);
            _this._estimatedPageHeight = 0;
            _this._totalEstimates = 0;
            _this._requiredWindowsAhead = 0;
            _this._requiredWindowsBehind = 0;
            // Track the measure version for everything.
            _this._measureVersion = 0;
            // Ensure that scrolls are lazy updated.
            _this._onAsyncScroll = _this._async.debounce(_this._onAsyncScroll, MIN_SCROLL_UPDATE_DELAY, {
                leading: false,
                maxWait: MAX_SCROLL_UPDATE_DELAY
            });
            _this._onAsyncIdle = _this._async.debounce(_this._onAsyncIdle, IDLE_DEBOUNCE_DELAY, {
                leading: false
            });
            _this._onAsyncResize = _this._async.debounce(_this._onAsyncResize, RESIZE_DELAY, {
                leading: false
            });
            _this._onScrollingDone = _this._async.debounce(_this._onScrollingDone, DONE_SCROLLING_WAIT, {
                leading: false
            });
            _this._cachedPageHeights = {};
            _this._estimatedPageHeight = 0;
            _this._focusedIndex = -1;
            _this._pageCache = {};
            return _this;
        }
        /**
         * Scroll to the given index. By default will bring the page the specified item is on into the view. If a callback
         * to measure the height of an individual item is specified, will only scroll to bring the specific item into view.
         *
         * Note: with items of variable height and no passed in `getPageHeight` method, the list might jump after scrolling
         * when windows before/ahead are being rendered, and the estimated height is replaced using actual elements.
         *
         * @param index - Index of item to scroll to
         * @param measureItem - Optional callback to measure the height of an individual item
         * @param scrollToMode - Optional defines where in the window the item should be positioned to when scrolling
         */
        List.prototype.scrollToIndex = function (index, measureItem, scrollToMode) {
            if (scrollToMode === void 0) { scrollToMode = List_types_1.ScrollToMode.auto; }
            var startIndex = this.props.startIndex;
            var renderCount = this._getRenderCount();
            var endIndex = startIndex + renderCount;
            var allowedRect = this._allowedRect;
            var scrollTop = 0;
            var itemsPerPage = 1;
            for (var itemIndex = startIndex; itemIndex < endIndex; itemIndex += itemsPerPage) {
                var pageSpecification = this._getPageSpecification(itemIndex, allowedRect);
                var pageHeight = pageSpecification.height;
                itemsPerPage = pageSpecification.itemCount;
                var requestedIndexIsInPage = itemIndex <= index && itemIndex + itemsPerPage > index;
                if (requestedIndexIsInPage) {
                    // We have found the page. If the user provided a way to measure an individual item, we will try to scroll in just
                    // the given item, otherwise we'll only bring the page into view
                    if (measureItem && this._scrollElement) {
                        var scrollRect = _measureScrollRect(this._scrollElement);
                        var scrollWindow = {
                            top: this._scrollElement.scrollTop,
                            bottom: this._scrollElement.scrollTop + scrollRect.height
                        };
                        // Adjust for actual item position within page
                        var itemPositionWithinPage = index - itemIndex;
                        for (var itemIndexInPage = 0; itemIndexInPage < itemPositionWithinPage; ++itemIndexInPage) {
                            scrollTop += measureItem(itemIndex + itemIndexInPage);
                        }
                        var scrollBottom = scrollTop + measureItem(index);
                        // If scrollToMode is set to something other than auto, we always want to
                        // scroll the item into a specific position on the page.
                        switch (scrollToMode) {
                            case List_types_1.ScrollToMode.top:
                                this._scrollElement.scrollTop = scrollTop;
                                return;
                            case List_types_1.ScrollToMode.bottom:
                                this._scrollElement.scrollTop = scrollBottom - scrollRect.height;
                                return;
                            case List_types_1.ScrollToMode.center:
                                this._scrollElement.scrollTop = (scrollTop + scrollBottom - scrollRect.height) / 2;
                                return;
                            case List_types_1.ScrollToMode.auto:
                            default:
                                break;
                        }
                        var itemIsFullyVisible = scrollTop >= scrollWindow.top && scrollBottom <= scrollWindow.bottom;
                        if (itemIsFullyVisible) {
                            // Item is already visible, do nothing.
                            return;
                        }
                        var itemIsPartiallyAbove = scrollTop < scrollWindow.top;
                        var itemIsPartiallyBelow = scrollBottom > scrollWindow.bottom;
                        if (itemIsPartiallyAbove) {
                            //  We will just scroll to 'scrollTop'
                            //  .------.   - scrollTop
                            //  |Item  |
                            //  | .----|-. - scrollWindow.top
                            //  '------' |
                            //    |      |
                            //    '------'
                        }
                        else if (itemIsPartiallyBelow) {
                            //  Adjust scrollTop position to just bring in the element
                            // .------.  - scrollTop
                            // |      |
                            // | .------.
                            // '-|----' | - scrollWindow.bottom
                            //   | Item |
                            //   '------' - scrollBottom
                            scrollTop = scrollBottom - scrollRect.height;
                        }
                    }
                    this._scrollElement.scrollTop = scrollTop;
                    return;
                }
                scrollTop += pageHeight;
            }
        };
        List.prototype.getStartItemIndexInView = function (measureItem) {
            var pages = this.state.pages || [];
            for (var _i = 0, pages_1 = pages; _i < pages_1.length; _i++) {
                var page = pages_1[_i];
                var isPageVisible = !page.isSpacer && (this._scrollTop || 0) >= page.top && (this._scrollTop || 0) <= page.top + page.height;
                if (isPageVisible) {
                    if (!measureItem) {
                        var rowHeight = Math.floor(page.height / page.itemCount);
                        return page.startIndex + Math.floor((this._scrollTop - page.top) / rowHeight);
                    }
                    else {
                        var totalRowHeight = 0;
                        for (var itemIndex = page.startIndex; itemIndex < page.startIndex + page.itemCount; itemIndex++) {
                            var rowHeight = measureItem(itemIndex);
                            if (page.top + totalRowHeight <= this._scrollTop && this._scrollTop < page.top + totalRowHeight + rowHeight) {
                                return itemIndex;
                            }
                            else {
                                totalRowHeight += rowHeight;
                            }
                        }
                    }
                }
            }
            return 0;
        };
        List.prototype.componentDidMount = function () {
            this._updatePages();
            this._measureVersion++;
            this._scrollElement = Utilities_1.findScrollableParent(this._root.current);
            this._events.on(window, 'resize', this._onAsyncResize);
            if (this._root.current) {
                this._events.on(this._root.current, 'focus', this._onFocus, true);
            }
            if (this._scrollElement) {
                this._events.on(this._scrollElement, 'scroll', this._onScroll);
                this._events.on(this._scrollElement, 'scroll', this._onAsyncScroll);
            }
        };
        List.prototype.componentWillUnmount = function () {
            this._async.dispose();
            this._events.dispose();
        };
        // tslint:disable-next-line function-name
        List.prototype.UNSAFE_componentWillReceiveProps = function (newProps) {
            if (newProps.items !== this.props.items ||
                newProps.renderCount !== this.props.renderCount ||
                newProps.startIndex !== this.props.startIndex ||
                newProps.version !== this.props.version) {
                // We have received new items so we want to make sure that initially we only render a single window to
                // fill the currently visible rect, and then later render additional windows.
                this._resetRequiredWindows();
                this._requiredRect = null;
                this._measureVersion++;
                this._invalidatePageCache();
                this._updatePages(newProps);
            }
        };
        List.prototype.shouldComponentUpdate = function (newProps, newState) {
            var oldPages = this.state.pages;
            var newPages = newState.pages;
            var shouldComponentUpdate = false;
            // Update if the page stops scrolling
            if (!newState.isScrolling && this.state.isScrolling) {
                return true;
            }
            if (newProps.version !== this.props.version) {
                return true;
            }
            if (newProps.items === this.props.items && oldPages.length === newPages.length) {
                for (var i = 0; i < oldPages.length; i++) {
                    var oldPage = oldPages[i];
                    var newPage = newPages[i];
                    if (oldPage.key !== newPage.key || oldPage.itemCount !== newPage.itemCount) {
                        shouldComponentUpdate = true;
                        break;
                    }
                }
            }
            else {
                shouldComponentUpdate = true;
            }
            return shouldComponentUpdate;
        };
        List.prototype.forceUpdate = function () {
            this._invalidatePageCache();
            // Ensure that when the list is force updated we update the pages first before render.
            this._updateRenderRects(this.props, true);
            this._updatePages();
            this._measureVersion++;
            _super.prototype.forceUpdate.call(this);
        };
        /**
         * Get the current height the list and it's pages.
         */
        List.prototype.getTotalListHeight = function () {
            return this._surfaceRect.height;
        };
        List.prototype.render = function () {
            var _a = this.props, className = _a.className, _b = _a.role, role = _b === void 0 ? 'list' : _b;
            var _c = this.state.pages, pages = _c === void 0 ? [] : _c;
            var pageElements = [];
            var divProps = Utilities_1.getNativeProps(this.props, Utilities_1.divProperties);
            for (var _i = 0, pages_2 = pages; _i < pages_2.length; _i++) {
                var page = pages_2[_i];
                pageElements.push(this._renderPage(page));
            }
            return (React.createElement("div", tslib_1.__assign({ ref: this._root }, divProps, { role: pageElements.length > 0 ? role : undefined, className: Utilities_1.css('ms-List', className) }),
                React.createElement("div", { ref: this._surface, className: 'ms-List-surface', role: "presentation" }, pageElements)));
        };
        List.prototype._shouldVirtualize = function (props) {
            if (props === void 0) { props = this.props; }
            var onShouldVirtualize = props.onShouldVirtualize;
            return !onShouldVirtualize || onShouldVirtualize(props);
        };
        /**
         * when props.items change or forceUpdate called, throw away cached pages
         */
        List.prototype._invalidatePageCache = function () {
            this._pageCache = {};
        };
        List.prototype._renderPage = function (page) {
            var usePageCache = this.props.usePageCache;
            var cachedPage;
            // if usePageCache is set and cached page element can be found, just return cached page
            if (usePageCache) {
                cachedPage = this._pageCache[page.key];
                if (cachedPage && cachedPage.pageElement) {
                    return cachedPage.pageElement;
                }
            }
            var pageStyle = this._getPageStyle(page);
            var _a = this.props.onRenderPage, onRenderPage = _a === void 0 ? this._onRenderPage : _a;
            var pageElement = onRenderPage({
                page: page,
                className: 'ms-List-page',
                key: page.key,
                ref: page.key,
                style: pageStyle,
                role: 'presentation'
            }, this._onRenderPage);
            // cache the first page for now since it is re-rendered a lot times unnecessarily.
            // todo: a more aggresive caching mechanism is to cache pages constaining the items not changed.
            // now we re-render pages too frequently, for example, props.items increased from 30 to 60, although the
            // first 30 items did not change, we still re-rendered all of them in this props.items change.
            if (usePageCache && page.startIndex === 0) {
                this._pageCache[page.key] = {
                    page: page,
                    pageElement: pageElement
                };
            }
            return pageElement;
        };
        /** Generate the style object for the page. */
        List.prototype._getPageStyle = function (page) {
            var getPageStyle = this.props.getPageStyle;
            return tslib_1.__assign({}, (getPageStyle ? getPageStyle(page) : {}), (!page.items
                ? {
                    height: page.height
                }
                : {}));
        };
        /** Track the last item index focused so that we ensure we keep it rendered. */
        List.prototype._onFocus = function (ev) {
            var target = ev.target;
            while (target !== this._surface.current) {
                var indexString = target.getAttribute('data-list-index');
                if (indexString) {
                    this._focusedIndex = Number(indexString);
                    break;
                }
                target = Utilities_1.getParent(target);
            }
        };
        /**
         * Called synchronously to reset the required render range to 0 on scrolling. After async scroll has executed,
         * we will call onAsyncIdle which will reset it back to it's correct value.
         */
        List.prototype._onScroll = function () {
            if (!this.state.isScrolling) {
                this.setState({ isScrolling: true });
            }
            this._resetRequiredWindows();
            this._onScrollingDone();
        };
        List.prototype._resetRequiredWindows = function () {
            this._requiredWindowsAhead = 0;
            this._requiredWindowsBehind = 0;
        };
        /**
         * Debounced method to asynchronously update the visible region on a scroll event.
         */
        List.prototype._onAsyncScroll = function () {
            this._updateRenderRects();
            // Only update pages when the visible rect falls outside of the materialized rect.
            if (!this._materializedRect || !_isContainedWithin(this._requiredRect, this._materializedRect)) {
                this._updatePages();
            }
            else {
                // console.log('requiredRect contained in materialized', this._requiredRect, this._materializedRect);
            }
        };
        /**
         * This is an async debounced method that will try and increment the windows we render. If we can increment
         * either, we increase the amount we render and re-evaluate.
         */
        List.prototype._onAsyncIdle = function () {
            var _a = this.props, renderedWindowsAhead = _a.renderedWindowsAhead, renderedWindowsBehind = _a.renderedWindowsBehind;
            var _b = this, requiredWindowsAhead = _b._requiredWindowsAhead, requiredWindowsBehind = _b._requiredWindowsBehind;
            var windowsAhead = Math.min(renderedWindowsAhead, requiredWindowsAhead + 1);
            var windowsBehind = Math.min(renderedWindowsBehind, requiredWindowsBehind + 1);
            if (windowsAhead !== requiredWindowsAhead || windowsBehind !== requiredWindowsBehind) {
                // console.log('idling', windowsBehind, windowsAhead);
                this._requiredWindowsAhead = windowsAhead;
                this._requiredWindowsBehind = windowsBehind;
                this._updateRenderRects();
                this._updatePages();
            }
            if (renderedWindowsAhead > windowsAhead || renderedWindowsBehind > windowsBehind) {
                // Async increment on next tick.
                this._onAsyncIdle();
            }
        };
        /**
         * Function to call when the list is done scrolling.
         * This function is debounced.
         */
        List.prototype._onScrollingDone = function () {
            this.setState({ isScrolling: false });
        };
        List.prototype._onAsyncResize = function () {
            this.forceUpdate();
        };
        List.prototype._updatePages = function (props) {
            // console.log('updating pages');
            var _this = this;
            if (props === void 0) { props = this.props; }
            if (!this._requiredRect) {
                this._updateRenderRects(props);
            }
            var newListState = this._buildPages(props);
            var oldListPages = this.state.pages;
            this._notifyPageChanges(oldListPages, newListState.pages);
            this.setState(newListState, function () {
                // Multiple updates may have been queued, so the callback will reflect all of them.
                // Re-fetch the current props and states to avoid using a stale props or state captured in the closure.
                var finalProps = _this.props;
                var finalState = _this.state;
                // If we weren't provided with the page height, measure the pages
                if (!finalProps.getPageHeight) {
                    // If measured version is invalid since we've updated the DOM
                    var heightsChanged = _this._updatePageMeasurements(finalState.pages);
                    // On first render, we should re-measure so that we don't get a visual glitch.
                    if (heightsChanged) {
                        _this._materializedRect = null;
                        if (!_this._hasCompletedFirstRender) {
                            _this._hasCompletedFirstRender = true;
                            _this._updatePages(finalProps);
                        }
                        else {
                            _this._onAsyncScroll();
                        }
                    }
                    else {
                        // Enqueue an idle bump.
                        _this._onAsyncIdle();
                    }
                }
                else {
                    // Enqueue an idle bump
                    _this._onAsyncIdle();
                }
                // Notify the caller that rendering the new pages has completed
                if (finalProps.onPagesUpdated) {
                    finalProps.onPagesUpdated(finalState.pages);
                }
            });
        };
        /**
         * Notify consumers that the rendered pages have changed
         * @param oldPages - The old pages
         * @param newPages - The new pages
         * @param props - The props to use
         */
        List.prototype._notifyPageChanges = function (oldPages, newPages, props) {
            if (props === void 0) { props = this.props; }
            var onPageAdded = props.onPageAdded, onPageRemoved = props.onPageRemoved;
            if (onPageAdded || onPageRemoved) {
                var renderedIndexes = {};
                for (var _i = 0, oldPages_1 = oldPages; _i < oldPages_1.length; _i++) {
                    var page = oldPages_1[_i];
                    if (page.items) {
                        renderedIndexes[page.startIndex] = page;
                    }
                }
                for (var _a = 0, newPages_1 = newPages; _a < newPages_1.length; _a++) {
                    var page = newPages_1[_a];
                    if (page.items) {
                        if (!renderedIndexes[page.startIndex]) {
                            this._onPageAdded(page);
                        }
                        else {
                            delete renderedIndexes[page.startIndex];
                        }
                    }
                }
                for (var index in renderedIndexes) {
                    if (renderedIndexes.hasOwnProperty(index)) {
                        this._onPageRemoved(renderedIndexes[index]);
                    }
                }
            }
        };
        List.prototype._updatePageMeasurements = function (pages) {
            var heightChanged = false;
            // when not in virtualize mode, we render all the items without page measurement
            if (!this._shouldVirtualize()) {
                return heightChanged;
            }
            for (var i = 0; i < pages.length; i++) {
                var page = pages[i];
                if (page.items) {
                    heightChanged = this._measurePage(page) || heightChanged;
                }
            }
            return heightChanged;
        };
        /**
         * Given a page, measure its dimensions, update cache.
         * @returns True if the height has changed.
         */
        List.prototype._measurePage = function (page) {
            var hasChangedHeight = false;
            var pageElement = this.refs[page.key];
            var cachedHeight = this._cachedPageHeights[page.startIndex];
            // console.log('   * measure attempt', page.startIndex, cachedHeight);
            if (pageElement && this._shouldVirtualize() && (!cachedHeight || cachedHeight.measureVersion !== this._measureVersion)) {
                var newClientRect = {
                    width: pageElement.clientWidth,
                    height: pageElement.clientHeight
                };
                if (newClientRect.height || newClientRect.width) {
                    hasChangedHeight = page.height !== newClientRect.height;
                    // console.warn(' *** expensive page measure', page.startIndex, page.height, newClientRect.height);
                    page.height = newClientRect.height;
                    this._cachedPageHeights[page.startIndex] = {
                        height: newClientRect.height,
                        measureVersion: this._measureVersion
                    };
                    this._estimatedPageHeight = Math.round((this._estimatedPageHeight * this._totalEstimates + newClientRect.height) / (this._totalEstimates + 1));
                    this._totalEstimates++;
                }
            }
            return hasChangedHeight;
        };
        /** Called when a page has been added to the DOM. */
        List.prototype._onPageAdded = function (page) {
            var onPageAdded = this.props.onPageAdded;
            // console.log('page added', page.startIndex, this.state.pages.map(page => page.key).join(', '));
            if (onPageAdded) {
                onPageAdded(page);
            }
        };
        /** Called when a page has been removed from the DOM. */
        List.prototype._onPageRemoved = function (page) {
            var onPageRemoved = this.props.onPageRemoved;
            // console.log('  --- page removed', page.startIndex, this.state.pages.map(page => page.key).join(', '));
            if (onPageRemoved) {
                onPageRemoved(page);
            }
        };
        /** Build up the pages that should be rendered. */
        List.prototype._buildPages = function (props) {
            var renderCount = props.renderCount;
            var items = props.items, startIndex = props.startIndex, getPageHeight = props.getPageHeight;
            renderCount = this._getRenderCount(props);
            var materializedRect = tslib_1.__assign({}, EMPTY_RECT);
            var pages = [];
            var itemsPerPage = 1;
            var pageTop = 0;
            var currentSpacer = null;
            var focusedIndex = this._focusedIndex;
            var endIndex = startIndex + renderCount;
            var shouldVirtualize = this._shouldVirtualize(props);
            // First render is very important to track; when we render cells, we have no idea of estimated page height.
            // So we should default to rendering only the first page so that we can get information.
            // However if the user provides a measure function, let's just assume they know the right heights.
            var isFirstRender = this._estimatedPageHeight === 0 && !getPageHeight;
            var allowedRect = this._allowedRect;
            var _loop_1 = function (itemIndex) {
                var pageSpecification = this_1._getPageSpecification(itemIndex, allowedRect);
                var pageHeight = pageSpecification.height;
                var pageData = pageSpecification.data;
                var key = pageSpecification.key;
                itemsPerPage = pageSpecification.itemCount;
                var pageBottom = pageTop + pageHeight - 1;
                var isPageRendered = Utilities_1.findIndex(this_1.state.pages, function (page) { return !!page.items && page.startIndex === itemIndex; }) > -1;
                var isPageInAllowedRange = !allowedRect || (pageBottom >= allowedRect.top && pageTop <= allowedRect.bottom);
                var isPageInRequiredRange = !this_1._requiredRect || (pageBottom >= this_1._requiredRect.top && pageTop <= this_1._requiredRect.bottom);
                var isPageVisible = (!isFirstRender && (isPageInRequiredRange || (isPageInAllowedRange && isPageRendered))) || !shouldVirtualize;
                var isPageFocused = focusedIndex >= itemIndex && focusedIndex < itemIndex + itemsPerPage;
                var isFirstPage = itemIndex === startIndex;
                // console.log('building page', itemIndex, 'pageTop: ' + pageTop, 'inAllowed: ' +
                // isPageInAllowedRange, 'inRequired: ' + isPageInRequiredRange);
                // Only render whats visible, focused, or first page,
                // or when running in fast rendering mode (not in virtualized mode), we render all current items in pages
                if (isPageVisible || isPageFocused || isFirstPage) {
                    if (currentSpacer) {
                        pages.push(currentSpacer);
                        currentSpacer = null;
                    }
                    var itemsInPage = Math.min(itemsPerPage, endIndex - itemIndex);
                    var newPage = this_1._createPage(key, items.slice(itemIndex, itemIndex + itemsInPage), itemIndex, undefined, undefined, pageData);
                    newPage.top = pageTop;
                    newPage.height = pageHeight;
                    if (this_1._visibleRect && this_1._visibleRect.bottom) {
                        newPage.isVisible = pageBottom >= this_1._visibleRect.top && pageTop <= this_1._visibleRect.bottom;
                    }
                    pages.push(newPage);
                    if (isPageInRequiredRange && this_1._allowedRect) {
                        _mergeRect(materializedRect, {
                            top: pageTop,
                            bottom: pageBottom,
                            height: pageHeight,
                            left: allowedRect.left,
                            right: allowedRect.right,
                            width: allowedRect.width
                        });
                    }
                }
                else {
                    if (!currentSpacer) {
                        currentSpacer = this_1._createPage(SPACER_KEY_PREFIX + itemIndex, undefined, itemIndex, 0, undefined, pageData, true /*isSpacer*/);
                    }
                    currentSpacer.height = (currentSpacer.height || 0) + (pageBottom - pageTop) + 1;
                    currentSpacer.itemCount += itemsPerPage;
                }
                pageTop += pageBottom - pageTop + 1;
                // in virtualized mode, we render need to render first page then break and measure,
                // otherwise, we render all items without measurement to make rendering fast
                if (isFirstRender && shouldVirtualize) {
                    return "break";
                }
            };
            var this_1 = this;
            for (var itemIndex = startIndex; itemIndex < endIndex; itemIndex += itemsPerPage) {
                var state_1 = _loop_1(itemIndex);
                if (state_1 === "break")
                    break;
            }
            if (currentSpacer) {
                currentSpacer.key = SPACER_KEY_PREFIX + 'end';
                pages.push(currentSpacer);
            }
            this._materializedRect = materializedRect;
            // console.log('materialized: ', materializedRect);
            return {
                pages: pages,
                measureVersion: this._measureVersion
            };
        };
        List.prototype._getPageSpecification = function (itemIndex, visibleRect) {
            var getPageSpecification = this.props.getPageSpecification;
            if (getPageSpecification) {
                var pageData = getPageSpecification(itemIndex, visibleRect);
                var _a = pageData.itemCount, itemCount = _a === void 0 ? this._getItemCountForPage(itemIndex, visibleRect) : _a;
                var _b = pageData.height, height = _b === void 0 ? this._getPageHeight(itemIndex, visibleRect, itemCount) : _b;
                return {
                    itemCount: itemCount,
                    height: height,
                    data: pageData.data,
                    key: pageData.key
                };
            }
            else {
                var itemCount = this._getItemCountForPage(itemIndex, visibleRect);
                return {
                    itemCount: itemCount,
                    height: this._getPageHeight(itemIndex, visibleRect, itemCount)
                };
            }
        };
        /**
         * Get the pixel height of a give page. Will use the props getPageHeight first, and if not provided, fallback to
         * cached height, or estimated page height, or default page height.
         */
        List.prototype._getPageHeight = function (itemIndex, visibleRect, itemsPerPage) {
            if (this.props.getPageHeight) {
                return this.props.getPageHeight(itemIndex, visibleRect, itemsPerPage);
            }
            else {
                var cachedHeight = this._cachedPageHeights[itemIndex];
                return cachedHeight ? cachedHeight.height : this._estimatedPageHeight || DEFAULT_PAGE_HEIGHT;
            }
        };
        List.prototype._getItemCountForPage = function (itemIndex, visibileRect) {
            var itemsPerPage = this.props.getItemCountForPage ? this.props.getItemCountForPage(itemIndex, visibileRect) : DEFAULT_ITEMS_PER_PAGE;
            return itemsPerPage ? itemsPerPage : DEFAULT_ITEMS_PER_PAGE;
        };
        List.prototype._createPage = function (pageKey, items, startIndex, count, style, data, isSpacer) {
            if (startIndex === void 0) { startIndex = -1; }
            if (count === void 0) { count = items ? items.length : 0; }
            if (style === void 0) { style = {}; }
            pageKey = pageKey || PAGE_KEY_PREFIX + startIndex;
            var cachedPage = this._pageCache[pageKey];
            if (cachedPage && cachedPage.page) {
                return cachedPage.page;
            }
            return {
                key: pageKey,
                startIndex: startIndex,
                itemCount: count,
                items: items,
                style: style,
                top: 0,
                height: 0,
                data: data,
                isSpacer: isSpacer || false
            };
        };
        List.prototype._getRenderCount = function (props) {
            var _a = props || this.props, items = _a.items, startIndex = _a.startIndex, renderCount = _a.renderCount;
            return renderCount === undefined ? (items ? items.length - startIndex : 0) : renderCount;
        };
        /** Calculate the visible rect within the list where top: 0 and left: 0 is the top/left of the list. */
        List.prototype._updateRenderRects = function (props, forceUpdate) {
            props = props || this.props;
            var renderedWindowsAhead = props.renderedWindowsAhead, renderedWindowsBehind = props.renderedWindowsBehind;
            var pages = this.state.pages;
            // when not in virtualize mode, we render all items without measurement to optimize page rendering perf
            if (!this._shouldVirtualize(props)) {
                return;
            }
            var surfaceRect = this._surfaceRect || tslib_1.__assign({}, EMPTY_RECT);
            var scrollHeight = this._scrollElement && this._scrollElement.scrollHeight;
            var scrollTop = this._scrollElement ? this._scrollElement.scrollTop : 0;
            // WARNING: EXPENSIVE CALL! We need to know the surface top relative to the window.
            // This needs to be called to recalculate when new pages should be loaded.
            // We check to see how far we've scrolled and if it's further than a third of a page we run it again.
            if (this._surface.current &&
                (forceUpdate ||
                    !pages ||
                    !this._surfaceRect ||
                    !scrollHeight ||
                    scrollHeight !== this._scrollHeight ||
                    Math.abs(this._scrollTop - scrollTop) > this._estimatedPageHeight / 3)) {
                surfaceRect = this._surfaceRect = _measureSurfaceRect(this._surface.current);
                this._scrollTop = scrollTop;
            }
            // If the scroll height has changed, something in the container likely resized and
            // we should redo the page heights incase their content resized.
            if (forceUpdate || !scrollHeight || scrollHeight !== this._scrollHeight) {
                this._measureVersion++;
            }
            this._scrollHeight = scrollHeight;
            // If the surface is above the container top or below the container bottom, or if this is not the first
            // render return empty rect.
            // The first time the list gets rendered we need to calculate the rectangle. The width of the list is
            // used to calculate the width of the list items.
            var visibleTop = Math.max(0, -surfaceRect.top);
            var win = Utilities_1.getWindow(this._root.current);
            var visibleRect = {
                top: visibleTop,
                left: surfaceRect.left,
                bottom: visibleTop + win.innerHeight,
                right: surfaceRect.right,
                width: surfaceRect.width,
                height: win.innerHeight
            };
            // The required/allowed rects are adjusted versions of the visible rect.
            this._requiredRect = _expandRect(visibleRect, this._requiredWindowsBehind, this._requiredWindowsAhead);
            this._allowedRect = _expandRect(visibleRect, renderedWindowsBehind, renderedWindowsAhead);
            // store the visible rect for later use.
            this._visibleRect = visibleRect;
        };
        List.defaultProps = {
            startIndex: 0,
            onRenderCell: function (item, index, containsFocus) { return React.createElement(React.Fragment, null, (item && item.name) || ''); },
            renderedWindowsAhead: DEFAULT_RENDERED_WINDOWS_AHEAD,
            renderedWindowsBehind: DEFAULT_RENDERED_WINDOWS_BEHIND
        };
        return List;
    }(React.Component));
    exports.List = List;
    function _expandRect(rect, pagesBefore, pagesAfter) {
        var top = rect.top - pagesBefore * rect.height;
        var height = rect.height + (pagesBefore + pagesAfter) * rect.height;
        return {
            top: top,
            bottom: top + height,
            height: height,
            left: rect.left,
            right: rect.right,
            width: rect.width
        };
    }
    function _isContainedWithin(innerRect, outerRect) {
        return (innerRect.top >= outerRect.top &&
            innerRect.left >= outerRect.left &&
            innerRect.bottom <= outerRect.bottom &&
            innerRect.right <= outerRect.right);
    }
    function _mergeRect(targetRect, newRect) {
        targetRect.top = newRect.top < targetRect.top || targetRect.top === -1 ? newRect.top : targetRect.top;
        targetRect.left = newRect.left < targetRect.left || targetRect.left === -1 ? newRect.left : targetRect.left;
        targetRect.bottom = newRect.bottom > targetRect.bottom || targetRect.bottom === -1 ? newRect.bottom : targetRect.bottom;
        targetRect.right = newRect.right > targetRect.right || targetRect.right === -1 ? newRect.right : targetRect.right;
        targetRect.width = targetRect.right - targetRect.left + 1;
        targetRect.height = targetRect.bottom - targetRect.top + 1;
        return targetRect;
    }
});
//# sourceMappingURL=List.js.map