text: /**
   * Copyright (c) 2015, Facebook, Inc.  All rights reserved.
   *
   * Facebook, Inc. (“Facebook”) owns all right, title and interest, including
   * all intellectual property and other proprietary rights, in and to the React
   * Native CustomComponents software (the “Software”).  Subject to your
   * compliance with these terms, you are hereby granted a non-exclusive,
   * worldwide, royalty-free copyright license to (1) use and copy the Software;
   * and (2) reproduce and distribute the Software as part of your own software
   * (“Your Software”).  Facebook reserves all rights not expressly granted to
   * you in this license agreement.
   *
   * THE SOFTWARE AND DOCUMENTATION, IF ANY, ARE PROVIDED "AS IS" AND ANY EXPRESS
   * OR IMPLIED WARRANTIES (INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE) ARE DISCLAIMED.
   * IN NO EVENT SHALL FACEBOOK OR ITS AFFILIATES, OFFICERS, DIRECTORS OR
   * EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THE SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * @providesModule ListViewDataSource
   * @typechecks
   * @flow
   */
  'use strict';
  
  var invariant = require('invariant');
  var isEmpty = require('isEmpty');
  var warning = require('warning');
  
  /**
   * ListViewDataSource - Provides efficient data processing and access to the
   * ListView component.  A ListViewDataSource is created with functions for
   * extracting data from the input blob, and comparing elements (with default
   * implementations for convenience).  The input blob can be as simple as an
   * array of strings, or an object with rows nested inside section objects.
   *
   * To update the data in the datasource, use `cloneWithRows` (or
   * `cloneWithRowsAndSections` if you care about sections).  The data in the
   * data source is immutable, so you can't modify it directly.  The clone methods
   * suck in the new data and compute a diff for each row so ListView knows
   * whether to re-render it or not.
   *
   * In this example, a component receives data in chunks, handled by
   * `_onDataArrived`, which concats the new data onto the old data and updates the
   * data source.  We use `concat` to create a new array - mutating `this._data`,
   * e.g. with `this._data.push(newRowData)`, would be an error. `_rowHasChanged`
   * understands the shape of the row data and knows how to efficiently compare
   * it.
   *
   *   getInitialState: function() {
   *     var ds = new ListViewDataSource({rowHasChanged: this._rowHasChanged});
   *     return {ds};
   *   },
   *   _onDataArrived(newData) {
   *     this._data = this._data.concat(newData);
   *     this.setState({
   *       ds: this.state.ds.cloneWithRows(this._data)
   *     });
   *   }
   */
  
  function defaultGetRowData(
    dataBlob: any,
    sectionID: number | string,
    rowID: number | string
  ): any {
    return dataBlob[sectionID][rowID];
  }
  
  function defaultGetSectionHeaderData(
    dataBlob: any,
    sectionID: number | string
  ): any {
    return dataBlob[sectionID];
  }
  
  type differType = (data1: any, data2: any) => bool;
  
  type ParamType = {
    rowHasChanged: differType;
    getRowData: ?typeof defaultGetRowData;
    sectionHeaderHasChanged: ?differType;
    getSectionHeaderData: ?typeof defaultGetSectionHeaderData;
  }
  
  class ListViewDataSource {
  
    /**
     * @param {ParamType} params
     *
     * You can provide custom extraction and 'hasChanged' functions for section
     * headers and rows.  If absent, data will be extracted with the
     * `defaultGetRowData` and `defaultGetSectionHeaderData` functions.
     *
     * - getRowData(dataBlob, sectionID, rowID);
     * - getSectionHeaderData(dataBlob, sectionID);
     * - rowHasChanged(prevRowData, nextRowData);
     * - sectionHeaderHasChanged(prevSectionData, nextSectionData);
     */
    constructor(params: ParamType) {
      invariant(
        params && typeof params.rowHasChanged === 'function',
        'Must provide a rowHasChanged function.'
      );
      this._rowHasChanged = params.rowHasChanged;
      this._getRowData = params.getRowData || defaultGetRowData;
      this._sectionHeaderHasChanged = params.sectionHeaderHasChanged;
      this._getSectionHeaderData =
        params.getSectionHeaderData || defaultGetSectionHeaderData;
  
      this._dataBlob = null;
      this._dirtyRows = [];
      this._dirtySections = [];
      this._cachedRowCount = 0;
  
      // These two private variables are accessed by outsiders because ListView
      // uses them to iterate over the data in this class.
      this.rowIdentities = [];
      this.sectionIdentities = [];
    }
  
    /**
    * @param {object} dataBlob -- This is an arbitrary blob of data. An extractor
    *    function was defined at construction time.  The default extractor assumes
    *    the data is a plain array or keyed object.
    */
    cloneWithRows(
      dataBlob: Array<any> | {[key: string]: any},
      rowIdentities: ?Array<string>
    ): ListViewDataSource {
      var rowIds = rowIdentities ? [rowIdentities] : null;
      if (!this._sectionHeaderHasChanged) {
        this._sectionHeaderHasChanged = () => false;
      }
      return this.cloneWithRowsAndSections({s1: dataBlob}, ['s1'], rowIds);
    }
  
    /**
     * @param {object} dataBlob -- This is an arbitrary blob of data. An extractor
     *    function was defined at construction time.  The default extractor assumes
     *    the data is a nested array or keyed object of the form:
     *
     *      { sectionID_1: { rowID_1: <rowData1>, ... }, ... }
     *
     *    or
     *
     *      [ [ <rowData1>, <rowData2>, ... ], ... ]
     *
     * @param {array} sectionIdentities -- This is an array of identifiers for
     *    sections. ie. ['s1', 's2', ...].  If not provided, it's assumed that the
     *    keys of dataBlob are the section identities.
     * @param {array} rowIdentities -- This is a 2D array of identifiers for rows.
     *    ie. [['a1', 'a2'], ['b1', 'b2', 'b3'], ...].  If not provided, it's
     *    assumed that the keys of the section data are the row identities.
     *
     * Note: this returns a new object!
     */
    cloneWithRowsAndSections(
      dataBlob: any,
      sectionIdentities: ?Array<string>,
      rowIdentities: ?Array<Array<string>>
    ): ListViewDataSource {
      invariant(
        typeof this._sectionHeaderHasChanged === 'function',
        'Must provide a sectionHeaderHasChanged function with section data.'
      );
      var newSource = new ListViewDataSource({
        getRowData: this._getRowData,
        getSectionHeaderData: this._getSectionHeaderData,
        rowHasChanged: this._rowHasChanged,
        sectionHeaderHasChanged: this._sectionHeaderHasChanged,
      });
      newSource._dataBlob = dataBlob;
      if (sectionIdentities) {
        newSource.sectionIdentities = sectionIdentities;
      } else {
        newSource.sectionIdentities = Object.keys(dataBlob);
      }
      if (rowIdentities) {
        newSource.rowIdentities = rowIdentities;
      } else {
        newSource.rowIdentities = [];
        newSource.sectionIdentities.forEach((sectionID) => {
          newSource.rowIdentities.push(Object.keys(dataBlob[sectionID]));
        });
      }
      newSource._cachedRowCount = countRows(newSource.rowIdentities);
  
      newSource._calculateDirtyArrays(
        this._dataBlob,
        this.sectionIdentities,
        this.rowIdentities
      );
  
      return newSource;
    }
  
    getRowCount(): number {
      return this._cachedRowCount;
    }
  
    /**
     * @param {number} sectionIndex
     * @param {number} rowIndex
     *
     * Returns if the row is dirtied and needs to be rerendered
     */
    rowShouldUpdate(sectionIndex: number, rowIndex: number): bool {
      var needsUpdate = this._dirtyRows[sectionIndex][rowIndex];
      warning(needsUpdate !== undefined,
        'missing dirtyBit for section, row: ' + sectionIndex + ', ' + rowIndex);
      return needsUpdate;
    }
  
    /**
     * @param {number} sectionIndex
     * @param {number} rowIndex
     *
     * Gets the data required to render the row.
     */
    getRowData(sectionIndex: number, rowIndex: number): any {
      var sectionID = this.sectionIdentities[sectionIndex];
      var rowID = this.rowIdentities[sectionIndex][rowIndex];
      warning(
        sectionID !== undefined && rowID !== undefined,
        'rendering invalid section, row: ' + sectionIndex + ', ' + rowIndex
      );
      return this._getRowData(this._dataBlob, sectionID, rowID);
    }
  
    /**
     * @param {number} index
     *
     * Gets the rowID at index provided if the dataSource arrays were flattened,
     * or null of out of range indexes.
     */
    getRowIDForFlatIndex(index: number): ?string {
      var accessIndex = index;
      for (var ii = 0; ii < this.sectionIdentities.length; ii++) {
        if (accessIndex >= this.rowIdentities[ii].length) {
          accessIndex -= this.rowIdentities[ii].length;
        } else {
          return this.rowIdentities[ii][accessIndex];
        }
      }
      return null;
    }
  
    /**
     * @param {number} index
     *
     * Gets the sectionID at index provided if the dataSource arrays were flattened,
     * or null for out of range indexes.
     */
    getSectionIDForFlatIndex(index: number): ?string {
      var accessIndex = index;
      for (var ii = 0; ii < this.sectionIdentities.length; ii++) {
        if (accessIndex >= this.rowIdentities[ii].length) {
          accessIndex -= this.rowIdentities[ii].length;
        } else {
          return this.sectionIdentities[ii];
        }
      }
      return null;
    }
  
    /**
     * Returns an array containing the number of rows in each section
     */
    getSectionLengths(): Array<number> {
      var results = [];
      for (var ii = 0; ii < this.sectionIdentities.length; ii++) {
        results.push(this.rowIdentities[ii].length);
      }
      return results;
    }
  
    /**
     * @param {number} sectionIndex
     *
     * Returns if the section header is dirtied and needs to be rerendered
     */
    sectionHeaderShouldUpdate(sectionIndex: number): bool {
      var needsUpdate = this._dirtySections[sectionIndex];
      warning(needsUpdate !== undefined,
        'missing dirtyBit for section: ' + sectionIndex);
      return needsUpdate;
    }
  
    /**
     * @param {number} sectionIndex
     *
     * Gets the data required to render the section header
     */
    getSectionHeaderData(sectionIndex: number): any {
      if (!this._getSectionHeaderData) {
        return null;
      }
      var sectionID = this.sectionIdentities[sectionIndex];
      warning(sectionID !== undefined,
        'renderSection called on invalid section: ' + sectionIndex);
      return this._getSectionHeaderData(this._dataBlob, sectionID);
    }
  
    /**
     * Private members and methods.
     */
  
    _getRowData: typeof defaultGetRowData;
    _getSectionHeaderData: typeof defaultGetSectionHeaderData;
    _rowHasChanged: differType;
    _sectionHeaderHasChanged: ?differType;
  
    _dataBlob: any;
    _dirtyRows: Array<Array<bool>>;
    _dirtySections: Array<bool>;
    _cachedRowCount: number;
  
    // These two 'protected' variables are accessed by ListView to iterate over
    // the data in this class.
    rowIdentities: Array<Array<string>>;
    sectionIdentities: Array<string>;
  
    _calculateDirtyArrays(
      prevDataBlob: any,
      prevSectionIDs: Array<string>,
      prevRowIDs: Array<Array<string>>
    ): void {
      // construct a hashmap of the existing (old) id arrays
      var prevSectionsHash = keyedDictionaryFromArray(prevSectionIDs);
      var prevRowsHash = {};
      for (var ii = 0; ii < prevRowIDs.length; ii++) {
        var sectionID = prevSectionIDs[ii];
        warning(
          !prevRowsHash[sectionID],
          'SectionID appears more than once: ' + sectionID
        );
        prevRowsHash[sectionID] = keyedDictionaryFromArray(prevRowIDs[ii]);
      }
  
      // compare the 2 identity array and get the dirtied rows
      this._dirtySections = [];
      this._dirtyRows = [];
  
      var dirty;
      for (var sIndex = 0; sIndex < this.sectionIdentities.length; sIndex++) {
        var sectionID = this.sectionIdentities[sIndex];
        // dirty if the sectionHeader is new or _sectionHasChanged is true
        dirty = !prevSectionsHash[sectionID];
        var sectionHeaderHasChanged = this._sectionHeaderHasChanged;
        if (!dirty && sectionHeaderHasChanged) {
          dirty = sectionHeaderHasChanged(
            this._getSectionHeaderData(prevDataBlob, sectionID),
            this._getSectionHeaderData(this._dataBlob, sectionID)
          );
        }
        this._dirtySections.push(!!dirty);
  
        this._dirtyRows[sIndex] = [];
        for (var rIndex = 0; rIndex < this.rowIdentities[sIndex].length; rIndex++) {
          var rowID = this.rowIdentities[sIndex][rIndex];
          // dirty if the section is new, row is new or _rowHasChanged is true
          dirty =
            !prevSectionsHash[sectionID] ||
            !prevRowsHash[sectionID][rowID] ||
            this._rowHasChanged(
              this._getRowData(prevDataBlob, sectionID, rowID),
              this._getRowData(this._dataBlob, sectionID, rowID)
            );
          this._dirtyRows[sIndex].push(!!dirty);
        }
      }
    }
  }
  
  function countRows(allRowIDs) {
    var totalRows = 0;
    for (var sectionIdx = 0; sectionIdx < allRowIDs.length; sectionIdx++) {
      var rowIDs = allRowIDs[sectionIdx];
      totalRows += rowIDs.length;
    }
    return totalRows;
  }
  
  function keyedDictionaryFromArray(arr) {
    if (isEmpty(arr)) {
      return {};
    }
    var result = {};
    for (var ii = 0; ii < arr.length; ii++) {
      var key = arr[ii];
      warning(!result[key], 'Value appears more than once in array: ' + key);
      result[key] = true;
    }
    return result;
  }
  
  
  module.exports = ListViewDataSource;
  