shift method

(NavCtntPair<T>, NavigatableList<T>) shift(NavCtntPair<T> currentPages, Navigatable<T> insertPage)

Implementation

(NavCtntPair<T>, NavigatableList<T>) shift(NavCtntPair<T> currentPages, Navigatable<T> insertPage){
  var navigates = currentPages.$1;
  var contents = currentPages.$2;
  var insertPageClass = insertPage.$1;
  var newColumnNumber = insertPage.$2;
  var isContentPage = insertPage.$1 <= contentPageClass;
  NavigatableList<T> removeList = [];
  var newpageInsertStartIndex = !isContentPage ?  navigates.indexWhere((page)=>insertPageClass >= page.$1) : -1;

  // List<int, int, T?> mapDecline(List<int, int, T?> willMap, ){
  //   return willMap.map((item){
  //       if(willFoldColumnNumber > 0){
  //         willFoldColumnNumber --;
  //         return (item.$1, item.$2 - 1, item.$3);
  //       } else {
  //         return item;
  //       }
  //     }).toList();
  // }

  //// https://immvpc32u2.feishu.cn/docx/R427dV9WbonppxxMv1xc1Jt4n8c#share-HA0odkwJsoOSmYxTx0ZcK4MfnLf
  //// 剔除算法
  if(newpageInsertStartIndex != -1){
    removeList.addAll(navigates.getRange(newpageInsertStartIndex, navigates.length));
    navigates.removeRange(newpageInsertStartIndex, navigates.length);
  }

  var current = [...navigates, ...contents ];
  int currentColumnsNum = current.fold<int>(0, (count, item)=>count + item.$2);
  /// 逻辑最小和逻辑最大不一定可用
  // int foldedColumnsNum = current.length;
  // int expandColumnsNum = current.fold(0, (count, item)=>count + item.$1);
  int foldedColumnsNum = current.fold<int>(0, (count, item)=>count + (availableColumns(item.$3.availableColumns, item.$1).lastOrNull ?? item.$2));

  // int minExpandNum = current.map((item){
  //   var next = nextColumnLess(item.$3.availableColumns, item.$2 + 1, item.$1);
  //   return next != null ? next - item.$2 : -1;
  // }).where((i)=>i > 0).sorted((a, b)=>b.compareTo(a)).lastOrNull ?? 0;
  // bool canExpand = minExpandNum > 0;
  // int expandMinColumnsNum = currentColumnsNum + minExpandNum;
  // int expandMaxColumnsNum = current.fold<int>(0, (count, item)=>count + (availableColumns(item.$3.availableColumns, item.$1).firstOrNull ?? item.$2));

  ///
  if(newColumnNumber + foldedColumnsNum >= screenColumn){
    var count = newColumnNumber + foldedColumnsNum - screenColumn;
    if(count > 0){
      var popIndex = contents.length - count;
      /// 执行退栈
      removeList.addAll(contents.getRange(popIndex, contents.length));
      contents.removeRange(popIndex, contents.length);
    }
    /// 执行最大折叠
    // navigates = navigates.map((willFold)=>(willFold.$1, 1, willFold.$3)).toList();
    // contents = contents.map((willFold)=>(willFold.$1, 1, willFold.$3)).toList();
    navigates = navigates.map((willFold)=>(willFold.$1, availableColumns(willFold.$3.availableColumns, willFold.$1).last, willFold.$3)).toList();
    contents = contents.map((willFold)=>(willFold.$1, availableColumns(willFold.$3.availableColumns, willFold.$1).last, willFold.$3)).toList();
  }else
  if(newColumnNumber + currentColumnsNum > screenColumn){
    /// 执行折叠算法-决定折叠谁 叠多少(必然有没折叠的)
    var willFoldColumnNumber = newColumnNumber + currentColumnsNum - screenColumn;
    /// 先将导航栈按照从大到小折叠，再将内容栈从旧到新折叠(逐一折叠：一次折一列(不一定是一列但最少是一列))
    while(willFoldColumnNumber > 0){
      navigates = navigates.map((nv){
        var next = nextColumnLess(nv.$3.availableColumns, nv.$2, nv.$1);
        if(willFoldColumnNumber > 0 && next != null){
        // if(willFoldColumnNumber > 0 && nv.$2 > 1){
          // willFoldColumnNumber --;
          // return (nv.$1, nv.$2 - 1, nv.$3);
          willFoldColumnNumber -= nv.$2 - next;
          return (nv.$1, next, nv.$3);
        } else {
          return nv;
        }
      }).toList();
      if(willFoldColumnNumber > 0){
        contents = contents.reversed.map((ct){
          var next = nextColumnLess(ct.$3.availableColumns, ct.$2, ct.$1);
          if(willFoldColumnNumber > 0 && next != null){
          // if(willFoldColumnNumber > 0 && ct.$2 > 1){
            // willFoldColumnNumber --;
            // return (ct.$1, ct.$2 - 1, ct.$3);
            willFoldColumnNumber -= ct.$2 - next;
            return (ct.$1, next, ct.$3);
          } else {
            return ct;
          }
        }).toList().reversed.toList();
      }
    }
  }
  // else
  // /// 扩展算法有个前提： 最小扩展 > 0 最小扩展栏目数 <= screenColumn
  // if(newColumnNumber + currentColumnsNum < screenColumn && canExpand && expandMinColumnsNum <= screenColumn){
  //   /// 内容扩展算法(同时受到 可以展开的最大值 和 屏幕最大值两个限制)
  //   var willExpandColumnNumber = min(screenColumn - newColumnNumber - currentColumnsNum, expandMaxColumnsNum - currentColumnsNum);
  //   /// 先将内容栈按照从新到旧扩展，再从导航栈按照从小到大扩展
  //   while(willExpandColumnNumber > 0){
  //     contents = contents.map((ct){
  //       if(willExpandColumnNumber > 0 && ct.$2 <= ct.$1){
  //         willExpandColumnNumber --;
  //         return (ct.$1, ct.$2 + 1, ct.$3);
  //       } else {
  //         return ct;
  //       }
  //     }).toList();
  //     if(willExpandColumnNumber > 0){
  //       navigates = navigates.reversed.map((nv){
  //         if(willExpandColumnNumber > 0 && nv.$2 <= nv.$1){
  //           willExpandColumnNumber --;
  //           return (nv.$1, nv.$2 + 1, nv.$3);
  //         } else {
  //           return nv;
  //         }
  //       }).toList().reversed.toList();
  //     }
  //   }
  // }
  /// 插入元素
  if(isContentPage){
    return ((navigates, contents ..insert(0, insertPage)), removeList);
  }else
  if(newpageInsertStartIndex != -1){
    return ((navigates ..insert(newpageInsertStartIndex, insertPage), contents), removeList);
  }else{
    return ((navigates ..add(insertPage), contents), removeList);
  }
}