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refactor: Simplify shift code (#3230)
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@seakayone
seakayone authored May 7, 2024
1 parent 1dcf47b commit a9f0840
Showing 1 changed file with 39 additions and 122 deletions.
161 changes: 39 additions & 122 deletions webapi/src/main/scala/org/knora/webapi/responders/admin/ListsResponder.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,6 @@

package org.knora.webapi.responders.admin

import zio.IO
import zio.Task
import zio.ZIO
import zio.ZLayer
Expand Down Expand Up @@ -525,16 +524,6 @@ final case class ListsResponder(
case child: ListCreateChildNodeRequest => (child.id, child.projectIri, child.name, child.position)
}

def getPositionOfNewChild(children: Seq[ListChildNodeADM]): IO[BadRequestException, Int] = {
val size = children.size
position.map(_.value) match {
case Some(pos) if pos > size =>
ZIO.fail(BadRequestException(s"Invalid position given $pos, maximum allowed position is = $size."))
case Some(pos) if pos >= 0 => ZIO.succeed(pos)
case _ => ZIO.succeed(size)
}
}

def getRootNodeIri(parentListNode: ListNodeADM): IRI =
parentListNode match {
case root: ListRootNodeADM => root.id
Expand All @@ -549,32 +538,18 @@ final case class ListsResponder(
/* Verify that the list node exists by retrieving the whole node including children one level deep (need for position calculation) */
parentListNode <- listNodeGetADM(parentNodeIri, shallow = true)
.someOrFail(BadRequestException(s"List node '$parentNodeIri' not found."))
children = parentListNode.children
position <- getPositionOfNewChild(children)

// Is the node supposed to be inserted in a specific position in array of children?
_ <-
if (position != children.size) {
// Yes. Shift the siblings after the given position to right in order to free the position.
for {
// shift siblings that are after given position to right
updatedSiblings <- shiftNodes(
startPos = position,
endPos = children.size - 1,
nodes = children,
shiftToLeft = false,
dataNamedGraph = dataNamedGraph,
)
} yield updatedSiblings
} else {
// No. new node will be appended to the end, no shifting is necessary.
ZIO.succeed(children)
children = parentListNode.children
size = children.size
position <- {
position.map(_.value) match {
case Some(pos) if pos > size =>
ZIO.fail(BadRequestException(s"Invalid position given $pos, maximum allowed position is = $size."))
case Some(pos) if pos >= 0 => ZIO.succeed(pos)
case _ => ZIO.succeed(size)
}

/* get the root node, depending on the type of the parent */
rootNodeIri = getRootNodeIri(parentListNode)

} yield (Some(position), Some(rootNodeIri))
}
_ <- shiftNodes(position, size - 1, children, dataNamedGraph, ShiftRight).when(position != size)
} yield (Some(position), Some(getRootNodeIri(parentListNode)))

for {
/* Verify that the project exists by retrieving it. We need the project information so that we can calculate the data graph and IRI for the new node. */
Expand Down Expand Up @@ -997,27 +972,9 @@ final case class ListsResponder(
// update position of siblings
_ <-
if (currPosition < newPosition) {
for {
// shift siblings to left
updatedSiblings <- shiftNodes(
startPos = currPosition + 1,
endPos = newPosition,
nodes = parentChildren,
shiftToLeft = true,
dataNamedGraph = dataNamedGraph,
)
} yield updatedSiblings
shiftNodes(currPosition + 1, newPosition, parentChildren, dataNamedGraph, ShiftLeft)
} else if (currPosition > newPosition) {
for {
// shift siblings to right
updatedSiblings <- shiftNodes(
startPos = newPosition,
endPos = currPosition - 1,
nodes = parentChildren,
shiftToLeft = false,
dataNamedGraph = dataNamedGraph,
)
} yield updatedSiblings
shiftNodes(newPosition, currPosition - 1, parentChildren, dataNamedGraph, ShiftRight)
} else {
throw UpdateNotPerformedException(s"The given position is the same as node's current position.")
}
Expand Down Expand Up @@ -1055,11 +1012,8 @@ final case class ListsResponder(
currentNodePosition = node.position

// if givenPosition is -1, append the child to the end of the list of children
newPosition =
if (givenPosition == -1) {
newSiblings.size
} else givenPosition

newPosition = if (givenPosition == -1) { newSiblings.size }
else givenPosition
// update the position of the node itself
_ <- updatePositionOfNode(
nodeIri = node.id,
Expand All @@ -1068,41 +1022,22 @@ final case class ListsResponder(
)

// shift current siblings with a higher position to left as if the node is deleted
_ <- shiftNodes(
startPos = currentNodePosition + 1,
endPos = currentSiblings.last.position,
nodes = currentSiblings,
shiftToLeft = true,
dataNamedGraph = dataNamedGraph,
)
_ <-
shiftNodes(currentNodePosition + 1, currentSiblings.last.position, currentSiblings, dataNamedGraph, ShiftLeft)

// Is node supposed to be added to the end of new parent's children list?
_ <-
if (givenPosition == -1 || givenPosition == newSiblings.size) {
// Yes. New siblings should not be shifted
ZIO.attempt(newSiblings)
ZIO.succeed(newSiblings)
} else {
// No. Shift new siblings with the same and higher position
// to right, as if the node is inserted in the given position
for {
updatedSiblings <- shiftNodes(
startPos = newPosition,
endPos = newSiblings.last.position,
nodes = newSiblings,
shiftToLeft = false,
dataNamedGraph = dataNamedGraph,
)
} yield updatedSiblings
shiftNodes(newPosition, newSiblings.last.position, newSiblings, dataNamedGraph, ShiftRight)
}

/* update the sublists of parent nodes */
_ <- changeParentNode(
nodeIri = node.id,
oldParentIri = currParentIri,
newParentIri = newParentIri,
dataNamedGraph = dataNamedGraph,
)

_ <- changeParentNode(node.id, currParentIri, newParentIri, dataNamedGraph)
} yield newPosition

val updateTask =
Expand Down Expand Up @@ -1266,11 +1201,11 @@ final case class ListsResponder(
if (remainingChildren.nonEmpty) {
for {
shiftedChildren <- shiftNodes(
startPos = positionOfDeletedNode + 1,
endPos = remainingChildren.last.position,
nodes = remainingChildren,
shiftToLeft = true,
dataNamedGraph = dataNamedGraph,
positionOfDeletedNode + 1,
remainingChildren.last.position,
remainingChildren,
dataNamedGraph,
ShiftLeft,
)
} yield shiftedChildren
} else {
Expand Down Expand Up @@ -1520,45 +1455,27 @@ final case class ListsResponder(
.unless(childNode.position.equals(newPosition))
} yield childNode

sealed trait ShiftDir { def apply(num: Int): Int }
private case object ShiftLeft extends ShiftDir { def apply(num: Int): Int = num - 1 }
private case object ShiftRight extends ShiftDir { def apply(num: Int): Int = num + 1 }

/**
* Helper method to shift nodes between positions startPos and endPos to the left if 'shiftToLeft' is true,
* otherwise shift them one position to the right.
* Helper method to shift nodes between positions startPos and endPos.
*
* @param startPos the position of first node in range that must be shifted.
* @param endPos the position of last node in range that must be shifted.
* @param nodes the list of all nodes.
* @param shiftToLeft shift nodes to left if true, otherwise to right.
* @param dataNamedGraph the data named graph of the project.
* @throws UpdateNotPerformedException if the position of a node could not be updated.
* @param shift the [[ShiftDir]] direction to shift
* @param namedGraph the data named graph of the project.
* @return a sequence of [[ListChildNodeADM]].
*/
private def shiftNodes(
startPos: Int,
endPos: Int,
nodes: Seq[ListChildNodeADM],
shiftToLeft: Boolean,
dataNamedGraph: IRI,
): Task[Seq[ListChildNodeADM]] =
for {
nodesTobeUpdated <- ZIO.attempt(
nodes.filter(node => node.position >= startPos && node.position <= endPos),
)
staticStartNodes = nodes.filter(node => node.position < startPos)
staticEndNotes = nodes.filter(node => node.position > endPos)
updatePositionFutures = nodesTobeUpdated.map { child =>
val currPos = child.position
val newPos = if (shiftToLeft) {
currPos - 1
} else currPos + 1

updatePositionOfNode(
nodeIri = child.id,
newPosition = newPos,
dataNamedGraph = dataNamedGraph,
)
}
updatedNodes <- ZioHelper.sequence(updatePositionFutures)
} yield staticStartNodes ++ updatedNodes ++ staticEndNotes
private def shiftNodes(startPos: Int, endPos: Int, nodes: Seq[ListChildNodeADM], namedGraph: IRI, shift: ShiftDir) = {
val (start, rest) = nodes.partition(_.position < startPos)
val (needUpdate, end) = rest.partition(_.position <= endPos)
ZIO
.foreach(needUpdate)(node => updatePositionOfNode(node.id, shift(node.position), namedGraph))
.map(start ++ _ ++ end)
}

/**
* Helper method to change parent node of a node.
Expand Down

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