Work on schematic and parcel swaps

15 files changed, 311 insertions, 166 deletions

diff --git a/build.gradle.kts b/build.gradle.kts
index 06f2041..c745ca5 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -67,7 +67,7 @@ dependencies {
     c.kotlinStd(kotlin("stdlib-jdk8"))
     c.kotlinStd(kotlin("reflect"))
     c.kotlinStd(kotlinx("coroutines-core:0.26.1-eap13"))
-    c.kotlinStd("org.jetbrains.kotlinx:atomicfu-common:0.11.7-rc-conf")
+    c.kotlinStd("org.jetbrains.kotlinx:atomicfu-common:0.11.7-eap13")
 
     // not on sk89q maven repo yet
     compileClasspath(files("$rootDir/debug/plugins/worldedit-bukkit-7.0.0-beta-01.jar"))
diff --git a/src/main/kotlin/io/dico/parcels2/ParcelGenerator.kt b/src/main/kotlin/io/dico/parcels2/ParcelGenerator.kt
index d69984b..c11d557 100644
--- a/src/main/kotlin/io/dico/parcels2/ParcelGenerator.kt
+++ b/src/main/kotlin/io/dico/parcels2/ParcelGenerator.kt
@@ -59,7 +59,9 @@ interface ParcelBlockManager {
 
     fun clearParcel(parcel: ParcelId): Worker
 
-    fun submitBlockVisitor(parcelId: ParcelId, task: TimeLimitedTask): Worker
+    fun swapParcels(parcel1: ParcelId, parcel2: ParcelId): Worker
+
+    fun submitBlockVisitor(vararg parcelIds: ParcelId, task: TimeLimitedTask): Worker
 
     /**
      * Used to update owner blocks in the corner of the parcel
diff --git a/src/main/kotlin/io/dico/parcels2/PlayerProfile.kt b/src/main/kotlin/io/dico/parcels2/PlayerProfile.kt
index c430340..53e2d76 100644
--- a/src/main/kotlin/io/dico/parcels2/PlayerProfile.kt
+++ b/src/main/kotlin/io/dico/parcels2/PlayerProfile.kt
@@ -226,19 +226,19 @@ class PlayerProfile2 private constructor(uuid: UUID?,
                 ?: PlayerProfile(null, input, !allowFake)
         }
 
-        operator fun invoke(name: String): PlayerProfile {
+        operator fun createWith(name: String): PlayerProfile {
             if (name == star.name) return star
             return PlayerProfile(null, name)
         }
 
-        operator fun invoke(uuid: UUID): PlayerProfile {
+        operator fun createWith(uuid: UUID): PlayerProfile {
             if (uuid == star.uuid) return star
             return PlayerProfile(uuid, null)
         }
 
-        operator fun invoke(player: OfflinePlayer): PlayerProfile {
+        operator fun createWith(player: OfflinePlayer): PlayerProfile {
             // avoid UUID comparison against STAR
-            return if (player.isValid) PlayerProfile(player.uuid, player.name) else invoke(player.name)
+            return if (player.isValid) PlayerProfile(player.uuid, player.name) else createWith(player.name)
         }
     }
 
diff --git a/src/main/kotlin/io/dico/parcels2/Privilege.kt b/src/main/kotlin/io/dico/parcels2/Privilege.kt
index 040e5f5..72878a9 100644
--- a/src/main/kotlin/io/dico/parcels2/Privilege.kt
+++ b/src/main/kotlin/io/dico/parcels2/Privilege.kt
@@ -88,7 +88,7 @@ interface Privileges : PrivilegesMinimal {
         }
 
     fun changePrivilege(key: PrivilegeKey, positive: Boolean, update: Privilege): PrivilegeChangeResult =
-        if (key != keyOfOwner) FAIL_OWNER
+        if (key == keyOfOwner) FAIL_OWNER
         else if (getStoredPrivilege(key).isChangeInDirection(positive, update)
             && setStoredPrivilege(key, update)
         ) SUCCESS
diff --git a/src/main/kotlin/io/dico/parcels2/blockvisitor/Attachables.kt b/src/main/kotlin/io/dico/parcels2/blockvisitor/Attachables.kt
index 84d8a58..f5b7ad8 100644
--- a/src/main/kotlin/io/dico/parcels2/blockvisitor/Attachables.kt
+++ b/src/main/kotlin/io/dico/parcels2/blockvisitor/Attachables.kt
@@ -46,7 +46,7 @@ private val attachables = EnumSet.of(
 
 fun isAttachable(type: Material) = attachables.contains(type)
 
-fun supportingBlock(data: BlockData): Vec3i = when (data) {
+fun getSupportingBlock(data: BlockData): Vec3i = when (data) {
     //is MultipleFacing -> // fuck it xD this is good enough
 
     is Directional -> Vec3i.convert(when (data.material) {
diff --git a/src/main/kotlin/io/dico/parcels2/blockvisitor/RegionTraverser.kt b/src/main/kotlin/io/dico/parcels2/blockvisitor/RegionTraverser.kt
index 563d7a1..8f7f8f8 100644
--- a/src/main/kotlin/io/dico/parcels2/blockvisitor/RegionTraverser.kt
+++ b/src/main/kotlin/io/dico/parcels2/blockvisitor/RegionTraverser.kt
@@ -28,8 +28,8 @@ sealed class RegionTraverser {
     protected abstract suspend fun Scope.build(region: Region)
 
     companion object {
-        val upward = Directional(TraverseDirection(1, 1, 1), TraverseOrder(Dimension.Y, Dimension.X))
-        val downward = Directional(TraverseDirection(1, -1, 1), TraverseOrder(Dimension.Y, Dimension.X))
+        val upward = Directional(TraverseDirection(1, 1, 1), TraverseOrderFactory.createWith(Dimension.Y, Dimension.X))
+        val downward = Directional(TraverseDirection(1, -1, 1), TraverseOrderFactory.createWith(Dimension.Y, Dimension.X))
         val toClear get() = downward
         val toFill get() = upward
 
@@ -42,8 +42,34 @@ sealed class RegionTraverser {
         val direction: TraverseDirection,
         val order: TraverseOrder
     ) : RegionTraverser() {
+
+        private inline fun iterate(max: Int, increasing: Boolean, action: (Int) -> Unit) {
+            for (i in 0..max) {
+                action(if (increasing) i else max - i)
+            }
+        }
+
         override suspend fun Scope.build(region: Region) {
-            //traverserLogic(region, order, direction)
+            val order = order
+            val (primary, secondary, tertiary) = order.toArray()
+            val (origin, size) = region
+
+            val maxOfPrimary = primary.extract(size) - 1
+            val maxOfSecondary = secondary.extract(size) - 1
+            val maxOfTertiary = tertiary.extract(size) - 1
+
+            val isPrimaryIncreasing = direction.isIncreasing(primary)
+            val isSecondaryIncreasing = direction.isIncreasing(secondary)
+            val isTertiaryIncreasing = direction.isIncreasing(tertiary)
+
+            iterate(maxOfPrimary, isPrimaryIncreasing) { p ->
+                iterate(maxOfSecondary, isSecondaryIncreasing) { s ->
+                    iterate(maxOfTertiary, isTertiaryIncreasing) { t ->
+                        yield(order.add(origin, p, s, t))
+                    }
+                }
+            }
+
         }
 
     }
@@ -77,6 +103,38 @@ sealed class RegionTraverser {
         }
     }
 
+    fun childForPosition(position: Vec3i): Directional {
+        var cur = this
+        while (true) {
+            when (cur) {
+                is Directional ->
+                    return cur
+                is Slicing ->
+                    cur =
+                        if (position.y <= cur.bottomSectionMaxY) cur.bottomTraverser
+                        else cur.topTraverser
+            }
+        }
+    }
+
+    fun comesFirst(current: Vec3i, block: Vec3i): Boolean {
+        var cur = this
+        while (true) {
+            when (cur) {
+                is Directional -> return cur.direction.comesFirst(current, block)
+                is Slicing -> {
+                    val border = cur.bottomSectionMaxY
+                    cur = when {
+                        current.y <= border && block.y <= border -> cur.bottomTraverser
+                        current.y <= border -> return !cur.bottomFirst
+                        block.y <= border -> return cur.bottomFirst
+                        else -> cur.topTraverser
+                    }
+                }
+            }
+        }
+    }
+
 }
 
 enum class Dimension {
@@ -97,8 +155,18 @@ enum class Dimension {
     }
 }
 
+object TraverseOrderFactory {
+    private fun isSwap(primary: Dimension, secondary: Dimension) = secondary.ordinal != (primary.ordinal + 1) % 3
+
+    fun createWith(primary: Dimension, secondary: Dimension): TraverseOrder {
+        // tertiary is implicit
+        if (primary == secondary) throw IllegalArgumentException()
+        return TraverseOrder(primary, isSwap(primary, secondary))
+    }
+}
+
 inline class TraverseOrder(val orderNum: Int) {
-    private constructor(first: Dimension, swap: Boolean)
+    constructor(first: Dimension, swap: Boolean)
         : this(if (swap) first.ordinal + 3 else first.ordinal)
 
     @Suppress("NOTHING_TO_INLINE")
@@ -126,18 +194,8 @@ inline class TraverseOrder(val orderNum: Int) {
      */
     fun toArray() = arrayOf(primary, secondary, tertiary)
 
-    companion object {
-        private fun isSwap(primary: Dimension, secondary: Dimension) = secondary.ordinal != (primary.ordinal + 1) % 3
-
-        operator fun invoke(primary: Dimension, secondary: Dimension): TraverseOrder {
-            // tertiary is implicit
-            if (primary == secondary) throw IllegalArgumentException()
-            return TraverseOrder(primary, isSwap(primary, secondary))
-        }
-    }
-
     fun add(vec: Vec3i, dp: Int, ds: Int, dt: Int): Vec3i =
-        // optimize this, will be called lots
+    // optimize this, will be called lots
         when (orderNum) {
             0 -> vec.add(dp, ds, dt) // xyz
             1 -> vec.add(dt, dp, ds) // yzx
@@ -149,48 +207,19 @@ inline class TraverseOrder(val orderNum: Int) {
         }
 }
 
-class AltTraverser(val size: Vec3i,
-                   val order: TraverseOrder,
-                   val direction: TraverseDirection) {
-
-
-    suspend fun Scope.build() {
-        doPrimary()
-    }
-
-    private suspend fun Scope.doPrimary() {
-        val dimension = order.primary
-        direction.directionOf(dimension).traverse(dimension.extract(size)) { value ->
-
-        }
-    }
-
-    private fun Dimension.setValue(value: Int) {
-
-    }
-
-}
-
-enum class Increment(val offset: Int) {
-    UP(1),
-    DOWN(-1);
-
-    companion object {
-        fun convert(bool: Boolean) = if (bool) UP else DOWN
-    }
-
-    inline fun traverse(size: Int, op: (Int) -> Unit) {
-        when (this) {
-            UP -> repeat(size, op)
-            DOWN -> repeat(size) { op(size - it - 1) }
-        }
-    }
-
-}
-
 inline class TraverseDirection(val bits: Int) {
-
-    fun directionOf(dimension: Dimension) = Increment.convert((1 shl dimension.ordinal) and bits != 0)
+    fun isIncreasing(dimension: Dimension) = (1 shl dimension.ordinal) and bits != 0
+
+    fun comesFirst(current: Vec3i, block: Vec3i, dimension: Dimension): Boolean =
+        if (isIncreasing(dimension))
+            dimension.extract(block) <= dimension.extract(current)
+        else
+            dimension.extract(block) >= dimension.extract(current)
+
+    fun comesFirst(current: Vec3i, block: Vec3i) =
+        comesFirst(current, block, Dimension.X)
+        && comesFirst(current, block, Dimension.Y)
+        && comesFirst(current, block, Dimension.Z)
 
     companion object {
         operator fun invoke(x: Int, y: Int, z: Int) = invoke(Vec3i(x, y, z))
diff --git a/src/main/kotlin/io/dico/parcels2/blockvisitor/Schematic.kt b/src/main/kotlin/io/dico/parcels2/blockvisitor/Schematic.kt
index 8d2084b..9d9a2aa 100644
--- a/src/main/kotlin/io/dico/parcels2/blockvisitor/Schematic.kt
+++ b/src/main/kotlin/io/dico/parcels2/blockvisitor/Schematic.kt
@@ -6,6 +6,7 @@ import io.dico.parcels2.util.get
 import org.bukkit.Bukkit
 import org.bukkit.Material
 import org.bukkit.World
+import org.bukkit.block.Block
 import org.bukkit.block.data.BlockData
 
 private val air = Bukkit.createBlockData(Material.AIR)
@@ -20,19 +21,21 @@ class Schematic {
         }
 
     private var blockDatas: Array<BlockData?>? = null
-    //private var extra: Map<Vec3i, (Block) -> Unit>? = null
+    private val extra = mutableMapOf<Vec3i, (Block) -> Unit>()
     private var isLoaded = false; private set
     private val traverser: RegionTraverser = RegionTraverser.upward
 
-    fun getLoadTask(world: World, region: Region): TimeLimitedTask = {
+    suspend fun WorkerScope.load(world: World, region: Region) {
         _size = region.size
 
         val data = arrayOfNulls<BlockData>(region.blockCount).also { blockDatas = it }
-        //val extra = mutableMapOf<Vec3i, (Block) -> Unit>().also { extra = it }
         val blocks = traverser.traverseRegion(region)
+        val total = region.blockCount.toDouble()
 
         for ((index, vec) in blocks.withIndex()) {
             markSuspensionPoint()
+            setProgress(index / total)
+
             val block = world[vec]
             if (block.y > 255) continue
             val blockData = block.blockData
@@ -42,30 +45,56 @@ class Schematic {
         isLoaded = true
     }
 
-    fun getPasteTask(world: World, position: Vec3i): TimeLimitedTask = {
+    suspend fun WorkerScope.paste(world: World, position: Vec3i) {
         if (!isLoaded) throw IllegalStateException()
         val region = Region(position, _size!!)
         val blocks = traverser.traverseRegion(region, worldHeight = world.maxHeight)
         val blockDatas = blockDatas!!
+        var postponed = hashMapOf<Vec3i, BlockData>()
+
+        // 90% of the progress of this job is allocated to this code block
+        delegateWork(0.9) {
+            for ((index, vec) in blocks.withIndex()) {
+                markSuspensionPoint()
+                val block = world[vec]
+                val type = blockDatas[index] ?: air
+                if (type !== air && isAttachable(type.material)) {
+                    val supportingBlock = vec + getSupportingBlock(type)
+
+                    if (!postponed.containsKey(supportingBlock) && traverser.comesFirst(vec, supportingBlock)) {
+                        block.blockData = type
+                    } else {
+                        postponed[vec] = type
+                    }
+
+                } else {
+                    block.blockData = type
+                }
+            }
+        }
 
-        val postponed = mutableListOf<Pair<Vec3i, BlockData>>()
-
-        for ((index, vec) in blocks.withIndex()) {
-            markSuspensionPoint()
-            val block = world[vec]
-            val type = blockDatas[index] ?: air
-            if (type !== air && isAttachable(type.material)) {
-
-
-                postponed += vec to type
-            } else {
-                block.blockData = type
+        delegateWork {
+            while (!postponed.isEmpty()) {
+                val newMap = hashMapOf<Vec3i, BlockData>()
+                for ((vec, type) in postponed) {
+                    val supportingBlock = vec + getSupportingBlock(type)
+                    if (supportingBlock in postponed && supportingBlock != vec) {
+                        newMap[vec] = type
+                    } else {
+                        world[vec].blockData = type
+                    }
+                }
+                postponed = newMap
             }
         }
+    }
 
-        for ((vec, data) in postponed) {
+    fun getLoadTask(world: World, region: Region): TimeLimitedTask = {
+        load(world, region)
+    }
 
-        }
+    fun getPasteTask(world: World, position: Vec3i): TimeLimitedTask = {
+        paste(world, position)
     }
 
 }
diff --git a/src/main/kotlin/io/dico/parcels2/blockvisitor/WorktimeLimiter.kt b/src/main/kotlin/io/dico/parcels2/blockvisitor/WorktimeLimiter.kt
index 4cfd2a3..553362e 100644
--- a/src/main/kotlin/io/dico/parcels2/blockvisitor/WorktimeLimiter.kt
+++ b/src/main/kotlin/io/dico/parcels2/blockvisitor/WorktimeLimiter.kt
@@ -2,6 +2,7 @@ package io.dico.parcels2.blockvisitor
 
 import io.dico.parcels2.ParcelsPlugin
 import io.dico.parcels2.logger
+import io.dico.parcels2.util.ext.clampMin
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.CoroutineStart.LAZY
@@ -14,7 +15,6 @@ import kotlin.coroutines.Continuation
 import kotlin.coroutines.intrinsics.COROUTINE_SUSPENDED
 import kotlin.coroutines.intrinsics.suspendCoroutineUninterceptedOrReturn
 import kotlin.coroutines.resume
-import kotlin.coroutines.suspendCoroutine
 
 typealias TimeLimitedTask = suspend WorkerScope.() -> Unit
 typealias WorkerUpdateLister = Worker.(Double, Long) -> Unit
@@ -48,9 +48,9 @@ interface Timed {
 
 interface Worker : Timed {
     /**
-     * The coroutine associated with this worker, if any
+     * The coroutine associated with this worker
      */
-    val job: Job?
+    val job: Job
 
     /**
      * true if this worker has completed
@@ -65,9 +65,9 @@ interface Worker : Timed {
 
     /**
      * A value indicating the progress of this worker, in the range 0.0 <= progress <= 1.0
-     * with no guarantees to its accuracy. May be null.
+     * with no guarantees to its accuracy.
      */
-    val progress: Double?
+    val progress: Double
 
     /**
      * Calls the given [block] whenever the progress of this worker is updated,
@@ -89,6 +89,11 @@ interface Worker : Timed {
      * Await completion of this worker
      */
     suspend fun awaitCompletion()
+
+    /**
+     * An object attached to this worker
+     */
+    //val attachment: Any?
 }
 
 interface WorkerScope : Timed {
@@ -98,9 +103,34 @@ interface WorkerScope : Timed {
     suspend fun markSuspensionPoint()
 
     /**
+     * A value indicating the progress of this worker, in the range 0.0 <= progress <= 1.0
+     * with no guarantees to its accuracy.
+     */
+    val progress: Double
+
+    /**
      * A task should call this method to indicate its progress
      */
     fun setProgress(progress: Double)
+
+    /**
+     * Indicate that this job is complete
+     */
+    fun markComplete() = setProgress(1.0)
+
+    /**
+     * Get a [WorkerScope] that is responsible for [portion] part of the progress
+     * If [portion] is negative, the remainder of the progress is used
+     */
+    fun delegateWork(portion: Double = -1.0): WorkerScope
+}
+
+inline fun <T> WorkerScope.delegateWork(portion: Double = -1.0, block: WorkerScope.() -> T): T {
+    delegateWork(portion).apply {
+        val result = block()
+        markComplete()
+        return result
+    }
 }
 
 interface WorkerInternal : Worker, WorkerScope {
@@ -179,37 +209,32 @@ class TickWorktimeLimiter(private val plugin: ParcelsPlugin, var options: TickWo
 
 }
 
-private class WorkerImpl(
-    val scope: CoroutineScope,
-    val task: TimeLimitedTask
-) : WorkerInternal, CoroutineScope by scope {
-    override var job: Job? = null; private set
+private class WorkerImpl(scope: CoroutineScope, task: TimeLimitedTask) : WorkerInternal {
+    override val job: Job = scope.launch(start = LAZY) { task() }
+
+    private var continuation: Continuation<Unit>? = null
+    private var nextSuspensionTime: Long = 0L
+    private var completeForcefully = false
+    private var isStarted = false
 
     override val elapsedTime
-        get() = job?.let {
-            if (it.isCompleted) startTimeOrElapsedTime
+        get() =
+            if (job.isCompleted) startTimeOrElapsedTime
             else currentTimeMillis() - startTimeOrElapsedTime
-        } ?: 0L
 
-    override val isComplete get() = job?.isCompleted == true
+    override val isComplete get() = job.isCompleted
 
+    private var _progress = 0.0
+    override val progress get() = _progress
     override var completionException: Throwable? = null; private set
 
-    override var progress: Double? = null; private set
-
     private var startTimeOrElapsedTime: Long = 0L // startTime before completed, elapsed time otherwise
     private var onProgressUpdate: WorkerUpdateLister? = null
     private var progressUpdateInterval: Int = 0
     private var lastUpdateTime: Long = 0L
     private var onCompleted: WorkerUpdateLister? = null
-    private var continuation: Continuation<Unit>? = null
-    private var nextSuspensionTime: Long = 0L
-    private var completeForcefully = false
 
-    private fun initJob(job: Job) {
-        this.job?.let { throw IllegalStateException() }
-        this.job = job
-        startTimeOrElapsedTime = System.currentTimeMillis()
+    init {
         job.invokeOnCompletion { exception ->
             // report any error that occurred
             completionException = exception?.also {
@@ -264,7 +289,7 @@ private class WorkerImpl(
     }
 
     override fun setProgress(progress: Double) {
-        this.progress = progress
+        this._progress = progress
         val onProgressUpdate = onProgressUpdate ?: return
         val time = System.currentTimeMillis()
         if (time > lastUpdateTime + progressUpdateInterval) {
@@ -274,46 +299,54 @@ private class WorkerImpl(
     }
 
     override fun resume(worktime: Long): Boolean {
+        if (isComplete) return true
+
         if (worktime > 0) {
             nextSuspensionTime = currentTimeMillis() + worktime
         } else {
             completeForcefully = true
         }
 
-        continuation?.let {
-            continuation = null
-            it.resume(Unit)
-            return continuation == null
-        }
-
-        job?.let {
-            nextSuspensionTime = 0L
-            throw IllegalStateException()
+        if (isStarted) {
+            continuation?.let {
+                continuation = null
+                it.resume(Unit)
+                return continuation == null
+            }
+            return true
         }
 
-        try {
-            val job = launch(start = LAZY) { task() }
-            initJob(job = job)
-            job.start()
-        } catch (t: Throwable) {
-            // do nothing: handled by job.invokeOnCompletion()
-        }
+        startTimeOrElapsedTime = System.currentTimeMillis()
+        job.start()
 
         return continuation == null
     }
 
     override suspend fun awaitCompletion() {
-        if (isComplete) return
+        job.join()
+    }
 
-        // easy path - if the job was initialized already
-        job?.apply { join(); return }
+    private fun delegateWork(curPortion: Double, portion: Double): WorkerScope =
+        DelegateScope(progress, curPortion * (if (portion < 0) 1.0 - progress else portion).clampMin(0.0))
 
-        // other way.
-        return suspendCoroutine { cont ->
-            onCompleted { prog, el -> cont.resume(Unit) }
-        }
-    }
+    override fun delegateWork(portion: Double): WorkerScope = delegateWork(1.0, portion)
+
+    private inner class DelegateScope(val progressStart: Double, val portion: Double) : WorkerScope {
+        override val elapsedTime: Long
+            get() = this@WorkerImpl.elapsedTime
 
+        override suspend fun markSuspensionPoint() =
+            this@WorkerImpl.markSuspensionPoint()
+
+        override val progress: Double
+            get() = (this@WorkerImpl.progress - progressStart) / portion
+
+        override fun setProgress(progress: Double) =
+            this@WorkerImpl.setProgress(progressStart + progress * portion)
+
+        override fun delegateWork(portion: Double): WorkerScope =
+            this@WorkerImpl.delegateWork(this.portion, portion)
+    }
 }
 
 /*
diff --git a/src/main/kotlin/io/dico/parcels2/command/AbstractParcelCommands.kt b/src/main/kotlin/io/dico/parcels2/command/AbstractParcelCommands.kt
index faafca9..6d62729 100644
--- a/src/main/kotlin/io/dico/parcels2/command/AbstractParcelCommands.kt
+++ b/src/main/kotlin/io/dico/parcels2/command/AbstractParcelCommands.kt
@@ -4,7 +4,7 @@ import io.dico.dicore.command.*
 import io.dico.parcels2.ParcelWorld
 import io.dico.parcels2.ParcelsPlugin
 import io.dico.parcels2.PlayerProfile
-import io.dico.parcels2.PrivilegeChangeResult
+import io.dico.parcels2.blockvisitor.Worker
 import io.dico.parcels2.util.ext.hasPermAdminManage
 import io.dico.parcels2.util.ext.parcelLimit
 import org.bukkit.entity.Player
@@ -43,14 +43,17 @@ abstract class AbstractParcelCommands(val plugin: ParcelsPlugin) : ICommandRecei
     protected fun ParcelScope.clearWithProgressUpdates(context: ExecutionContext, action: String) {
         Validate.isTrue(!parcel.hasBlockVisitors, "A process is already running in this parcel")
         world.blockManager.clearParcel(parcel.id)
-            .onProgressUpdate(1000, 1000) { progress, elapsedTime ->
-                val alt = context.getFormat(EMessageType.NUMBER)
-                val main = context.getFormat(EMessageType.INFORMATIVE)
-                context.sendMessage(
-                    EMessageType.INFORMATIVE, false, "$action progress: $alt%.02f$main%%, $alt%.2f${main}s elapsed"
-                        .format(progress * 100, elapsedTime / 1000.0)
-                )
-            }
+    }
+
+    protected fun Worker.reportProgressUpdates(context: ExecutionContext, action: String) {
+        onProgressUpdate(1000, 1000) { progress, elapsedTime ->
+            val alt = context.getFormat(EMessageType.NUMBER)
+            val main = context.getFormat(EMessageType.INFORMATIVE)
+            context.sendMessage(
+                EMessageType.INFORMATIVE, false, "$action progress: $alt%.02f$main%%, $alt%.2f${main}s elapsed"
+                    .format(progress * 100, elapsedTime / 1000.0)
+            )
+        }
     }
 
     protected fun err(message: String): Nothing = throw CommandException(message)
diff --git a/src/main/kotlin/io/dico/parcels2/command/CommandsAdmin.kt b/src/main/kotlin/io/dico/parcels2/command/CommandsAdmin.kt
index 0b155f2..9975535 100644
--- a/src/main/kotlin/io/dico/parcels2/command/CommandsAdmin.kt
+++ b/src/main/kotlin/io/dico/parcels2/command/CommandsAdmin.kt
@@ -1,11 +1,15 @@
 package io.dico.parcels2.command
 
+import io.dico.dicore.command.CommandException
 import io.dico.dicore.command.ExecutionContext
+import io.dico.dicore.command.Validate
 import io.dico.dicore.command.annotation.Cmd
 import io.dico.dicore.command.annotation.Flag
 import io.dico.parcels2.ParcelsPlugin
 import io.dico.parcels2.PlayerProfile
 import io.dico.parcels2.Privilege
+import io.dico.parcels2.command.ParcelTarget.Companion.ID
+import io.dico.parcels2.command.ParcelTarget.Kind
 
 class CommandsAdmin(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
 
@@ -28,18 +32,34 @@ class CommandsAdmin(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
     @Cmd("reset")
     @RequireParcelPrivilege(Privilege.ADMIN)
     fun ParcelScope.cmdReset(context: ExecutionContext, @Flag sure: Boolean): Any? {
+        Validate.isTrue(!parcel.hasBlockVisitors, "A process is already running in this parcel")
         if (!sure) return areYouSureMessage(context)
+
         parcel.dispose()
-        clearWithProgressUpdates(context, "Reset")
-        return null
+        world.blockManager.clearParcel(parcel.id).reportProgressUpdates(context, "Reset")
+        return "Data of (${parcel.id.idString}) has been disposed"
     }
 
     @Cmd("swap")
     @RequireParcelPrivilege(Privilege.ADMIN)
-    fun ParcelScope.cmdSwap(context: ExecutionContext, @Flag sure: Boolean): Any? {
+    fun ParcelScope.cmdSwap(context: ExecutionContext,
+                            @Kind(ID) target: ParcelTarget,
+                            @Flag sure: Boolean): Any? {
+        Validate.isTrue(!parcel.hasBlockVisitors, "A process is already running in this parcel")
         if (!sure) return areYouSureMessage(context)
-        TODO("implement swap")
-    }
 
+        val parcel2 = (target as ParcelTarget.ByID).getParcel()
+            ?: throw CommandException("Invalid parcel target")
+
+        Validate.isTrue(parcel2.world == world, "Parcel must be in the same world")
+        Validate.isTrue(!parcel2.hasBlockVisitors, "A process is already running in this parcel")
+
+        val data = parcel.data
+        parcel.copyData(parcel2.data)
+        parcel2.copyData(data)
+
+        world.blockManager.swapParcels(parcel.id, parcel2.id).reportProgressUpdates(context, "Swap")
+        return null
+    }
 
 }
\ No newline at end of file
diff --git a/src/main/kotlin/io/dico/parcels2/command/CommandsDebug.kt b/src/main/kotlin/io/dico/parcels2/command/CommandsDebug.kt
index 916fccd..969d964 100644
--- a/src/main/kotlin/io/dico/parcels2/command/CommandsDebug.kt
+++ b/src/main/kotlin/io/dico/parcels2/command/CommandsDebug.kt
@@ -3,10 +3,12 @@ package io.dico.parcels2.command
 import io.dico.dicore.command.CommandException
 import io.dico.dicore.command.EMessageType
 import io.dico.dicore.command.ExecutionContext
+import io.dico.dicore.command.Validate
 import io.dico.dicore.command.annotation.Cmd
 import io.dico.parcels2.ParcelsPlugin
 import io.dico.parcels2.Privilege
 import io.dico.parcels2.blockvisitor.RegionTraverser
+import io.dico.parcels2.blockvisitor.TickWorktimeLimiter
 import io.dico.parcels2.doBlockOperation
 import org.bukkit.Bukkit
 import org.bukkit.Material
@@ -35,6 +37,8 @@ class CommandsDebug(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
     @Cmd("make_mess")
     @RequireParcelPrivilege(Privilege.OWNER)
     fun ParcelScope.cmdMakeMess(context: ExecutionContext) {
+        Validate.isTrue(!parcel.hasBlockVisitors, "A process is already running in this parcel")
+
         val server = plugin.server
         val blockDatas = arrayOf(
             server.createBlockData(Material.BLUE_WOOL),
@@ -72,4 +76,18 @@ class CommandsDebug(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
             blockData.javaClass.interfaces!!.contentToString()
     }
 
+    @Cmd("visitors")
+    fun cmdVisitors(): Any? {
+        val workers = plugin.worktimeLimiter.workers
+        println(workers.map { it.job }.joinToString(separator = "\n"))
+        return "Task count: ${workers.size}"
+    }
+
+    @Cmd("force_visitors")
+    fun cmdForceVisitors(): Any? {
+        val workers = plugin.worktimeLimiter.workers
+        plugin.worktimeLimiter.completeAllTasks()
+        return "Task count: ${workers.size}"
+    }
+
 }
\ No newline at end of file
diff --git a/src/main/kotlin/io/dico/parcels2/command/CommandsGeneral.kt b/src/main/kotlin/io/dico/parcels2/command/CommandsGeneral.kt
index 3cb0621..750fd96 100644
--- a/src/main/kotlin/io/dico/parcels2/command/CommandsGeneral.kt
+++ b/src/main/kotlin/io/dico/parcels2/command/CommandsGeneral.kt
@@ -120,9 +120,9 @@ class CommandsGeneral(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
     @Cmd("clear")
     @RequireParcelPrivilege(Privilege.OWNER)
     fun ParcelScope.cmdClear(context: ExecutionContext, @Flag sure: Boolean): Any? {
+        Validate.isTrue(!parcel.hasBlockVisitors, "A process is already running in this parcel")
         if (!sure) return areYouSureMessage(context)
-
-        clearWithProgressUpdates(context, "Clear")
+        world.blockManager.clearParcel(parcel.id).reportProgressUpdates(context, "Clear")
         return null
     }
 
@@ -130,8 +130,8 @@ class CommandsGeneral(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
     @RequireParcelPrivilege(Privilege.OWNER)
     fun ParcelScope.cmdSetbiome(context: ExecutionContext, biome: Biome): Any? {
         Validate.isTrue(!parcel.hasBlockVisitors, "A process is already running in this parcel")
-        world.blockManager.setBiome(parcel.id, biome)
-        return "Biome has been set to $biome"
+        world.blockManager.setBiome(parcel.id, biome).reportProgressUpdates(context, "Biome change")
+        return null
     }
 
 }
\ No newline at end of file
diff --git a/src/main/kotlin/io/dico/parcels2/command/CommandsPrivilegesLocal.kt b/src/main/kotlin/io/dico/parcels2/command/CommandsPrivilegesLocal.kt
index ea422a5..5202683 100644
--- a/src/main/kotlin/io/dico/parcels2/command/CommandsPrivilegesLocal.kt
+++ b/src/main/kotlin/io/dico/parcels2/command/CommandsPrivilegesLocal.kt
@@ -12,6 +12,13 @@ import org.bukkit.entity.Player
 
 class CommandsPrivilegesLocal(plugin: ParcelsPlugin) : AbstractParcelCommands(plugin) {
 
+    private fun ParcelScope.checkPrivilege(sender: Player, player: OfflinePlayer) {
+        if (!sender.hasPermAdminManage) {
+            Validate.isTrue(parcel.owner != null, "This parcel is unowned")
+            Validate.isTrue(parcel.privilege(sender) > parcel.privilege(player), "You may not change the privilege of ${player.name}")
+        }
+    }
+
     @Cmd("entrust")
     @Desc(
         "Allows a player to manage this parcel",
@@ -52,8 +59,7 @@ class CommandsPrivilegesLocal(plugin: ParcelsPlugin) : AbstractParcelCommands(pl
     )
     @RequireParcelPrivilege(Privilege.CAN_MANAGE)
     fun ParcelScope.cmdAllow(sender: Player, player: OfflinePlayer): Any? {
-        Validate.isTrue(parcel.owner != null || sender.hasPermAdminManage, "This parcel is unowned")
-        Validate.isTrue(parcel.privilege(sender) > parcel.privilege(player), "You may not change the privilege of ${player.name}")
+        checkPrivilege(sender, player)
 
         return when (parcel.allowBuild(player)) {
             FAIL_OWNER -> err("The target already owns the parcel")
@@ -70,8 +76,7 @@ class CommandsPrivilegesLocal(plugin: ParcelsPlugin) : AbstractParcelCommands(pl
     )
     @RequireParcelPrivilege(Privilege.CAN_MANAGE)
     fun ParcelScope.cmdDisallow(sender: Player, player: OfflinePlayer): Any? {
-        Validate.isTrue(parcel.owner != null || sender.hasPermAdminManage, "This parcel is unowned")
-        Validate.isTrue(parcel.privilege(sender) > parcel.privilege(player), "You may not change the privilege of ${player.name}")
+        checkPrivilege(sender, player)
 
         return when (parcel.disallowBuild(player)) {
             FAIL_OWNER -> err("The target owns the parcel")
@@ -88,8 +93,7 @@ class CommandsPrivilegesLocal(plugin: ParcelsPlugin) : AbstractParcelCommands(pl
     )
     @RequireParcelPrivilege(Privilege.CAN_MANAGE)
     fun ParcelScope.cmdBan(sender: Player, player: OfflinePlayer): Any? {
-        Validate.isTrue(parcel.owner != null || sender.hasPermAdminManage, "This parcel is unowned")
-        Validate.isTrue(parcel.privilege(sender) > parcel.privilege(player), "You may not change the privilege of ${player.name}")
+        checkPrivilege(sender, player)
 
         return when (parcel.disallowBuild(player)) {
             FAIL_OWNER -> err("The target owns the parcel")
@@ -106,8 +110,7 @@ class CommandsPrivilegesLocal(plugin: ParcelsPlugin) : AbstractParcelCommands(pl
     )
     @RequireParcelPrivilege(Privilege.CAN_MANAGE)
     fun ParcelScope.cmdUnban(sender: Player, player: OfflinePlayer): Any? {
-        Validate.isTrue(parcel.owner != null || sender.hasPermAdminManage, "This parcel is unowned")
-        Validate.isTrue(parcel.privilege(sender) > parcel.privilege(player), "You may not change the privilege of ${player.name}")
+        checkPrivilege(sender, player)
 
         return when (parcel.disallowBuild(player)) {
             FAIL_OWNER -> err("The target owns the parcel")
diff --git a/src/main/kotlin/io/dico/parcels2/defaultimpl/DefaultParcelGenerator.kt b/src/main/kotlin/io/dico/parcels2/defaultimpl/DefaultParcelGenerator.kt
index 8c8f303..dddb221 100644
--- a/src/main/kotlin/io/dico/parcels2/defaultimpl/DefaultParcelGenerator.kt
+++ b/src/main/kotlin/io/dico/parcels2/defaultimpl/DefaultParcelGenerator.kt
@@ -1,10 +1,7 @@
 package io.dico.parcels2.defaultimpl
 
 import io.dico.parcels2.*
-import io.dico.parcels2.blockvisitor.RegionTraverser
-import io.dico.parcels2.blockvisitor.TimeLimitedTask
-import io.dico.parcels2.blockvisitor.Worker
-import io.dico.parcels2.blockvisitor.WorktimeLimiter
+import io.dico.parcels2.blockvisitor.*
 import io.dico.parcels2.options.DefaultGeneratorOptions
 import io.dico.parcels2.util.Region
 import io.dico.parcels2.util.Vec2i
@@ -225,15 +222,18 @@ class DefaultParcelGenerator(
             return world.getParcelById(parcelId)
         }
 
-        override fun submitBlockVisitor(parcelId: ParcelId, task: TimeLimitedTask): Worker {
-            val parcel = getParcel(parcelId) ?: return worktimeLimiter.submit(task)
-            if (parcel.hasBlockVisitors) throw IllegalArgumentException("This parcel already has a block visitor")
+        override fun submitBlockVisitor(vararg parcelIds: ParcelId, task: TimeLimitedTask): Worker {
+            val parcels = parcelIds.mapNotNull { getParcel(it) }
+            if (parcels.isEmpty()) return worktimeLimiter.submit(task)
+            if (parcels.any { it.hasBlockVisitors }) throw IllegalArgumentException("This parcel already has a block visitor")
 
             val worker = worktimeLimiter.submit(task)
 
-            launch(start = UNDISPATCHED) {
-                parcel.withBlockVisitorPermit {
-                    worker.awaitCompletion()
+            for (parcel in parcels) {
+                launch(start = UNDISPATCHED) {
+                    parcel.withBlockVisitorPermit {
+                        worker.awaitCompletion()
+                    }
                 }
             }
 
@@ -276,6 +276,13 @@ class DefaultParcelGenerator(
             }
         }
 
+        override fun swapParcels(parcel1: ParcelId, parcel2: ParcelId): Worker = submitBlockVisitor(parcel1, parcel2) {
+            val schematicOf1 = delegateWork(0.15) { Schematic().apply { load(world, getRegion(parcel1)) } }
+            val schematicOf2 = delegateWork(0.15) { Schematic().apply { load(world, getRegion(parcel2)) } }
+            delegateWork(0.35) { with(schematicOf1) { paste(world, getRegion(parcel2).origin) } }
+            delegateWork(0.35) { with(schematicOf2) { paste(world, getRegion(parcel1).origin) } }
+        }
+
         override fun getParcelsWithOwnerBlockIn(chunk: Chunk): Collection<Vec2i> {
             /*
              * Get the offsets for the world out of the way
diff --git a/src/main/kotlin/io/dico/parcels2/util/ext/Math.kt b/src/main/kotlin/io/dico/parcels2/util/ext/Math.kt
index f3b6d3b..a123bcf 100644
--- a/src/main/kotlin/io/dico/parcels2/util/ext/Math.kt
+++ b/src/main/kotlin/io/dico/parcels2/util/ext/Math.kt
@@ -33,6 +33,7 @@ fun IntRange.clamp(min: Int, max: Int): IntRange {
 
 // the name coerceAtMost is bad
 fun Int.clampMax(max: Int) = coerceAtMost(max)
+fun Double.clampMin(min: Double) = coerceAtLeast(min)
 
 // Why does this not exist?
 infix fun Int.ceilDiv(divisor: Int): Int {