From 2db3a3946f92084bb58adb2b8d2a5f81333d2b83 Mon Sep 17 00:00:00 2001
From: adam-arold <arold.adam@gmail.com>
Date: Fri, 17 May 2019 22:58:15 +0200
Subject: [PATCH] Add items and inventory

---
 gradle.properties                             |  6 +-
 .../org/hexworks/cavesofzircon/GameConfig.kt  |  1 +
 .../cavesofzircon/attributes/Inventory.kt     | 34 ++++++++++
 .../cavesofzircon/attributes/ItemIcon.kt      |  6 ++
 .../attributes/types/EntityTypes.kt           |  6 +-
 .../cavesofzircon/attributes/types/Item.kt    | 16 +++++
 .../attributes/types/ItemHolder.kt            | 15 +++++
 .../cavesofzircon/builders/EntityFactory.kt   | 23 ++++++-
 .../cavesofzircon/builders/GameColors.kt      |  1 +
 .../builders/GameTileRepository.kt            |  6 ++
 .../cavesofzircon/commands/DropItem.kt        | 13 ++++
 .../commands/InspectInventory.kt              | 11 ++++
 .../cavesofzircon/commands/PickItemUp.kt      | 14 ++++
 .../extensions/EntityExtensions.kt            | 10 +++
 .../cavesofzircon/extensions/TypeAliases.kt   |  6 ++
 .../cavesofzircon/systems/InputReceiver.kt    | 12 ++++
 .../systems/InventoryInspector.kt             | 64 +++++++++++++++++++
 .../cavesofzircon/systems/ItemDropper.kt      | 26 ++++++++
 .../cavesofzircon/systems/ItemPicker.kt       | 39 +++++++++++
 .../hexworks/cavesofzircon/view/StartView.kt  |  4 ++
 .../view/fragment/InventoryFragment.kt        | 42 ++++++++++++
 .../view/fragment/InventoryRowFragment.kt     | 28 ++++++++
 .../cavesofzircon/world/GameBuilder.kt        |  9 +++
 23 files changed, 386 insertions(+), 6 deletions(-)
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/attributes/Inventory.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/attributes/ItemIcon.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/Item.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/ItemHolder.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/commands/DropItem.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/commands/InspectInventory.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/commands/PickItemUp.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/systems/InventoryInspector.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemDropper.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemPicker.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryFragment.kt
 create mode 100644 src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryRowFragment.kt

diff --git a/gradle.properties b/gradle.properties
index eabc4f0..98066ce 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -9,9 +9,9 @@ version=2019.0.1-PREVIEW
 kotlin_version=1.3.21
 shadow_version=4.0.2
 
-cobalt_version=2018.1.1-PREVIEW
-amethyst_version=2019.0.4-PREVIEW
-zircon_version=2019.0.14-PREVIEW
+cobalt_version=2019.1.0-PREVIEW
+amethyst_version=2019.1.0-PREVIEW
+zircon_version=2019.1.0-PREVIEW
 
 junit_version=4.12
 mockito_version=1.10.19
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/GameConfig.kt b/src/main/kotlin/org/hexworks/cavesofzircon/GameConfig.kt
index be43394..a14fc43 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/GameConfig.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/GameConfig.kt
@@ -25,6 +25,7 @@ object GameConfig {
     // entities
     const val FUNGI_PER_LEVEL = 15
     const val BATS_PER_LEVEL = 10
+    const val ZIRCONS_PER_LEVEL = 20
     const val MAXIMUM_FUNGUS_SPREAD = 20
 
     fun buildAppConfig() = AppConfigs.newConfig()
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/attributes/Inventory.kt b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/Inventory.kt
new file mode 100644
index 0000000..7a925f3
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/Inventory.kt
@@ -0,0 +1,34 @@
+package org.hexworks.cavesofzircon.attributes
+
+import org.hexworks.amethyst.api.Attribute
+import org.hexworks.cavesofzircon.extensions.GameItem
+import org.hexworks.cobalt.datatypes.Identifier
+import org.hexworks.cobalt.datatypes.Maybe
+
+class Inventory(val size: Int) : Attribute {
+
+    private val currentItems = mutableListOf<GameItem>()
+
+    val items: List<GameItem>
+        get() = currentItems.toList()
+
+    val isEmpty: Boolean
+        get() = currentItems.isEmpty()
+
+    val isFull: Boolean
+        get() = currentItems.size >= size
+
+    fun findItemBy(id: Identifier): Maybe<GameItem> {
+        return Maybe.ofNullable(items.firstOrNull { it.id == id })
+    }
+
+    fun addItem(item: GameItem): Boolean {
+        return if (isFull.not()) {
+            currentItems.add(item)
+        } else false
+    }
+
+    fun removeItem(entity: GameItem): Boolean {
+        return currentItems.remove(entity)
+    }
+}
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/attributes/ItemIcon.kt b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/ItemIcon.kt
new file mode 100644
index 0000000..47aaf74
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/ItemIcon.kt
@@ -0,0 +1,6 @@
+package org.hexworks.cavesofzircon.attributes
+
+import org.hexworks.amethyst.api.Attribute
+import org.hexworks.zircon.api.data.GraphicalTile
+
+data class ItemIcon(val iconTile: GraphicalTile) : Attribute
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/EntityTypes.kt b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/EntityTypes.kt
index 2c01dee..63eeb90 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/EntityTypes.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/EntityTypes.kt
@@ -3,7 +3,7 @@ package org.hexworks.cavesofzircon.attributes.types
 import org.hexworks.amethyst.api.base.BaseEntityType
 
 object Player : BaseEntityType(
-        name = "player"), Combatant
+        name = "player"), Combatant, ItemHolder
 
 object Wall : BaseEntityType(
         name = "wall")
@@ -20,4 +20,8 @@ object StairsDown : BaseEntityType(
 object StairsUp : BaseEntityType(
         name = "stairs up")
 
+object Zircon : BaseEntityType(
+        name = "Zircon",
+        description = "A small piece of Zircon. Its value is unfathomable."), Item
+
 object FogOfWarType : BaseEntityType()
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/Item.kt b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/Item.kt
new file mode 100644
index 0000000..c93705f
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/Item.kt
@@ -0,0 +1,16 @@
+package org.hexworks.cavesofzircon.attributes.types
+
+import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.attributes.EntityTile
+import org.hexworks.cavesofzircon.attributes.ItemIcon
+import org.hexworks.cavesofzircon.extensions.GameEntity
+import org.hexworks.zircon.api.data.GraphicalTile
+import org.hexworks.zircon.api.data.Tile
+
+interface Item : EntityType
+
+val GameEntity<Item>.tile: Tile
+    get() = findAttribute(EntityTile::class).get().tile
+
+val GameEntity<Item>.iconTile: GraphicalTile
+    get() = findAttribute(ItemIcon::class).get().iconTile
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/ItemHolder.kt b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/ItemHolder.kt
new file mode 100644
index 0000000..4066b9b
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/attributes/types/ItemHolder.kt
@@ -0,0 +1,15 @@
+package org.hexworks.cavesofzircon.attributes.types
+
+import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.attributes.Inventory
+import org.hexworks.cavesofzircon.extensions.GameItem
+import org.hexworks.cavesofzircon.extensions.GameItemHolder
+
+interface ItemHolder : EntityType
+
+fun GameItemHolder.addItem(item: GameItem) = inventory.addItem(item)
+
+fun GameItemHolder.removeItem(item: GameItem) = inventory.removeItem(item)
+
+val GameItemHolder.inventory: Inventory
+    get() = findAttribute(Inventory::class).get()
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/builders/EntityFactory.kt b/src/main/kotlin/org/hexworks/cavesofzircon/builders/EntityFactory.kt
index 83d773c..294fe76 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/builders/EntityFactory.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/builders/EntityFactory.kt
@@ -8,6 +8,8 @@ import org.hexworks.cavesofzircon.attributes.EntityActions
 import org.hexworks.cavesofzircon.attributes.EntityPosition
 import org.hexworks.cavesofzircon.attributes.EntityTile
 import org.hexworks.cavesofzircon.attributes.FungusSpread
+import org.hexworks.cavesofzircon.attributes.Inventory
+import org.hexworks.cavesofzircon.attributes.ItemIcon
 import org.hexworks.cavesofzircon.attributes.Vision
 import org.hexworks.cavesofzircon.attributes.flags.BlockOccupier
 import org.hexworks.cavesofzircon.attributes.flags.VisionBlocker
@@ -17,6 +19,7 @@ import org.hexworks.cavesofzircon.attributes.types.Player
 import org.hexworks.cavesofzircon.attributes.types.StairsDown
 import org.hexworks.cavesofzircon.attributes.types.StairsUp
 import org.hexworks.cavesofzircon.attributes.types.Wall
+import org.hexworks.cavesofzircon.attributes.types.Zircon
 import org.hexworks.cavesofzircon.commands.Attack
 import org.hexworks.cavesofzircon.commands.Dig
 import org.hexworks.cavesofzircon.entities.FogOfWar
@@ -26,12 +29,17 @@ import org.hexworks.cavesofzircon.systems.Destructible
 import org.hexworks.cavesofzircon.systems.Diggable
 import org.hexworks.cavesofzircon.systems.FungusGrowth
 import org.hexworks.cavesofzircon.systems.InputReceiver
+import org.hexworks.cavesofzircon.systems.InventoryInspector
+import org.hexworks.cavesofzircon.systems.ItemDropper
+import org.hexworks.cavesofzircon.systems.ItemPicker
 import org.hexworks.cavesofzircon.systems.Movable
 import org.hexworks.cavesofzircon.systems.StairClimber
 import org.hexworks.cavesofzircon.systems.StairDescender
 import org.hexworks.cavesofzircon.systems.Wanderer
 import org.hexworks.cavesofzircon.world.Game
 import org.hexworks.cavesofzircon.world.GameContext
+import org.hexworks.zircon.api.GraphicalTilesetResources
+import org.hexworks.zircon.api.Tiles
 
 fun <T : EntityType> newGameEntityOfType(type: T, init: EntityBuilder<T, GameContext>.() -> Unit) =
         Entities.newEntityOfType(type, init)
@@ -69,9 +77,11 @@ object EntityFactory {
                         attackValue = 10,
                         defenseValue = 5),
                 EntityTile(GameTileRepository.PLAYER),
-                EntityActions(Dig::class, Attack::class))
+                EntityActions(Dig::class, Attack::class),
+                Inventory(10))
         behaviors(InputReceiver)
-        facets(Movable, CameraMover, StairClimber, StairDescender, Attackable, Destructible)
+        facets(Movable, CameraMover, StairClimber, StairDescender, Attackable, Destructible, ItemPicker,
+                InventoryInspector, ItemDropper)
     }
 
     fun newFungus(fungusSpread: FungusSpread = FungusSpread()) = newGameEntityOfType(Fungus) {
@@ -99,5 +109,14 @@ object EntityFactory {
         facets(Movable, Attackable, Destructible)
         behaviors(Wanderer)
     }
+
+    fun newZircon() = newGameEntityOfType(Zircon) {
+        attributes(ItemIcon(Tiles.newBuilder()
+                .withName("white gem")
+                .withTileset(GraphicalTilesetResources.nethack16x16())
+                .buildGraphicTile()),
+                EntityPosition(),
+                EntityTile(GameTileRepository.ZIRCON))
+    }
 }
 
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameColors.kt b/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameColors.kt
index 9ebe6d3..09cb182 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameColors.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameColors.kt
@@ -13,6 +13,7 @@ object GameColors {
     val BAT_COLOR = TileColors.fromString("#2348b2")
 
     val ACCENT_COLOR = TileColors.fromString("#FFCD22")
+    val ZIRCON_COLOR = TileColors.fromString("#dddddd")
 
     val UNREVEALED_COLOR = TileColors.fromString("#000000")
 }
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameTileRepository.kt b/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameTileRepository.kt
index ef1fb9b..7451e28 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameTileRepository.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/builders/GameTileRepository.kt
@@ -50,6 +50,12 @@ object GameTileRepository {
             .withForegroundColor(GameColors.BAT_COLOR)
             .buildCharacterTile()
 
+    val ZIRCON  = Tiles.newBuilder()
+            .withCharacter(',')
+            .withBackgroundColor(GameColors.FLOOR_BACKGROUND)
+            .withForegroundColor(GameColors.ZIRCON_COLOR)
+            .buildCharacterTile()
+
     val UNREVEALED = Tiles.newBuilder()
             .withCharacter(' ')
             .withBackgroundColor(GameColors.UNREVEALED_COLOR)
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/commands/DropItem.kt b/src/main/kotlin/org/hexworks/cavesofzircon/commands/DropItem.kt
new file mode 100644
index 0000000..35129a2
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/commands/DropItem.kt
@@ -0,0 +1,13 @@
+package org.hexworks.cavesofzircon.commands
+
+import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.extensions.GameCommand
+import org.hexworks.cavesofzircon.extensions.GameItem
+import org.hexworks.cavesofzircon.extensions.GameItemHolder
+import org.hexworks.cavesofzircon.world.GameContext
+import org.hexworks.zircon.api.data.impl.Position3D
+
+data class DropItem(override val context: GameContext,
+                    override val source: GameItemHolder,
+                    val item: GameItem,
+                    val position: Position3D) : GameCommand<EntityType>
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/commands/InspectInventory.kt b/src/main/kotlin/org/hexworks/cavesofzircon/commands/InspectInventory.kt
new file mode 100644
index 0000000..f125ec5
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/commands/InspectInventory.kt
@@ -0,0 +1,11 @@
+package org.hexworks.cavesofzircon.commands
+
+import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.extensions.GameCommand
+import org.hexworks.cavesofzircon.extensions.GameItemHolder
+import org.hexworks.cavesofzircon.world.GameContext
+import org.hexworks.zircon.api.data.impl.Position3D
+
+data class InspectInventory(override val context: GameContext,
+                            override val source: GameItemHolder,
+                            val position: Position3D) : GameCommand<EntityType>
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/commands/PickItemUp.kt b/src/main/kotlin/org/hexworks/cavesofzircon/commands/PickItemUp.kt
new file mode 100644
index 0000000..ecb3da5
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/commands/PickItemUp.kt
@@ -0,0 +1,14 @@
+package org.hexworks.cavesofzircon.commands
+
+import org.hexworks.cavesofzircon.attributes.types.ItemHolder
+import org.hexworks.cavesofzircon.extensions.GameCommand
+import org.hexworks.cavesofzircon.extensions.GameItemHolder
+import org.hexworks.cavesofzircon.world.GameContext
+import org.hexworks.zircon.api.data.impl.Position3D
+
+/**
+ * A [GameCommand] representing [source] picking up an item at [position].
+ */
+data class PickItemUp(override val context: GameContext,
+                      override val source: GameItemHolder,
+                      val position: Position3D) : GameCommand<ItemHolder>
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/extensions/EntityExtensions.kt b/src/main/kotlin/org/hexworks/cavesofzircon/extensions/EntityExtensions.kt
index 16d8367..c08d3dc 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/extensions/EntityExtensions.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/extensions/EntityExtensions.kt
@@ -1,15 +1,20 @@
+@file:Suppress("UNCHECKED_CAST")
+
 package org.hexworks.cavesofzircon.extensions
 
 import org.hexworks.amethyst.api.Attribute
 import org.hexworks.amethyst.api.Consumed
 import org.hexworks.amethyst.api.Pass
 import org.hexworks.amethyst.api.Response
+import org.hexworks.amethyst.api.entity.Entity
+import org.hexworks.amethyst.api.entity.EntityType
 import org.hexworks.cavesofzircon.attributes.EntityActions
 import org.hexworks.cavesofzircon.attributes.EntityPosition
 import org.hexworks.cavesofzircon.attributes.EntityTile
 import org.hexworks.cavesofzircon.attributes.flags.BlockOccupier
 import org.hexworks.cavesofzircon.attributes.flags.VisionBlocker
 import org.hexworks.cavesofzircon.attributes.types.Combatant
+import org.hexworks.cavesofzircon.attributes.types.Item
 import org.hexworks.cavesofzircon.attributes.types.Player
 import org.hexworks.cavesofzircon.attributes.types.combatStats
 import org.hexworks.cavesofzircon.world.GameContext
@@ -17,6 +22,7 @@ import org.hexworks.cobalt.datatypes.extensions.map
 import org.hexworks.cobalt.datatypes.extensions.orElseThrow
 import org.hexworks.zircon.api.data.Tile
 import kotlin.reflect.KClass
+import kotlin.reflect.full.isSuperclassOf
 
 var AnyGameEntity.position
     get() = tryToFindAttribute(EntityPosition::class).position
@@ -35,6 +41,10 @@ val AnyGameEntity.tile: Tile
 val AnyGameEntity.isPlayer: Boolean
     get() = this.type == Player
 
+inline fun <reified T : EntityType> Iterable<AnyGameEntity>.filterType(): List<Entity<T, GameContext>> {
+    return filter { T::class.isSuperclassOf(it.type::class) }.toList() as List<Entity<T, GameContext>>
+}
+
 val AnyGameEntity.blocksVision: Boolean
     get() = this.findAttribute(VisionBlocker::class).isPresent
 
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/extensions/TypeAliases.kt b/src/main/kotlin/org/hexworks/cavesofzircon/extensions/TypeAliases.kt
index ee8eac1..76c901f 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/extensions/TypeAliases.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/extensions/TypeAliases.kt
@@ -3,6 +3,8 @@ package org.hexworks.cavesofzircon.extensions
 import org.hexworks.amethyst.api.Command
 import org.hexworks.amethyst.api.entity.Entity
 import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.attributes.types.Item
+import org.hexworks.cavesofzircon.attributes.types.ItemHolder
 import org.hexworks.cavesofzircon.world.GameContext
 
 /**
@@ -19,3 +21,7 @@ typealias GameEntity<T> = Entity<T, GameContext>
  * Specializes [Command] with our [GameContext] type.
  */
 typealias GameCommand<T> = Command<T, GameContext>
+
+typealias GameItem = GameEntity<Item>
+
+typealias GameItemHolder = GameEntity<ItemHolder>
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/systems/InputReceiver.kt b/src/main/kotlin/org/hexworks/cavesofzircon/systems/InputReceiver.kt
index 987bcd8..2b54794 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/systems/InputReceiver.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/systems/InputReceiver.kt
@@ -3,9 +3,11 @@ package org.hexworks.cavesofzircon.systems
 import org.hexworks.amethyst.api.base.BaseBehavior
 import org.hexworks.amethyst.api.entity.EntityType
 import org.hexworks.cavesofzircon.attributes.types.Player
+import org.hexworks.cavesofzircon.commands.InspectInventory
 import org.hexworks.cavesofzircon.commands.MoveDown
 import org.hexworks.cavesofzircon.commands.MoveTo
 import org.hexworks.cavesofzircon.commands.MoveUp
+import org.hexworks.cavesofzircon.commands.PickItemUp
 import org.hexworks.cavesofzircon.extensions.GameEntity
 import org.hexworks.cavesofzircon.extensions.position
 import org.hexworks.cavesofzircon.world.GameContext
@@ -29,6 +31,8 @@ object InputReceiver : BaseBehavior<GameContext>() {
                 KeyCode.KEY_D -> player.moveTo(currentPos.withRelativeX(1), context)
                 KeyCode.KEY_R -> player.moveUp(context)
                 KeyCode.KEY_F -> player.moveDown(context)
+                KeyCode.KEY_P -> player.pickItemUp(currentPos, context)
+                KeyCode.KEY_I -> player.inspectInventory(currentPos, context)
                 else -> {
                     logger.debug("UI Event ($uiEvent) does not have a corresponding command, it is ignored.")
                 }
@@ -37,6 +41,14 @@ object InputReceiver : BaseBehavior<GameContext>() {
         return true
     }
 
+    private fun GameEntity<Player>.inspectInventory(position: Position3D, context: GameContext) {
+        executeCommand(InspectInventory(context, this, position))
+    }
+
+    private fun GameEntity<Player>.pickItemUp(position: Position3D, context: GameContext) {
+        executeCommand(PickItemUp(context, this, position))
+    }
+
     private fun GameEntity<Player>.moveTo(position: Position3D, context: GameContext) {
         executeCommand(MoveTo(context, this, position))
     }
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/systems/InventoryInspector.kt b/src/main/kotlin/org/hexworks/cavesofzircon/systems/InventoryInspector.kt
new file mode 100644
index 0000000..38ce29e
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/systems/InventoryInspector.kt
@@ -0,0 +1,64 @@
+package org.hexworks.cavesofzircon.systems
+
+import org.hexworks.amethyst.api.Consumed
+import org.hexworks.amethyst.api.base.BaseFacet
+import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.GameConfig
+import org.hexworks.cavesofzircon.attributes.types.inventory
+import org.hexworks.cavesofzircon.commands.DropItem
+import org.hexworks.cavesofzircon.commands.InspectInventory
+import org.hexworks.cavesofzircon.extensions.GameCommand
+import org.hexworks.cavesofzircon.view.fragment.InventoryFragment
+import org.hexworks.cavesofzircon.world.GameContext
+import org.hexworks.zircon.api.Components
+import org.hexworks.zircon.api.Sizes
+import org.hexworks.zircon.api.builder.component.ModalBuilder
+import org.hexworks.zircon.api.component.ComponentAlignment.BOTTOM_LEFT
+import org.hexworks.zircon.api.extensions.onComponentEvent
+import org.hexworks.zircon.api.uievent.ComponentEventType.ACTIVATED
+import org.hexworks.zircon.api.uievent.Processed
+import org.hexworks.zircon.internal.component.modal.EmptyModalResult
+
+object InventoryInspector : BaseFacet<GameContext>() {
+
+    val DIALOG_SIZE = Sizes.create(33, 14)
+
+    override fun executeCommand(command: GameCommand<out EntityType>) = command
+            .responseWhenCommandIs(InspectInventory::class) { (context, itemHolder, position) ->
+
+                val screen = context.screen
+
+                val fragment = InventoryFragment(itemHolder.inventory, DIALOG_SIZE.width - 3) { item ->
+                    itemHolder.executeCommand(DropItem(context, itemHolder, item, position))
+                }
+
+                val panel = Components.panel()
+                        .withSize(DIALOG_SIZE)
+                        .wrapWithBox(true)
+                        .wrapWithShadow(true)
+                        .withTitle("Inventory")
+                        .build()
+
+                panel.addFragment(fragment)
+
+                val modal = ModalBuilder.newBuilder<EmptyModalResult>()
+                        .withParentSize(screen.size)
+                        .withComponent(panel)
+                        .build()
+
+                panel.addComponent(Components.button()
+                        .withText("Close")
+                        .withAlignmentWithin(panel, BOTTOM_LEFT)
+                        .build().apply {
+                            onComponentEvent(ACTIVATED) {
+                                modal.close(EmptyModalResult)
+                                Processed
+                            }
+                        })
+
+                modal.applyColorTheme(GameConfig.THEME)
+                screen.openModal(modal)
+                Consumed
+            }
+
+}
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemDropper.kt b/src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemDropper.kt
new file mode 100644
index 0000000..e7f49fa
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemDropper.kt
@@ -0,0 +1,26 @@
+package org.hexworks.cavesofzircon.systems
+
+import org.hexworks.amethyst.api.Consumed
+import org.hexworks.amethyst.api.base.BaseFacet
+import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.attributes.types.inventory
+import org.hexworks.cavesofzircon.attributes.types.removeItem
+import org.hexworks.cavesofzircon.commands.DropItem
+import org.hexworks.cavesofzircon.extensions.GameCommand
+import org.hexworks.cavesofzircon.extensions.isPlayer
+import org.hexworks.cavesofzircon.functions.logGameEvent
+import org.hexworks.cavesofzircon.world.GameContext
+
+object ItemDropper : BaseFacet<GameContext>() {
+
+    override fun executeCommand(command: GameCommand<out EntityType>) = command
+            .responseWhenCommandIs(DropItem::class) { (context, itemHolder, item, position) ->
+                if (itemHolder.removeItem(item)) {
+                    context.world.addEntity(item, position)
+                    val subject = if (itemHolder.isPlayer) "You" else "The $itemHolder"
+                    val verb = if (itemHolder.isPlayer) "drop" else "drops"
+                    logGameEvent("$subject $verb the $item.")
+                }
+                Consumed
+            }
+}
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemPicker.kt b/src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemPicker.kt
new file mode 100644
index 0000000..5eb0498
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/systems/ItemPicker.kt
@@ -0,0 +1,39 @@
+package org.hexworks.cavesofzircon.systems
+
+import org.hexworks.amethyst.api.Consumed
+import org.hexworks.amethyst.api.base.BaseFacet
+import org.hexworks.amethyst.api.entity.EntityType
+import org.hexworks.cavesofzircon.attributes.types.Item
+import org.hexworks.cavesofzircon.attributes.types.addItem
+import org.hexworks.cavesofzircon.commands.PickItemUp
+import org.hexworks.cavesofzircon.extensions.GameCommand
+import org.hexworks.cavesofzircon.extensions.filterType
+import org.hexworks.cavesofzircon.extensions.isPlayer
+import org.hexworks.cavesofzircon.functions.logGameEvent
+import org.hexworks.cavesofzircon.world.GameContext
+import org.hexworks.cavesofzircon.world.World
+import org.hexworks.cobalt.datatypes.Maybe
+import org.hexworks.cobalt.datatypes.extensions.flatMap
+import org.hexworks.cobalt.datatypes.extensions.map
+import org.hexworks.zircon.api.data.impl.Position3D
+
+object ItemPicker : BaseFacet<GameContext>() {
+
+    override fun executeCommand(command: GameCommand<out EntityType>) = command.responseWhenCommandIs(PickItemUp::class) { (context, itemHolder, position) ->
+        val world = context.world
+        world.findTopItem(position).map { item ->
+            if (itemHolder.addItem(item)) {
+                world.removeEntity(item)
+                val subject = if (itemHolder.isPlayer) "You" else "The $itemHolder"
+                val verb = if (itemHolder.isPlayer) "pick up" else "picks up"
+                logGameEvent("$subject $verb the $item.")
+            }
+        }
+        Consumed
+    }
+
+    private fun World.findTopItem(position: Position3D) =
+            fetchBlockAt(position).flatMap { block ->
+                Maybe.ofNullable(block.entities.filterType<Item>().firstOrNull())
+            }
+}
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/view/StartView.kt b/src/main/kotlin/org/hexworks/cavesofzircon/view/StartView.kt
index 4374248..81f9c22 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/view/StartView.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/view/StartView.kt
@@ -1,5 +1,8 @@
 package org.hexworks.cavesofzircon.view
 
+import org.hexworks.cavesofzircon.attributes.Inventory
+import org.hexworks.cavesofzircon.builders.EntityFactory
+import org.hexworks.cavesofzircon.view.fragment.InventoryFragment
 import org.hexworks.zircon.api.ColorThemes
 import org.hexworks.zircon.api.Components
 import org.hexworks.zircon.api.component.ComponentAlignment
@@ -36,6 +39,7 @@ class StartView : BaseView() {
             close()
             Processed
         }
+
         screen.addComponent(header)
         screen.addComponent(startButton)
     }
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryFragment.kt b/src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryFragment.kt
new file mode 100644
index 0000000..ac8083c
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryFragment.kt
@@ -0,0 +1,42 @@
+package org.hexworks.cavesofzircon.view.fragment
+
+import org.hexworks.cavesofzircon.attributes.Inventory
+import org.hexworks.cavesofzircon.extensions.GameItem
+import org.hexworks.zircon.api.Components
+import org.hexworks.zircon.api.component.Fragment
+import org.hexworks.zircon.api.extensions.onComponentEvent
+import org.hexworks.zircon.api.uievent.ComponentEventType.ACTIVATED
+import org.hexworks.zircon.api.uievent.Processed
+
+class InventoryFragment(inventory: Inventory,
+                        width: Int,
+                        onDrop: (GameItem) -> Unit) : Fragment {
+
+    override val root = Components.vbox()
+            .withSize(width, inventory.size + 1)
+            .build().apply {
+                val list = this
+                addComponent(Components.hbox()
+                        .withSpacing(1)
+                        .withSize(width, 1)
+                        .build().apply {
+                            addComponent(Components.label().withText("").withSize(1, 1))
+                            addComponent(Components.header().withText("Name").withSize(NAME_COLUMN_WIDTH, 1))
+                            addComponent(Components.header().withText("Actions").withSize(ACTIONS_COLUMN_WIDTH, 1))
+                        })
+                inventory.items.forEach { item ->
+                    addFragment(InventoryRowFragment(width, item).apply {
+                        dropButton.onComponentEvent(ACTIVATED) {
+                            list.removeComponent(this.root)
+                            onDrop(item)
+                            Processed
+                        }
+                    })
+                }
+            }
+
+    companion object {
+        const val NAME_COLUMN_WIDTH = 15
+        const val ACTIONS_COLUMN_WIDTH = 10
+    }
+}
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryRowFragment.kt b/src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryRowFragment.kt
new file mode 100644
index 0000000..b6c3329
--- /dev/null
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/view/fragment/InventoryRowFragment.kt
@@ -0,0 +1,28 @@
+package org.hexworks.cavesofzircon.view.fragment
+
+import org.hexworks.cavesofzircon.attributes.types.iconTile
+import org.hexworks.cavesofzircon.extensions.GameItem
+import org.hexworks.zircon.api.Components
+import org.hexworks.zircon.api.component.Fragment
+import org.hexworks.zircon.api.graphics.Symbols
+
+class InventoryRowFragment(width: Int, item: GameItem) : Fragment {
+
+    val dropButton = Components.button()
+            .wrapSides(false)
+            .withText("${Symbols.ARROW_DOWN}")
+            .build()
+
+    override val root = Components.hbox()
+            .withSpacing(1)
+            .withSize(width, 1)
+            .build().apply {
+                addComponent(Components.icon()
+                        .withIcon(item.iconTile))
+                addComponent(Components.label()
+                        .withSize(InventoryFragment.NAME_COLUMN_WIDTH, 1)
+                        .withText(item.name))
+                addComponent(dropButton)
+            }
+
+}
diff --git a/src/main/kotlin/org/hexworks/cavesofzircon/world/GameBuilder.kt b/src/main/kotlin/org/hexworks/cavesofzircon/world/GameBuilder.kt
index 8470c18..b476dbc 100644
--- a/src/main/kotlin/org/hexworks/cavesofzircon/world/GameBuilder.kt
+++ b/src/main/kotlin/org/hexworks/cavesofzircon/world/GameBuilder.kt
@@ -30,6 +30,7 @@ class GameBuilder(val worldSize: Size3D = WORLD_SIZE) {
         val player = addPlayer()
         addFungi()
         addBats()
+        addZircons()
 
         val game = Game.create(
                 player = player,
@@ -58,6 +59,14 @@ class GameBuilder(val worldSize: Size3D = WORLD_SIZE) {
         }
     }
 
+    private fun addZircons() = also {
+        repeat(world.actualSize().zLength) { level ->
+            repeat(GameConfig.ZIRCONS_PER_LEVEL) {
+                EntityFactory.newZircon().addToWorld(level)
+            }
+        }
+    }
+
     private fun addBats() = also {
         repeat(world.actualSize().zLength) { level ->
             repeat(BATS_PER_LEVEL) {