Add support for adventage, disadventage and emphasis rolls.

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/RollUseCase.kt

@@ -1,13 +1,67 @@
 package com.pixelized.desktop.lwa.business
 
+import com.pixelized.desktop.lwa.parser.arithmetic.Instruction
+import kotlin.math.abs
+import kotlin.math.max
+import kotlin.math.min
+
 class RollUseCase {
 
     fun rollD100(): Int {
-        return roll(quantity = 1, faces = 100)
+        return roll(modifier = null, quantity = 1, faces = 100)
     }
 
-    fun roll(quantity: Int, faces: Int): Int {
-        return sum(count = quantity) { (Math.random() * faces.toDouble() + 1).toInt() }
+    fun roll(dice: Instruction.Dice): Int {
+        return roll(
+            modifier = dice.modifier,
+            quantity = dice.quantity,
+            faces = dice.faces,
+        )
+    }
+
+    fun roll(modifier: Instruction.Dice.Modifier?, quantity: Int, faces: Int): Int {
+        print("{")
+        return sum(count = quantity) {
+            when (modifier) {
+                Instruction.Dice.Modifier.ADVANTAGE -> {
+                    val roll1 = roll(faces = faces)
+                    val roll2 = roll(faces = faces)
+                    print("[$roll1,$roll2]")
+                    max(roll1, roll2)
+                }
+
+                Instruction.Dice.Modifier.DISADVANTAGE -> {
+                    val roll1 = roll(faces = faces)
+                    val roll2 = roll(faces = faces)
+                    print("[$roll1,$roll2]")
+                    min(roll1, roll2)
+                }
+
+                Instruction.Dice.Modifier.EMPHASIS -> {
+                    val roll1 = roll(faces = faces)
+                    val roll2 = roll(faces = faces)
+                    print("[$roll1,$roll2]")
+                    val half = faces / 2
+                    val roll1Abs = abs(half - roll1)
+                    val roll2Abs = abs(half - roll2)
+                    when {
+                        roll1Abs == roll2Abs -> max(roll1, roll2)
+                        roll1Abs < roll2Abs -> roll2
+                        else -> roll1
+                    }
+                }
+
+                null -> {
+                    roll(faces = faces).also { print("$it") }
+                }
+            }
+        }.also {
+            print("}:")
+        }
+    }
+
+    private fun roll(faces: Int): Int {
+        return (Math.random() * faces.toDouble() + 1).toInt()
     }
 
     private fun sum(count: Int, block: () -> Int): Int {

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/business/SkillValueComputationUseCase.kt

@@ -53,11 +53,9 @@ class SkillValueComputationUseCase(
     ): Int { // TODO Roll detail instead of an simple Int.
         print("Roll ->")
         return arithmeticParser.parse(roll).sumOf { instruction ->
+            print(" ($instruction):")
             val value = when (instruction) {
-                is Instruction.Dice -> rollUseCase.roll(
-                    quantity = instruction.quantity,
-                    faces = instruction.faces
-                )
+                is Instruction.Dice -> rollUseCase.roll(dice = instruction)
 
                 is Instruction.Flat -> instruction.value
 
@@ -68,10 +66,7 @@ class SkillValueComputationUseCase(
                                 .parse(sheet.damageBonus)
                                 .firstOrNull()
                             if (damageBonusInstructions is Instruction.Dice) {
-                                rollUseCase.roll(
-                                    quantity = damageBonusInstructions.quantity,
-                                    faces = damageBonusInstructions.faces
-                                )
+                                rollUseCase.roll(dice = damageBonusInstructions)
                             } else {
                                 0
                             }
@@ -83,6 +78,7 @@ class SkillValueComputationUseCase(
                                 .firstOrNull()
                             if (damageBonusInstructions is Instruction.Dice) {
                                 rollUseCase.roll(
+                                    modifier = damageBonusInstructions.modifier,
                                     quantity = damageBonusInstructions.quantity,
                                     faces = damageBonusInstructions.faces / 2,
                                 )
@@ -100,9 +96,9 @@ class SkillValueComputationUseCase(
                         Instruction.Word.Type.CHA -> sheet.charisma
                     }
                 }
-            } * instruction.sign
+            }
 
-            value.also { print(" ($instruction):$it") }
+            (value * instruction.sign).also { print("$it") }
         }.also { println() }
     }
 

composeApp/src/commonMain/kotlin/com/pixelized/desktop/lwa/parser/arithmetic/Instruction.kt

@@ -18,7 +18,14 @@ sealed class Instruction(
         }
 
         override fun toString(): String {
-            return "${sign.sign}${quantity}d${faces}"
+            return "${sign.sign}${
+                when (modifier) {
+                    Modifier.ADVANTAGE -> "a"
+                    Modifier.DISADVANTAGE -> "d"
+                    Modifier.EMPHASIS -> "e"
+                    null -> ""
+                }
+            }${quantity}d${faces}"
         }
     }