Add editor image badges and drag moves

src/ReactorMaintenance.Simulation/LevelEditor.cs

@@ -2,26 +2,106 @@
 
 public static class LevelEditor
 {
+    public sealed record MoveOccupantResult(bool Success, LevelState Level, string Reason)
+    {
+        public static MoveOccupantResult Succeeded(LevelState level)
+        {
+            return new(true, level, string.Empty);
+        }
+
+        public static MoveOccupantResult Failed(LevelState level, string reason)
+        {
+            return new(false, level, reason);
+        }
+    }
+
     public static LevelState MoveOccupant(LevelState level, GridPosition source, GridPosition destination)
     {
-        if (!level.InBounds(source) || !level.IsFloor(destination) || source == destination)
-            return level;
+        return TryMoveOccupant(level, source, destination).Level;
+    }
+
+    public static MoveOccupantResult TryMoveOccupant(LevelState level, GridPosition source, GridPosition destination)
+    {
+        if (!level.InBounds(source))
+            return MoveOccupantResult.Failed(level, "Drag start is outside the level.");
+
+        if (!level.InBounds(destination))
+            return MoveOccupantResult.Failed(level, "Drop target is outside the level.");
+
+        if (source == destination)
+            return MoveOccupantResult.Failed(level, "Drop target is the same cell.");
 
         var prop = level.GetProp(source);
-        if (prop.Type == EPropType.None)
-            return level.Robot.Position == source ? level with { Robot = level.Robot with { Position = destination } } : level;
+        if (prop.Type != EPropType.None)
+            return TryMoveProp(level, source, destination, prop);
+
+        var leak = level.Leaks.FirstOrDefault(leak => !leak.Repaired && (leak.AccessPosition == source || leak.UndergroundPosition == source));
+        if (leak is not null)
+            return TryMoveLeak(level, leak, destination);
+
+        return level.Robot.Position == source
+            ? TryMoveRobot(level, destination)
+            : MoveOccupantResult.Failed(level, "No movable robot, prop, source, or leak starts here.");
+    }
+
+    private static MoveOccupantResult TryMoveRobot(LevelState level, GridPosition destination)
+    {
+        if (!level.IsFloor(destination))
+            return MoveOccupantResult.Failed(level, "Robot destination must be a floor cell.");
+
+        return MoveOccupantResult.Succeeded(level with { Robot = level.Robot with { Position = destination } });
+    }
+
+    private static MoveOccupantResult TryMoveProp(LevelState level, GridPosition source, GridPosition destination, PropState prop)
+    {
+        if (!level.IsFloor(destination))
+            return MoveOccupantResult.Failed(level, "Prop destination must be a floor cell.");
 
         if (level.GetProp(destination).Type != EPropType.None)
-            return level;
+            return MoveOccupantResult.Failed(level, "Prop destination is already occupied.");
 
         var next = level.SetProp(source, new()).SetProp(destination, prop);
         if (prop.Type != EPropType.ReactorControl)
-            return next;
+            return MoveOccupantResult.Succeeded(next);
 
-        return next with {
+        return MoveOccupantResult.Succeeded(next with {
             Reactors = next.Reactors
                            .Select(reactor => reactor.ControlPosition == source ? reactor with { ControlPosition = destination } : reactor)
                            .ToArray()
+        });
+    }
+
+    private static MoveOccupantResult TryMoveLeak(LevelState level, LeakState leak, GridPosition destination)
+    {
+        if (leak.Carrier is ECarrierType.Fuel or ECarrierType.Coolant)
+        {
+            if (!level.IsFloor(destination))
+                return MoveOccupantResult.Failed(level, "Fuel and coolant leaks must move to a floor cell.");
+
+            var next = ClearLeak(level, leak)
+                .SetUnderground(leak.UndergroundPosition, leak.Carrier, new());
+            return MoveOccupantResult.Succeeded(SetLeak(next, destination, destination, leak.Carrier));
+        }
+
+        if (leak.Carrier == ECarrierType.Electricity)
+        {
+            if (!level.IsFloor(destination))
+                return MoveOccupantResult.Failed(level, "Electric leak destination must be an adjacent floor access cell.");
+
+            var undergroundPosition = leak.UndergroundPosition;
+            if (undergroundPosition.ManhattanDistance(destination) != 1)
+                return MoveOccupantResult.Failed(level, "Electric leak destination must stay adjacent to its underground wall cell.");
+
+            return MoveOccupantResult.Succeeded(SetLeak(ClearLeak(level, leak), undergroundPosition, destination, leak.Carrier));
+        }
+
+        return MoveOccupantResult.Failed(level, "Unsupported leak carrier.");
+    }
+
+    private static LevelState ClearLeak(LevelState level, LeakState leak)
+    {
+        return level with {
+            Leaks = level.Leaks.Where(candidate => candidate != leak).ToArray()
         };
     }
 
@@ -61,7 +141,7 @@ public static class LevelEditor
             EEditorTool.Flow => SetCarrierProp(level, position, EPropType.Flow, command.Carrier),
             EEditorTool.Consumer => SetFloorProp(level, position, new() { Type = EPropType.Consumer, SwitchState = EPropSwitchState.Enabled }),
             EEditorTool.Junction => SetFloorProp(level, position, new() { Type = EPropType.Junction }),
-            EEditorTool.Door => SetFloorProp(level, position, new() { Type = EPropType.Door }),
+            EEditorTool.Door => ToggleOrSetDoor(level, position),
             EEditorTool.AllSeeingEyeTerminal => SetFloorProp(level, position, new() { Type = EPropType.AllSeeingEyeTerminal }),
             EEditorTool.RemedySupply => SetFloorProp(level, position, new() { Type = EPropType.RemedySupply, RemedyType = command.RemedyType }),
             EEditorTool.ReactorControl => SetReactorControl(level, position),
@@ -129,6 +209,21 @@ public static class LevelEditor
         return level.IsFloor(position) ? level.SetProp(position, prop) : level;
     }
 
+    private static LevelState ToggleOrSetDoor(LevelState level, GridPosition position)
+    {
+        if (!level.IsFloor(position))
+            return level;
+
+        var prop = level.GetProp(position);
+        if (prop.Type == EPropType.Door)
+        {
+            var nextState = prop.DoorState == EDoorState.Open ? EDoorState.Closed : EDoorState.Open;
+            return level.SetProp(position, prop with { DoorState = nextState });
+        }
+
+        return level.SetProp(position, new() { Type = EPropType.Door, DoorState = EDoorState.Closed });
+    }
+
     private static LevelState SetReactorControl(LevelState level, GridPosition position)
     {
         if (!level.IsFloor(position))