From fc54775df980be7be4d568da30743e5dffa9c2e9 Mon Sep 17 00:00:00 2001
From: Marc Di Luzio <marc.diluzio@gmail.com>
Date: Sun, 7 Jun 2020 19:03:16 +0100
Subject: [PATCH] Stop movement into non-empty tiles

---
 pkg/game/world.go      | 15 ++++++++++-----
 pkg/game/world_test.go |  9 +++++++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/pkg/game/world.go b/pkg/game/world.go
index 1710a54..d0ccb5c 100644
--- a/pkg/game/world.go
+++ b/pkg/game/world.go
@@ -124,13 +124,18 @@ func (w *World) MoveRover(id uuid.UUID, bearing Direction) (RoverAttributes, err
 		// Calculate the full movement based on the bearing
 		move := bearing.Vector().Multiplied(distance)
 
-		// TODO: Verify there's nothing blocking this movement
+		// Try the new move position
+		newPos := i.Attributes.Pos.Added(move)
 
-		// Increment the position by the movement
-		i.Attributes.Pos.Add(move)
+		// Get the tile and verify it's empty
+		if tile, err := w.Atlas.GetTile(newPos); err != nil {
+			return i.Attributes, fmt.Errorf("couldn't get tile for new position")
+		} else if tile == TileEmpty {
+			// Perform the move
+			i.Attributes.Pos = newPos
+			w.Rovers[id] = i
+		}
 
-		// Set the rover values to the new ones
-		w.Rovers[id] = i
 		return i.Attributes, nil
 	} else {
 		return RoverAttributes{}, fmt.Errorf("no rover matching id")
diff --git a/pkg/game/world_test.go b/pkg/game/world_test.go
index b33662d..cb88d21 100644
--- a/pkg/game/world_test.go
+++ b/pkg/game/world_test.go
@@ -60,8 +60,8 @@ func TestWorld_GetSetMovePosition(t *testing.T) {
 	assert.NoError(t, err, "Failed to get rover attribs")
 
 	pos := Vector{
-		X: 1.0,
-		Y: 2.0,
+		X: 0.0,
+		Y: 0.0,
 	}
 
 	err = world.WarpRover(a, pos)
@@ -77,6 +77,11 @@ func TestWorld_GetSetMovePosition(t *testing.T) {
 	assert.NoError(t, err, "Failed to set position for rover")
 	pos.Add(Vector{0, attribs.Speed * duration}) // We should have move one unit of the speed north
 	assert.Equal(t, pos, newAttribs.Pos, "Failed to correctly move position for rover")
+
+	// Place a tile in front of the rover
+	assert.NoError(t, world.Atlas.SetTile(Vector{0, 2}, TileWall))
+	newAttribs, err = world.MoveRover(a, bearing)
+	assert.Equal(t, pos, newAttribs.Pos, "Failed to correctly not move position for rover into wall")
 }
 
 func TestWorld_RadarFromRover(t *testing.T) {