2 files changed, 47 insertions, 23 deletions

diff --git a/src/libsok/sok-ctx.c b/src/libsok/sok-ctx.c
index d9985d7..d19682a 100644
--- a/src/libsok/sok-ctx.c
+++ b/src/libsok/sok-ctx.c
@@ -145,6 +145,40 @@ LEVEL_PARSER_CBS = {
   .on_junk = on_junk,
 };
 
+static size_t
+pos_find(
+  const sok_pos_t pos,
+  const sok_pos_t * const set,
+  const size_t len
+) {
+  for (size_t i = 0; i < len; i++) {
+    if (POINTS_EQUAL(pos, set[i])) {
+      return i;
+    }
+  }
+
+  return len;
+}
+
+static size_t
+sok_ctx_count_goals_left(
+  sok_ctx_t * const ctx
+) {
+  const size_t num_boxes = ctx->level.num_boxes;
+  size_t r = 0;
+
+  for (size_t i = 0; i < ctx->level.num_goals; i++) {
+    r += pos_find(
+      ctx->level.goals[i],
+      ctx->boxes,
+      num_boxes
+    ) < num_boxes ? 0 : 1;
+  }
+
+  return r;
+}
+
+
 void
 sok_ctx_init(sok_ctx_t * const ctx, void *user_data) {
   memset(ctx, 0, sizeof(sok_ctx_t));
@@ -175,6 +209,9 @@ sok_ctx_set_level(
   ctx->home = ctx->level.home;
   memcpy(ctx->boxes, ctx->level.boxes, ctx->level.num_boxes * sizeof(sok_pos_t));
 
+  // count number of goals left
+  ctx->num_goals_left = sok_ctx_count_goals_left(ctx);
+
   // return success
   return true;
 }
@@ -191,21 +228,6 @@ tile_is_floor(
   );
 }
 
-static size_t
-pos_find(
-  const sok_pos_t pos,
-  const sok_pos_t * const set,
-  const size_t len
-) {
-  for (size_t i = 0; i < len; i++) {
-    if (POINTS_EQUAL(pos, set[i])) {
-      return i;
-    }
-  }
-
-  return len;
-}
-
 static bool
 tile_is_box(
   const sok_ctx_t * const ctx,
@@ -274,10 +296,15 @@ sok_ctx_move_box(
                box_ofs = pos_find(old_pos, ctx->boxes, num_boxes);
 
   if (box_ofs < num_boxes) {
+    // update box and goal count
     ctx->boxes[box_ofs] = new_pos;
+    ctx->num_goals_left = sok_ctx_count_goals_left(ctx);
+
+    // return success
     return true;
   }
 
+  // return failure
   return false;
 }
 
@@ -285,14 +312,7 @@ bool
 sok_ctx_is_done(
   sok_ctx_t * const ctx
 ) {
-  for (size_t i = 0; i < ctx->level.num_goals; i++) {
-    if (!tile_is_box(ctx, ctx->level.goals[i])) {
-      return false;
-    }
-  }
-
-  // return success
-  return true;
+  return ctx->num_goals_left == 0;
 }
 
 bool
diff --git a/src/libsok/sok.h b/src/libsok/sok.h
index 54e6c93..3e64afd 100644
--- a/src/libsok/sok.h
+++ b/src/libsok/sok.h
@@ -107,9 +107,13 @@ typedef struct {
 typedef struct {
   sok_level_t level;
 
+  // moves
   sok_move_t moves[SOK_CTX_MAX_MOVES];
   size_t num_moves;
 
+  // number of open goals
+  size_t num_goals_left;
+
   // player position
   sok_pos_t home;