Implement harvest worker AI

game/unit_ai.h

@@ -1,5 +1,51 @@
 #ifndef PIXELDEFENSE_UNIT_AI_H
 #define PIXELDEFENSE_UNIT_AI_H
 
+#include <flecs.h>
+
+#include "components.h"
+#include "unit_actions.h"
+
+typedef struct Game Game;
+
+typedef enum AIType {
+    AI_NONE,
+    AI_WORKER_BUILD,
+    AI_WORKER_HARVEST,
+    AI_COUNT,
+} AIType;
+
+
+typedef struct AIWorkerHarvest {
+    ResourceType resource;
+    ecs_entity_t target;
+    Position     targetPosition;
+} AIWorkerHarvest;
+
+typedef struct AIWorkerBuild {
+    ecs_entity_t buildTarget;
+} AIWorkerBuild;
+
+typedef struct UnitAI UnitAI;
+
+typedef void (*UnitAIFunc)(ecs_entity_t entity, UnitAI *ai, Game *game);
+
+typedef struct UnitAI {
+    AIType type;
+    union {
+        AIWorkerHarvest workerHarvest;
+        AIWorkerBuild   workerBuild;
+    } as;
+
+    Action *action;
+
+    // vtable
+    UnitAIFunc onSet;
+    UnitAIFunc onRemove;
+    UnitAIFunc onUpdate;
+} UnitAI;
+
+void updateUnitAI(ecs_entity_t entity, UnitAI *unitAI, Game *game);
+void setUnitAI(ecs_entity_t entity, Game *game, const UnitAI *unitAI);
 
 #endif //PIXELDEFENSE_UNIT_AI_H