From bd6adcc15773b4ce9d6144954379a45a5563ecb0 Mon Sep 17 00:00:00 2001
From: sippeangelo <holmberg.simon@gmail.com>
Date: Wed, 16 Dec 2015 12:05:31 +0100
Subject: [PATCH] Added SetParent to World

---
 include/Engine/Core/World.h |  3 +++
 src/Engine/Core/World.cpp   | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/Engine/Core/World.h b/include/Engine/Core/World.h
index da31d369..92378816 100644
--- a/include/Engine/Core/World.h
+++ b/include/Engine/Core/World.h
@@ -31,6 +31,8 @@ public:
     const ComponentPool* GetComponents(std::string componentType);
     // Get entity parent
     EntityID GetParent(EntityID entity);
+    // Change the parent of an entity
+    void SetParent(EntityID entity, EntityID parent);
     // Get all component pools
     const std::unordered_map<std::string, ComponentPool*>& GetComponentPools() const { return m_ComponentPools; }
     // Get the entity children map
@@ -40,6 +42,7 @@ private:
     EntityID m_CurrentEntityID = 1;
 
     std::unordered_map<EntityID, EntityID> m_EntityParents;
+    // TODO: This should be a more effective structure
     std::unordered_multimap<EntityID, EntityID> m_EntityChildren;
     std::unordered_map<std::string, ComponentPool*> m_ComponentPools;
 
diff --git a/src/Engine/Core/World.cpp b/src/Engine/Core/World.cpp
index 7ee5e6a7..5443d388 100644
--- a/src/Engine/Core/World.cpp
+++ b/src/Engine/Core/World.cpp
@@ -99,6 +99,22 @@ EntityID World::GetParent(EntityID entity)
     return m_EntityParents.at(entity);
 }
 
+
+void World::SetParent(EntityID entity, EntityID parent)
+{
+    EntityID lastParent = m_EntityParents.at(entity);
+    auto parentChildren = m_EntityChildren.equal_range(lastParent);
+    for (auto it = parentChildren.first; it != parentChildren.second; it++) {
+        if (it->second == entity) {
+            m_EntityChildren.erase(it);
+            break;
+        }
+    }
+
+    m_EntityParents[entity] = parent;
+    m_EntityChildren.insert(std::make_pair(parent, entity));
+}
+
 EntityID World::generateEntityID()
 {
     // TODO: Make EntityID generation smarter