Merge pull request #16110 from Treeston/3.3.5-instancerevive

Game/Maps: Clean up instance zone-in handling
(cherry picked from commit eb3dc8a4f064d89b78248a511bcf67f805ea3314)

13 files changed, 241 insertions, 141 deletions

diff --git a/sql/updates/world/2016_03_21_01_world_2015_12_27_instancerevive.sql b/sql/updates/world/2016_03_21_01_world_2015_12_27_instancerevive.sql
new file mode 100644
index 00000000000..3bee62963ef
--- /dev/null
+++ b/sql/updates/world/2016_03_21_01_world_2015_12_27_instancerevive.sql
@@ -0,0 +1,4 @@
+--
+DELETE FROM `trinity_string` WHERE `entry`=11014;
+INSERT INTO `trinity_string` (`entry`,`content_default`) VALUES
+(11014,"You are already locked to %s.");
diff --git a/src/server/game/Entities/Player/Player.cpp b/src/server/game/Entities/Player/Player.cpp
index a9b7aa12b6b..f30b4ac5c44 100644
--- a/src/server/game/Entities/Player/Player.cpp
+++ b/src/server/game/Entities/Player/Player.cpp
@@ -1558,7 +1558,7 @@ bool Player::TeleportTo(uint32 mapid, float x, float y, float z, float orientati
 
         // Check enter rights before map getting to avoid creating instance copy for player
         // this check not dependent from map instance copy and same for all instance copies of selected map
-        if (!sMapMgr->CanPlayerEnter(mapid, this, false))
+        if (sMapMgr->PlayerCannotEnter(mapid, this, false))
             return false;
 
         // Seamless teleport can happen only if cosmetic maps match
@@ -16634,7 +16634,7 @@ bool Player::LoadFromDB(ObjectGuid guid, SQLQueryHolder *holder)
 
     // NOW player must have valid map
     // load the player's map here if it's not already loaded
-    Map* map = sMapMgr->CreateMap(mapId, this);
+    Map* map = sMapMgr->CreateMap(mapId, this, instanceId);
     AreaTriggerStruct const* areaTrigger = nullptr;
     bool check = false;
 
@@ -16645,8 +16645,28 @@ bool Player::LoadFromDB(ObjectGuid guid, SQLQueryHolder *holder)
     }
     else if (map->IsDungeon()) // if map is dungeon...
     {
-        if (!((InstanceMap*)map)->CanEnter(this) || !CheckInstanceLoginValid(map)) // ... and can't enter map, then look for entry point.
+        if (Map::EnterState denyReason = ((InstanceMap*)map)->CannotEnter(this)) // ... and can't enter map, then look for entry point.
         {
+            switch (denyReason)
+            {
+                case Map::CANNOT_ENTER_DIFFICULTY_UNAVAILABLE:
+                    SendTransferAborted(map->GetId(), TRANSFER_ABORT_DIFFICULTY, map->GetDifficultyID());
+                    break;
+                case Map::CANNOT_ENTER_INSTANCE_BIND_MISMATCH:
+                    ChatHandler(GetSession()).PSendSysMessage(GetSession()->GetTrinityString(LANG_INSTANCE_BIND_MISMATCH), map->GetMapName());
+                    break;
+                case Map::CANNOT_ENTER_TOO_MANY_INSTANCES:
+                    SendTransferAborted(map->GetId(), TRANSFER_ABORT_TOO_MANY_INSTANCES);
+                    break;
+                case Map::CANNOT_ENTER_MAX_PLAYERS:
+                    SendTransferAborted(map->GetId(), TRANSFER_ABORT_MAX_PLAYERS);
+                    break;
+                case Map::CANNOT_ENTER_ZONE_IN_COMBAT:
+                    SendTransferAborted(map->GetId(), TRANSFER_ABORT_ZONE_IN_COMBAT);
+                    break;
+                default:
+                    break;
+            }
             areaTrigger = sObjectMgr->GetGoBackTrigger(mapId);
             check = true;
         }
@@ -16692,6 +16712,10 @@ bool Player::LoadFromDB(ObjectGuid guid, SQLQueryHolder *holder)
 
     SetMap(map);
 
+    // now that map position is determined, check instance validity
+    if (!CheckInstanceValidity(true) && !IsInstanceLoginGameMasterException())
+        m_InstanceValid = false;
+
     // randomize first save time in range [CONFIG_INTERVAL_SAVE] around [CONFIG_INTERVAL_SAVE]
     // this must help in case next save after mass player load after server startup
     m_nextSave = urand(m_nextSave / 2, m_nextSave * 3 / 2);
@@ -18387,37 +18411,68 @@ bool Player::Satisfy(AccessRequirement const* ar, uint32 target_map, bool report
     return true;
 }
 
-bool Player::CheckInstanceLoginValid(Map* map)
+bool Player::IsInstanceLoginGameMasterException() const
 {
-    if (!map->IsDungeon() || IsInstanceLoginGameMasterException())
+    if (CanBeGameMaster())
+    {
+        ChatHandler(GetSession()).SendSysMessage(LANG_INSTANCE_LOGIN_GAMEMASTER_EXCEPTION);
+        return true;
+    }
+    else
+        return false;
+}
+
+bool Player::CheckInstanceValidity(bool /*isLogin*/)
+{
+    // game masters' instances are always valid
+    if (IsGameMaster())
+        return true;
+
+    // non-instances are always valid
+    Map* map = GetMap();
+    if (!map || !map->IsDungeon())
         return true;
 
-    if (map->IsRaid())
+    // raid instances require the player to be in a raid group to be valid
+    if (map->IsRaid() && !sWorld->getBoolConfig(CONFIG_INSTANCE_IGNORE_RAID))
+        if (!GetGroup() || !GetGroup()->isRaidGroup())
+            return false;
+
+    if (Group* group = GetGroup())
     {
-        // cannot be in raid instance without a group
-        if (!GetGroup())
+        // check if player's group is bound to this instance
+        InstanceGroupBind* bind = group->GetBoundInstance(map->GetDifficultyID(), map->GetId());
+        if (!bind || !bind->save || bind->save->GetInstanceId() != map->GetInstanceId())
             return false;
+
+        Map::PlayerList const& players = map->GetPlayers();
+        if (!players.isEmpty())
+            for (Map::PlayerList::const_iterator it = players.begin(); it != players.end(); ++it)
+            {
+                if (Player* otherPlayer = it->GetSource())
+                {
+                    if (otherPlayer->IsGameMaster())
+                        continue;
+                    if (!otherPlayer->m_InstanceValid) // ignore players that currently have a homebind timer active
+                        continue;
+                    if (group != otherPlayer->GetGroup())
+                        return false;
+                }
+            }
     }
     else
     {
-        // cannot be in normal instance without a group and more players than 1 in instance
-        if (!GetGroup() && map->GetPlayersCountExceptGMs() > 1)
+        // instance is invalid if we are not grouped and there are other players
+        if (map->GetPlayersCountExceptGMs() > 1)
             return false;
-    }
-
-    // do checks for satisfy accessreqs, instance full, encounter in progress (raid), perm bind group != perm bind player
-    return sMapMgr->CanPlayerEnter(map->GetId(), this, true);
-}
 
-bool Player::IsInstanceLoginGameMasterException() const
-{
-    if (CanBeGameMaster())
-    {
-        ChatHandler(GetSession()).SendSysMessage(LANG_INSTANCE_LOGIN_GAMEMASTER_EXCEPTION);
-        return true;
+        // check if the player is bound to this instance
+        InstancePlayerBind* bind = GetBoundInstance(map->GetId(), map->GetDifficultyID());
+        if (!bind || !bind->save || bind->save->GetInstanceId() != map->GetInstanceId())
+            return false;
     }
-    else
-        return false;
+
+    return true;
 }
 
 bool Player::CheckInstanceCount(uint32 instanceId) const
diff --git a/src/server/game/Entities/Player/Player.h b/src/server/game/Entities/Player/Player.h
index 6dccc24290d..0679fc9167f 100644
--- a/src/server/game/Entities/Player/Player.h
+++ b/src/server/game/Entities/Player/Player.h
@@ -2355,7 +2355,7 @@ class Player : public Unit, public GridObject<Player>
         void SendRaidInfo();
         static void ConvertInstancesToGroup(Player* player, Group* group, bool switchLeader);
         bool Satisfy(AccessRequirement const* ar, uint32 target_map, bool report = false);
-        bool CheckInstanceLoginValid(Map* map);
+        bool CheckInstanceValidity(bool /*isLogin*/);
         bool CheckInstanceCount(uint32 instanceId) const;
         void AddInstanceEnterTime(uint32 instanceId, time_t enterTime);
 
diff --git a/src/server/game/Handlers/MiscHandler.cpp b/src/server/game/Handlers/MiscHandler.cpp
index b94b4ce838e..a9db9d52572 100644
--- a/src/server/game/Handlers/MiscHandler.cpp
+++ b/src/server/game/Handlers/MiscHandler.cpp
@@ -534,8 +534,69 @@ void WorldSession::HandleAreaTriggerOpcode(WorldPackets::Misc::AreaTrigger& pack
     bool teleported = false;
     if (player->GetMapId() != at->target_mapId)
     {
-        if (!sMapMgr->CanPlayerEnter(at->target_mapId, player, false))
+        if (Map::EnterState denyReason = sMapMgr->PlayerCannotEnter(at->target_mapId, player, false))
+        {
+            bool reviveAtTrigger = false; // should we revive the player if he is trying to enter the correct instance?
+            switch (denyReason)
+            {
+                case Map::CANNOT_ENTER_NO_ENTRY:
+                    TC_LOG_DEBUG("maps", "MAP: Player '%s' attempted to enter map with id %d which has no entry", player->GetName().c_str(), at->target_mapId);
+                    break;
+                case Map::CANNOT_ENTER_UNINSTANCED_DUNGEON:
+                    TC_LOG_DEBUG("maps", "MAP: Player '%s' attempted to enter dungeon map %d but no instance template was found", player->GetName().c_str(), at->target_mapId);
+                    break;
+                case Map::CANNOT_ENTER_DIFFICULTY_UNAVAILABLE:
+                    TC_LOG_DEBUG("maps", "MAP: Player '%s' attempted to enter instance map %d but the requested difficulty was not found", player->GetName().c_str(), at->target_mapId);
+                    if (MapEntry const* entry = sMapStore.LookupEntry(at->target_mapId))
+                        player->SendTransferAborted(entry->ID, TRANSFER_ABORT_DIFFICULTY, player->GetDifficultyID(entry));
+                    break;
+                case Map::CANNOT_ENTER_NOT_IN_RAID:
+                    TC_LOG_DEBUG("maps", "MAP: Player '%s' must be in a raid group to enter map %d", player->GetName().c_str(), at->target_mapId);
+                    player->SendRaidGroupOnlyMessage(RAID_GROUP_ERR_ONLY, 0);
+                    reviveAtTrigger = true;
+                    break;
+                case Map::CANNOT_ENTER_CORPSE_IN_DIFFERENT_INSTANCE:
+                    player->GetSession()->SendPacket(WorldPackets::Misc::AreaTriggerNoCorpse().Write());
+                    TC_LOG_DEBUG("maps", "MAP: Player '%s' does not have a corpse in instance map %d and cannot enter", player->GetName().c_str(), at->target_mapId);
+                    break;
+                case Map::CANNOT_ENTER_INSTANCE_BIND_MISMATCH:
+                    if (MapEntry const* entry = sMapStore.LookupEntry(at->target_mapId))
+                    {
+                        char const* mapName = entry->MapName_lang;
+                        TC_LOG_DEBUG("maps", "MAP: Player '%s' cannot enter instance map '%s' because their permanent bind is incompatible with their group's", player->GetName().c_str(), mapName);
+                        // is there a special opcode for this?
+                        // @todo figure out how to get player localized difficulty string (e.g. "10 player", "Heroic" etc)
+                        ChatHandler(player->GetSession()).PSendSysMessage(player->GetSession()->GetTrinityString(LANG_INSTANCE_BIND_MISMATCH), mapName);
+                    }
+                    reviveAtTrigger = true;
+                    break;
+                case Map::CANNOT_ENTER_TOO_MANY_INSTANCES:
+                    player->SendTransferAborted(at->target_mapId, TRANSFER_ABORT_TOO_MANY_INSTANCES);
+                    TC_LOG_DEBUG("maps", "MAP: Player '%s' cannot enter instance map %d because he has exceeded the maximum number of instances per hour.", player->GetName().c_str(), at->target_mapId);
+                    reviveAtTrigger = true;
+                    break;
+                case Map::CANNOT_ENTER_MAX_PLAYERS:
+                    player->SendTransferAborted(at->target_mapId, TRANSFER_ABORT_MAX_PLAYERS);
+                    reviveAtTrigger = true;
+                    break;
+                case Map::CANNOT_ENTER_ZONE_IN_COMBAT:
+                    player->SendTransferAborted(at->target_mapId, TRANSFER_ABORT_ZONE_IN_COMBAT);
+                    reviveAtTrigger = true;
+                    break;
+                default:
+                    break;
+            }
+
+            if (reviveAtTrigger) // check if the player is touching the areatrigger leading to the map his corpse is on
+                if (!player->IsAlive() && player->HasCorpse())
+                    if (player->GetCorpseLocation().GetMapId() == at->target_mapId)
+                    {
+                        player->ResurrectPlayer(0.5f);
+                        player->SpawnCorpseBones();
+                    }
+
             return;
+        }
 
         if (Group* group = player->GetGroup())
             if (group->isLFGGroup() && player->GetMap()->IsDungeon())
diff --git a/src/server/game/Handlers/MovementHandler.cpp b/src/server/game/Handlers/MovementHandler.cpp
index 3ab9f683dea..697060078bc 100644
--- a/src/server/game/Handlers/MovementHandler.cpp
+++ b/src/server/game/Handlers/MovementHandler.cpp
@@ -77,9 +77,9 @@ void WorldSession::HandleMoveWorldportAckOpcode()
     }
 
     // relocate the player to the teleport destination
-    // the CanEnter checks are done in TeleporTo but conditions may change
+    // the CannotEnter checks are done in TeleporTo but conditions may change
     // while the player is in transit, for example the map may get full
-    if (!newMap || !newMap->CanEnter(GetPlayer()))
+    if (!newMap || newMap->CannotEnter(GetPlayer()))
     {
         TC_LOG_ERROR("network", "Map %d (%s) could not be created for %s (%s), porting player to homebind", loc.GetMapId(), newMap ? newMap->GetMapName() : "Unknown", GetPlayer()->GetGUID().ToString().c_str(), GetPlayer()->GetName().c_str());
         GetPlayer()->TeleportTo(GetPlayer()->m_homebindMapId, GetPlayer()->m_homebindX, GetPlayer()->m_homebindY, GetPlayer()->m_homebindZ, GetPlayer()->GetOrientation());
@@ -157,19 +157,18 @@ void WorldSession::HandleMoveWorldportAckOpcode()
     }
 
     // resurrect character at enter into instance where his corpse exist after add to map
-    Corpse* corpse = GetPlayer()->GetMap()->GetCorpseByPlayer(GetPlayer()->GetGUID());
-    if (corpse && corpse->GetType() != CORPSE_BONES)
-    {
-        if (mEntry->IsDungeon())
+
+    if (mEntry->IsDungeon() && !GetPlayer()->IsAlive())
+        if (GetPlayer()->GetCorpseLocation().GetMapId() == mEntry->ID)
         {
             GetPlayer()->ResurrectPlayer(0.5f, false);
             GetPlayer()->SpawnCorpseBones();
         }
-    }
 
     bool allowMount = !mEntry->IsDungeon() || mEntry->IsBattlegroundOrArena();
     if (mInstance)
     {
+        // check if this instance has a reset time and send it to player if so
         Difficulty diff = GetPlayer()->GetDifficultyID(mEntry);
         if (MapDifficultyEntry const* mapDiff = GetMapDifficultyData(mEntry->ID, diff))
         {
@@ -182,6 +181,12 @@ void WorldSession::HandleMoveWorldportAckOpcode()
                 }
             }
         }
+
+        // check if instance is valid
+        if (!GetPlayer()->CheckInstanceValidity(false))
+            GetPlayer()->m_InstanceValid = false;
+
+        // instance mounting is handled in InstanceTemplate
         allowMount = mInstance->AllowMount;
     }
 
diff --git a/src/server/game/Instances/InstanceScript.h b/src/server/game/Instances/InstanceScript.h
index 56e97217e2a..02c9bfa408e 100644
--- a/src/server/game/Instances/InstanceScript.h
+++ b/src/server/game/Instances/InstanceScript.h
@@ -161,7 +161,7 @@ class InstanceScript : public ZoneScript
 
         virtual void Update(uint32 /*diff*/) { }
 
-        // Used by the map's CanEnter function.
+        // Used by the map's CannotEnter function.
         // This is to prevent players from entering during boss encounters.
         virtual bool IsEncounterInProgress() const;
 
diff --git a/src/server/game/Maps/Map.cpp b/src/server/game/Maps/Map.cpp
index 90c02b10477..3dbed19fc98 100644
--- a/src/server/game/Maps/Map.cpp
+++ b/src/server/game/Maps/Map.cpp
@@ -3062,62 +3062,38 @@ void InstanceMap::InitVisibilityDistance()
 /*
     Do map specific checks to see if the player can enter
 */
-bool InstanceMap::CanEnter(Player* player)
+Map::EnterState InstanceMap::CannotEnter(Player* player)
 {
     if (player->GetMapRef().getTarget() == this)
     {
-        TC_LOG_ERROR("maps", "InstanceMap::CanEnter - player %s(%s) already in map %d, %d, %d!", player->GetName().c_str(), player->GetGUID().ToString().c_str(), GetId(), GetInstanceId(), GetSpawnMode());
+        TC_LOG_ERROR("maps", "InstanceMap::CannotEnter - player %s(%s) already in map %d, %d, %d!", player->GetName().c_str(), player->GetGUID().ToString().c_str(), GetId(), GetInstanceId(), GetSpawnMode());
         ABORT();
-        return false;
+        return CANNOT_ENTER_ALREADY_IN_MAP;
     }
 
     // allow GM's to enter
     if (player->IsGameMaster())
-        return Map::CanEnter(player);
+        return Map::CannotEnter(player);
 
     // cannot enter if the instance is full (player cap), GMs don't count
     uint32 maxPlayers = GetMaxPlayers();
     if (GetPlayersCountExceptGMs() >= maxPlayers)
     {
         TC_LOG_WARN("maps", "MAP: Instance '%u' of map '%s' cannot have more than '%u' players. Player '%s' rejected", GetInstanceId(), GetMapName(), maxPlayers, player->GetName().c_str());
-        player->SendTransferAborted(GetId(), TRANSFER_ABORT_MAX_PLAYERS);
-        return false;
+        return CANNOT_ENTER_MAX_PLAYERS;
     }
 
-    // cannot enter while an encounter is in progress
-    // allow if just loading
+    // cannot enter while an encounter is in progress (unless this is a relog, in which case it is permitted)
     if (!player->IsLoading() && IsRaid() && GetInstanceScript() && GetInstanceScript()->IsEncounterInProgress())
-    {
-        player->SendTransferAborted(GetId(), TRANSFER_ABORT_ZONE_IN_COMBAT);
-        return false;
-    }
+        return CANNOT_ENTER_ZONE_IN_COMBAT;
 
-    // cannot enter if instance is in use by another party/soloer that have a
-    // permanent save in the same instance id
+    // cannot enter if player is permanent saved to a different instance id
+    if (InstancePlayerBind* playerBind = player->GetBoundInstance(GetId(), GetDifficultyID()))
+        if (playerBind->perm && playerBind->save)
+            if (playerBind->save->GetInstanceId() != GetInstanceId())
+                return CANNOT_ENTER_INSTANCE_BIND_MISMATCH;
 
-    PlayerList const &playerList = GetPlayers();
-
-    if (!playerList.isEmpty())
-        for (PlayerList::const_iterator i = playerList.begin(); i != playerList.end(); ++i)
-            if (Player* iPlayer = i->GetSource())
-            {
-                if (iPlayer->IsGameMaster()) // bypass GMs
-                    continue;
-                if (!player->GetGroup()) // player has not group and there is someone inside, deny entry
-                {
-                    player->SendTransferAborted(GetId(), TRANSFER_ABORT_MAX_PLAYERS);
-                    return false;
-                }
-                // player inside instance has no group or his groups is different to entering player's one, deny entry
-                if (!iPlayer->GetGroup() || iPlayer->GetGroup() != player->GetGroup())
-                {
-                    player->SendTransferAborted(GetId(), TRANSFER_ABORT_MAX_PLAYERS);
-                    return false;
-                }
-                break;
-            }
-
-    return Map::CanEnter(player);
+    return Map::CannotEnter(player);
 }
 
 /*
@@ -3474,21 +3450,21 @@ void BattlegroundMap::InitVisibilityDistance()
     m_VisibilityNotifyPeriod = World::GetVisibilityNotifyPeriodInBGArenas();
 }
 
-bool BattlegroundMap::CanEnter(Player* player)
+Map::EnterState BattlegroundMap::CannotEnter(Player* player)
 {
     if (player->GetMapRef().getTarget() == this)
     {
-        TC_LOG_ERROR("maps", "BGMap::CanEnter - %s is already in map!", player->GetGUID().ToString().c_str());
+        TC_LOG_ERROR("maps", "BGMap::CannotEnter - player %s is already in map!", player->GetGUID().ToString().c_str());
         ABORT();
-        return false;
+        return CANNOT_ENTER_ALREADY_IN_MAP;
     }
 
     if (player->GetBattlegroundId() != GetInstanceId())
-        return false;
+        return CANNOT_ENTER_INSTANCE_BIND_MISMATCH;
 
     // player number limit is checked in bgmgr, no need to do it here
 
-    return Map::CanEnter(player);
+    return Map::CannotEnter(player);
 }
 
 bool BattlegroundMap::AddPlayerToMap(Player* player, bool initPlayer /*= true*/)
diff --git a/src/server/game/Maps/Map.h b/src/server/game/Maps/Map.h
index 34aa00e4bf9..d51f05bc32a 100644
--- a/src/server/game/Maps/Map.h
+++ b/src/server/game/Maps/Map.h
@@ -365,7 +365,23 @@ class Map : public GridRefManager<NGridType>
 
         uint32 GetInstanceId() const { return i_InstanceId; }
         uint8 GetSpawnMode() const { return (i_spawnMode); }
-        virtual bool CanEnter(Player* /*player*/) { return true; }
+
+        enum EnterState
+        {
+            CAN_ENTER = 0,
+            CANNOT_ENTER_ALREADY_IN_MAP = 1, // Player is already in the map
+            CANNOT_ENTER_NO_ENTRY, // No map entry was found for the target map ID
+            CANNOT_ENTER_UNINSTANCED_DUNGEON, // No instance template was found for dungeon map
+            CANNOT_ENTER_DIFFICULTY_UNAVAILABLE, // Requested instance difficulty is not available for target map
+            CANNOT_ENTER_NOT_IN_RAID, // Target instance is a raid instance and the player is not in a raid group
+            CANNOT_ENTER_CORPSE_IN_DIFFERENT_INSTANCE, // Player is dead and their corpse is not in target instance
+            CANNOT_ENTER_INSTANCE_BIND_MISMATCH, // Player's permanent instance save is not compatible with their group's current instance bind
+            CANNOT_ENTER_TOO_MANY_INSTANCES, // Player has entered too many instances recently
+            CANNOT_ENTER_MAX_PLAYERS, // Target map already has the maximum number of players allowed
+            CANNOT_ENTER_ZONE_IN_COMBAT, // A boss encounter is currently in progress on the target map
+            CANNOT_ENTER_UNSPECIFIED_REASON
+        };
+        virtual EnterState CannotEnter(Player* /*player*/) { return CAN_ENTER; }
         const char* GetMapName() const;
 
         // have meaning only for instanced map (that have set real difficulty)
@@ -751,7 +767,7 @@ class InstanceMap : public Map
         InstanceScript* GetInstanceScript() { return i_data; }
         void PermBindAllPlayers(Player* source);
         void UnloadAll() override;
-        bool CanEnter(Player* player) override;
+        EnterState CannotEnter(Player* player) override;
         void SendResetWarnings(uint32 timeLeft) const;
         void SetResetSchedule(bool on);
 
@@ -774,7 +790,7 @@ class BattlegroundMap : public Map
 
         bool AddPlayerToMap(Player* player, bool initPlayer = true) override;
         void RemovePlayerFromMap(Player*, bool) override;
-        bool CanEnter(Player* player) override;
+        EnterState CannotEnter(Player* player) override;
         void SetUnload();
         //void UnloadAll(bool pForce);
         void RemoveAllPlayers() override;
diff --git a/src/server/game/Maps/MapInstanced.cpp b/src/server/game/Maps/MapInstanced.cpp
index 70623e1d7ab..4c065f836b9 100644
--- a/src/server/game/Maps/MapInstanced.cpp
+++ b/src/server/game/Maps/MapInstanced.cpp
@@ -111,12 +111,12 @@ void MapInstanced::UnloadAll()
 - create the instance if it's not created already
 - the player is not actually added to the instance (only in InstanceMap::Add)
 */
-Map* MapInstanced::CreateInstanceForPlayer(const uint32 mapId, Player* player)
+Map* MapInstanced::CreateInstanceForPlayer(const uint32 mapId, Player* player, uint32 loginInstanceId)
 {
     if (GetId() != mapId || !player)
-        return NULL;
+        return nullptr;
 
-    Map* map = NULL;
+    Map* map = nullptr;
     uint32 newInstanceId = 0;                       // instanceId of the resulting map
 
     if (IsBattlegroundOrArena())
@@ -125,7 +125,7 @@ Map* MapInstanced::CreateInstanceForPlayer(const uint32 mapId, Player* player)
         // the instance id is set in battlegroundid
         newInstanceId = player->GetBattlegroundId();
         if (!newInstanceId)
-            return NULL;
+            return nullptr;
 
         map = sMapMgr->FindMap(mapId, newInstanceId);
         if (!map)
@@ -135,20 +135,29 @@ Map* MapInstanced::CreateInstanceForPlayer(const uint32 mapId, Player* player)
             else
             {
                 player->TeleportToBGEntryPoint();
-                return NULL;
+                return nullptr;
             }
         }
     }
     else if (!IsGarrison())
     {
         InstancePlayerBind* pBind = player->GetBoundInstance(GetId(), player->GetDifficultyID(GetEntry()));
-        InstanceSave* pSave = pBind ? pBind->save : NULL;
+        InstanceSave* pSave = pBind ? pBind->save : nullptr;
 
-        // the player's permanent player bind is taken into consideration first
-        // then the player's group bind and finally the solo bind.
+        // priority:
+        // 1. player's permanent bind
+        // 2. player's current instance id if this is at login
+        // 3. group's current bind
+        // 4. player's current bind
         if (!pBind || !pBind->perm)
         {
-            InstanceGroupBind* groupBind = NULL;
+            if (loginInstanceId) // if the player has a saved instance id on login, we either use this instance or relocate him out (return null)
+            {
+                map = FindInstanceMap(loginInstanceId);
+                return (map && map->GetId() == GetId()) ? map : nullptr; // is this check necessary? or does MapInstanced only find instances of itself?
+            }
+
+            InstanceGroupBind* groupBind = nullptr;
             Group* group = player->GetGroup();
             // use the player's difficulty setting (it may not be the same as the group's)
             if (group)
@@ -288,8 +297,8 @@ bool MapInstanced::DestroyInstance(InstancedMaps::iterator &itr)
     return true;
 }
 
-bool MapInstanced::CanEnter(Player* /*player*/)
+Map::EnterState MapInstanced::CannotEnter(Player* /*player*/)
 {
     //ABORT();
-    return true;
+    return CAN_ENTER;
 }
diff --git a/src/server/game/Maps/MapInstanced.h b/src/server/game/Maps/MapInstanced.h
index f0d185bd796..4fb334cb0ce 100644
--- a/src/server/game/Maps/MapInstanced.h
+++ b/src/server/game/Maps/MapInstanced.h
@@ -39,13 +39,13 @@ class MapInstanced : public Map
         void DelayedUpdate(const uint32 diff) override;
         //void RelocationNotify();
         void UnloadAll() override;
-        bool CanEnter(Player* player) override;
+        EnterState CannotEnter(Player* /*player*/) override;
 
-        Map* CreateInstanceForPlayer(const uint32 mapId, Player* player);
+        Map* CreateInstanceForPlayer(const uint32 mapId, Player* player, uint32 loginInstanceId=0);
         Map* FindInstanceMap(uint32 instanceId) const
         {
             InstancedMaps::const_iterator i = m_InstancedMaps.find(instanceId);
-            return(i == m_InstancedMaps.end() ? NULL : i->second);
+            return(i == m_InstancedMaps.end() ? nullptr : i->second);
         }
         bool DestroyInstance(InstancedMaps::iterator &itr);
 
diff --git a/src/server/game/Maps/MapManager.cpp b/src/server/game/Maps/MapManager.cpp
index 81302671762..184af8fc360 100644
--- a/src/server/game/Maps/MapManager.cpp
+++ b/src/server/game/Maps/MapManager.cpp
@@ -103,12 +103,12 @@ Map* MapManager::FindBaseNonInstanceMap(uint32 mapId) const
     return map;
 }
 
-Map* MapManager::CreateMap(uint32 id, Player* player)
+Map* MapManager::CreateMap(uint32 id, Player* player, uint32 loginInstanceId)
 {
     Map* m = CreateBaseMap(id);
 
     if (m && m->Instanceable())
-        m = ((MapInstanced*)m)->CreateInstanceForPlayer(id, player);
+        m = ((MapInstanced*)m)->CreateInstanceForPlayer(id, player, loginInstanceId);
 
     return m;
 }
@@ -125,47 +125,36 @@ Map* MapManager::FindMap(uint32 mapid, uint32 instanceId) const
     return ((MapInstanced*)map)->FindInstanceMap(instanceId);
 }
 
-bool MapManager::CanPlayerEnter(uint32 mapid, Player* player, bool loginCheck)
+Map::EnterState MapManager::PlayerCannotEnter(uint32 mapid, Player* player, bool loginCheck)
 {
     MapEntry const* entry = sMapStore.LookupEntry(mapid);
     if (!entry)
-        return false;
+        return Map::CANNOT_ENTER_NO_ENTRY;
 
     if (!entry->IsDungeon())
-        return true;
+        return Map::CAN_ENTER;
 
     InstanceTemplate const* instance = sObjectMgr->GetInstanceTemplate(mapid);
     if (!instance)
-        return false;
+        return Map::CANNOT_ENTER_UNINSTANCED_DUNGEON;
 
     Difficulty targetDifficulty, requestedDifficulty;
     targetDifficulty = requestedDifficulty = player->GetDifficultyID(entry);
     // Get the highest available difficulty if current setting is higher than the instance allows
     MapDifficultyEntry const* mapDiff = GetDownscaledMapDifficultyData(entry->ID, targetDifficulty);
     if (!mapDiff)
-    {
-        player->SendTransferAborted(mapid, TRANSFER_ABORT_DIFFICULTY, requestedDifficulty);
-        return false;
-    }
+        return Map::CANNOT_ENTER_DIFFICULTY_UNAVAILABLE;
 
     //Bypass checks for GMs
     if (player->IsGameMaster())
-        return true;
+        return Map::CAN_ENTER;
 
     char const* mapName = entry->MapName_lang;
 
     Group* group = player->GetGroup();
-    if (entry->IsRaid())
-    {
-        // can only enter in a raid group
+    if (entry->IsRaid()) // can only enter in a raid group
         if ((!group || !group->isRaidGroup()) && !sWorld->getBoolConfig(CONFIG_INSTANCE_IGNORE_RAID))
-        {
-            /// @todo this is not a good place to send the message
-            player->SendRaidGroupOnlyMessage(RAID_GROUP_ERR_ONLY, 0);
-            TC_LOG_DEBUG("maps", "MAP: Player '%s' must be in a raid group to enter instance '%s'", player->GetName().c_str(), mapName);
-            return false;
-        }
-    }
+            return Map::CANNOT_ENTER_NOT_IN_RAID;
 
     if (!player->IsAlive())
     {
@@ -183,12 +172,7 @@ bool MapManager::CanPlayerEnter(uint32 mapid, Player* player, bool loginCheck)
             } while (corpseMap);
 
             if (!corpseMap)
-            {
-                WorldPackets::Misc::AreaTriggerNoCorpse packet;
-                player->GetSession()->SendPacket(packet.Write());
-                TC_LOG_DEBUG("maps", "MAP: Player '%s' does not have a corpse in instance '%s' and cannot enter.", player->GetName().c_str(), mapName);
-                return false;
-            }
+                return Map::CANNOT_ENTER_CORPSE_IN_DIFFERENT_INSTANCE;
 
             TC_LOG_DEBUG("maps", "MAP: Player '%s' has corpse in instance '%s' and can enter.", player->GetName().c_str(), mapName);
         }
@@ -197,23 +181,13 @@ bool MapManager::CanPlayerEnter(uint32 mapid, Player* player, bool loginCheck)
     }
 
     //Get instance where player's group is bound & its map
-    if (group)
+    if (!loginCheck && group)
     {
         InstanceGroupBind* boundInstance = group->GetBoundInstance(entry);
         if (boundInstance && boundInstance->save)
             if (Map* boundMap = sMapMgr->FindMap(mapid, boundInstance->save->GetInstanceId()))
-                if (!loginCheck && !boundMap->CanEnter(player))
-                    return false;
-            /*
-                This check has to be moved to InstanceMap::CanEnter()
-                // Player permanently bounded to different instance than groups one
-                InstancePlayerBind* playerBoundedInstance = player->GetBoundInstance(mapid, player->GetDifficultyID(entry));
-                if (playerBoundedInstance && playerBoundedInstance->perm && playerBoundedInstance->save &&
-                    boundedInstance->save->GetInstanceId() != playerBoundedInstance->save->GetInstanceId())
-                {
-                    /// @todo send some kind of error message to the player
-                    return false;
-                }*/
+                if (Map::EnterState denyReason = boundMap->CannotEnter(player))
+                    return denyReason;
     }
 
     // players are only allowed to enter 5 instances per hour
@@ -225,14 +199,14 @@ bool MapManager::CanPlayerEnter(uint32 mapid, Player* player, bool loginCheck)
 
         // instanceId can never be 0 - will not be found
         if (!player->CheckInstanceCount(instanceIdToCheck) && !player->isDead())
-        {
-            player->SendTransferAborted(mapid, TRANSFER_ABORT_TOO_MANY_INSTANCES);
-            return false;
-        }
+            return Map::CANNOT_ENTER_TOO_MANY_INSTANCES;
     }
 
     //Other requirements
-    return player->Satisfy(sObjectMgr->GetAccessRequirement(mapid, targetDifficulty), mapid, true);
+    if (player->Satisfy(sObjectMgr->GetAccessRequirement(mapid, targetDifficulty), mapid, true))
+        return Map::CAN_ENTER;
+    else
+        return Map::CANNOT_ENTER_UNSPECIFIED_REASON;
 }
 
 void MapManager::Update(uint32 diff)
diff --git a/src/server/game/Maps/MapManager.h b/src/server/game/Maps/MapManager.h
index 24cbbf4ef4d..5d679cbe4d9 100644
--- a/src/server/game/Maps/MapManager.h
+++ b/src/server/game/Maps/MapManager.h
@@ -35,7 +35,7 @@ class MapManager
 
         Map* CreateBaseMap(uint32 mapId);
         Map* FindBaseNonInstanceMap(uint32 mapId) const;
-        Map* CreateMap(uint32 mapId, Player* player);
+        Map* CreateMap(uint32 mapId, Player* player, uint32 loginInstanceId=0);
         Map* FindMap(uint32 mapId, uint32 instanceId) const;
 
         uint32 GetAreaId(uint32 mapid, float x, float y, float z) const
@@ -102,7 +102,7 @@ class MapManager
 
         void DoDelayedMovesAndRemoves();
 
-        bool CanPlayerEnter(uint32 mapid, Player* player, bool loginCheck = false);
+        Map::EnterState PlayerCannotEnter(uint32 mapid, Player* player, bool loginCheck = false);
         void InitializeVisibilityDistanceInfo();
 
         /* statistics */
diff --git a/src/server/game/Miscellaneous/Language.h b/src/server/game/Miscellaneous/Language.h
index 76d7a1380bf..4ca67fbadfc 100644
--- a/src/server/game/Miscellaneous/Language.h
+++ b/src/server/game/Miscellaneous/Language.h
@@ -1212,8 +1212,8 @@ enum TrinityStrings
 
     LANG_NPCINFO_INHABIT_TYPE                     = 11008,
     LANG_NPCINFO_FLAGS_EXTRA                      = 11009,
+    LANG_INSTANCE_LOGIN_GAMEMASTER_EXCEPTION      = 11010,
 
-    LANG_INSTANCE_LOGIN_GAMEMASTER_EXCEPTION      = 11010
-
+    LANG_INSTANCE_BIND_MISMATCH                   = 11014
 };
 #endif