Game/Maps: Clean up instance handling.

- Rename Map::CanEnter to Map::CannotEnter. Return value changed from boolean (true means player can enter) to enum Map::EnterState (CAN_ENTER=0 means player can enter, any other value is a reason for deny).
- Move hack-y player error messages from within Map::CanEnter to the function calling CanEnter as appropriate (primarily WorldSession::HandleAreaTriggerOpcode).
- Modify WorldSession::HandleAreaTriggerOpcode to properly revive the player upon touching the portal leading to the instance they died in even if they are currently unable to zone in. Fixes and closes #15758.
- Modify Player::LoadFromDB to properly spawn players in the instance they logged off in if possible. Fixes and closes #15561.
- Modify permanent save behavior to be blizzlike: Players can always enter an instance they are saved to (assuming there are no map constraints against it), but get a homebind timer if the instance is already in use.

1 files changed, 70 insertions, 1 deletions

diff --git a/src/server/game/Handlers/MiscHandler.cpp b/src/server/game/Handlers/MiscHandler.cpp
index 6dcd3242a6c..345202dc329 100644
--- a/src/server/game/Handlers/MiscHandler.cpp
+++ b/src/server/game/Handlers/MiscHandler.cpp
@@ -866,8 +866,77 @@ void WorldSession::HandleAreaTriggerOpcode(WorldPacket& recvData)
     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->MapID, TRANSFER_ABORT_DIFFICULTY, player->GetDifficulty(entry->IsRaid()));
+                    break;
+                case Map::CANNOT_ENTER_NOT_IN_RAID:
+                    if (MapEntry const* entry = sMapStore.LookupEntry(at->target_mapId))
+                    {
+                        char const* mapName = entry->name[player->GetSession()->GetSessionDbcLocale()];
+                        TC_LOG_DEBUG("maps", "MAP: Player '%s' must be in a raid group to enter instance '%s'", player->GetName().c_str(), mapName);
+                        // probably there must be special opcode, because client has this string constant in GlobalStrings.lua
+                        player->GetSession()->SendAreaTriggerMessage(player->GetSession()->GetTrinityString(LANG_INSTANCE_RAID_GROUP_ONLY), mapName);
+                    }
+                    reviveAtTrigger = true;
+                    break;
+                case Map::CANNOT_ENTER_CORPSE_IN_DIFFERENT_INSTANCE:
+                {
+                    WorldPacket data(SMSG_CORPSE_NOT_IN_INSTANCE);
+                    player->GetSession()->SendPacket(&data);
+                    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->name[player->GetSession()->GetSessionDbcLocale()];
+                        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())