Fix: Dismount cleanup (mod-playerbots#2413)

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DESIGN PHILOSOPHY: We prioritize STABILITY, PERFORMANCE, AND
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## Pull Request Description
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Cleans some stale flight flags, and gets rid of the parachute given in
forced flight dismount. Refactors some dismount code, and get rid of the
unused mountData parameter in CalculateMasterMountSpeed as well

`MOVEMENTFLAG_WATERWALKING` was removed because it might've been added
to protect MOVEMENTFLAG_CAN_FLY, but if the bot remounts over water,
MOVEMENTFLAG_CAN_FLY would be reapplied anyway. However if it has a
function that I missed, we can re-add it.

## Feature Evaluation
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- Describe the **processing cost** when this logic executes across many
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Feature is currently at minimum cost.


## How to Test the Changes
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1. As GM hover high above Dalaran, but not high enough that you are
outside the resting zone.
2. .summon some lvl +70 bots until you get some that are on a flying
mount.
3. Watch as they lose their mount after 10 seconds, and be given a
parachute as they fall.
4. When they reach the ground, they should be stuck with a parachute
forever, and they shouldn't be stuck hovering just above the ground
forever.


## Impact Assessment
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tick) can help you here. -->
- Does this change increase per-bot/per-tick processing or risk scaling
poorly with thousands of bots?
    - - [x] No, not at all
    - - [ ] Minimal impact (**explain below**)
    - - [ ] Moderate impact (**explain below**)



- Does this change modify default bot behavior?
    - - [x] No
    - - [ ] Yes (**explain why**)



- Does this change add new decision branches or increase maintenance
complexity?
    - - [ ] No
    - - [x] Yes (**explain below**)
Checks if bot has `HasFeatherFallAura` to remove any stale flight flags.


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## Final Checklist

- - [x] Stability is not compromised.
- - [x] Performance impact is understood, tested, and acceptable.
- - [x] Added logic complexity is justified and explained.
- - [x] Any new bot dialogue lines are translated.
- - [x] Documentation updated if needed (Conf comments, WiKi commands).

## Notes for Reviewers
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Comment paragraph might be verbose, but worth it for whomever is looking
at the code years from now trying to figure out why bots need special
treatment with dismounting anyway.

Author: NoxMax

src/Ai/Base/Actions/CheckMountStateAction.cpp

@@ -17,6 +17,7 @@
 #include "SpellAuraEffects.h"
 
 static constexpr uint32 SPELL_COLD_WEATHER_FLYING = 54197;
+static constexpr float PARACHUTE_LAND_THRESHOLD = 15.0f;
 
 // Define the static map / init bool for caching bot preferred mount data globally
 std::unordered_map<uint32, PreferredMountCache> CheckMountStateAction::mountCache;
@@ -61,6 +62,21 @@ MountData CollectMountData(const Player* bot)
 
 bool CheckMountStateAction::Execute(Event /*event*/)
 {
+    // Forced flight dismount:
+    // Bots get stale flight movement flags after a forced dismount (e.g: Dalaran) because the post landing dismount cleanup
+    // needs MSG_MOVE_FALL_LAND (a client opcode) and client movement packets. The stale flags cause the bot to be stuck with
+    // the parachute, or even keep the bot hovering indefinitely and block MMAP routing.
+    // Note: Without MSG_MOVE_FALL_LAND, HandleFall doesn't trigger, meaning bots don't get fall damage in forced dismounts anyway,
+    // so the parachute usage here is more of an immersion feature.
+    if (bot->HasFeatherFallAura())
+    {
+        float floorZ = bot->GetMapHeight(bot->GetPositionX(), bot->GetPositionY(), bot->GetPositionZ());
+        if (floorZ != INVALID_HEIGHT && floorZ != VMAP_INVALID_HEIGHT_VALUE &&
+            bot->GetPositionZ() - floorZ <= PARACHUTE_LAND_THRESHOLD)
+            bot->RemoveAurasByType(SPELL_AURA_FEATHER_FALL);
+    }
+    ClearStaleFlightFlags();
+
     // Determine if there are no attackers
     bool noAttackers = !AI_VALUE2(bool, "combat", "self target") || !AI_VALUE(uint8, "attacker count");
     bool enemy = AI_VALUE(Unit*, "enemy player target");
@@ -204,7 +220,7 @@ bool CheckMountStateAction::Mount()
     // Get bot mount data
     MountData mountData = CollectMountData(bot);
     int32 masterMountType = GetMountType(master);
-    int32 masterSpeed = CalculateMasterMountSpeed(master, mountData);
+    int32 masterSpeed = CalculateMasterMountSpeed(master);
 
     // Try shapeshift
     if (TryForms(master, masterMountType, masterSpeed))
@@ -234,14 +250,17 @@ void CheckMountStateAction::Dismount()
     WorldPacket emptyPacket;
     bot->GetSession()->HandleCancelMountAuraOpcode(emptyPacket);
 
-    bool const wantsFly = bot->HasIncreaseMountedFlightSpeedAura() || bot->HasFlyAura();
-    bool const isWaterWalking = bot->HasUnitMovementFlag(MOVEMENTFLAG_WATERWALKING);
-    bool const isFlying = bot->HasUnitMovementFlag(MOVEMENTFLAG_FLYING);
-    bool const hasGravityDisabled = bot->HasUnitMovementFlag(MOVEMENTFLAG_DISABLE_GRAVITY);
-    if (!wantsFly && !isWaterWalking && (isFlying || hasGravityDisabled))
+    ClearStaleFlightFlags();
+}
+
+void CheckMountStateAction::ClearStaleFlightFlags()
+{
+    if (bot->HasIncreaseMountedFlightSpeedAura() || bot->HasFlyAura())
+        return;
+
+    if (bot->HasUnitMovementFlag(MOVEMENTFLAG_FLYING | MOVEMENTFLAG_DISABLE_GRAVITY))
     {
-        bot->RemoveUnitMovementFlag(
-            MOVEMENTFLAG_FLYING | MOVEMENTFLAG_CAN_FLY | MOVEMENTFLAG_DISABLE_GRAVITY);
+        bot->RemoveUnitMovementFlag(MOVEMENTFLAG_FLYING | MOVEMENTFLAG_DISABLE_GRAVITY | MOVEMENTFLAG_CAN_FLY);
         if (!bot->IsRooted())
             bot->SendMovementFlagUpdate();
     }
@@ -490,7 +509,7 @@ static bool BotCanUseFlyingMount(Player const* bot)
     return true;
 }
 
-int32 CheckMountStateAction::CalculateMasterMountSpeed(Player* master, const MountData& mountData) const
+int32 CheckMountStateAction::CalculateMasterMountSpeed(Player* master) const
 {
     // Check riding skill and level requirements
     int32 ridingSkill = bot->GetPureSkillValue(SKILL_RIDING);

src/Ai/Base/Actions/CheckMountStateAction.h

@@ -53,9 +53,10 @@ class CheckMountStateAction : public UseItemAction
     float CalculateDismountDistance() const;
     float CalculateMountDistance() const;
     void Dismount();
+    void ClearStaleFlightFlags();
     bool ShouldFollowMasterMountState(Player* master, bool noAttackers, bool shouldMount) const;
     bool ShouldDismountForMaster(Player* master) const;
-    int32 CalculateMasterMountSpeed(Player* master, const MountData& mountData) const;
+    int32 CalculateMasterMountSpeed(Player* master) const;
     bool CheckForSwiftMount() const;
     std::map<uint32, std::map<int32, std::vector<uint32>>> GetAllMountSpells() const;
     bool TryForms(Player* master, int32 masterMountType, int32 masterSpeed) const;