/*
 * This file is part of the AzerothCore Project. See AUTHORS file for Copyright information
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Affero General Public License as published by the
 * Free Software Foundation; either version 3 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "CreatureAI.h"
#include "AreaBoundary.h"
#include "Creature.h"
#include "CreatureAIImpl.h"
#include "CreatureGroups.h"
#include "CreatureTextMgr.h"
#include "GameObjectAI.h"
#include "Log.h"
#include "MapReference.h"
#include "Player.h"
#include "ScriptMgr.h"
#include "TemporarySummon.h"
#include "World.h"
#include "Vehicle.h"
#include "ZoneScript.h"
#include <functional>

//Disable CreatureAI when charmed
void CreatureAI::OnCharmed(bool /*apply*/)
{
    //me->IsAIEnabled = !apply;*/
    me->NeedChangeAI = true;
    me->IsAIEnabled = false;
}

AISpellInfoType* UnitAI::AISpellInfo;
AISpellInfoType* GetAISpellInfo(uint32 i) { return &CreatureAI::AISpellInfo[i]; }

/**
 * @brief Causes the creature to talk/say the text assigned to their entry in the `creature_text` database table.
 *
 * @param uint8 id Text ID from `creature_text`.
 * @param WorldObject target The target of the speech, in case it has elements such as $n, where the target's name will be referrenced.
 * @param Milliseconds delay Delay until the creature says the text line. Creatures will talk immediately by default.
 */
void CreatureAI::Talk(uint8 id, WorldObject const* target /*= nullptr*/, Milliseconds delay /*= 0s*/)
{
    if (delay > Seconds::zero())
    {
        ObjectGuid targetGuid;

        if (target)
            targetGuid = target->GetGUID();

        me->m_Events.AddEventAtOffset([this, id, targetGuid]()
        {
            // Target can be nullptr here, it will be handled inside the function.
            sCreatureTextMgr->SendChat(me, id, ObjectAccessor::GetUnit(*me, targetGuid));
        }, delay);
    }
    else
        sCreatureTextMgr->SendChat(me, id, target);
}

/**
 * @brief Returns the summoner creature/object, if the creature is a temporary summon.
 */
WorldObject* CreatureAI::GetSummoner() const
{
    if (TempSummon* summon = me->ToTempSummon())
        return summon->GetSummoner();

    return nullptr;
}

inline bool IsValidCombatTarget(Creature* source, Player* target)
{
    if (target->IsGameMaster())
    {
        return false;
    }

    if (!source->IsInWorld() || !target->IsInWorld())
    {
        return false;
    }

    if (!source->IsAlive() || !target->IsAlive())
    {
        return false;
    }

    if (!source->InSamePhase(target))
    {
        return false;
    }

    if (source->HasUnitState(UNIT_STATE_IN_FLIGHT) || target->HasUnitState(UNIT_STATE_IN_FLIGHT))
    {
        return false;
    }

    return true;
}

void CreatureAI::DoZoneInCombat(Creature* creature /*= nullptr*/, float maxRangeToNearestTarget /*= 250.0f*/)
{
    if (!creature)
    {
        creature = me;
    }

    if (creature->IsInEvadeMode())
    {
        return;
    }

    Map* map = creature->GetMap();
    if (!map->IsDungeon())                                  //use IsDungeon instead of Instanceable, in case battlegrounds will be instantiated
    {
        LOG_ERROR("entities.unit.ai", "DoZoneInCombat call for map {} that isn't a dungeon (creature entry = {})", map->GetId(), creature->IsCreature() ? creature->ToCreature()->GetEntry() : 0);
        return;
    }

    Map::PlayerList const& playerList = map->GetPlayers();
    if (playerList.IsEmpty())
    {
        return;
    }

    for (Map::PlayerList::const_iterator itr = playerList.begin(); itr != playerList.end(); ++itr)
    {
        if (Player* player = itr->GetSource())
        {
            if (!IsValidCombatTarget(creature, player))
            {
                continue;
            }

            if (!creature->IsWithinDistInMap(player, maxRangeToNearestTarget))
            {
                continue;
            }

            creature->SetInCombatWith(player);
            player->SetInCombatWith(creature);

            if (creature->CanHaveThreatList())
            {
                creature->AddThreat(player, 0.0f);
            }
        }
    }
}

// scripts does not take care about MoveInLineOfSight loops
// MoveInLineOfSight can be called inside another MoveInLineOfSight and cause stack overflow
void CreatureAI::MoveInLineOfSight_Safe(Unit* who)
{
    if (m_MoveInLineOfSight_locked)
    {
        return;
    }
    m_MoveInLineOfSight_locked = true;
    MoveInLineOfSight(who);
    m_MoveInLineOfSight_locked = false;
}

void CreatureAI::MoveInLineOfSight(Unit* who)
{
    if (me->IsEngaged())
        return;

    // pussywizard: civilian, non-combat pet or any other NOT HOSTILE TO ANYONE (!)
    if (me->IsMoveInLineOfSightDisabled())
        if (me->GetCreatureType() == CREATURE_TYPE_NON_COMBAT_PET ||      // nothing more to do, return
                !who->IsInCombat() ||                                         // if not in combat, nothing more to do
                !me->IsWithinDist(who, ATTACK_DISTANCE, true, false))                      // if in combat and in dist - neutral to all can actually assist other creatures
            return;

    if (me->HasReactState(REACT_AGGRESSIVE) && me->CanStartAttack(who))
        AttackStart(who);
}

// Distract creature, if player gets too close while stealthed/prowling
void CreatureAI::TriggerAlert(Unit const* who) const
{
    // If there's no target, or target isn't a player do nothing
    if (!who || !who->IsPlayer())
        return;
    // If this unit isn't an NPC, is already distracted, is in combat, is confused, stunned or fleeing, do nothing
    if (!me->IsCreature() || me->IsEngaged() || me->HasUnitState(UNIT_STATE_CONFUSED | UNIT_STATE_STUNNED | UNIT_STATE_FLEEING | UNIT_STATE_DISTRACTED))
        return;
    // Only alert for hostiles!
    if (me->IsCivilian() || me->HasReactState(REACT_PASSIVE) || !me->IsHostileTo(who) || !me->_IsTargetAcceptable(who))
        return;
    // Only alert if target is within line of sight
    if (!me->IsWithinLOSInMap(who))
        return;
    // Send alert sound (if any) for this creature
    me->SendAIReaction(AI_REACTION_ALERT);
    // Face the unit (stealthed player) and set distracted state for 5 seconds
    me->SetFacingTo(me->GetAngle(who->GetPositionX(), who->GetPositionY()));
    me->StopMoving();
    me->GetMotionMaster()->MoveDistract(5 * IN_MILLISECONDS);
}

void CreatureAI::EnterEvadeMode(EvadeReason why)
{
    if (!_EnterEvadeMode(why))
        return;

    LOG_DEBUG("entities.unit", "Creature {} enters evade mode.", me->GetEntry());

    if (!me->GetVehicle()) // otherwise me will be in evade mode forever
    {
        if (Unit* owner = me->GetCharmerOrOwner())
        {
            me->GetMotionMaster()->Clear(false);
            me->GetMotionMaster()->MoveFollow(owner, PET_FOLLOW_DIST, me->GetFollowAngle(), MOTION_SLOT_ACTIVE);
        }
        else
        {
            // Required to prevent attacking creatures that are evading and cause them to reenter combat
            // Does not apply to MoveFollow
            me->AddUnitState(UNIT_STATE_EVADE);
            me->GetMotionMaster()->MoveTargetedHome();
        }
    }

    Reset();
    if (me->IsVehicle()) // use the same sequence of addtoworld, aireset may remove all summons!
    {
        me->GetVehicleKit()->Reset(true);
    }

    sScriptMgr->OnUnitEnterEvadeMode(me, why);

    // despawn bosses at reset - only verified tbc/woltk bosses with this reset type
    CreatureTemplate const* cInfo = sObjectMgr->GetCreatureTemplate(me->GetEntry());
    if (cInfo && cInfo->HasFlagsExtra(CREATURE_FLAG_EXTRA_HARD_RESET))
    {
        me->DespawnOnEvade();
    }
}

/*void CreatureAI::AttackedBy(Unit* attacker)
{
    if (!me->GetVictim())
        AttackStart(attacker);
}*/

void CreatureAI::SetGazeOn(Unit* target)
{
    if (me->IsValidAttackTarget(target))
    {
        AttackStart(target);
        me->SetReactState(REACT_PASSIVE);
    }
}

bool CreatureAI::UpdateVictimWithGaze()
{
    if (!me->IsEngaged())
        return false;

    if (me->HasReactState(REACT_PASSIVE))
    {
        if (me->GetVictim())
            return true;
        else
            me->SetReactState(REACT_AGGRESSIVE);
    }

    if (Unit* victim = me->SelectVictim())
        AttackStart(victim);
    return me->GetVictim();
}

bool CreatureAI::UpdateVictim()
{
    if (!me->IsEngaged())
        return false;

    if (!me->HasReactState(REACT_PASSIVE))
    {
        if (Unit* victim = me->SelectVictim())
            AttackStart(victim);
        return me->GetVictim();
    }
    // xinef: if we have any victim, just return true
    else if (me->GetVictim() && me->GetExactDist(me->GetVictim()) < 30.0f)
        return true;
    else if (me->GetThreatMgr().isThreatListEmpty())
    {
        EnterEvadeMode();
        return false;
    }

    return true;
}

bool CreatureAI::_EnterEvadeMode(EvadeReason /*why*/)
{
    if (!me->IsAlive())
    {
        return false;
    }

    // don't remove vehicle auras, passengers aren't supposed to drop off the vehicle
    // don't remove clone caster on evade (to be verified)
    me->RemoveEvadeAuras();

    me->ClearComboPointHolders(); // Remove all combo points targeting this unit
    // sometimes bosses stuck in combat?
    me->GetThreatMgr().ClearAllThreat();
    me->CombatStop(true);
    me->LoadCreaturesAddon(true);
    me->SetLootRecipient(nullptr);
    me->ResetPlayerDamageReq();
    me->ClearLastLeashExtensionTimePtr();
    me->SetCannotReachTarget();

    if (ZoneScript* zoneScript = me->GetZoneScript() ? me->GetZoneScript() : (ZoneScript*)me->GetInstanceScript())
        zoneScript->OnCreatureEvade(me);

    if (me->IsInEvadeMode())
    {
        return false;
    }
    else if (CreatureGroup* formation = me->GetFormation())
    {
        formation->MemberEvaded(me);
    }

    if (TempSummon* summon = me->ToTempSummon())
    {
        if (WorldObject* summoner = summon->GetSummoner())
        {
            if (summoner->ToCreature() && summoner->ToCreature()->IsAIEnabled)
            {
                summoner->ToCreature()->AI()->SummonedCreatureEvade(me);
            }
            else if (summoner->ToGameObject() && summoner->ToGameObject()->AI())
            {
                summoner->ToGameObject()->AI()->SummonedCreatureEvade(me);
            }
        }
    }

    return true;
}

void CreatureAI::MoveCircleChecks()
{
    Unit *victim = me->GetVictim();

    if (
        !victim ||
        !me->IsFreeToMove() || me->HasUnitMovementFlag(MOVEMENTFLAG_ROOT) ||
        !me->IsWithinMeleeRange(victim) || me == victim->GetVictim()
    )
    {
        return;
    }

    /**
     *  optimization, disable circling movement for NPC vs NPC combat
     */
    if (!sWorld->getBoolConfig(CONFIG_CREATURE_REPOSITION_AGAINST_NPCS) && !victim->IsPlayer() && !victim->IsPet())
        return;

    me->GetMotionMaster()->MoveCircleTarget(me->GetVictim());
}

void CreatureAI::MoveBackwardsChecks()
{
    Unit *victim = me->GetVictim();

    if (!victim || !me->IsFreeToMove() || me->HasUnitMovementFlag(MOVEMENTFLAG_ROOT))
        return;

    /**
     *  optimization, disable backwards movement for NPC vs NPC combat
     */
    if (!sWorld->getBoolConfig(CONFIG_CREATURE_REPOSITION_AGAINST_NPCS) && !victim->IsPlayer() && !victim->IsPet())
    {
        return;
    }

    float moveDist = me->GetMeleeRange(victim) / 2;

    me->GetMotionMaster()->MoveBackwards(victim, moveDist);
}

int32 CreatureAI::VisualizeBoundary(uint32 duration, Unit* owner, bool fill, bool checkZ) const
{
    static constexpr float BOUNDARY_STEP = 5.0f;
    static constexpr uint32 BOUNDARY_VISUALIZE_CREATURE = 21659; // Floaty Flavor Eye
    static constexpr float BOUNDARY_VISUALIZE_CREATURE_SCALE = 0.25f;
    static constexpr uint32 BOUNDARY_MAX_SPAWNS = 8000;
    static constexpr float BOUNDARY_MAX_DISTANCE = MAX_SEARCHER_DISTANCE;

    float boundaryStep = fill && checkZ ? BOUNDARY_STEP * 2 : BOUNDARY_STEP;

    Position const boundaryDirections[6] = {
        {boundaryStep,  0,             0            },
        {-boundaryStep, 0,             0            },
        {0,             boundaryStep,  0            },
        {0,             -boundaryStep, 0            },
        {0,             0,             boundaryStep },
        {0,             0,             -boundaryStep}
    };

    if (!owner)
        return -1;

    if (!_boundary || _boundary->empty())
        return LANG_CREATURE_MOVEMENT_NOT_BOUNDED;

    Position startPosition = owner->GetPosition();
    if (!IsInBoundary(&startPosition)) // fall back to creature position
    {
        startPosition = me->GetPosition();
        if (!IsInBoundary(&startPosition)) // fall back to creature home position
        {
            startPosition = me->GetHomePosition();
            if (!IsInBoundary(&startPosition))
                return LANG_CREATURE_NO_INTERIOR_POINT_FOUND;
        }
    }

    // Helper to spawn visualization creature
    auto spawnVisualizationCreature = [owner, duration, checkZ](Position const& pos)
    {
        if (TempSummon* summon =
                owner->SummonCreature(BOUNDARY_VISUALIZE_CREATURE, pos, TEMPSUMMON_TIMED_DESPAWN, duration))
        {
            summon->SetObjectScale(BOUNDARY_VISUALIZE_CREATURE_SCALE);
            summon->SetUnitFlag(UNIT_FLAG_STUNNED);
            summon->SetImmuneToAll(true);
            summon->SetUnitFlag(UNIT_FLAG_NON_ATTACKABLE_2);
            if (!checkZ)
                summon->SetDisableGravity(false);
        }
    };

    struct PositionHash
    {
        std::size_t operator()(Position const& pos) const
        {
            // Convert to fixed precision coordinates.
            // We lose precision here, but we don't care about the exact position
            int32 x = int32(pos.m_positionX);
            int32 y = int32(pos.m_positionY);
            int32 z = int32(pos.m_positionZ);

            return std::hash<int32_t>()(x) ^ std::hash<int32_t>()(y) ^ std::hash<int32_t>()(z);
        }
    };

    std::unordered_set<Position, PositionHash> visited;
    std::queue<Position> queue;
    queue.push(startPosition);
    visited.insert(startPosition);
    uint8 maxDirections = checkZ ? 6 : 4;
    uint32 spawns = 0;

    while (!queue.empty())
    {
        Position currentPosition = queue.front();
        queue.pop();

        for (uint8 i = 0; i < maxDirections; ++i)
        {
            Position const& direction = boundaryDirections[i];
            Position nextPosition = currentPosition;
            nextPosition.RelocateOffset(direction);

            if (startPosition.GetExactDist(&nextPosition) > BOUNDARY_MAX_DISTANCE)
                break;

            if (visited.find(nextPosition) != visited.end())
                continue; // already visited

            visited.insert(nextPosition);

            bool isInBoundary = IsInBoundary(&nextPosition);

            if ((isInBoundary && fill) || !isInBoundary)
            {
                spawnVisualizationCreature(currentPosition);
                ++spawns;
                if (spawns > BOUNDARY_MAX_SPAWNS)
                    return LANG_CREATURE_MOVEMENT_MAYBE_UNBOUNDED;
            }

            if (isInBoundary)
                queue.push(nextPosition); // continue visiting
        }
    }
    return 0;
}

bool CreatureAI::IsInBoundary(Position const* who) const
{
    if (!_boundary)
        return true;

    if (!who)
        who = me;

    return (CreatureAI::IsInBounds(*_boundary, who) != _negateBoundary);
}

bool CreatureAI::IsInBounds(CreatureBoundary const& boundary, Position const* pos)
{
    for (AreaBoundary const* areaBoundary : boundary)
        if (!areaBoundary->IsWithinBoundary(pos))
            return false;

    return true;
}

bool CreatureAI::CheckInRoom()
{
    if (IsInBoundary())
        return true;
    else
    {
        EnterEvadeMode(EVADE_REASON_BOUNDARY);
        return false;
    }
}

void CreatureAI::SetBoundary(CreatureBoundary const* boundary, bool negateBoundaries /*= false*/)
{
    _boundary = boundary;
    _negateBoundary = negateBoundaries;
    me->DoImmediateBoundaryCheck();
}

Creature* CreatureAI::DoSummon(uint32 entry, const Position& pos, uint32 despawnTime, TempSummonType summonType)
{
    return me->SummonCreature(entry, pos, summonType, despawnTime);
}

Creature* CreatureAI::DoSummon(uint32 entry, WorldObject* obj, float radius, uint32 despawnTime, TempSummonType summonType)
{
    Position pos = obj->GetRandomNearPosition(radius);
    return me->SummonCreature(entry, pos, summonType, despawnTime);
}

Creature* CreatureAI::DoSummonFlyer(uint32 entry, WorldObject* obj, float flightZ, float radius, uint32 despawnTime, TempSummonType summonType)
{
    Position pos = obj->GetRandomNearPosition(radius);
    pos.m_positionZ += flightZ;
    return me->SummonCreature(entry, pos, summonType, despawnTime);
}