#include "combat.hpp"

#include <components/misc/rng.hpp>
#include <components/settings/settings.hpp>

#include <components/sceneutil/positionattitudetransform.hpp>

#include "../mwbase/environment.hpp"
#include "../mwbase/world.hpp"
#include "../mwbase/mechanicsmanager.hpp"
#include "../mwbase/soundmanager.hpp"
#include "../mwbase/windowmanager.hpp"

#include "../mwworld/class.hpp"
#include "../mwworld/inventorystore.hpp"
#include "../mwworld/esmstore.hpp"

#include "npcstats.hpp"
#include "movement.hpp"
#include "spellcasting.hpp"
#include "spellresistance.hpp"
#include "difficultyscaling.hpp"
#include "actorutil.hpp"
#include "pathfinding.hpp"

namespace
{

float signedAngleRadians (const osg::Vec3f& v1, const osg::Vec3f& v2, const osg::Vec3f& normal)
{
    return std::atan2((normal * (v1 ^ v2)), (v1 * v2));
}

}

namespace MWMechanics
{

    bool applyOnStrikeEnchantment(const MWWorld::Ptr& attacker, const MWWorld::Ptr& victim, const MWWorld::Ptr& object, const osg::Vec3f& hitPosition, const bool fromProjectile)
    {
        std::string enchantmentName = !object.isEmpty() ? object.getClass().getEnchantment(object) : "";
        if (!enchantmentName.empty())
        {
            const ESM::Enchantment* enchantment = MWBase::Environment::get().getWorld()->getStore().get<ESM::Enchantment>().find(
                        enchantmentName);
            if (enchantment->mData.mType == ESM::Enchantment::WhenStrikes)
            {
                MWMechanics::CastSpell cast(attacker, victim, fromProjectile);
                cast.mHitPosition = hitPosition;
                cast.cast(object, false);
                return true;
            }
        }
        return false;
    }

    bool blockMeleeAttack(const MWWorld::Ptr &attacker, const MWWorld::Ptr &blocker, const MWWorld::Ptr &weapon, float damage, float attackStrength)
    {
        if (!blocker.getClass().hasInventoryStore(blocker))
            return false;

        MWMechanics::CreatureStats& blockerStats = blocker.getClass().getCreatureStats(blocker);

        if (blockerStats.getKnockedDown() // Used for both knockout or knockdown
                || blockerStats.getHitRecovery()
                || blockerStats.isParalyzed())
            return false;

        if (!MWBase::Environment::get().getMechanicsManager()->isReadyToBlock(blocker))
            return false;

        MWWorld::InventoryStore& inv = blocker.getClass().getInventoryStore(blocker);
        MWWorld::ContainerStoreIterator shield = inv.getSlot(MWWorld::InventoryStore::Slot_CarriedLeft);
        if (shield == inv.end() || shield->getTypeName() != typeid(ESM::Armor).name())
            return false;

        if (!blocker.getRefData().getBaseNode())
            return false; // shouldn't happen

        float angleDegrees = osg::RadiansToDegrees(
                    signedAngleRadians (
                    (attacker.getRefData().getPosition().asVec3() - blocker.getRefData().getPosition().asVec3()),
                    blocker.getRefData().getBaseNode()->getAttitude() * osg::Vec3f(0,1,0),
                    osg::Vec3f(0,0,1)));

        const MWWorld::Store<ESM::GameSetting>& gmst = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>();
        if (angleDegrees < gmst.find("fCombatBlockLeftAngle")->mValue.getFloat())
            return false;
        if (angleDegrees > gmst.find("fCombatBlockRightAngle")->mValue.getFloat())
            return false;

        MWMechanics::CreatureStats& attackerStats = attacker.getClass().getCreatureStats(attacker);

        float blockTerm = blocker.getClass().getSkill(blocker, ESM::Skill::Block) + 0.2f * blockerStats.getAttribute(ESM::Attribute::Agility).getModified()
            + 0.1f * blockerStats.getAttribute(ESM::Attribute::Luck).getModified();
        float enemySwing = attackStrength;
        float swingTerm = enemySwing * gmst.find("fSwingBlockMult")->mValue.getFloat() + gmst.find("fSwingBlockBase")->mValue.getFloat();

        float blockerTerm = blockTerm * swingTerm;
        if (blocker.getClass().getMovementSettings(blocker).mPosition[1] <= 0)
            blockerTerm *= gmst.find("fBlockStillBonus")->mValue.getFloat();
        blockerTerm *= blockerStats.getFatigueTerm();

        float attackerSkill = 0;
        if (weapon.isEmpty())
            attackerSkill = attacker.getClass().getSkill(attacker, ESM::Skill::HandToHand);
        else
            attackerSkill = attacker.getClass().getSkill(attacker, weapon.getClass().getEquipmentSkill(weapon));
        float attackerTerm = attackerSkill + 0.2f * attackerStats.getAttribute(ESM::Attribute::Agility).getModified()
                + 0.1f * attackerStats.getAttribute(ESM::Attribute::Luck).getModified();
        attackerTerm *= attackerStats.getFatigueTerm();

        int x = int(blockerTerm - attackerTerm);
        int iBlockMaxChance = gmst.find("iBlockMaxChance")->mValue.getInteger();
        int iBlockMinChance = gmst.find("iBlockMinChance")->mValue.getInteger();
        x = std::min(iBlockMaxChance, std::max(iBlockMinChance, x));

        if (Misc::Rng::roll0to99() < x)
        {
            // Reduce shield durability by incoming damage
            int shieldhealth = shield->getClass().getItemHealth(*shield);

            shieldhealth -= std::min(shieldhealth, int(damage));
            shield->getCellRef().setCharge(shieldhealth);
            if (shieldhealth == 0)
                inv.unequipItem(*shield, blocker);
            // Reduce blocker fatigue
            const float fFatigueBlockBase = gmst.find("fFatigueBlockBase")->mValue.getFloat();
            const float fFatigueBlockMult = gmst.find("fFatigueBlockMult")->mValue.getFloat();
            const float fWeaponFatigueBlockMult = gmst.find("fWeaponFatigueBlockMult")->mValue.getFloat();
            MWMechanics::DynamicStat<float> fatigue = blockerStats.getFatigue();
            float normalizedEncumbrance = blocker.getClass().getNormalizedEncumbrance(blocker);
            normalizedEncumbrance = std::min(1.f, normalizedEncumbrance);
            float fatigueLoss = fFatigueBlockBase + normalizedEncumbrance * fFatigueBlockMult;
            if (!weapon.isEmpty())
                fatigueLoss += weapon.getClass().getWeight(weapon) * attackStrength * fWeaponFatigueBlockMult;
            fatigue.setCurrent(fatigue.getCurrent() - fatigueLoss);
            blockerStats.setFatigue(fatigue);

            blockerStats.setBlock(true);

            if (blocker == getPlayer())
                blocker.getClass().skillUsageSucceeded(blocker, ESM::Skill::Block, 0);

            return true;
        }
        return false;
    }

    bool isNormalWeapon(const MWWorld::Ptr &weapon)
    {
        if (weapon.isEmpty())
            return false;

        const int flags = weapon.get<ESM::Weapon>()->mBase->mData.mFlags;
        bool isSilver = flags & ESM::Weapon::Silver;
        bool isMagical = flags & ESM::Weapon::Magical;
        bool isEnchanted = !weapon.getClass().getEnchantment(weapon).empty();

        return !isSilver && !isMagical && (!isEnchanted || !Settings::Manager::getBool("enchanted weapons are magical", "Game"));
    }

    void resistNormalWeapon(const MWWorld::Ptr &actor, const MWWorld::Ptr& attacker, const MWWorld::Ptr &weapon, float &damage)
    {
        if (damage == 0 || weapon.isEmpty() || !isNormalWeapon(weapon))
            return;

        const MWMechanics::MagicEffects& effects = actor.getClass().getCreatureStats(actor).getMagicEffects();
        const float resistance = effects.get(ESM::MagicEffect::ResistNormalWeapons).getMagnitude() / 100.f;
        const float weakness = effects.get(ESM::MagicEffect::WeaknessToNormalWeapons).getMagnitude() / 100.f;

        damage *= 1.f - std::min(1.f, resistance-weakness);

        if (damage == 0 && attacker == getPlayer())
            MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicTargetResistsWeapons}");
    }

    void applyWerewolfDamageMult(const MWWorld::Ptr &actor, const MWWorld::Ptr &weapon, float &damage)
    {
        if (damage == 0 || weapon.isEmpty() || !actor.getClass().isNpc())
            return;

        const int flags = weapon.get<ESM::Weapon>()->mBase->mData.mFlags;
        bool isSilver = flags & ESM::Weapon::Silver;

        if (isSilver && actor.getClass().getNpcStats(actor).isWerewolf())
        {
            const MWWorld::ESMStore& store = MWBase::Environment::get().getWorld()->getStore();
            damage *= store.get<ESM::GameSetting>().find("fWereWolfSilverWeaponDamageMult")->mValue.getFloat();
        }
    }

    void projectileHit(const MWWorld::Ptr& attacker, const MWWorld::Ptr& victim, MWWorld::Ptr weapon, const MWWorld::Ptr& projectile,
                       const osg::Vec3f& hitPosition, float attackStrength)
    {
        MWBase::World *world = MWBase::Environment::get().getWorld();
        const MWWorld::Store<ESM::GameSetting> &gmst = world->getStore().get<ESM::GameSetting>();

        bool validVictim = !victim.isEmpty() && victim.getClass().isActor();

        float damage = 0.f;
        if (validVictim)
        {
            if (attacker == getPlayer())
                MWBase::Environment::get().getWindowManager()->setEnemy(victim);

            int weaponSkill = ESM::Skill::Marksman;
            if (!weapon.isEmpty())
                weaponSkill = weapon.getClass().getEquipmentSkill(weapon);

            int skillValue = attacker.getClass().getSkill(attacker, weapon.getClass().getEquipmentSkill(weapon));

            if (Misc::Rng::roll0to99() >= getHitChance(attacker, victim, skillValue))
            {
                victim.getClass().onHit(victim, damage, false, projectile, attacker, osg::Vec3f(), false);
                MWMechanics::reduceWeaponCondition(damage, false, weapon, attacker);
                return;
            }

            const unsigned char* attack = weapon.get<ESM::Weapon>()->mBase->mData.mChop;
            damage = attack[0] + ((attack[1] - attack[0]) * attackStrength); // Bow/crossbow damage

            // Arrow/bolt damage
            // NB in case of thrown weapons, we are applying the damage twice since projectile == weapon
            attack = projectile.get<ESM::Weapon>()->mBase->mData.mChop;
            damage += attack[0] + ((attack[1] - attack[0]) * attackStrength);

            adjustWeaponDamage(damage, weapon, attacker);
            if (weapon == projectile || Settings::Manager::getBool("only appropriate ammunition bypasses resistance", "Game") || isNormalWeapon(weapon))
                resistNormalWeapon(victim, attacker, projectile, damage);
            applyWerewolfDamageMult(victim, projectile, damage);

            if (attacker == getPlayer())
                attacker.getClass().skillUsageSucceeded(attacker, weaponSkill, 0);

            const MWMechanics::AiSequence& sequence = victim.getClass().getCreatureStats(victim).getAiSequence();
            bool unaware = attacker == getPlayer() && !sequence.isInCombat()
                && !MWBase::Environment::get().getMechanicsManager()->awarenessCheck(attacker, victim);
            bool knockedDown = victim.getClass().getCreatureStats(victim).getKnockedDown();
            if (knockedDown || unaware)
            {
                damage *= gmst.find("fCombatKODamageMult")->mValue.getFloat();
                if (!knockedDown)
                    MWBase::Environment::get().getSoundManager()->playSound3D(victim, "critical damage", 1.0f, 1.0f);
            }
        }

        reduceWeaponCondition(damage, validVictim, weapon, attacker);

        // Apply "On hit" effect of the projectile
        bool appliedEnchantment = applyOnStrikeEnchantment(attacker, victim, projectile, hitPosition, true);

        if (validVictim)
        {
            // Non-enchanted arrows shot at enemies have a chance to turn up in their inventory
            if (victim != getPlayer() && !appliedEnchantment)
            {
                float fProjectileThrownStoreChance = gmst.find("fProjectileThrownStoreChance")->mValue.getFloat();
                if (Misc::Rng::rollProbability() < fProjectileThrownStoreChance / 100.f)
                    victim.getClass().getContainerStore(victim).add(projectile, 1, victim);
            }

            victim.getClass().onHit(victim, damage, true, projectile, attacker, hitPosition, true);
        }
    }

    float getHitChance(const MWWorld::Ptr &attacker, const MWWorld::Ptr &victim, int skillValue)
    {
        MWMechanics::CreatureStats &stats = attacker.getClass().getCreatureStats(attacker);
        const MWMechanics::MagicEffects &mageffects = stats.getMagicEffects();

        MWBase::World *world = MWBase::Environment::get().getWorld();
        const MWWorld::Store<ESM::GameSetting> &gmst = world->getStore().get<ESM::GameSetting>();

        float defenseTerm = 0;
        MWMechanics::CreatureStats& victimStats = victim.getClass().getCreatureStats(victim);
        if (victimStats.getFatigue().getCurrent() >= 0)
        {
            // Maybe we should keep an aware state for actors updated every so often instead of testing every time
            bool unaware = (!victimStats.getAiSequence().isInCombat())
                    && (attacker == getPlayer())
                    && (!MWBase::Environment::get().getMechanicsManager()->awarenessCheck(attacker, victim));
            if (!(victimStats.getKnockedDown() ||
                    victimStats.isParalyzed()
                    || unaware ))
            {
                defenseTerm = victimStats.getEvasion();
            }
            defenseTerm += std::min(100.f,
                                    gmst.find("fCombatInvisoMult")->mValue.getFloat() *
                                    victimStats.getMagicEffects().get(ESM::MagicEffect::Chameleon).getMagnitude());
            defenseTerm += std::min(100.f,
                                    gmst.find("fCombatInvisoMult")->mValue.getFloat() *
                                    victimStats.getMagicEffects().get(ESM::MagicEffect::Invisibility).getMagnitude());
        }
        float attackTerm = skillValue +
                          (stats.getAttribute(ESM::Attribute::Agility).getModified() / 5.0f) +
                          (stats.getAttribute(ESM::Attribute::Luck).getModified() / 10.0f);
        attackTerm *= stats.getFatigueTerm();
        attackTerm += mageffects.get(ESM::MagicEffect::FortifyAttack).getMagnitude() -
                     mageffects.get(ESM::MagicEffect::Blind).getMagnitude();

        return round(attackTerm - defenseTerm);
    }

    void applyElementalShields(const MWWorld::Ptr &attacker, const MWWorld::Ptr &victim)
    {
        // Don't let elemental shields harm the player in god mode.
        bool godmode = attacker == getPlayer() && MWBase::Environment::get().getWorld()->getGodModeState();
        if (godmode)
            return;
        for (int i=0; i<3; ++i)
        {
            float magnitude = victim.getClass().getCreatureStats(victim).getMagicEffects().get(ESM::MagicEffect::FireShield+i).getMagnitude();

            if (!magnitude)
                continue;

            CreatureStats& attackerStats = attacker.getClass().getCreatureStats(attacker);
            float saveTerm = attacker.getClass().getSkill(attacker, ESM::Skill::Destruction)
                    + 0.2f * attackerStats.getAttribute(ESM::Attribute::Willpower).getModified()
                    + 0.1f * attackerStats.getAttribute(ESM::Attribute::Luck).getModified();

            float fatigueMax = attackerStats.getFatigue().getModified();
            float fatigueCurrent = attackerStats.getFatigue().getCurrent();

            float normalisedFatigue = floor(fatigueMax)==0 ? 1 : std::max (0.0f, (fatigueCurrent/fatigueMax));

            saveTerm *= 1.25f * normalisedFatigue;

            float x = std::max(0.f, saveTerm - Misc::Rng::roll0to99());

            int element = ESM::MagicEffect::FireDamage;
            if (i == 1)
                element = ESM::MagicEffect::ShockDamage;
            if (i == 2)
                element = ESM::MagicEffect::FrostDamage;

            float elementResistance = MWMechanics::getEffectResistanceAttribute(element, &attackerStats.getMagicEffects());

            x = std::min(100.f, x + elementResistance);

            static const float fElementalShieldMult = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find("fElementalShieldMult")->mValue.getFloat();
            x = fElementalShieldMult * magnitude * (1.f - 0.01f * x);

            // Note swapped victim and attacker, since the attacker takes the damage here.
            x = scaleDamage(x, victim, attacker);

            MWMechanics::DynamicStat<float> health = attackerStats.getHealth();
            health.setCurrent(health.getCurrent() - x);
            attackerStats.setHealth(health);

            MWBase::Environment::get().getSoundManager()->playSound3D(attacker, "Health Damage", 1.0f, 1.0f);
        }
    }

    void reduceWeaponCondition(float damage, bool hit, MWWorld::Ptr &weapon, const MWWorld::Ptr &attacker)
    {
        if (weapon.isEmpty())
            return;

        if (!hit)
            damage = 0.f;

        const bool weaphashealth = weapon.getClass().hasItemHealth(weapon);
        if(weaphashealth)
        {
            int weaphealth = weapon.getClass().getItemHealth(weapon);

            bool godmode = attacker == MWMechanics::getPlayer() && MWBase::Environment::get().getWorld()->getGodModeState();

            // weapon condition does not degrade when godmode is on
            if (!godmode)
            {
                const float fWeaponDamageMult = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find("fWeaponDamageMult")->mValue.getFloat();
                float x = std::max(1.f, fWeaponDamageMult * damage);

                weaphealth -= std::min(int(x), weaphealth);
                weapon.getCellRef().setCharge(weaphealth);
            }

            // Weapon broken? unequip it
            if (weaphealth == 0)
                weapon = *attacker.getClass().getInventoryStore(attacker).unequipItem(weapon, attacker);
        }
    }

    void adjustWeaponDamage(float &damage, const MWWorld::Ptr &weapon, const MWWorld::Ptr& attacker)
    {
        if (weapon.isEmpty())
            return;

        const bool weaphashealth = weapon.getClass().hasItemHealth(weapon);
        if (weaphashealth)
        {
            damage *= weapon.getClass().getItemNormalizedHealth(weapon);
        }

        static const float fDamageStrengthBase = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>()
                .find("fDamageStrengthBase")->mValue.getFloat();
        static const float fDamageStrengthMult = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>()
                .find("fDamageStrengthMult")->mValue.getFloat();
        damage *= fDamageStrengthBase +
                (attacker.getClass().getCreatureStats(attacker).getAttribute(ESM::Attribute::Strength).getModified() * fDamageStrengthMult * 0.1f);
    }

    void getHandToHandDamage(const MWWorld::Ptr &attacker, const MWWorld::Ptr &victim, float &damage, bool &healthdmg, float attackStrength)
    {
        const MWWorld::ESMStore& store = MWBase::Environment::get().getWorld()->getStore();
        float minstrike = store.get<ESM::GameSetting>().find("fMinHandToHandMult")->mValue.getFloat();
        float maxstrike = store.get<ESM::GameSetting>().find("fMaxHandToHandMult")->mValue.getFloat();
        damage  = static_cast<float>(attacker.getClass().getSkill(attacker, ESM::Skill::HandToHand));
        damage *= minstrike + ((maxstrike-minstrike)*attackStrength);

        MWMechanics::CreatureStats& otherstats = victim.getClass().getCreatureStats(victim);
        healthdmg = otherstats.isParalyzed()
                || otherstats.getKnockedDown();
        bool isWerewolf = (attacker.getClass().isNpc() && attacker.getClass().getNpcStats(attacker).isWerewolf());

        // Options in the launcher's combo box: unarmedFactorsStrengthComboBox
        // 0 = Do not factor strength into hand-to-hand combat.
        // 1 = Factor into werewolf hand-to-hand combat.
        // 2 = Ignore werewolves.
        int factorStrength = Settings::Manager::getInt("strength influences hand to hand", "Game");
        if (factorStrength == 1 || (factorStrength == 2 && !isWerewolf)) {
            damage *= attacker.getClass().getCreatureStats(attacker).getAttribute(ESM::Attribute::Strength).getModified() / 40.0f;
        }

        if(isWerewolf)
        {
            healthdmg = true;
            // GLOB instead of GMST because it gets updated during a quest
            damage *= MWBase::Environment::get().getWorld()->getGlobalFloat("werewolfclawmult");
        }
        if(healthdmg)
            damage *= store.get<ESM::GameSetting>().find("fHandtoHandHealthPer")->mValue.getFloat();

        MWBase::SoundManager *sndMgr = MWBase::Environment::get().getSoundManager();
        if(isWerewolf)
        {
            const ESM::Sound *sound = store.get<ESM::Sound>().searchRandom("WolfHit");
            if(sound)
                sndMgr->playSound3D(victim, sound->mId, 1.0f, 1.0f);
        }
        else if (!healthdmg)
            sndMgr->playSound3D(victim, "Hand To Hand Hit", 1.0f, 1.0f);
    }

    void applyFatigueLoss(const MWWorld::Ptr &attacker, const MWWorld::Ptr &weapon, float attackStrength)
    {
        // somewhat of a guess, but using the weapon weight makes sense
        const MWWorld::Store<ESM::GameSetting>& store = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>();
        const float fFatigueAttackBase = store.find("fFatigueAttackBase")->mValue.getFloat();
        const float fFatigueAttackMult = store.find("fFatigueAttackMult")->mValue.getFloat();
        const float fWeaponFatigueMult = store.find("fWeaponFatigueMult")->mValue.getFloat();
        CreatureStats& stats = attacker.getClass().getCreatureStats(attacker);
        MWMechanics::DynamicStat<float> fatigue = stats.getFatigue();
        const float normalizedEncumbrance = attacker.getClass().getNormalizedEncumbrance(attacker);

        bool godmode = attacker == MWMechanics::getPlayer() && MWBase::Environment::get().getWorld()->getGodModeState();

        if (!godmode)
        {
            float fatigueLoss = fFatigueAttackBase + normalizedEncumbrance * fFatigueAttackMult;
            if (!weapon.isEmpty())
                fatigueLoss += weapon.getClass().getWeight(weapon) * attackStrength * fWeaponFatigueMult;
            fatigue.setCurrent(fatigue.getCurrent() - fatigueLoss);
            stats.setFatigue(fatigue);
        }
    }

    float getFightDistanceBias(const MWWorld::Ptr& actor1, const MWWorld::Ptr& actor2)
    {
        osg::Vec3f pos1 (actor1.getRefData().getPosition().asVec3());
        osg::Vec3f pos2 (actor2.getRefData().getPosition().asVec3());

        float d = getAggroDistance(actor1, pos1, pos2);

        static const int iFightDistanceBase = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find(
                    "iFightDistanceBase")->mValue.getInteger();
        static const float fFightDistanceMultiplier = MWBase::Environment::get().getWorld()->getStore().get<ESM::GameSetting>().find(
                    "fFightDistanceMultiplier")->mValue.getFloat();

        return (iFightDistanceBase - fFightDistanceMultiplier * d);
    }

    bool isTargetMagicallyHidden(const MWWorld::Ptr& target)
    {
        const MagicEffects& magicEffects = target.getClass().getCreatureStats(target).getMagicEffects();
        return (magicEffects.get(ESM::MagicEffect::Invisibility).getMagnitude() > 0)
            || (magicEffects.get(ESM::MagicEffect::Chameleon).getMagnitude() > 75);
    }

    float getAggroDistance(const MWWorld::Ptr& actor, const osg::Vec3f& lhs, const osg::Vec3f& rhs)
    {
        if (canActorMoveByZAxis(actor))
            return distanceIgnoreZ(lhs, rhs);
        return distance(lhs, rhs);
    }
}
