local npcId = 70000;
local minionId = 70001;
local minion2Id = 70002;
local portalId = 70005;

local CREATURE_EVENT_ON_ENTER_COMBAT            = 1;
local CREATURE_EVENT_ON_LEAVE_COMBAT            = 2;
local CREATURE_EVENT_ON_DIED                    = 4;
local CREATURE_EVENT_ON_JUST_SUMMONED_CREATURE  = 19;
local CREATURE_EVENT_ON_SUMMONED_CREATURE_DIED  = 21;
local CREATURE_EVENT_ON_SUMMONED                = 22;
local CREATURE_EVENT_ON_RESET                   = 23;

local ACTION_MOVE_HOME                          = 1;
local ACTION_SPAWN_LIGHT_ZONE                   = 2;
local ACTION_ZONE_EXPLOSION                     = 3;
local ACTION_SPAWN_LIGHT_MINION                 = 4;
local ACTION_PREPARE_DARK_ZONE                  = 5;
local ACTION_DESTROY_DARK_ZONE                  = 6;

local VOID_ZONE_LIGHT                           = 40670;
local VOID_ZONE_DARK                            = 40672;
local VOID_ZONE_LIGHT_VISUAL                    = 74629;
local VOID_ZONE_DARK_VISUAL                     = 74803;
local VOID_ZONE_DARK_DAMAGE                     = 75874;

local SPELL_BEAM_OF_LIGHT                       = 46822;
local SPELL_ROOT                                = 38505;
local SPELL_SHADOW_AURA                         = 72523;
local SPELL_SHROUD_OF_SORROW                    = 70985;
local SPELL_SHADOW_EXPLOSION                    = 74799;
local SPELL_HOLY_NOVA                           = 35740;

local DISPLAY_ID_SHADOW_FORM                    = 25452;

local OBJECT_END                                = 0x0006;
local UNIT_FIELD_FLAGS                          = OBJECT_END + 0x0035;
local UNIT_FLAG_NOT_SELECTABLE                  = 0x02000000;
--local UNIT_FLAG_NOT_ATTACKABLE                    = 0x00000002;

local creatureSpells = {
    -- Light phase
    ["SMITE"] = {id = 71778, cooldown = 12},
    ["HOLY_FIRE"] = {id = 66538, cooldown = 15},
    ["DISARM"] = {id = 27581, cooldown = 20},

    -- Dark phase
    ["SHADOW_CLEAVE"] = {id = 70670, cooldown = 3},
    ["SHADOW_STRIKE"] = {id = 40685, cooldown = 18},
    ["DEATH_AND_DECAY"] = {id = 61603, cooldown = 15},
    ["DARK_SHELL"] = {id = 38759, cooldown = 30},
    ["SHADOW_BOLT"] = {id = 55851, cooldown = 10}
};


local arthura = {};
local function getClass(pUnit, AIFunc)
    local guid = pUnit:GetGUIDLow();
    if arthura[guid] == nil then
        arthura[guid] = AIFunc(pUnit);
    end
    return arthura[guid];
end

local function tableFind(tbl, value)
    for _, v in pairs(tbl) do
        if tostring(v) == tostring(value) then
            return true;
        end
    end
    return false;
end

-- Creature class ( sort of .. )
local function arthuraAI(pUnit)
    -- Private
    local phase = 1;
    local eventTimer = 0;
    local actionInProgress = false;

    local darkMinion;

    local cooldown = {};
    local function hasCooldown(name)
        if not cooldown[name] then
            return false;
        end
        if os.time() > cooldown[name] then
            return false;
        end
        return true;
    end
    local function setCooldown(name)
        cooldown[name] = os.time() + creatureSpells[name].cooldown;
    end

    local function getEntry(name)
        return creatureSpells[name].id;
    end

    local function getRandomPlayer()
        local targetList = pUnit:GetPlayersInRange();
        return targetList[math.random(#targetList)];
    end

    -- public
    local self = {};

    function self.onReset()
        phase = 1;
        actionInProgress = false;
        eventTimer = 0;

        pUnit:RemoveEvents();
    end

    function self.onCombatStart()
        pUnit:SendUnitYell("You were fools to come here, you will never walk out of here alive!", 0);
        pUnit:RegisterEvent(self.onAIUpdate, 1000, 0);
    end

    function self.onLeaveCombat()
        local unitDarkMinion = getClass(darkMinion, darkMinionAI);
        unitDarkMinion.onDestroy();

        local portal = pUnit:GetNearObject(50, 0, portalId)
        local voidZone = pUnit:GetNearObject(50, 0, VOID_ZONE_DARK)
        if portal then
            portal:DespawnOrUnsummon();
        end
        if voidZone then
            voidZone:DespawnOrUnsummon();
        end
    end

    function self.onJustDied(pKiller)
        pUnit:SendUnitYell("You beaten the combination of shadow and light! How?", 0)
    end

    function self.onJustSummoned(_, pSummoned)
        darkMinion = pSummoned;
    end

    function self.onAIUpdate()
        eventTimer = eventTimer + 1;
        -- :MoveTo() roots the boss, so I had to come up
        -- with something.
        if not actionInProgress then
            pUnit:MoveChase(pUnit:GetVictim(), 0, 0);
        end

        local healthPct = pUnit:GetHealthPct();
        if phase == 1 then
            if not pUnit:IsFullHealth() then
                pUnit:SetHealth(pUnit:GetHealth() + (pUnit:GetMaxHealth() * 0.001)); -- about 10000 a second.
            end

            if eventTimer % 30 == 0 and not actionInProgress then
                self.doAction(ACTION_MOVE_HOME);
            elseif actionInProgress and not pUnit:GetNearObject(50, 0, VOID_ZONE_LIGHT) then
                local x, y = pUnit:GetHomePosition();
                if pUnit:GetX() == x and pUnit:GetY() == y then
                    self.doAction(ACTION_SPAWN_LIGHT_ZONE);
                    CreateLuaEvent(function() self.doAction(ACTION_ZONE_EXPLOSION); end, 10000, 1);
                end
            end

            if eventTimer % 20 == 0 and not pUnit:GetNearObject(50, 0, minionId) then
                self.doAction(ACTION_SPAWN_LIGHT_MINION);
            end

            if not actionInProgress and not pUnit:GetCurrentSpell(1) then
                if not hasCooldown("SMITE") then
                    local target = getRandomPlayer();

                    pUnit:CastSpell(target, getEntry("SMITE"));
                    setCooldown("SMITE");
                elseif not hasCooldown("HOLY_FIRE") then
                    local targets = {};
                    local targetList = pUnit:GetPlayersInRange();
                    while #targets < 3 do
                        local target = targetList[math.random(#targetList)];
                        if not tableFind(targets, target) then
                            table.insert(targets, target);
                        end

                        if #targetList == #targets then break; end -- In case of < 3 targets.
                    end

                    for _, v in pairs(targets) do
                        pUnit:CastSpell(v, getEntry("HOLY_FIRE"), true);
                    end
                    setCooldown("HOLY_FIRE");
                elseif not hasCooldown("DISARM") then
                    pUnit:CastSpell(pUnit:GetVictim(), getEntry("DISARM"));
                    setCooldown("DISARM");
                end
            end

            if not actionInProgress and healthPct <= 50then
                pUnit:SendUnitYell("Weak is the light, I cannot ... control ... ARRGGGH!", 0);
                pUnit:CastSpell(pUnit, SPELL_SHADOW_EXPLOSION );
                pUnit:SetDisplayId(DISPLAY_ID_SHADOW_FORM);

                phase = 2;
            end

        elseif phase == 2 then

            if eventTimer % 5 == 0 then
                pUnit:CastSpell(pUnit, SPELL_SHROUD_OF_SORROW);
            end

            if eventTimer % 30 == 0 and not actionInProgress then
                self.doAction(ACTION_PREPARE_DARK_ZONE);
            end

            if not pUnit:GetCurrentSpell(1) then
                if not hasCooldown("SHADOW_CLEAVE") then
                    pUnit:CastSpell(pUnit:GetVictim(), getEntry("SHADOW_CLEAVE"));
                    setCooldown("SHADOW_CLEAVE");
                elseif not hasCooldown("SHADOW_STRIKE") then
                    pUnit:CastSpell(pUnit:GetVictim(), getEntry("SHADOW_STRIKE"));
                    setCooldown("SHADOW_STRIKE");
                elseif not hasCooldown("DEATH_AND_DECAY") then
                    local target = getRandomPlayer();

                    pUnit:CastSpell(target, getEntry("DEATH_AND_DECAY"));
                    setCooldown("DEATH_AND_DECAY");
                elseif not hasCooldown("DARK_SHELL") then
                    if not pUnit:HasAura(getEntry("DARK_SHELL")) then
                        pUnit:CastSpell(pUnit, getEntry("DARK_SHELL"))
                    end
                    setCooldown("DARK_SHELL");
                elseif not hasCooldown("SHADOW_BOLT") then
                    pUnit:CastSpell(pUnit, getEntry("SHADOW_BOLT"));
                    setCooldown("SHADOW_BOLT");
                end
            end
        end
    end

    function self.doAction(action)
        local function getRandomCoords()
            local x, y, z = pUnit:GetHomePosition();
            x = math.random(2) == 1 and x-25 or x+25;
            y = y + math.random(-25, 25);

            return x, y, z;
        end

        if action == ACTION_MOVE_HOME then
            local x, y, z = pUnit:GetHomePosition();
            pUnit:MoveTo(1, x, y, z, false);

            actionInProgress = true;
        elseif action == ACTION_SPAWN_LIGHT_ZONE then
            local x, y, z = pUnit:GetHomePosition();
            pUnit:SpawnCreature(VOID_ZONE_LIGHT, x+20, y+20, z, 0, 1, 20000);
            pUnit:SpawnCreature(VOID_ZONE_LIGHT, x-20, y-20, z, 0, 1, 20000);

            pUnit:SendUnitYell("Prepare for the true power of light!", 0)
        elseif action == ACTION_ZONE_EXPLOSION then
            pUnit:CastSpell(pUnit, SPELL_BEAM_OF_LIGHT);
            CreateLuaEvent(function() pUnit:RemoveAura(SPELL_BEAM_OF_LIGHT); end, 1000, 1);

            local targets = {};
            for _, v in pairs(pUnit:GetNearObjects(40, 0, VOID_ZONE_LIGHT)) do
                for _, target in pairs(pUnit:GetPlayersInRange()) do
                    local inTable = tableFind(targets, target);
                    if v:GetDistance(target) > 3 and inTable then
                        pUnit:Kill(target);
                    elseif v:GetDistance(target) > 3 and not inTable then
                        table.insert(targets, target);
                    end
                end
            end

            eventTimer = 0;
            actionInProgress = false;
        elseif action == ACTION_SPAWN_LIGHT_MINION then
            local x, y, z = getRandomCoords();
            pUnit:SpawnCreature(minionId, x, y, z, 0, 1, 20000);
        elseif action == ACTION_PREPARE_DARK_ZONE then
            local target = getRandomPlayer();
            pUnit:SpawnCreature(VOID_ZONE_DARK, target:GetX(), target:GetY(), target:GetZ(), 0, 1, 200000);

            local x, y, z = getRandomCoords();
            pUnit:SpawnCreature(portalId, x, y, z, 0, 1, 200000);

            x, y, z = pUnit:GetHomePosition();
            pUnit:SpawnCreature(minion2Id, x, y, z, 0, 1, 200000);

            actionInProgress = true;
        elseif action == ACTION_DESTROY_DARK_ZONE then
            local darkZone = pUnit:GetNearObject(50, 0, VOID_ZONE_DARK)
            if darkZone then
                darkZone:DespawnOrUnsummon();
            end

            eventTimer = 0;
            actionInProgress = false;
        end
    end

    return self;
end

local function handleArthuraAI(event, pUnit, ...)
    local self = getClass(pUnit, arthuraAI);
    if event == CREATURE_EVENT_ON_ENTER_COMBAT then
        self.onCombatStart();
    elseif event == CREATURE_EVENT_ON_LEAVE_COMBAT then
        self.onLeaveCombat();
    elseif event == CREATURE_EVENT_ON_DIED then
        local pKiller = select(1, ...);
        self.onJustDied(pKiller);
    elseif event == CREATURE_EVENT_ON_JUST_SUMMONED_CREATURE then
        local pSummoned = select(1, ...);
        self.onJustSummoned(pUnit, pSummoned);
    elseif event == CREATURE_EVENT_ON_SUMMONED_CREATURE_DIED then
        local pSummoned = select(1, ...);
        local pKiller = select(2, ...);
        self.onSummonedCreatureDied(pUnit, pSummoned, pKiller);
    elseif event == CREATURE_EVENT_ON_RESET then
        self.onReset();
    end
end

RegisterCreatureEvent(npcId, CREATURE_EVENT_ON_ENTER_COMBAT, handleArthuraAI);
RegisterCreatureEvent(npcId, CREATURE_EVENT_ON_LEAVE_COMBAT, handleArthuraAI);
RegisterCreatureEvent(npcId, CREATURE_EVENT_ON_DIED, handleArthuraAI);
RegisterCreatureEvent(npcId, CREATURE_EVENT_ON_JUST_SUMMONED_CREATURE, handleArthuraAI);
--RegisterCreatureEvent(npcId, CREATURE_EVENT_ON_SUMMONED_CREATURE_DIED, handleArthuraAI);
RegisterCreatureEvent(npcId, CREATURE_EVENT_ON_RESET, handleArthuraAI);

local function lightZoneAI(pUnit)
    -- private
    local summoner;

    local function getDamage()
        local damage = 50000;
        local vZone = pUnit:GetNearObject(60, 0, VOID_ZONE_LIGHT)
        for _, v in pairs(vZone:GetPlayersInRange()) do
            if vZone:GetDistance(v) <= 3 then
                return damage;
            end
        end
        return damage * 5;
    end

    local function handleVoidZone()
        if not summoner:IsAlive() then
            return pUnit:DespawnOrUnsummon();
        end

        local players = {}
        for _, v in pairs(pUnit:GetPlayersInRange()) do
            if pUnit:GetDistance(v) <= 3 then
                table.insert(players, v);
            end
        end

        local damage = getDamage() / #players;
        for _, v in pairs(players) do
            pUnit:DealDamage(v, damage);
        end

        pUnit:DespawnOrUnsummon(2000);
    end

    -- public
    local self = {};

    function self.onJustSummoned(pSummoner)
        summoner = pSummoner;

        pUnit:SetFaction(35);
        pUnit:CastSpell(pUnit, VOID_ZONE_LIGHT_VISUAL);
        pUnit:SetUInt32Value(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);

        pUnit:RegisterEvent(handleVoidZone, 10000, 1);
    end

    return self;
end

local function handleLightZoneAI(event, pUnit, ...)
    local self = getClass(pUnit, lightZoneAI);
    if event == CREATURE_EVENT_ON_SUMMONED then
        local pSummoner = select(1, ...);
        self.onJustSummoned(pSummoner);
    end
end

RegisterCreatureEvent(VOID_ZONE_LIGHT, CREATURE_EVENT_ON_SUMMONED, handleLightZoneAI);

local function lightMinionAI(pUnit)
    -- private
    local summoner;

    -- public
    local self = {};

    function self.onJustSummoned(pSummoner)
        summoner = pSummoner;
        pUnit:RegisterEvent(self.onAIUpdate, 1000, 0);
    end

    function self.onJustDied(pKiller)
        pUnit:DespawnOrUnsummon();
    end

    function self.onAIUpdate()
        pUnit:MoveChase(summoner, 0, 0);
        if pUnit:GetDistance(summoner) <= 2 then
            local maxHealth = summoner:GetMaxHealth();
            local mMaxHealth = summoner:GetHealth()+(maxHealth/20);
            if mMaxHealth > maxHealth then
                summoner:SetHealth(maxHealth);
            else
                summoner:SetHealth(mMaxHealth);
            end

            summoner:CastSpell(summoner, SPELL_HOLY_NOVA);
            pUnit:DespawnOrUnsummon();
        end
    end

    return self;
end

local function handleLightMinionAI(event, pUnit, ...)
    local self = getClass(pUnit, lightMinionAI);
    if event == CREATURE_EVENT_ON_SUMMONED then
        local pSummoner = select(1, ...);
        self.onJustSummoned(pSummoner);
    elseif event == CREATURE_EVENT_ON_DIED then
        local pKiller = select(1, ...);
        self.onJustDied(pKiller);
    end
end

RegisterCreatureEvent(minionId, CREATURE_EVENT_ON_SUMMONED, handleLightMinionAI);
RegisterCreatureEvent(minionId, CREATURE_EVENT_ON_DIED, handleLightMinionAI);

local function darkZoneAI(pUnit)
    -- private
    local summoner;
    local scale = 1;

    local function onDamageTick()
        local unitArthura = pUnit:GetNearObject(50, 0, npcId)
        if not unitArthura then return; end

        for _, v in pairs(pUnit:GetPlayersInRange()) do
            if pUnit:GetDistance(v) <= scale*3 then
                unitArthura:CastSpell(v, VOID_ZONE_DARK_DAMAGE);
            end
        end
    end

    -- public
    local self = {};

    function self.onJustSummoned(pSummoner)
        summoner = pSummoner;

        pUnit:SetFaction(35);
        pUnit:CastSpell(pUnit, VOID_ZONE_DARK_VISUAL);
        pUnit:SetUInt32Value(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);

        pUnit:RegisterEvent(self.onAIUpdate, 100, 0);
        pUnit:RegisterEvent(onDamageTick, 1000, 0);
    end

    function self.onAIUpdate()
        if not summoner:IsAlive() then
            return pUnit:DespawnOrUnsummon();
        end

        scale = scale + 0.02;
        pUnit:SetScale(scale);

        if scale >= 10 then
            pUnit:DespawnOrUnsummon();
        end
    end

    return self;
end

local function handleDarkZoneAI(event, pUnit, ...)
    local self = getClass(pUnit, darkZoneAI);
    if event == CREATURE_EVENT_ON_SUMMONED then
        local pSummoner = select(1, ...);
        self.onJustSummoned(pSummoner);
    end
end

RegisterCreatureEvent(VOID_ZONE_DARK, CREATURE_EVENT_ON_SUMMONED, handleDarkZoneAI);

local function portalAI(pUnit)
    -- private
    local summoner;

    -- public.
    local self = {};

    function self.onJustSummoned(pSummoner)
        summoner = pSummoner;

        pUnit:SetUInt32Value(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE);
        pUnit:RegisterEvent(self.onAIUpdate, 1000, 0);
    end

    function self.onAIUpdate()
        if not summoner:IsAlive() then
            return pUnit:DespawnOrUnsummon();
        end

        for _, v in pairs(pUnit:GetPlayersInRange()) do
            if pUnit:GetDistance(v) <= 3 then
                v:SetPhaseMask(4);
                return pUnit:DespawnOrUnsummon();
            end
        end
    end

    return self;
end

local function handlePortalAI(event, pUnit, ...)
    local self = getClass(pUnit, portalAI);
    if event == CREATURE_EVENT_ON_SUMMONED then
        local pSummoner = select(1, ...);
        self.onJustSummoned(pSummoner);
    end
end

RegisterCreatureEvent(portalId, CREATURE_EVENT_ON_SUMMONED, handlePortalAI);

local function darkMinionAI(pUnit)
    -- private
    local summoner;

    -- public
    local self = {};

    function self.onJustSummoned(pSummoner)
        summoner = pSummoner;
        pUnit:SetPhaseMask(4);
        pUnit:RegisterEvent(self.onAIUpdate, 1000, 0);
    end

    function self.onJustDied(pKiller)
        pKiller:SetPhaseMask(1);

        local unitArthura = getClass(summoner, arthuraAI);
        unitArthura.doAction(ACTION_DESTROY_DARK_ZONE);

        pUnit:DespawnOrUnsummon();
    end

    function self.onAIUpdate()
        if not summoner:IsAlive() then
            for _, v in pairs(pUnit:GetPlayersInRange()) do
                v:SetPhaseMask(1);
            end

            return pUnit:DespawnOrUnsummon();
        end

        if not pUnit:HasSpell(SPELL_ROOT) then
            pUnit:CastSpell(pUnit, SPELL_ROOT); pUnit:CastSpell(pUnit, SPELL_SHADOW_AURA);
        end
    end

    function self.onDestroy()
        for _, v in pairs(pUnit:GetPlayersInRange()) do
            v:SetPhaseMask(1);
        end

        pUnit:DespawnOrUnsummon();
    end

    return self;
end

local function handleDarkMinionAI(event, pUnit, ...)
    local self = getClass(pUnit, darkMinionAI);
    if event == CREATURE_EVENT_ON_SUMMONED then
        local pSummoner = select(1, ...);
        self.onJustSummoned(pSummoner);
    elseif event == CREATURE_EVENT_ON_DIED then
        local pKiller = select(1, ...);
        self.onJustDied(pKiller);
    end
end

RegisterCreatureEvent(minion2Id, CREATURE_EVENT_ON_SUMMONED, handleDarkMinionAI);
RegisterCreatureEvent(minion2Id, CREATURE_EVENT_ON_DIED, handleDarkMinionAI);