--------------------------------------------------------
-- Variable setup
--------------------------------------------------------

local gameInProgress = false
local grid_npc = {}
local grid_obj = {}
local a_npcs = {}
local h_npcs = {}
local current_npc = nil
local TURN = false
local clock = os.clock()

-- Format entry Id's: Castle, Bishop, Knight, King, Queen, Knight, Bishop, Castle, Pawn
local alliance_creatures = {68001, 68003, 68002, 68005, 68004, 68002, 68003, 68001, 68000}
local horde_creatures = {68007, 68009, 68008, 68011, 68010, 68008, 68009, 68007, 68006}
-- Creature entry ID's and what they are
local creature_index = {[68001] = "a_castle",
                        [68007] = "h_castle",
                        [68003] = "a_bishop",
                        [68009] = "h_bishop",
                        [68002] = "a_knight",
                        [68008] = "h_knight",
                        [68004] = "a_queen",
                        [68010] = "h_queen",
                        [68005] = "a_king",
                        [68011] = "h_king",
                        [68000] = "a_pawn",
                        [68006] = "h_pawn"}

--------------------------------------------------------
-- Event triggering (toggle)
--------------------------------------------------------

function chesschat(event, plr, message, mtype, language)
    if message == "#chess" then
        if gameInProgress then
            plr:SendBroadcastMessage("Ending chess.")
            DespawnChess()
        else
            plr:SendBroadcastMessage("Starting chess.")
            SpawnChess(plr)
        end
        return false
    end
end

RegisterServerHook(16, "chesschat")

--------------------------------------------------------
-- Spawn/Despawn grid
--------------------------------------------------------

function SpawnChess(pUnit)
    if pUnit == nil then
        return
    end
    if gameInProgress then
        pUnit:SendBroadcastMessage("Game is in progress - try again later.")
        return
    end
    gameInProgress = true
    local x = pUnit:GetX()
    local y = pUnit:GetY()
    local z = pUnit:GetZ()
    local i, j
    local a = 0
    local b = 0
    for i=0,35,5 do
        a = a + 1
        table.insert(a_npcs, pUnit:SpawnCreature(alliance_creatures[a], x+i, y, z+0.1, 1.5, 35, 0))
        for j=0,35,5 do
            if j == 5 then
                table.insert(a_npcs, pUnit:SpawnCreature(alliance_creatures[9], x+i, y+j, z+0.1, 1.5, 35, 0))
            elseif j == 30 then
                table.insert(h_npcs, pUnit:SpawnCreature(horde_creatures[9], x+i, y+j, z+0.1, 4.7, 35, 0))
            elseif j == 35 then
                b = b + 1
                table.insert(h_npcs, pUnit:SpawnCreature(horde_creatures[b], x+i, y+j, z+0.1, 4.7, 35, 0))
            end
            table.insert(grid_npc, pUnit:SpawnCreature(28816, x+i, y+j, z, 0, 35, 0))
            table.insert(grid_obj, pUnit:SpawnGameObject(185301, x+i, y+j, z-0.21, 0, 0, 100))
        end
    end
end

function DespawnChess()
    for _,v in ipairs(grid_npc) do
        if v then
            v:Despawn(1,0)
        end
    end
    for _,v in ipairs(grid_obj) do
        if v then
            v:Despawn(1,0)
        end
    end
    for _,v in ipairs(a_npcs) do
        if v then
            v:Despawn(1,0)
        end
    end
    for _,v in ipairs(h_npcs) do
        if v then
            v:Despawn(1,0)
        end
    end
    grid_npc = {}
    grid_obj = {}
    a_npcs = {}
    h_npcs = {}
    gameInProgress = false
    current_npc = nil
end

--------------------------------------------------------
-- Utility
--------------------------------------------------------

function IsHordeCreature(entry)
    for _,v in pairs(horde_creatures) do
        if v == entry then
            return true
        end
    end
    return false
end

function IsAllianceCreature(entry)
    for _,v in pairs(alliance_creatures) do
        if v == entry then
            return true
        end
    end
    return false
end

function checkValidTile(pUnit)
    if pUnit:HasAura(50236) then
        return
    end
    local u = pUnit:GetClosestFriend()
    if u then
        if u:GetDistanceYards(pUnit) > 2 then
            pUnit:CastSpell(50236) -- light beam
        end
    end
end

--------------------------------------------------------
-- Moving a piece
--------------------------------------------------------

function Chess_Piece_Move(pUnit)
    if os.clock() - clock < 5 then
        return
    end
    local plr = pUnit:GetClosestPlayer()
    if not plr then
        return
    end
    if plr:GetDistanceYards(pUnit) > 1.5 then
        return
    end
    if IsAllianceCreature(pUnit:GetEntry()) then
        if TURN then
            plr:SendBroadcastMessage("It isn't your turn.")
            return
        end
    end
    if IsHordeCreature(pUnit:GetEntry()) then
        if not TURN then
            plr:SendBroadcastMessage("It isn't your turn.")
            return
        end
    end
    -- Flags for stationary creatures
    --[[local _c = pUnit:GetInRangeUnits()
    for _,v in ipairs(_c) do
        if IsAllianceCreature(v:GetEntry()) or IsHordeCreature(v:GetEntry()) then
            if v:IsCreatureMoving() then
                pUnit:SendChatMessage(12,0,v:GetName().." is moving!")
                return
            end
        end
    end]]
    if current_npc then
        if current_npc:GetX() ~= pUnit:GetX() then
            current_npc:RemoveAura(50236) -- light beam
            --for _,v in pairs(grid_npc) do
            for _,v in pairs(pUnit:GetInRangeUnits()) do
                v:RemoveAura(50236)
            end
        end
    end
    current_npc = pUnit
    pUnit:CastSpell(50236) -- light beam visual
    ------------------------------------------------
    -- Handle where this unit can move
    ------------------------------------------------
    local piece = creature_index[pUnit:GetEntry()]
    if not piece then
        pUnit:SendChatMessage(12,0,"ERROR: I am not handled.")
        return
    end
    if piece == "h_king" or piece == "a_king" then
        king_move(pUnit)
    elseif piece == "a_pawn" or piece == "h_pawn" then
        pawn_move(pUnit)
    end
end

function GridNPCSpawn(pUnit, Event)
    pUnit:SetUInt32Value(0x0006+0x0035, 0x02000000) -- untargetable
    pUnit:RegisterEvent("CheckPlayerComeAtMe", 1000, 0)
end

function CheckPlayerComeAtMe(pUnit)
    if not pUnit:HasAura(50236) then
        return
    end
    local plr = pUnit:GetClosestPlayer()
    if not plr then
        return
    end
    if plr:GetDistanceYards(pUnit) > 1.5 then
        return
    end
    if current_npc then
        current_npc:MoveTo(pUnit:GetX(), pUnit:GetY(), pUnit:GetZ(), 0) -- orientation should be handled
        current_npc:RemoveAura(50236) -- light beam
        for _,v in pairs(grid_npc) do
            v:RemoveAura(50236)
        end
        TURN = not TURN
    end
end

RegisterUnitEvent(28816, 18, "GridNPCSpawn")

--------------------------------------------------------
-- Pawn movement
--------------------------------------------------------

function pawn_move(pUnit)
    local x, y, z = pUnit:GetX(), pUnit:GetY(), pUnit:GetZ()
    local _x, _y, _z = pUnit:GetSpawnLocation()
    -- Alliance pawn movement
    if IsAllianceCreature(pUnit:GetEntry()) then
        if x == _x then
            local n = pUnit:GetCreatureNearestCoords(x, y+10, z, 28816)
            if n then
                checkValidTile(n)
            end
        end
        local n = pUnit:GetCreatureNearestCoords(x, y+5, z, 28816)
        if n then
            checkValidTile(n)
        end
        current_npc = pUnit
        return
    end
    -- Horde pawn movement
    if x == _x then
        local n = pUnit:GetCreatureNearestCoords(x, y-10, z, 28816)
        if n then
            checkValidTile(n)
        end
    end
    local n = pUnit:GetCreatureNearestCoords(x, y-5, z, 28816)
    if n then
        checkValidTile(n)
    end
    current_npc = pUnit
end

--------------------------------------------------------
-- King movement
--------------------------------------------------------

function king_move(pUnit)
    local x, y, z = pUnit:GetX(), pUnit:GetY(), pUnit:GetZ()
    local n = pUnit:GetCreatureNearestCoords(x+5, y, z, 28816)
    if n then
        checkValidTile(n)
    end
    n = pUnit:GetCreatureNearestCoords(x-5, y, z, 28816)
    if n then
        checkValidTile(n)
    end
    n = pUnit:GetCreatureNearestCoords(x, y+5, z, 28816)
    if n then
        checkValidTile(n)
    end
    n = pUnit:GetCreatureNearestCoords(x, y-5, z, 28816)
    if n then
        checkValidTile(n)
    end
    current_npc = pUnit
end

--------------------------------------------------------
-- Piece events (spawn)
--------------------------------------------------------

function PieceSpawn(pUnit, Event)
    pUnit:RegisterEvent("Chess_Piece_Move", 1000, 0)
    local piece = creature_index[pUnit:GetEntry()]
    if piece == "a_knight" or piece == "h_knight" then
        pUnit:RegisterEvent("MountUpKnight_Piece", 1000, 1)
    end
end

function MountUpKnight_Piece(pUnit)
    local piece = creature_index[pUnit:GetEntry()]
    if piece == "a_knight" then
        pUnit:SetMount(14337)
    else
        pUnit:SetMount(14334)
    end
end

local m
for m=68000,68011 do
    RegisterUnitEvent(m, 18, "PieceSpawn")
end

--[[
local m
for m=1,#alliance_creatures do
    RegisterUnitEvent(alliance_creatures[m], 18, "PieceSpawn")
end
for m=1,#horde_creatures do
    RegisterUnitEvent(horde_creatures[m], 18, "PieceSpawn")
end
]]