propprotect = {}
propprotect.PlayerInfo = {}

function propprotect.StoreInfo(ply)
    local nick = ply:Nick()
    propprotect.PlayerInfo[ply:UniqueID()] =
    {
        steamid = ply:SteamID(),
        nick =  function() if ply:IsValid() then return ply:Nick() end return nick end,
        player = ply,
    }
end

function propprotect.CanModify(ply, ent)
    propprotect.StoreInfo(ply)
    return ply:CheckUserGroupLevel("moderators") or ply:AreFriends(ent:GetRealOwner()) or ent:GetRealOwner() == ply
end

do -- meta
    local ENT = FindMetaTable("Entity")

    function ENT:GetRealOwnerSteamID()
        local data = propprotect.PlayerInfo[self:GetNWString("pp_owner")]

        return data and data.steamid or ""
    end

    function ENT:GetRealOwnerNick()
        local data = propprotect.PlayerInfo[self:GetNWString("pp_owner")]

        return data and data.nick and data.nick() or ""
    end

    function ENT:GetRealOwner()
        local data = propprotect.PlayerInfo[self:GetNWString("pp_owner")]

        return data and data.player or NULL
    end

    function ENT:CPPIGetOwner()
        return self:GetRealOwner(), util.CRC("gm_" .. self:GetRealOwnerSteamID() .. "_gm")
    end
end

do -- pickup hooks
    hook.Add("CanTool", "propprotect", function(ply, data, mode)
        return propprotect.CanModify(ply, data.Entity)
    end)

    hook.Add("AllowPlayerPickup", "propprotect", function(ply, ent)
        return propprotect.CanModify(ply, ent)
    end)

    hook.Add("GravGunPickupAllowed", "propprotect", function(ply, ent)
        return propprotect.CanModify(ply, ent)
    end)

    hook.Add("PhysgunPickup", "propprotect", function(ply, ent)
        return propprotect.CanModify(ply, ent)
    end)

    hook.Add("PhysgunPickup", "propprotect", function(ply, ent)
        return propprotect.CanModify(ply, ent)
    end)

    hook.Add("EntityTakeDamage", "propprotect", function(ent, _, ply, _, dmginfo)
        if ply:IsPlayer() and ent:IsValid() and not propprotect.CanModify(ply, ent) then
            dmginfo:SetDamage(0)
        end
    end)
end

if CLIENT then
    usermessage.Hook("propprotect_spawn", function(umr)
        local ply = umr:ReadEntity()
        local ent = umr:ReadEntity()

        if ply:IsPlayer() and ent:IsValid() then
            propprotect.StoreInfo(ply)
        end
    end)

    timer.Create("propprotect_lookat", 1, 0, function()
        local ent = LocalPlayer():GetEyeTrace().Entity
        if ent:IsValid() then
            local nick = ent:GetRealOwnerNick()
            if nick ~= "" then
                local allowed = propprotect.CanModify(LocalPlayer(), ent)
                GAMEMODE:AddNotify(nick, allowed and NOTIFY_GENERIC or NOTIFY_ERROR, 1)
            end
        end
    end)
end

if SERVER then
    function propprotect.PlayerSpawnedEntity(ply, ent, skip_nw)
        ent:SetNWString("pp_owner", ply:UniqueID())

        if not skip_nw then
            umsg.Start("propprotect_spawn")
                umsg.Entity(ply)
                umsg.Entity(ent)
            umsg.End()
        end
    end

    do -- spawn hooks
        hook.Add("PlayerSpawnedEffect", "propprotect", function(ply, _, ent)
            propprotect.PlayerSpawnedEntity(ply, ent)
        end)

        hook.Add("PlayerSpawnedNPC", "propprotect", function(ply, ent)
            propprotect.PlayerSpawnedEntity(ply, ent)
        end)

        hook.Add("PlayerSpawnedProp", "propprotect", function(ply, _, ent)
            propprotect.PlayerSpawnedEntity(ply, ent)
        end)

        hook.Add("PlayerSpawnedRagdoll", "propprotect", function(ply, _, ent)
            propprotect.PlayerSpawnedEntity(ply, ent)
        end)

        hook.Add("PlayerSpawnedSENT", "propprotect", function(ply, ent)
            propprotect.PlayerSpawnedEntity(ply, ent)
        end)

        hook.Add("PlayerSpawnedVehicle", "propprotect", function(ply, ent)
            propprotect.PlayerSpawnedEntity(ply, ent)
        end)
    end
end