local VEHICLE_COLLISIONS = {}

VEHICLE_COLLISIONS.CACHE = {};

function VEHICLE_COLLISIONS:registerNewElement(Element)
    if not isElement(Element) then
        return
    end

    if not isElementStreamedIn(Element) then
        return
    end

    local ElementType = getElementType(Element);

    if ElementType ~= 'player' and ElementType ~= 'vehicle' then
        return
    end

    VEHICLE_COLLISIONS.CACHE[Element] = ElementType ~= 'player' and getElementData(Element, 'vehicle:lowCol') or false; -- Cache the lowCol state

    if VEHICLE_COLLISIONS.CACHE[Element] then
        if ElementType ~= 'player' then
            setElementAlpha(Element, 200)
        end

        for Element2, State in next, VEHICLE_COLLISIONS.CACHE, nil do
            if Element ~= Element2 and isElement(Element2) then
                if isElementCollidableWith(Element2, Element) then
                    setElementCollidableWith(Element2, Element, false)
                end

                if isElementCollidableWith(Element, Element2) then
                    setElementCollidableWith(Element, Element2, false)
                end
            end
        end
    else
        for Element2, State in next, VEHICLE_COLLISIONS.CACHE, nil do
            if Element ~= Element2 and isElement(Element2) then
                if State then
                    if isElementCollidableWith(Element2, Element) then
                        setElementCollidableWith(Element2, Element, false)
                    end

                    if isElementCollidableWith(Element2, Element) then
                        setElementCollidableWith(Element2, Element, false)
                    end
                end
            end
        end
    end
end

function VEHICLE_COLLISIONS:unregisterElement(Element)
    local ElementType = isElement(Element) and getElementType(Element);
    
    if ElementType and (ElementType ~= 'player' and ElementType ~= 'vehicle') then
        return
    end

    VEHICLE_COLLISIONS.CACHE[Element] = nil

    if isElement(Element) then
        if ElementType ~= 'player' then
            setElementAlpha(Element, 255)
        end

        for Element2, State in next, VEHICLE_COLLISIONS.CACHE, nil do
            if Element ~= Element2 and isElement(Element2) then
                if not State then
                    if not isElementCollidableWith(Element2, Element) then
                        setElementCollidableWith(Element2, Element, true)
                    end

                    if not isElementCollidableWith(Element, Element2) then
                        setElementCollidableWith(Element, Element2, true)
                    end
                end
            end
        end
    end
end

addEventHandler('onClientElementStreamIn', root, function()
    VEHICLE_COLLISIONS:registerNewElement(source)
end)

addEventHandler('onClientElementStreamOut', root, function()
    VEHICLE_COLLISIONS:unregisterElement(source)
end)

addEventHandler('onClientElementDestroy', root, function()
    VEHICLE_COLLISIONS:unregisterElement(source)
end)

addEventHandler('onClientVehicleEnter', root, function(player, seat)
    local source, player = source, player;

    if not isElement(source) then
        return
    end

    if not isElementStreamedIn(source) then
        return
    end

    if isElement(player) then
        VEHICLE_COLLISIONS:registerNewElement(player)
    end

    VEHICLE_COLLISIONS:registerNewElement(source)
end, true, 'low-99')

addEventHandler('onClientElementDataChange', root, function(dataName, oldValue, newValue)
    if not isElement(source) then
        return
    end

    if getElementType(source) ~= 'vehicle' then
        return
    end

    if dataName ~= 'vehicle:lowCol' then
        return
    end

    if newValue then
        if VEHICLE_COLLISIONS.CACHE[source] then
            return
        end

        if not isElementStreamedIn(source) then
            return
        end

        VEHICLE_COLLISIONS:registerNewElement(source)
    else
        if not VEHICLE_COLLISIONS.CACHE[source] then
            return
        end

        VEHICLE_COLLISIONS:unregisterElement(source)
    end
end)

addEventHandler('onClientResourceStart', resourceRoot, function()
    local Elements = {}
    local vehicles = getElementsByType('vehicle', root, true)
    local players = getElementsByType('player', root, true)
    
    for i, v in next, vehicles, nil do
        table.insert(Elements, v)
    end

    for i, v in next, players, nil do
        table.insert(Elements, v)
    end

    table.sort(Elements, function(a, b)
        return getElementData(a, 'vehicle:lowCol') and not getElementData(b, 'vehicle:lowCol')
    end)

    for _, Element in next, Elements, nil do
        VEHICLE_COLLISIONS:registerNewElement(Element)
    end
end)

addEventHandler('onClientResourceStop', resourceRoot, function()
    for Element in next, VEHICLE_COLLISIONS.CACHE, nil do
        VEHICLE_COLLISIONS:unregisterElement(Element)
    end
end)

setTimer(function()
    for elementA, state in next, VEHICLE_COLLISIONS.CACHE, nil do
        if isElement(elementA) and state then
            for elementB, stateB in next, VEHICLE_COLLISIONS.CACHE, nil do
                if isElement(elementB) and elementA ~= elementB then
                    if isElementCollidableWith(elementA, elementB) then
                        setElementCollidableWith(elementA, elementB, false)
                    end
                    if isElementCollidableWith(elementB, elementA) then
                        setElementCollidableWith(elementB, elementA, false)
                    end
                end
            end
        end
    end
end, 1500, 0)