local comparisons = {}

function comparisons.zsort(itemA, itemB)
    local _, aY, aZ, _, aH, aD = itemA.mainHitbox:getCube()
    local aDepth, aID, aType
    aDepth = itemA.depth
    aID = itemA.creationID
    aType = itemA.type
    aZ = math.ceil(aZ)
    aY = math.ceil(aY)

    local _, bY, bZ, _, bH, bD = itemB.mainHitbox:getCube()
    local bDepth, bID, bType
    bDepth = itemB.depth
    bID = itemB.creationID
    bType = itemB.type
    bZ = math.ceil(bZ)
    bY = math.ceil(bY)


    --print("comparing " .. aID .. " to " .. bID)

    --print("a", aY, aZ, aH, aD, aDepth, aID, itemA.type)
    --print("b", bY, bZ, bH, bD, bDepth, bID, itemB.type)

    local comparison = 0

    if aZ >= bZ + bD then
        -- item A is completely above item B
        --graph:add(itemB, itemA)
        comparison = 1
    elseif bZ >= aZ + aD then
        -- item B is completely above item A
        --graph:add(itemA, itemB)
        comparison = -1
    elseif aY + aH <= bY then
        -- item A is completely behind item B
        --graph:add(itemA, itemB)
        comparison = -1
    elseif bY + bH <= aY then
        -- item B is completely behind item A
        --graph:add(itemB, itemA)
        comparison = 1
    elseif aY + aH > bY + bH then --(aY - aZ) + aH > (bY - bZ) + bH then
        -- item A's forward-most point is in front of item B's forward-most point
        --graph:add(itemB, itemA)
        comparison = 1
    elseif aY + aH < bY + bH then --aY < (bY - bZ) + bH then
        -- item B's forward-most point is in front of item A's forward-most point
        --graph:add(itemA, itemB)
        comparison = -1
    else
        -- item A's forward-most point is the same than item B's forward-most point
        if aDepth > bDepth then
            --graph:add(itemB, itemA)
            comparison = 1
        elseif aDepth < bDepth then
            --graph:add(itemA, itemB)
            comparison = -1
        else
            if aID > bID then
                --graph:add(itemA, itemB)
                comparison = 1
            elseif aID < bID then
                --graph:add(itemB, itemA)
                comparison = -1
            end
        end
    end

    return comparison == -1
end

return comparisons