ugly.lua

Table = {1}
Tests = {
	{{1, 2}, {1, 1}},
	{{1, 1}, {1, 1}},
	{{0, 0}, {0, 0}},
	{{-5, 10}, {1, 1}},
	{{-2, nil}, {1, 1}},
	{{-2, 2}, {1, 1}},
	{{-2, 1}, {1, 1}},
	{{-2, -1}, {1, 1}},
	{{-2, -3}, {0, 0}},
	{{-5, 2}, {1, 1}},
	{{-5, 0}, {0, 0}},
	{{-5, -7}, {0, 0}},
	{{-5, -3}, {0, 0}}
}

Table = {1, 2, 3, 4, 5, 6, 7, 8, 9}
Tests = {
	{{1, 2}, {1, 2}},
	{{1, 1}, {1, 1}},
	{{0, 0}, {0, 0}},
	{{-5, 10}, {5, 9}},
	{{-2, nil}, {8, 9}},
	{{-2, 2}, {8, 9}},
	{{-2, 1}, {8, 8}},
	{{-2, -1}, {8, 9}},
	{{-2, -3}, {0, 0}},
	{{-5, 2}, {5, 6}},
	{{-5, 0}, {0, 0}},
	{{-5, -7}, {0, 0}},
	{{-5, -3}, {5, 7}},
	{{10, 11}, {0, 0}},
	{{15, 15}, {0, 0}},
	{{14, 4}, {0, 0}},
	{{4, 14}, {4, 9}},
	{{-14, -14}, {0, 0}},
	{{-14, -4}, {1, 6}},
	{{-4, -14}, {0, 0}},
	{{-4, -4}, {6, 6}}
}

NormalizeIndexRange = function(MaximumPosition, Begin, End)
    if not type(MaximumPosition) == "number" then
        MaximumPosition = #MaximumPosition
    end

    local Valid = not (Begin > MaximumPosition or End and (End < Begin or End < -MaximumPosition or End == 0))

    local FirstReturnValue = 0
	if Valid then
        if Begin < 0 then
            FirstReturnValue = MaximumPosition + Begin + 1
        else
            FirstReturnValue = Begin
        end
        FirstReturnValue = math.max(FirstReturnValue,1)
    end

    local SecondReturnValue = 0
    if Valid then
        if End then
            local Bottom
            if End < 0 then
                if End == Begin then
                    if Begin < 0 then
                        Bottom = MaximumPosition + Begin + 1
                    else
                        Bottom = Begin
                    end
                    Bottom = math.max(Bottom, 1)
                else
                    Bottom = MaximumPosition + End + 1
                end
            else
                if Begin < 0 then
                    Bottom = MaximumPosition + Begin + End
                else
                    if End < Begin then
                        Bottom = Begin
                    else
                        Bottom = End
                    end
                end
            end
            Bottom = math.max(Bottom, 1)
            SecondReturnValue = math.min(Bottom, MaximumPosition)
        else
            SecondReturnValue = MaximumPosition
        end
    end

    return FirstReturnValue, SecondReturnValue
end

for _, Test in next, Tests do
	local Result = {NormalizeIndexRange(#Table, Test[1][1], Test[1][2])}
	print((Result[1] == Test[2][1] and Result[2] == Test[2][2] and "Passed! " or "Fail! ") .. "Inputted " .. tostring(Test[1][1]) .. ", " .. tostring(Test[1][2]) .. ", expected " .. tostring(Test[2][1]) .. ", " .. tostring(Test[2][2]) .. ", got " .. tostring(Result[1]) .. ", " .. tostring(Result[2]))
end