--- Find any connected redstone energy cells.
-- @return the number of newly found energy cells
--
function updateConnectedRedstoneEnergyCells(cells)
    local count = 0
    local found = {}

    for _, name in pairs(peripheral.getNames()) do
        if peripheral.getType(name) == "redstone_energy_cell" then
            local handle = peripheral.wrap(name)
            found[name] = true

            if cells[name] == nil then
                cells[name] = handle
                count = count + 1
            end
        end
    end

    -- remove cells that have been removed from the system
    for name, _ in pairs(cells) do
        if found[name] == nil then
            cells[name] = nil
        end
    end

    return count
end

--- Get the number of connected redstone energy cells
--
function numConnectedRedstoneEnergyCells(cells)
    local count = 0

    for _, cell in pairs(cells) do
        count = count + 1
    end

    return count
end

--- Get the total amount of energy stored in the system
-- @return int the amount of energy stored
function getEnergyStored(cells)
    local energy = 0

    for _, cell in pairs(cells) do
        energy = energy + cell.getEnergyStored()
    end

    return energy
end

--- Get the max amount of energy that can be stored in the system
-- @return int the max amount of energy stored
function getMaxEnergyStored(cells)
    local energy = 0

    for _, cell in pairs(cells) do
        energy = energy + cell.getMaxEnergyStored()
    end

    return energy
end

--- Get the percentage of energy stored in the system as a float ( 0 <= x <= 100 )
-- @return float the percentage of energy stored in the system ( 0 <= x <= 100 )
function getPercentEnergyStored(cells)
    local energy = getEnergyStored(cells)
    local maxEnergy = getMaxEnergyStored(cells)

    if energy == 0 then
        return 0
    end

    return round((energy / maxEnergy) * 100, 2)
end