--Variable Declarations
    local mainShaftDim = "3x2"
    local sideShaftDim = "2x1"
    local shaftFreq = "3"
    local totalCost = 0
    local input = ""
    local length = 0
    local currentPos = 1
    local chestDist = 0
    local doFuel = false

    --Function Declarations
    function oreDetect()
            --[[ This function is a WIP system for the turtle to detect ores when it
            is mining and dig out the entire vein.  It will do so by comparing items
            around it to specific slots in its inventory which will contain common
            blocks such as smooth stone, gravel, dirt, etc.
            If one of these ores is identified, then the turtle will dig out the block
            and then move into the space that the block occupied and 'sense' the blocks
            around it again to try and find the continuation of the vein.
            Once the turtle has finished identifying the vein, it will return to it's
            initial position.  This last task may either be completed by recording
            movement as the turtle moves or by using a GPS wireless system and a
            basic 'goto' function for the initial coordinates.
            ]]
    end

    function refuel()
            for i=1,15,1 do
                    turtle.select(i)
                    turtle.refuel(turtle.getItemCount(i))
            end
            turtle.select(1)
    end

    function mainShaft()
            turtle.select(1)
            for i=1,4,1 do
                    while turtle.detect() == true do
                            turtle.dig()
                    end
                    turtle.forward()
                    if not turtle.detectDown() then
                            turtle.placeDown()
                    end
                    while turtle.detectUp() do
                            turtle.digUp()
                    end
                    turtle.turnRight()
                    while turtle.detect() == true do
                            turtle.dig()
                    end
                    turtle.forward()
                    if not turtle.detectDown() then
                            turtle.placeDown()
                    end
                    while turtle.detectUp() do
                            turtle.digUp()
                    end
                    turtle.turnRight()
                    turtle.turnRight()
                    while turtle.detect() do
                            turtle.dig()
                    end
                    turtle.forward()
                    if not turtle.detectDown() then
                            turtle.placeDown()
                    end
                    turtle.turnRight()
            end
            turtle.turnRight()
            turtle.turnRight()
            turtle.select(16)
            turtle.forward()
            turtle.placeUp()
            turtle.turnLeft()
            turtle.forward()
            turtle.placeUp()
            turtle.turnLeft()
            turtle.forward()
            turtle.turnLeft()
            turtle.forward()
            turtle.turnRight()
    end

    function sideShaft()
            turtle.select(1)
            for i=0,20,1 do
                    while turtle.detect() == true do
                            turtle.dig()
                    end
                    turtle.forward()
                    if turtle.detectDown() == false then
                            turtle.placeDown()
                    end
                    while turtle.detectUp() == true do
                            turtle.digUp()
                    end
                    while turtle.detectDown() == true do
                            turtle.digdown()
                            turtle.down()
                    end
            end
            turtle.select(16)
            turtle.turnRight()
            turtle.turnRight()
            turtle.place()
            turtle.turnRight()
            turtle.turnRight()
            turtle.select(1)
            for i=0,20,1 do
                    while turtle.detect() == true do
                            turtle.dig()
                    end
                    turtle.forward()
                    if turtle.detectDown() == false then
                            turtle.placeDown()
                    end
                    while turtle.detectUp() == true do
                            turtle.digUp()
                    end
            end
            turtle.turnRight()
            turtle.turnRight()
            turtle.select(16)
            turtle.place()
            turtle.up()
            for i=1,23,1 do
                    while turtle.detect() do
                            turtle.dig()
                    end
                    turtle.forward()
            end
            turtle.down()
    end

    function deposit()
            for i=1, (chestDist), 1 do
                    turtle.forward()
            end
            for i=1, 15, 1 do
                    turtle.select(i)
                    turtle.drop()
            end
            refuel()
            if turtle.getItemCount(16) < 6 then
                    stopMining()
            end
            if turtle.getFuelLevel() < (108 + 2 * chestDist) then
                    stopMining()
            end
            turtle.turnRight()
            turtle.turnRight()
            for i=1, (chestDist), 1 do
                    turtle.forward()
            end

    end

    function stopMining()
            if turtle.getFuelLevel() < (108 + 2 * chestDist) then
                    print("I am low on fuel.")
                    local remainFuel = 0
                    for i=currentPos, length, 1 do
                            remainFuel = (108 + 2 * (4 * i + 1))
                    end
                    print("I need "..remainFuel.." to finish.")
                    print("That's "..(remainFuel/80).." coal or "..(remainFuel/1000).." lava.")
                    print("Type (cont) to refuel & continue mining.")
                    doFuel = true
            end
            if turtle.getItemCount(16) < 6 then
                    print("I am low on torches.")
                    print("Place more in slot 16...")
                    while turtle.getItemCount(16) < 6 do
                            sleep(1)
                    end
                    print("Type (cont) to continue mining.")
                    doFuel = false
            end
            local cont = false
            while cont == false do
                    --[[if rs.getInput("right") == true then --Flickers RS torch on right of chest
                            rs.setOutput("right", false)
                    else
                            rs.setOutput("right", true)
                    end]]
                    local input = io.read()
                    if input == "cont" then
                            if doFuel then
                                    refuel()
                            end
                            turtle.turnRight()
                            turtle.turnRight()
                            for i=1, chestDist, 1 do
                                    turtle.forward()
                            end
                            currentPos = currentPos + 1
                            run()
                    else
                            print("Incorrect input.")
                    end
            end
    end

    function run()
            while currentPos < length do
                    chestDist = (currentPos * 4 + 4)
                    mainShaft()
                    turtle.turnLeft()
                    sideShaft()
                    sideShaft()
                    turtle.turnLeft()
                    deposit()
                    currentPos = currentPos + 1
            end
    end

    function idle()
            print("Mining Complete")
            print("Type (end) to terminate program")
            local input = "null"
            rs.setOutput("right", true)
            while input ~= "end" do
                    input = io.read()
            end
            rs.setOutput("right", false)
    end

    --Execution
    print("----------------------------------")
    print("Branch Mine Turtle Activated")
    print("----------------------------------")
    sleep(2)
    print("Beginning Mine w. Following Specs:")
    print("Main Shaft: "..mainShaftDim)
    print("Side Shafts: "..sideShaftDim)
    print("Branch Frequency: "..shaftFreq)
    print("----------------------------------")

    print("Number of Shafts:")
    length = tonumber(read())
    currentPos = 0
    print("----------------------------------")
    for x = length, 0, -1 do
            totalCost = totalCost + (108 + 2 * (4 * x + 1))
    end
    print("Current Fuel: "..turtle.getFuelLevel())
    print("Fuel cost: "..totalCost)
    print("Coal cost: "..(totalCost/80))
    print("Lava cost: "..(totalCost/1000))
    sleep(2)
    print("----------------------------------")
    print("Would you like to refuel now (y/n)?")
    input = io.read()
    if input == "y" then
            refuel()
            print("Refueled.")
    else
            print("Did not refuel.")
    end
    print("Turtle now has "..turtle.getFuelLevel().." fuel.")
    print("----------------------------------")
    print("Now beginning mining!")

    run()
    turtle.turnRight()
    turtle.turnRight()
    for i=1, chestDist, 1 do
            turtle.forward()
    end
    idle()