Recursive Vein Mining

-- Function to check if turtle has sufficient fuel --

function sufficientFuel(vector1,vector2,fuel,remainder)
    local distance = math.abs(vector1.x - vector2.x) + math.abs(vector1.y - vector2.y) + math.abs(vector1.z - vector2.z)
    if(fuel <= distance + remainder) then
        return false
    else
        return true
    end
end


-- Function to refuel turtle appropriately --

function consumeFuel(maxFuel)
    local refuel = false
    for i = 1, 16 do
        turtle.select(i)
        local x = turtle.getItemDetail(i)
        if(x ~= nil) then
            local istr = string.sub(x.name,string.find(x.name,":",0)+1)
            print(istr,"    t")
            if(istr == "planks" or istr == "stick" or istr == "log") then
                turtle.refuel()
                refuel = true
            end
            if(turtle.getFuelLevel() < maxFuel and istr == "coal") then
                turtle.refuel(1)
                refuel = true
            end
        end
    end
    turtle.select(1)
    print(turtle.getFuelLevel())
    return refuel
end


-- Function to check for inv space --

function invSpace()
    for i = 1, 16 do
        turtle.select(i)
        local x = turtle.getItemDetail(i)
        if(x == nil or turtle.compare()) then
            turtle.select(1)
            return true
        end
    end
    turtle.select(1)
    return false
end


-- Function to sort inventory --

function sortInv()
    for i = 1, 16 do -- loop through the slots
        turtle.select(i)
        if(turtle.getItemDetail(i) ~= nil) then
            for c = i, 16 do
                if(turtle.getItemDetail(c) ~= nil) then
                    if(turtle.compareTo(c)) then
                        turtle.select(c)
                        turtle.transferTo(i)
                        turtle.select(i)
                    end
                end
            end
        end
    end
    turtle.select(1)
end


function mineVein(start,moves,back)
    local current = vector.new(gps.locate())
    if(not sufficientFuel(start,current,turtle.getFuelLevel(),5 + moves)) then
        if(not consumeFuel(400)) then
            return false
        end
    end
    if(not invSpace()) then
        sortInv()
        if(not invSpace()) then
            return false
        end
    end


    local success,data = turtle.inspect()
    if(success) then
        local istr = string.sub(data.name,string.find(data.name,":",0)+1)
        print(istr)
        if(istr == "iron_ore") then
            turtle.dig()
            turtle.forward()
            mineVein(start,moves+1,false)
            turtle.back()
        end
    end
    if(moves < 1) then
        return true
    end
    turtle.turnLeft()
    local success,data = turtle.inspect()
    if(success) then
        local istr = string.sub(data.name,string.find(data.name,":",0)+1)
        print(istr)
        if(istr == "iron_ore") then
            turtle.dig()
            turtle.forward()
            mineVein(start,moves+1,false)
            turtle.back()
        end
    end
    if(back) then
        turtle.turnLeft()
        local success,data = turtle.inspect()
        if(success) then
            local istr = string.sub(data.name,string.find(data.name,":",0)+1)
            print(istr)
            if(istr == "iron_ore") then
                turtle.dig()
                turtle.forward()
                mineVein(start,moves+1,false)
                turtle.back()
            end
        end
        turtle.turnLeft()
        local success,data = turtle.inspect()
        if(success) then
            local istr = string.sub(data.name,string.find(data.name,":",0)+1)
            print(istr)
            if(istr == "iron_ore") then
                turtle.dig()
                turtle.forward()
                mineVein(start,moves+1,false)
                turtle.back()
            end
        end
        turtle.turnLeft()
        local success,data = turtle.inspectUp()
        if(success) then
            local istr = string.sub(data.name,string.find(data.name,":",0)+1)
            print(istr)
            if(istr == "iron_ore") then
                turtle.digUp()
                turtle.up()
                mineVein(start,moves+1,true)
                turtle.down()
            end
        end
        --
        local success,data = turtle.inspectDown()
        if(success) then
            local istr = string.sub(data.name,string.find(data.name,":",0)+1)
            print(istr)
            if(istr == "iron_ore") then
                turtle.digDown()
                turtle.down()
                mineVein(start,moves+1,true)
                turtle.up()
            end
        end
        --
    else
        turtle.turnRight()
        turtle.turnRight()
        local success,data = turtle.inspect()
        if(success) then
            local istr = string.sub(data.name,string.find(data.name,":",0)+1)
            print(istr)
            if(istr == "iron_ore") then
                turtle.dig()
                turtle.forward()
                mineVein(start,moves+1,false)
                turtle.back()
            end
        end
        turtle.turnLeft()
        local success,data = turtle.inspectUp()
        if(success) then
            local istr = string.sub(data.name,string.find(data.name,":",0)+1)
            print(istr)
            if(istr == "iron_ore") then
                turtle.digUp()
                turtle.up()
                mineVein(start,moves+1,true)
                turtle.down()
            end
        end
        --
        local success,data = turtle.inspectDown()
        if(success) then
            local istr = string.sub(data.name,string.find(data.name,":",0)+1)
            print(istr)
            if(istr == "iron_ore") then
                turtle.digDown()
                turtle.down()
                mineVein(start,moves+1,true)
                turtle.up()
            end
        end
        --
    end
    return true
end

gpsData = fs.open("GPS_DATA","r")
local start = vector.new(gps.locate())

mineVein(start,0,false)