nexcavate.lua

x_pos = 0
y_pos = 0
z_pos = 0
orientation = 0

function orient_to(target_orientation)
    delta_orientation = ((target_orientation % 4) - orientation) % 4

    if delta_orientation == 3 then
        delta_orientation = -1
    end

    if delta_orientation == -3 then
        delta_orientation = 1
    end

    while delta_orientation > 0 do
        turtle.turnRight()
        delta_orientation = delta_orientation - 1
    end

    while delta_orientation < 0 do
        turtle.turnLeft()
        delta_orientation = delta_orientation + 1
    end

    orientation = target_orientation
    serialize_current_pos()
end


function move_up()
    turtle.digUp()
    turtle.attackUp()
    turtle.suckUp()

    r = turtle.up()
    if r then
        y_pos = y_pos + 1
    end

    serialize_current_pos()
    return r
end


function move_down()
    turtle.digDown()
    turtle.attackDown()
    turtle.suckDown()

    r = turtle.down()
    if r then
        y_pos = y_pos - 1
    end

    serialize_current_pos()
    return r
end

function move_forward()
    turtle.dig()
    turtle.attack()
    turtle.suck()

    r = turtle.forward()
    if r then
        if orientation == 0 then
            z_pos = z_pos + 1
        elseif orientation == 1 then
            x_pos = x_pos + 1
        elseif orientation == 2 then
            z_pos = z_pos - 1
        elseif orientation == 3 then
            x_pos = x_pos - 1
        end
    end

    serialize_current_pos()
    return r
end


function move_to_pos_step(target_x, target_z, target_y)
    -- prioritize y over x over z

    -- we're under the target point
    if y_pos < target_y then
        move_up()
    end

    -- we're above the target point
    if y_pos > target_y then
        move_down()
    end

    -- we're to the west of the target point
    if x_pos < target_x then
        orient_to(1)
        move_forward()
    end

    -- we're to the east of the target point
    if x_pos > target_x then
        orient_to(3)
        move_forward()
    end

    -- we're to the south of the target point
    if z_pos < target_z then
        orient_to(0)
        move_forward()
    end

    -- we're to the north of the target point
    if z_pos > target_z then
        orient_to(2)
        move_forward()
    end

    if x_pos == target_x and y_pos == target_y and z_pos == target_z then
        return true
    else
        return false
    end
end

function move_to_pos(target_x, target_y, target_z)
    while not move_to_pos_step(target_x, target_y, target_z) do
    end
end

function inventory_has_empty_slot()
    for i = 1, 16 do
        if turtle.getItemCount(i) == 0 then
            return true
        end
    end

    return false
end

function serialize_current_pos()
    file = fs.open("current_pos", "w");
    file.write(string.format("x_pos=%f;y_pos=%f;z_pos=%f;orientation=%f;", x_pos, y_pos, z_pos, orientation));
    file.close();
end

function serialize_progress(width, length, height)
    file = fs.open("current_progress", "w");
    file.write(string.format("target_x=%f;target_y=%f;target_z=%f;target_orientation=%f;width=%f;length=%f;height=%f;", x_pos, y_pos, z_pos, orientation, width, length, height));
    file.close();
end

function load_state()
    dofile("current_progress");
    dofile("current_pos");
    move_to_pos(target_x, target_z, target_y);
    orient_to(target_orientation);
    excavate(width, length, height);
end

function check_fuel()
    if turtle.getFuelLevel() ~= "unlimited" and turtle.getFuelLevel() < 1 then
        saved_x_pos = x_pos
        saved_y_pos = y_pos
        saved_z_pos = z_pos
        saved_orientation = orientation
        move_to_pos(0, 0, 0)


        -- empty items
        orient_to(2)
        for i = 1, 16 do
            turtle.select(i)
            while turtle.drop() == false do end
        end

        -- refuel :)
        orient_to(3)
        while turtle.getFuelLevel < 5000 do
            turtle.suck()
            turtle.refuel()
        end

        --return
        move_to_pos(saved_x_pos, saved_z_pos, saved_y_pos)
        orient_to(saved_orientation)
    end
end


function excavate(width, length, height)
    if height < 3 then
        height = 3
    end

    if width < 1 then
        width = 1
    end

    height = height + (height % 3)
    toright = true

    while true do
        while inventory_has_empty_slot() do
            check_fuel()
            local should_move_forward = true

            serialize_progress(width, length, height)

            -- prioritize width over length
            if toright then
                if x_pos >= (width - 1) then
                    toright = false

                    if z_pos >= (length - 1) then
                        if y_pos < (-height) then
                            -- We're done, pack up and go
                            move_to_pos(0, 0, 0)
                            orient_to(0)
                            return
                        end

                        -- Move to the next level
                        move_to_pos(0, 0, y_pos - 3)
                        turtle.digDown()
                        toright = true
                        should_move_forward = false
                    end

                    orient_to(0)
                else
                    orient_to(1)
                end
            else
                if x_pos <= 0 then
                    toright = true

                    if z_pos >= (length - 1) then
                        if y_pos < (-height) then
                            move_to_pos(0, 0, 0)
                            orient_to(0)
                            return
                        end

                        move_to_pos(0, 0, y_pos - 3)
                        turtle.digDown()
                        toright = true
                        should_move_forward = false
                    end

                    orient_to(0)
                else
                    orient_to(3)
                end
            end

            if should_move_forward == true then
                while not move_forward() do end
            end

            turtle.digUp()
            turtle.digDown()
        end

        saved_x_pos = x_pos
        saved_y_pos = y_pos
        saved_z_pos = z_pos
        saved_orientation = orientation

        move_to_pos(0, 0, 0)

        -- drop to south
        orient_to(2)
        for i = 1, 16 do
            turtle.select(i)
            while turtle.drop() == false do end
        end

        move_to_pos(saved_x_pos, saved_z_pos, saved_y_pos)
        orient_to(saved_orientation)
    end

    move_to_pos(0, 0, 0)
    orient_to(0)
end

function main()
    term.clear()
    term.setCursorPos(1, 1)
    print("----- Excavate program -----")
    print("")
    print("What dimensions?")
    print("")
    term.write("Width (to the right of the turtle): ")
    z = math.abs(tonumber(io.read()))

    term.write("Length (in front of the turtle): ")
    x = math.abs(tonumber(io.read()))

    term.write("Height (multiple of 3): ")
    y = math.abs(tonumber(io.read()))

    print("Excavating...")
    move_to_pos(0, 0, -1)
    excavate(z, x, y)
    print("Done!")
end

main()