Feeder (OpenPeripheral)

-- Feeder
-- ----------------------------------------------------------

-- Goes around and dumps various forms of animal food into
-- automated feeder units.

-- ----------------------------------------------------------

-- Initialise important values:

-- ----------------------------------------------------------

-- Locations of interest:
local node = {{255,447,66,"south"}, --   1, feed chest (turtle will face south when it gets here, make sure that's where the ME system is)
    {255,441,65,"west",true},   --   2, chickens. (turtle will face west here, but all feed will be placed downwards)
    {255,443,65,"west"},        --   3, a way point where no feeding will be performed.
    {255,442,65,"west"},        --   4, another waypoint.
    {255,442,65,"west",true}}   --   5, another feeding point.

local facing = {"north","east","south","west"}
local direction,x,y,z,counter
local modem = peripheral.wrap("right")

-- ----------------------------------------------------------

-- Functions and stuff:

-- ----------------------------------------------------------

-- Returns true if the turtle is carrying anything.
local function carrying()
    for i=1,16 do if turtle.getItemCount(i) ~= 0 then return true end end
    return false
end

-- Accepts strings representing compass-facings to turn the turtle.
local function faceDirection(targetdirection)
    local tardir = 1
    for i=1,4 do if targetdirection == facing[i] then tardir = i end end

    if tardir < direction then
        if tardir == 1 and direction == 4 then
            turtle.turnRight()
        else
            for i=1,direction-tardir do turtle.turnLeft() end
        end
    elseif tardir > direction then
        if tardir == 4 and direction == 1 then
            turtle.turnLeft()
        else
            for i=1,tardir-direction do turtle.turnRight() end
        end
    end

    direction = tardir
end

-- Travel to a co-ordinate.
local function goToPos(target,digger)
    while (x ~= node[target][1]) or (y ~= node[target][2]) or (z ~= node[target][3]) do
        if z > node[target][3] then
            if turtle.down() then z = z - 1 elseif digger then turtle.digDown() end
        elseif z < node[target][3] then
            if turtle.up() then z = z + 1 elseif digger then turtle.digUp() end
        end

        if x > node[target][1] then
            if direction ~= 4 then faceDirection("west") end
            if turtle.forward() then x = x - 1 elseif digger then turtle.dig() end
        elseif x < node[target][1] then
            if direction ~= 2 then faceDirection("east") end
            if turtle.forward() then x = x + 1 elseif digger then turtle.dig() end
        end

        if y > node[target][2] then
            if direction ~= 1 then faceDirection("north") end
            if turtle.forward() then y = y - 1 elseif digger then turtle.dig() end
        elseif y < node[target][2] then
            if direction ~= 3 then faceDirection("south") end
            if turtle.forward() then y = y + 1 elseif digger then turtle.dig() end
        end
    end

    faceDirection(node[target][4])
end

-- ----------------------------------------------------------

-- I've just booted up. Where am I? Who am I? etc...

-- ----------------------------------------------------------

x, y, z = gps.locate(5)

-- Ping the GPS servers until I get a valid reading.
while x == nil or y == nil or z == nil do
    print("GPS servers aren't answering; trying again...")
    x, y, z = gps.locate(5)
    sleep(5)
end

-- Just a way of isolating some throw-away local variables.
do
    while not turtle.forward() do
      turtle.down()
      turtle.turnLeft()
    end

    local tempx, tempy, tempz = gps.locate(5)

    if x > tempx then
        direction = 4
    elseif x < tempx then
        direction = 2
    elseif y > tempy then
        direction = 1
    else direction = 3 end
end

x, y, z = gps.locate(5)
print("I'm at "..x..","..y..","..z..", I have "..turtle.getFuelLevel().." fuel and I'm facing "..facing[direction]..".")
print("")

while true do
    print("Heading to stock...")
    print("")

    goToPos(1)

    stock = peripheral.wrap("front")

    for i=1,16 do
        if turtle.getItemCount(i) > 0 then
            turtle.select(i)
            turtle.drop(i)
        end
    end

    if turtle.getFuelLevel() < 1000 then
        turtle.select(1)
        stock.pushItem("south",6,64)  -- Assuming the turtle is south of the ME system, and you have charcoal or whatever in slot 6 of the ME system.
        if turtle.getItemCount(1) == 0 then print("Warning: ME system out of turtle fuel! Will continue until out of power...")
        turtle.refuel()
    end

    counter = 1

    for i=2,#node do
        if node[i][5] then
            turtle.select(counter)
            stock.pushItem("south",counter,64)
            if turtle.getItemCount(counter) == 0 then error("Error: ME system out of food!!! Exiting...") end
            counter = counter + 1
        end
    end

    counter = 1

    print("Feeding critters...")
    print("")

    for i=2,#node do
        goToPos(i)

        if node[i][5] then
            turtle.select(counter)
            turtle.dropDown()
            counter = counter + 1
        end
    end
end