Familiar

owner = "yogo_dude"
mob = peripheral.wrap("back")
mob.disableAI()
gear = mob.getEquipment()
gearStore = "ender_chest"
modem = peripheral.find("modem")
hostile = nil
droppedItem = nil
defaultDump = "inventory"
backupDump = "ender_chest"

local function readFile(fileName)
    if not fs.exists(fileName) then return nil end
    local file = fs.open(fileName,"r")
    local data = file.readAll()
    file.close()
    return data
end

local function saveFile(fileName,data)
    if fs.exists(fileName) then fs.delete(fileName) end
    local file = fs.open(fileName,"w")
    file.write(data)
    file.close()
end

local function getRelativePos(target)
    local x,y,z = target.x,target.y,target.z
    local pos = {}
    pos.yaw = math.deg(math.atan2(-x, z))
    pos.pitch = math.deg(-math.atan2(y, math.sqrt(x * x + z * z)))
    pos.dist = math.sqrt((x^2)+(y^2)+(z^2))
    return pos
end

local function goTowards(target)
    local pos = getRelativePos(target)
    mob.look(pos.yaw,pos.pitch)
    if pos.dist > 2.5 then
        mob.launch(pos.yaw,pos.pitch,(math.tan((pos.dist-1)/20)))
    elseif pos.dist < 2.5 then
        me = mob.getMetaOwner()
        if me.motionY^2 > (me.motionX^2 + me.motionZ^2) and pos.y < 0 then
            me.motionY = me.motionY*2
            mob.launch(0,-90,math.sqrt(me.motionY^2)*2)
        else
            mob.launch(pos.yaw-360,pos.pitch-180, math.sqrt(me.motionX^2 + me.motionY^2 + me.motionZ^2))
        end
    end
end

local function guard(target)
    if getRelativePos(target).dist > 10 then
        hostile = nil
        goTowards(target)
    else
        goTowards(mob.getMetaByID(hostile))
        gear.pullItems(gearStore,25,1)
        mob.swing()
        gear.pushItems(gearStore,1,25)
    end
end

local function heal()
    local prevItem = gear.getItemMeta(1)
    if prevItem then
        gear.pushItems("ender_chest",1,prevItem.tmp)
    end
    for s = 19,22 do
        gear.pullItems("ender_chest",s,1,1)
        mob.use(0,"main")
    end
    if prevItem then
        for slot,item in pairs(mob.getEnder().list()) do
            if item.name == prevItem.name then
                gear.pullItems("ender_chest",slot,1,1)
                break
            end
        end
    end
end

local function collect(target)
    if getRelativePos(mob.getMetaByName(owner)).dist > 10 then
        droppedItem = nil
        goTowards(mob.getMetaByName(owner))
    else
        if not target then droppedItem = nil end
        goTowards(target)
        gear.suck(1)
        if not gear.pushItems(defaultDump,1) then
            gear.pushItems(backupDump,1)
        end
        droppedItem = nil
    end
end

local function recall()
    while mob.getBlockMeta(0,-1,0).name == "minecraft:air" do
        if mob.getMetaByName(owner) then return end
        mob.launch(0,90,0.1)
        sleep(1)
    end
    mob.launch(0,-90,(mob.getMetaOwner().motionY*-2.2))
    sleep(3)
    if mob.getMetaByName(owner) then return end
    mob.look(0,90)
    gear.pullItems(gearStore,27,1,1)
    mob.use()
    gear.pushItems(gearStore,1,1,27)
end

local function getHostile()
    while true do
        if not (hostile and mob.getMetaByID(hostile)) then
            hostile = nil
            local currentScan = mob.sense()
            for _,entity in pairs(currentScan) do
                local nextEntity = mob.getMetaByID(entity.id)
                if nextEntity then
                    if (kos[nextEntity.displayName] and (getRelativePos(nextEntity).dist < 10)) then
                        hostile = nextEntity.id
                        break
                    elseif string.match(nextEntity.displayName,"item.") then
                        if not droppedItem then droppedItem = nextEntity.id end
                    elseif kos[nextEntity.displayName] == nil then
                        kos[nextEntity.displayName] = false
                        saveFile("hostileList",textutils.serialise(kos))
                    end
                end
            end
            if hostile = nil then sleep(3) end
        end
    end
end

local function main()
hasTrust = true
while true do
    if not gear.getItemMeta(2) then
        gear.pullItems(gearStore,24,1,2)
    elseif (mob.getMetaOwner().health < 14) and hasTrust then
        heal()
        if mob.getMetaOwner().health < 14 then
            hasTrust = false
        end
    elseif not mob.getMetaByName(owner) then
        recall()
    elseif hostile then
        guard(mob.getMetaByName(owner))
    elseif droppedItem then
        collect(mob.getMetaByID(droppedItem))
    else
        goTowards(mob.getMetaByName(owner))
    end
    sleep()
end
end

term.clear()
term.setCursorPos(1,1)
print("If lost please return to "..owner)
kos = readFile("hostileList")
if not kos then
    kos = {}
else
    kos = textutils.unserialise(kos)
end
parallel.waitForAny(main,getHostile)