tLib

local tFuel = {
    'charcoal',
    'coal',
}

local tInverseDirection = {
    ['north'] = 'south',
    ['east'] = 'west',
    ['south'] = 'north',
    ['west'] = 'east',
}

local tDirection = {
    ['north'] = 0, [0] = 'north',
    ['east'] = 1, [1] = 'east',
    ['south'] = 2, [2] = 'south',
    ['west'] = 3, [3] = 'west',
}

local direction = tDirection['north']

local function setDirection(newDirection)
    if tDirection[newDirection] then
        direction = tDirection[newDirection]
        print('Direction set to ' .. tDirection[direction])
    else
        print('ERROR in setDirection(): "' .. (newDirection or 'nil') .. '" is not a valid argument')
    end
end

local function getDirection()
    return tDirection[direction]
end

local function setFuel(fuelTable)
    if type(fuelTable) ~= 'table' then
        print('ERROR: fuel table not set!')
        return
    end
    tFuel = {}
    for i,v in ipairs(fuelTable) do
        print('Registered ' .. v .. ' as fuel item.')
        tFuel[i] = v
    end
end

local function selectItem(itemName)
    local item
    for slot = 1,16 do
        item = turtle.getItemDetail(slot)
        if item and ((item.name == 'minecraft:' .. itemName) or (item.name == itemName)) then
            turtle.select(slot)
            return true
        end
    end

    return false
end

local function existItem(itemName)
    local item
    for slot = 1,16 do
        item = turtle.getItemDetail(slot)
        if item and (item.name == 'minecraft:' .. itemName) then
            return true
        end
    end

    return false
end

local function dropAll(itemName)
    itemName = 'minecraft:' .. itemName
    for slot = 1,16 do
        local item = turtle.getItemDetail(slot)
        if item and (item.name == itemName) then
            turtle.select(slot)
            turtle.drop()
        end
    end
end

local function dropAllButOneStack(itemName)
    itemName = 'minecraft:' .. itemName
    local amount = 0
    local slots = {}
    for slot = 16, 1, -1 do
        item = turtle.getItemDetail(slot)
        if item and (item.name == itemName) then
            amount = amount + turtle.getItemCount(slot)
            table.insert(slots, slot)
        end
    end
    if amount > 64 then
        amount = amount - 64
        for i, slot in ipairs(slots) do
            local drop = math.min(amount, turtle.getItemCount(slot))
            turtle.select(slot)
            if turtle.drop(math.min(drop, 64)) then
                amount = amount - drop
                if amount == 0 then
                    return
                end
            end
        end
    end
end

local function refuel()
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" or fuelLevel > 0 then
        return
    end

    selectedSlot = turtle.getSelectedSlot()

    local function tryRefuel()
        for _, item in ipairs(tFuel) do
            if selectItem(item) then
                if turtle.refuel(1) then
                    return true
                end
            end
        end
        return false
    end

    if not tryRefuel() then
            print( 'Add more fuel to continue.' )
            while not tryRefuel() do
                    sleep(1)
            end
            print( 'Resuming work...' )
    end
    turtle.select(selectedSlot)
end

local function forward()
    refuel()
    while not turtle.forward() do
            if turtle.detect() then
                    turtle.dig()
            elseif turtle.attack() then
                -- attack
            else
                    sleep( 0.5 )
            end
    end
    return true
end

local function up()
    refuel()
    while not turtle.up() do
            if turtle.detectUp() then
                    turtle.digUp()
            elseif turtle.attackUp() then
                -- attack
            else
                    sleep( 0.5 )
            end
    end
    return true
end

local function down()
    refuel()
    while not turtle.down() do
            if turtle.detectDown() then
                    turtle.digDown()
            elseif turtle.attackDown() then
                -- attack
            else
                    sleep( 0.5 )
            end
    end
    return true
end

local function back()
    refuel()
    if not turtle.back() then
        turtle.turnLeft()
        turtle.turnLeft()
        while not turtle.forward() do
                if turtle.detect() then
                        turtle.dig()
                elseif turtle.attack() then
                    -- attack
                else
                        sleep( 0.5 )
                end
        end
        turtle.turnLeft()
        turtle.turnLeft()
    end
    return true
end

local function turnLeft(turns)
    t = turns or 1
    for n=1, t do
        direction = (direction + 3) % 4
        turtle.turnLeft()
    end
end

local function turnRight(turns)
    t = turns or 1
    for n=1, t do
        direction = (direction + 1) % 4
        turtle.turnRight()
    end
end

local function turnAround()
    turnRight(2)
end

local function turnTo(newDirection)
    print('direction: ' .. direction .. '\tnew direction: '.. tDirection[newDirection])
    turns = direction - tDirection[newDirection]
    if turns == -3 then
        turns = 1
    elseif turns == 3 then
        turns = -1
    end
    if turns < 0 then
        print(turns .. ' turnRight()')
        turnRight(math.abs(turns))
    elseif turns > 0 then
        print(turns .. ' turnLeft()')
        turnLeft(math.abs(turns))
    else
        return
    end

    print(tDirection[direction])
end

return {
    selectItem = selectItem,
    existItem = existItem,
    dropAll = dropAll,
    dropAllButOneStack = dropAllButOneStack,
    setFuel = setFuel,
    setDirection = setDirection,
    getDirection = getDirection,
    forward = forward,
    up = up,
    down = down,
    back = back,
    tInverseDirection = tInverseDirection,
    turnLeft = turnLeft,
    turnRight = turnRight,
    turnAround = turnAround,
    turnTo = turnTo,
    }