-- 'Hole' program, version 1.4
-- Created by Pyro_
-- Credit:
--      theoriginalbit
-- Also:
--      BigSHinyToys
--      BombMan

-- Stores data about current mode
local speedy = false
local noFuel = false
local fuelChest = false

-- Stores turtle status data
local isRefuelling = false
local fuelLevel = 0

-- Stores dimensions for the hole
local sizeX, sizeZ, depth = 0,0,0

-- Stores current turtle position, relative to start point
local xPos, yPos, zPos = 0,0,0


-- Stores current direction, positive x is directly forwards from start point
-- positive z is directly right
local xDir, zDir = 1,0

-- Stores last saved position (Save 1)
local xSav1, ySav1, zSav1 = 0,0,0
local xDirSav1, zDirSav1 = 0,0
local save1Mutex = 0

-- Save 2
local xSav2, ySav2, zSav2 = 0,0,0
local xDirSav2, zDirSav2 = 0,0
local save2Mutex = 0

-- Function is required in movement functions
-- Calculates distance to home, with small buffer
local function distToHome()
    local distance
    distance = xPos + yPos + zPos + 5
    return distance
end

-- **************************************************
-- Movement / Turning functions
local function moveForwardRF()
    local retVal = true
    -- Account for falling blocks, such as sand and gravel
    if not speedy then
        while turtle.detect() do
            turtle.dig()
            sleep(0.8)
        end
    else
        turtle.dig()
    end
    -- If there is any mob infront of the turtle, or we are out of fuel
    -- DEV NOTE: Will be modified later to refuel, or message over rednet wifi
    while not turtle.forward() do
        turtle.attack()
    end

    -- Update position
    xPos = xPos + xDir
    zPos = zPos + zDir

    if not noFuel then
        -- Update fuel info
        fuelLevel = fuelLevel - 1

        -- Fuel checking
        if distToHome() >= fuelLevel then
            retVal = false
        end
    end

    return retVal
end

local function moveUpRF()
    local retVal = true
    -- Account for falling blocks
    if not speedy then
        while turtle.detectUp() do
            turtle.digUp()
            sleep(0.8)
        end
    else
        turtle.digUp()
    end
    --Update position
    yPos = yPos + 1

    while not turtle.up() do
        turtle.attackUp()
    end

    if not noFuel then
        -- Update fuel info
        fuelLevel = fuelLevel - 1

        -- Fuel checking
        if distToHome() >= fuelLevel then
            retVal = false
        end
    end

    return retVal
end

local function moveDownRF()
    local retVal = true
    -- No need to account for falling blocks
    turtle.digDown()

    -- Update position
    yPos = yPos - 1

    while not turtle.down() do
        turtle.attackDown()
    end

    if not noFuel then
        -- Update fuel info
        fuelLevel = fuelLevel - 1

        -- Fuel checking
        if distToHome() >= fuelLevel then
            retVal = false
        end
    end

    return retVal
end

-- Move functions, with fuel checking (will be ignored if noFuel mode is selected)
local function moveForward()
    if not moveForwardRF() then
        refuel()
    end
end

local function moveUp()
    if not moveUpRF() then
        refuel()
    end
end

local function moveDown()
    if not moveDownRF() then
        refuel()
    end
end

local function turnLeft()
    -- Update direction vector
    zDir, xDir = -xDir, zDir

    turtle.turnLeft()
end

local function turnRight()
    -- Update direction vector
    zDir, xDir = xDir, -zDir

    turtle.turnRight()
end

local function turnAround()
    -- Update direction
    zDir, xDir = -zDir, -xDir

    turtle.turnLeft()
    turtle.turnLeft()
end

-- Turns the turtle to the prompted direction
local function turnToDir(x, z)
    if x == 1 and xDir == 0 then
        if zDir == 1 then
            turnLeft()
        else
            turnRight()
        end
    elseif x == 1 and xDir == -1 then
        turnAround()
    elseif x == -1 and xDir == 0 then
        if zDir == 1 then
            turnRight()
        else
            turnLeft()
        end
    elseif x == -1 and xDir == 1 then
        turnAround()
    elseif z == 1 and zDir == 0 then
        if xDir == 1 then
            turnRight()
        else
            turnLeft()
        end
    elseif z == 1 and zDir == -1 then
        turnAround()
    elseif z == -1 and zDir == 0 then
        if xDir == 1 then
            turnLeft()
        else
            turnRight()
        end
    elseif z == -1 and zDir == 1 then
        turnAround()
    else
        return false
    end
    return true
end

-- Takes in a coordinate and moves the turtle there
-- IMPLEMENTATION NOTE: Turtle will be facing in whatever direction it finishes in.
--                      Keep this in mind, as it might affect what happens next.
local function moveToPos(x, y, z)

    -- Move the turtle to the required X value
        if x > xPos then
            turnToDir(1, 0)
            while x > xPos do
                moveForward()
            end
        elseif x < xPos then
            turnToDir(-1, 0)
            while x < xPos do
                moveForward()
            end
        end

    -- Move the turtle to the required Z value
        if z > zPos then
            turnToDir(0, 1)
            while z > zPos do
                moveForward()
            end
        elseif z < zPos then
            turnToDir(0, -1)
            while z < zPos do
                moveForward()
            end
        end

    -- Move the turtle to the required Y value
        if y > yPos then
            while y > yPos do
                moveUp()
            end
        else
            while y < yPos do
                moveDown()
            end
        end
end

-- End of movement functions
-- **************************************************

-- ++++++++++++++++++++++++++++++++++++++++++++++++++
-- Logic functions

-- Saves the current dig position and direction
local function saveDig()
    local retVal = 0
    if save1Mutex == 0 then
        xSav1 = xPos
        ySav1 = yPos
        zSav1 = zPos
        xDirSav1 = xDir
        zDirSav1 = zDir
        save1Mutex = 1
        retVal = 1
    elseif save2Mutex == 0 then
        xSav2 = xPos
        ySav2 = yPos
        zSav2 = zPos
        xDirSav2 = xDir
        zDirSav2 = zDir
        save2Mutex = 1
        retVal = 2
    end
    return retVal
end

-- Dumps the load into a chest or thin air
local function dumpLoad()
    for n = 1, 16 do
        turtle.select(n)
        turtle.drop()
    end
end


-- Moves the turtle back to the last saved position and direction
local function resumeDig(save)
    if save == 1 then
        moveToPos(xSav1, ySav1, zSav1)
        turnToDir(xDirSav1, zDirSav1)
        save1Mutex = 0
    elseif save == 2 then
        moveToPos(xSav2, ySav2, zSav2)
        turnToDir(xDirSav2, xDirSav2)
        save2Mutex = 0
    end
end

-- Move the turtle to the home and fuel chests, dump load and refuel, then
-- resume digging
function refuel()
    local save

    isRefuelling = 1

    save = saveDig()
    moveToPos(0, 0, 0)
    turnToDir(-1, 0)
    dumpLoad()
    turnToDir(0, -1)
    turtle.select(1)
    turtle.suck()
    turtle.refuel()

    fuelLevel = turtle.getFuelLevel()

    resumeDig(save)

    isRefuelling = 0
end


-- Simply checks if the turtle is full
-- DEV NOTE: this is kind of brute-forcish, I wonder if there's a better way?
local function isFull()
    local retVal = true
    for n = 1, 16 do
        if turtle.getItemCount(n) == 0 then
            retVal = false
        end
    end
    return retVal
end

-- Digs the current strip in the current layer
local function digStrip()
    for i = 2, sizeX do
        moveForward()
        if isFull() then
            local save
            save = saveDig()
            moveToPos(0,0,0)
            turnToDir(-1, 0)
            dumpLoad()
            resumeDig(save)
        end
    end
end

-- Turns the turtle in the correct direction at the end of digging a strip
local function stripTurn(strips)
    if strips ~= sizeZ - 1 and sizeZ % 2 == 1 then
        if strips % 2 == 1 then
            turnLeft()
            moveForward()
            turnLeft()
        else
            turnRight()
            moveForward()
            turnRight()
        end
    elseif strips ~= sizeZ -1 and sizeZ % 2 == 0 then
        if yPos % 2 == 0 and strips % 2 == 0 then
            turnRight()
            moveForward()
            turnRight()
        elseif yPos % 2 == 1 and strips % 2 == 1 then
            turnRight()
            moveForward()
            turnRight()
        else
            turnLeft()
            moveForward()
            turnLeft()
        end
    end
end

-- Digs the current layer
local function digLayer()
    local strips = 0
    print("Beginning layer: "..yPos)
    for i = 1, sizeZ do
        digStrip()
        stripTurn(strips)
        strips = strips + 1
    end
end


-- This function controls the digging of the hole
local function digOut()
-- This for loop controls how many layers we are going to dig
    for n = 1, depth do
        digLayer()
        -- If this was no the last layer, then start digging the next one, otherwise,
        -- head home and empty contents into the chest
        if n ~= depth then
            turnAround()
            moveDown()
        elseif n == depth then
            moveToPos(0, 0, 0)
            turnToDir(-1, 0)
            dumpLoad()
            turnToDir(1, 0)
        end
    end
end

local function validateInputs(argv)
    local retVal = true
    if not type(argv[1], "number") then
        retVal = false
        print("Fail 1")
    elseif not type(argv[2], "number") then
        retVal = false
        print("Fail 2")
    elseif not type(argv[3], "number") then
        retVal = false
        print("Fail 3")
    elseif argv[4] ~= nil and argv[4] ~= "-s" and argv[4] ~= "-fc" then
        retVal = false
        print("Fail 4")
    elseif argv[5] ~= nil and argv[5] ~= "-fc" then
        retVal = false
        print("Fail 5")
    end
    return retVal
end


-- End of logic functions
-- ++++++++++++++++++++++++++++++++++++++++++++++++++

-- Main function controls flow of program
local function main(argc, argv)
    if not validateInputs(argv) then
        --[[print("Usage: hole <size X> <size Z> <depth> -s -fc")
        print("")
        print("-s : speed mode, does not check for falling blocks")
        print("-fc : fuel chest present, should be filled with fuel and placed to the left of the turtle before starting")
        print("")
        print("Created by: Pyro_")
        print("Credit to: theoriginalbit, BigSHinyToys and BombMan")
        return false]]
    end

    -- Test if the 'speedy' or 'fuel chest' flags were set
    if argv[4] == "-s" then
        speedy = true
        print("Speed mode")
    elseif argv[4] == "-fc" then
        fuelChest = true
        print("Fuel chest mode")
    else
    -- If we're not in fuel chest mode, then ignore fuel checking
        noFuel = true
    end

    -- Since users may want fuel chest mode and speedy mode
    if argv[5] == "-fc" then
        fuelChest = true
        print("Fuel chest mode")
    else
    -- If we're not in fuel chest mode, then ignore fuel checking
        noFuel = true
    end

    -- Backwards compatability, think C ternary operation
    -- fuelLevel will be ignored if noFuel flag is set
    fuelLevel = turtle.getFuelLevel and turtle.getFuelLevel() or "unlimited"

    -- Will skip fuel checking
    if fuelLevel == "unlimited" then
        noFuel = true
    end

    sizeX = tonumber(argv[1])
    sizeZ = tonumber(argv[2])
    depth = tonumber(argv[3])

    local dims = string.format("Dimensions: X: %i Z: %i Depth: %i", sizeX, sizeZ, depth)

    print("Beginning dig...")
    print(dims)
    digOut()
    print("Finished dig...")

end

main(#{...}, {...})