-- Configuration
local refuelLevel = 20   -- Minimum fuel level before refueling
local fuelSlot = 16      -- Slot where fuel (coal) is stored
local tunnelLength = 10  -- Length of the tunnel
local startYLevel = 70   -- Starting Y level (assumed Y=70)
local targetYLevel = 12  -- Target Y level to stop at (Y=12)
local diggingDepth = startYLevel - targetYLevel  -- Depth to dig down (58 blocks)

-- Movement tracking (stack-based approach)
local movementLog = {}  -- Stack to store movements for backtracking
local currentY = startYLevel  -- Track Y level manually

-- List of valuables (all ores) to detect in Minecraft 1.7.10
local valuables = {
    "minecraft:iron_ore",
    "minecraft:coal_ore",
    "minecraft:gold_ore",
    "minecraft:diamond_ore",
    "minecraft:redstone_ore",
    "minecraft:emerald_ore",
    "minecraft:lapis_ore",
    "minecraft:quartz_ore"
}

-- Function to refuel the turtle
function refuel()
    if turtle.getFuelLevel() < refuelLevel then
        turtle.select(fuelSlot)
        if turtle.refuel(1) then
            print("Turtle refueled.")
        else
            print("No fuel available!")
        end
    end
end

-- Function to move forward with tracking
function moveForward()
    turtle.dig()  -- Dig if there's a block in front
    turtle.forward()
    table.insert(movementLog, "forward")  -- Track movement
end

-- Function to move down with tracking, stops at Y=12
function moveDown()
    if currentY > targetYLevel then
        turtle.digDown()  -- Dig if there's a block below
        turtle.down()     -- Move down
        currentY = currentY - 1  -- Update Y level manually
        table.insert(movementLog, "down")  -- Track movement
    else
        print("Reached target Y-level: " .. targetYLevel)
    end
end

-- Function to move up with tracking
function moveUp()
    turtle.up()
    currentY = currentY + 1  -- Update Y level manually
    table.insert(movementLog, "up")  -- Track movement
end

-- Function to move back with tracking
function moveBackward()
    turtle.back()
    table.insert(movementLog, "backward")  -- Track movement
end

-- Function to check if a block is valuable
function isValuable(blockName)
    for _, valuable in ipairs(valuables) do
        if blockName == valuable then
            return true
        end
    end
    return false
end

-- Function to check and mine valuables around the turtle
function checkAndMineValuables()
    -- Helper function to inspect and mine a block in the current direction
    local function inspectAndMine()
        local success, block = turtle.inspect()
        if success and isValuable(block.name) then
            print("Valuable ore detected in front, mining...")
            moveForward()
            turtle.digUp()  -- Clean up above the ore
            turtle.digDown() -- Clean below the ore
            moveBackward()  -- Go back to tunnel
        end
    end

    -- Check all four directions around the turtle (left, right, back, and forward)
    inspectAndMine() -- Check front first

    -- Turn and check left
    turtle.turnLeft()
    inspectAndMine()
    turtle.turnRight() -- Return to original direction

    -- Turn and check right
    turtle.turnRight()
    inspectAndMine()
    turtle.turnLeft() -- Return to original direction

    -- Check above
    local successUp, blockUp = turtle.inspectUp()
    if successUp and isValuable(blockUp.name) then
        print("Valuable ore detected above, mining...")
        turtle.digUp()
    end

    -- Check below
    local successDown, blockDown = turtle.inspectDown()
    if successDown and isValuable(blockDown.name) then
        print("Valuable ore detected below, mining...")
        turtle.digDown()
    end
end

-- Function to dig a tunnel and look for valuables
function digTunnel(length)
    print("Digging tunnel...")
    for i = 1, length do
        checkAndMineValuables() -- Check for valuables nearby before moving
        moveForward()  -- Move forward and track the movement
        turtle.digUp() -- Clear the block above
        refuel()  -- Refuel as needed
    end
end

-- Function to dig down from Y=70 to Y=12
function digDownToY()
    print("Digging down from Y=" .. startYLevel .. " to Y=" .. targetYLevel .. "...")
    while currentY > targetYLevel do
        moveDown()
        refuel()  -- Refuel as needed
    end
    print("Reached Y=12!")
end

-- Function to backtrack to the starting point
function backtrack()
    print("Backtracking...")
    while #movementLog > 0 do
        local lastMove = table.remove(movementLog)  -- Get the last movement

        -- Reverse the last movement
        if lastMove == "forward" then
            turtle.back()
        elseif lastMove == "down" then
            turtle.up()  -- Go back up
            currentY = currentY + 1  -- Track Y level correctly
        elseif lastMove == "up" then
            turtle.down()  -- Go back down
            currentY = currentY - 1  -- Track Y level correctly
        elseif lastMove == "backward" then
            turtle.forward()  -- Move forward to undo a back movement
        end
    end
    print("Returned to starting point at Y=70!")
end

-- Main Program
refuel()  -- Initial refuel

-- Step 1: Dig down from Y=70 to Y=12, and track the depth
digDownToY()

-- Step 2: Dig a 10-block tunnel and look for valuables
digTunnel(tunnelLength)

-- Step 3: Return to the starting point at Y=70
backtrack()