Strip 4

-- Configuration
local mainTunnelLength = 1000
local branchLength = 20
local branchSpacing = 5
local fuelLimit = 100
local maxOreSearchDepth = 30

-- Position tracking
local pos = {x=0, y=0, z=0}
local dir = 0 -- 0 = north, 1 = east, 2 = south, 3 = west
local resumePoint = nil

-- Movement helpers
local function turnLeft()
    turtle.turnLeft()
    dir = (dir - 1) % 4
end

local function turnRight()
    turtle.turnRight()
    dir = (dir + 1) % 4
end

local function faceDirection(targetDir)
    while dir ~= targetDir do
        turnRight()
    end
end

local function moveForward()
    refuelIfNeeded()
    while turtle.detect() do
        turtle.dig()
        sleep(0.5)
    end
    while not turtle.forward() do
        turtle.dig()
        sleep(0.5)
    end

    if dir == 0 then pos.z = pos.z - 1
    elseif dir == 1 then pos.x = pos.x + 1
    elseif dir == 2 then pos.z = pos.z + 1
    elseif dir == 3 then pos.x = pos.x - 1 end
end

local function moveBack()
    while not turtle.back() do
        turtle.turnLeft()
        turtle.turnLeft()
        turtle.dig()
        turtle.turnLeft()
        turtle.turnLeft()
        sleep(0.2)
    end
    if dir == 0 then pos.z = pos.z + 1
    elseif dir == 1 then pos.x = pos.x - 1
    elseif dir == 2 then pos.z = pos.z - 1
    elseif dir == 3 then pos.x = pos.x + 1 end
end

local function moveUp()
    while not turtle.up() do turtle.digUp(); sleep(0.2) end
    pos.y = pos.y + 1
end

local function moveDown()
    while not turtle.down() do turtle.digDown(); sleep(0.2) end
    pos.y = pos.y - 1
end

-- Refuel
function refuelIfNeeded()
    if turtle.getFuelLevel() < fuelLimit then
        for i = 1, 16 do
            turtle.select(i)
            if turtle.refuel(1) then
                print("Refueled with slot " .. i)
                break
            end
        end
        turtle.select(1)
    end
end

-- Inventory management
local function keepItem(name)
    local patterns = {"cobblestone", "gravel", "flint", "marble", "dirt", "apatite", "thaumcraft", "xycronium", "thermalfoundation:material"}
    for _, pattern in ipairs(patterns) do
        if string.find(name, pattern) then return false end
    end
    return true
end

local function cleanInventory()
    for i = 1, 16 do
        turtle.select(i)
        local item = turtle.getItemDetail()
        if item and not keepItem(item.name) then
            turtle.drop()
        end
    end
    turtle.select(1)
end

local function isInventoryFull()
    for i = 2, 16 do
        if turtle.getItemCount(i) == 0 then
            return false
        end
    end
    return true
end

-- Position restore
local function savePosition()
    resumePoint = {x = pos.x, y = pos.y, z = pos.z, dir = dir}
end

local function resumePosition()
    if not resumePoint then return end

    if pos.x < resumePoint.x then faceDirection(1)
    elseif pos.x > resumePoint.x then faceDirection(3) end
    while pos.x ~= resumePoint.x do moveForward() end

    if pos.z < resumePoint.z then faceDirection(2)
    elseif pos.z > resumePoint.z then faceDirection(0) end
    while pos.z ~= resumePoint.z do moveForward() end

    while pos.y < resumePoint.y do moveUp() end
    while pos.y > resumePoint.y do moveDown() end

    faceDirection(resumePoint.dir)
end

-- Ore detection
local function isOre(name)
    local patterns = {"ore", "Ore", "ic2", "thermal", "gregtech", "forestry", "redpower"}
    for _, pattern in ipairs(patterns) do
        if string.find(name, pattern) then return true end
    end
    return false
end

local function inspectBlock(inspectFunc)
    local success, data = inspectFunc()
    return success and data.name and isOre(data.name)
end

local function mineOreVein(depth)
    if depth > maxOreSearchDepth then return end

    local function tryMine(dirFunc, moveFunc, returnFunc)
        if dirFunc() then
            moveFunc()
            mineOreVein(depth + 1)
            returnFunc()
        end
    end

    tryMine(function() return inspectBlock(turtle.inspect) end, moveForward, moveBack)

    turnLeft()
    tryMine(function() return inspectBlock(turtle.inspect) end, moveForward, moveBack)
    turnRight()
    turnRight()
    tryMine(function() return inspectBlock(turtle.inspect) end, moveForward, moveBack)
    turnLeft()

    tryMine(function() return inspectBlock(turtle.inspectUp) end, moveUp, moveDown)
    tryMine(function() return inspectBlock(turtle.inspectDown) end, moveDown, moveUp)
end

-- Mining
local function mineBranch()
    for i = 1, branchLength do
        moveForward()
        mineOreVein(0)
    end
    turnLeft()
    turnLeft()
    for i = 1, branchLength do
        moveForward()
    end
    if isInventoryFull() then
        savePosition()
        returnToStart()
        dropAllItems()
        resumePosition()
    end
    cleanInventory()
    turnLeft()
    turnLeft()
end

local function stripMine()
    for i = 0, mainTunnelLength - 1 do
        moveForward()
        mineOreVein(0)
        if i % branchSpacing == 0 then
            turnLeft()
            mineBranch()
            turnRight()
            turnRight()
            mineBranch()
            turnLeft()
        end
    end
end

-- Return and unload
function returnToStart()
    print("Returning to start...")
    if pos.x > 0 then faceDirection(3)
    elseif pos.x < 0 then faceDirection(1) end
    while pos.x ~= 0 do moveForward() end

    if pos.z > 0 then faceDirection(0)
    elseif pos.z < 0 then faceDirection(2) end
    while pos.z ~= 0 do moveForward() end

    while pos.y > 0 do moveDown() end
    while pos.y < 0 do moveUp() end

    faceDirection(0)
end

function dropAllItems()
    print("Dropping off items...")
    for i = 2, 16 do
        turtle.select(i)
        turtle.dropDown()
    end
    turtle.select(1)
end

-- Start
print("Starting enhanced strip mining...")
stripMine()
returnToStart()
dropAllItems()
print("Mining complete. Turtle has returned.")