--[[

    Vertical shaft miner 0.1
        Copyleft Blastbot 2012

    Description:

        Digs a vertical shaft.

        To start place it in an area that you would like to mine.

        Type the name of the program, and the turtle will start
        searching forward for the deposit location.

        The deposit location will be where the turtle bumps
        into something. From here he will head back to the "starting tile".

        At the "starting tile" the turtle will start mining down and unload
        at the deposit location if he can't carry anymore.

        It will send a redstone pulse for every item it drops, so any
        transposer or filter can pick it up.

        It will stop when all the tiles have been traversed (from start to deposit).

]]--

local data = {
    params = {...},
    currentDepth = 1,
    currentTile = 1,
    lastTile = 1,
    lastSlot = 9,
    dug = 0,
    unload = false,
    msg = "%s @ %d-%d"
}

local function report(msg)
    rednet.broadcast(msg)
    print(msg)
end

local function forward()
    if not turtle.forward() then
        return false
    end
    data.currentTile = data.currentTile - 1
    return true
end

local function back()
    if not turtle.back() then
        return false
    end
    data.currentTile = data.currentTile + 1
    return true
end

local function up()
    if not turtle.up() then
        return false
    end
    data.currentDepth = data.currentDepth - 1
    return true
end

local function down()
    if not turtle.down() then
        return false
    end
    data.currentDepth = data.currentDepth + 1
    return true
end

local function getCap()
    local capacity = 0
    for i = 1, data.lastSlot do
        capacity = capacity + turtle.getItemSpace(i)
    end
    return capacity
end

local function unloadInventory()
    local itemCount = 0
    local slotItemCount = nil
    for i = 1, data.lastSlot do
        slotItemCount = turtle.getItemCount(i)
        if slotItemCount > 0 then
            redstone.setOutput("front", true)
            turtle.select(i)
            turtle.drop()
            sleep(0.2)
            redstone.setOutput("front", false)
            sleep(0.2)
            itemCount = itemCount + slotItemCount
        end
    end
    report("Deposited " .. itemCount  .. " items")
end

local function canMine()
    local slotsTaken = 0
    for i = 1, data.lastSlot do
        if turtle.getItemCount(i) > 0 then
            turtle.select(i)
            if turtle.compareDown() then
                return true
            else
                slotsTaken = slotsTaken + 1
            end
        end
    end
    turtle.select(1)
    return slotsTaken ~= data.lastSlot
end

local function surface()
    while data.currentDepth ~= 1 do
        if not up() then
            return false
        end
        sleep(0.2)
    end
    return true
end

local function moveToDeposit()
    if not surface() then
        return false
    end
    while data.currentTile ~= 1 do
        if not forward() then
            return false
        end
    end
    return true
end

local function moveToNextTile()
    if not surface() then
        --report("moveToNextTile, could not surface")
        return false
    end
    if forward() then
        data.lastTile = data.lastTile - 1
    else
        --report("moveToNextTile, could not move forward")
        return false
    end
    return true
end

local function moveToLastTile()
    if not surface() then
        return false
    end
    while data.currentTile < data.lastTile do
        if not back() then
            return false
        end
    end
    return true
end

-- returns busy, full, moveerror or digerror

local function shaft()
    if 0 == getCap() then
        return "full"
    end

    if turtle.detectDown() then
        if canMine() then
            if not turtle.digDown() then
                return "digerror"
            end
            data.dug = data.dug + 1
            report("Dug " .. data.dug .. " blocks so far")
            return "busy"
        else
            return "full"
        end
    elseif not down() then
        return "moveerror"
    else
        return "busy"
    end
end

local function init()
    -- Enable rednet
    rednet.open("right")

    -- Detect params
    if 1 == #data.params then
        data.lastSlot = 16
    end

    -- Find deposit location
    while not turtle.detect() do
        turtle.forward()
        data.lastTile = data.lastTile + 1
    end

    if data.lastTile < 2 then
        report("Invalid mining area")
        return
    end

    report("Found deposit location")

    report("Gathering...")

    -- Go back to the last tile
    if not moveToLastTile() then
        report("Error moving to mining area")
        return
    end

    local status = shaft()

    report(data.msg:format(status, data.currentDepth, data.currentTile))

    -- Work
    while "busy" == status do

        status = shaft()
        report(data.msg:format(status, data.currentDepth, data.currentTile))

        if "full" == status then
            if not moveToDeposit() then
                if not surface() then
                    status = "dpfullstuck"
                else
                    status = "dpfullsurfaced"
                end
            else
                unloadInventory()
                if not moveToLastTile() then
                    if not surface() then
                        status = "ltfullstuck"
                    else
                        status = "ltfullsurfaced"
                    end
                else
                    status = "busy"
                end
            end

        elseif status ~= "busy" then
            if 1 == data.currentTile then
                if not moveToDeposit() then
                    if not surface() then
                        status = "!fulldpstuck"
                    else
                        status = "!fulldpsurfaced"
                    end
                else
                    status = "done"
                end
            else
                if not moveToNextTile() then
                    if not surface() then
                        status = "!fullltstuck"
                    else
                        status = "!fullltsurfaced"
                    end
                else
                    status = "busy"
                end
            end
        end
        report(data.msg:format(status, data.currentDepth, data.currentTile))
    end

    rednet.close("right")
end

init()