ThaumicEnergistics + ComputerCraft Example

-- Aspect Monitor
-- Description: Example ComputerCraft script that monitors certain aspect levels on an AE network via a connected Essentia Provider,
--  and sets a redstone signal based on the amounts. In effect, this operates just like the Essentia Level Emitter, but with more flexibility.
-- This script demonstrates using the watcher event system as an alternative to polling the provider for amounts.
-- Author: Nividica

-- Declare methods, because Lua
local main = nil
local processEvents = nil
local processEssentiaEvent = nil
local getIndexOf = nil
local getAmountOf = nil
local registerForEvents = nil
local showDisplay = nil
local onAspectAmountChanged = nil
local resetToSafeState = nil

-- Declare essentia event types:
--- Sent when a watched essentia level changes
local Ess_EssentiaChange = 1

--- Sent when the provider goes online or offline
local Ess_PowerChange = 2

--- Sent when the computer detaches from the provider. (Most likely the network link was broken)
local Ess_Detach = 3

-- Declare variables
local essentiaToWatch = { "Aqua", "Meto" }
local essentiaAmount = {}
local userWantsToExit = false
local isRegistered = false
local isOnline = false
local provider = nil
local status = ""

-- This is where you would do something useful with the information
onAspectAmountChanged = function()
  -- Make sure the provider is online, and that it is powered. Otherwise the amounts could be out of sync
  if( ( provider == nil ) or ( not isOnline ) ) then
    -- Stale
    return
  end

  -- If Aqua is less than 500, turn on redstone, else turn it off
  aquaAmount = getAmountOf( "Aqua" )
  if( aquaAmount ~= -1 ) then
    rs.setOutput( "back", ( aquaAmount < 500 ) );
  end

  -- If Meto is less than 200, turn on redstone, else turn it off
  metoAmount = getAmountOf( "Meto" )
  if( metoAmount ~= -1 ) then
    rs.setOutput( "top", ( metoAmount < 200 ) );
  end

end

-- Called automatically when the provider is no longer accessible due to a power loss, or removal.
-- If you have a default or safe state, this is a good time to transition into it.
-- For example, if you have it setup such that when you output a redstone signal an
-- export bus does work, you should make sure that signal is turned off here.
resetToSafeState = function()
  -- Turn redstone off
  rs.setOutput( "back", false )
  rs.setOutput( "top", false )
end

-- Main loop
main = function()
  -- Init timeout
  recheckTimeout = nil

  -- Reset state
  resetToSafeState()

  -- Loop until the user elects to exit
  while( not userWantsToExit ) do

    -- Reset the timeout
    recheckTimeout = nil

    -- Is the provider nil?
    if( provider == nil ) then
      -- Try to locate the essentia provider
      result = {pcall( peripheral.find, "EssentiaProvider" )}

      -- Was a provider found?
      if( result[1] and ( result[2] ~= nil ) ) then
        -- Set the provider
        provider = result[2]

      else
        -- Set status to searching
        status = "Searching for provider..."

        -- Check again in 5 seconds
        recheckTimeout = 5

      end
    end

    -- Should the computer register for essentia events?
    if( ( provider ~= nil ) and ( not isRegistered ) )then

      -- Get the providers power state
      isOnline = provider.isOnline()

      -- Can the computer register for essentia events?
      if( isOnline ) then
        registerForEvents()
      else
      -- Set status
      status = "Waiting for provider to be ready..."

      -- Check again in 5 seconds
        recheckTimeout = 5
      end
    end

    -- Display the status screen
    showDisplay()

    -- Wait for an event
    processEvents( recheckTimeout )
  end

  -- Make sure to un-register
  if( ( provider ~= nil ) and isRegistered )then
    provider.unregisterAsWatcher()
  end

  -- Return to the safe state before exiting
  resetToSafeState()

  -- Done
  print( "Exiting" )
end

-- Event processor, optional timeout value
processEvents = function( timeout )
  -- Is there a timeout?
  if( timeout ~= nil ) then
    -- Start a timer
    os.startTimer(timeout)
  end

  -- Pull an event
  event = { os.pullEvent() }

  -- Was the event a character key press?
  if( event[1] == "char" ) then
    -- Was the key a q?
    if( event[2] == "q" or event[2] == "Q" ) then
      -- User wants to exit
      userWantsToExit = true
    end

  -- Was the event from the essentia provider?
  elseif( event[1] == "essentia" ) then
    processEssentiaEvent( event )
  end

end

-- Processes an essentia event
processEssentiaEvent = function( event )
  -- Has the providers power changed?
  if( event[2] == Ess_PowerChange ) then
    -- Get the new power state
    isOnline = event[3]

    -- Is the power going off?
    if( not isOnline ) then
      -- No longer registered
      isRegistered = false

      -- Update status
      status = "Provider offline, amounts shown may not be correct."

      -- Reset state
      resetToSafeState()
    end

  -- Essentia amount update?
  elseif( event[2] == Ess_EssentiaChange ) then
    -- Get the index of the essentia changed
    index = getIndexOf( essentiaToWatch, event[3] )
    if( index ~= -1 ) then
      -- Update the amount
      essentiaAmount[index] = event[4] + ( essentiaAmount[index] or 0 )

      -- Call the changed event handler
      onAspectAmountChanged()
    end

  -- Detached?
  elseif( event[2] == Ess_Detach ) then
    -- Reset everything
    provider = nil
    isOnline = false
    isRegistered = false
    resetToSafeState()

  end

end

-- Returns the index of the item in the table
-- If the item is not in the table, returns -1
getIndexOf = function( t, item )
  -- Search the table
  for index,v in ipairs(t) do
    -- Do the items match?
    if v == item then
      -- Return the index
      return index
    end
  end

  -- Item not found
  return -1
end

-- Helper function that returns how much of the aspect is stored
-- Returns -1 if the aspect is not being tracked
getAmountOf = function( aspect )
  -- Get the index
  index = getIndexOf( essentiaToWatch, aspect )

  -- Is the essentia not being tracked
  if( index == -1 ) then
    return -1
  end

  -- Return the amount
  return essentiaAmount[index] or 0
end

-- Registers the computer to receive essentia updates from the provider
registerForEvents = function()
  -- Start by getting the essentia amounts
  for index,aspect in ipairs( essentiaToWatch ) do
    essentiaAmount[index] = provider.getAmount( aspect )
  end

  -- Register for essentia events
  isRegistered = provider.registerAsWatcher( unpack( essentiaToWatch ) )

  if( isRegistered ) then
    -- Set status
    status = "Watching Network For Changes."

    -- Call the changed event handler
    onAspectAmountChanged()
  end

end

-- Displays what the program is doing
showDisplay = function()
  -- Reset the terminal
  term.clear()
  term.setCursorPos( 1, 1 )

  -- Display each essentia and amount
  for index,aspect in ipairs( essentiaToWatch ) do
    print( aspect , ": " , essentiaAmount[index] )
  end

  -- Divider line
  print( "----------" )

  -- Display the status
  print( "Status: ".. status )

  -- Display how to quit
  print( "Press Q to exit" )
end

-- Call main
main()