--
-- Control turbines of a active cooled Big Reactor (http://big-reactors.com/).
--
-- Author: kla_sch
--
-- History:
--     v0.1, 2014-12-29:
--         - first version
--
--     v0.2, 2015-01-02:
--         - Big Reactor since 0.3.4A: Feature to disengage coil to
--           startup faster (see config value useDisengageCoils).
--         - minor bugfixes
--         - some code improvments (thanks to wieselkatze)
--
-- Save as "startup"


--
-- Constant values (configuration)
-- ===============================


-- Maximum loop time of controller (default: 0.5s)
local loopT=0.5

-- Display loop time, of controller has been switched off (default: 1s).
local displayT=1

-- Modem channel to listen for status requests. If it is set to 0,
-- the remote status requests are disabled.
-- The sender sould simply send "BR_turbine_get_state" to this channel. The
-- turbine replies with status informations to the replay channel.
local stateRequestChannel = 32768 -- Broadcast channel.

--
-- Enable remote control.
-- Set to "true" if you want to enable this feature.
--
local remoteControl = false

--
-- Use disengaged coil for faster speedup. (Big Reactor >= 0.3.4A).
-- Set this to "false" if you want to disable this feature.
--
local useDisengageCoils = true


local maxRF = 1000000

--
-- Internal values:
-- ================

-- File to save last known controller state:
local saveFilename = "turbine_crtl.save"

local Kp, Kd, Ki, errSum, errOld -- global PID controller values
local tSpeed -- target speed
local turbine -- wraped turbine
local reactor -- wraped reactor
local maxFRate -- maximum float rate of turbine
local floatRateChanged = false -- flag: true on float rate change


--
-- Find the first connected big turbine and return the wraped handle.
--
-- If no turbine was found this function terminate the program.
--
-- Return:
--     Handle of first connected turbine found.
--
local function getTurbineHandle()
   local pList = peripheral.getNames()
   local i, name
   for i, name in pairs(pList) do
      if peripheral.getType(name) == "BigReactors-Turbine" then
         return peripheral.wrap(name)
      end
   end

   error("No turbine connected: Exit program")
end

local function getReactorHandle()
   local pList = peripheral.getNames()
   local i, name
   for i, name in pairs(pList) do
      if peripheral.getType(name) == "BigReactors-Reactor" then
         return peripheral.wrap(name)
      end
   end

   error("No reactor connected: Exit program")
end


--
-- Search for any modem and open it to recieve modem requests.
--
local function searchAndOpenModems()
   if stateRequestChannel <= 0 then
      return -- feature disabled
   end

   local pList = peripheral.getNames()
   local i, name
   for i, name in pairs(pList) do
      if peripheral.getType(name) == "modem" then
         peripheral.call(name, "open", stateRequestChannel)
         peripheral.call(name, "open", os.getComputerID())
      end
   end
end


--
-- Saves current controller state
--
local function saveControllerState()
   local tmpFilename = saveFilename .. ".tmp"

   fs.delete(tmpFilename)
   local sFile = fs.open(tmpFilename, "w")
   if sFile == nil then
      error("cannot open status file for writing.")
   end

   sFile.writeLine("V0.1")
   sFile.writeLine(tostring(tSpeed))
   sFile.writeLine(tostring(loopT))
   sFile.writeLine(tostring(Kp))
   sFile.writeLine(tostring(errSum))
   sFile.writeLine(tostring(errOld))
   sFile.writeLine("EOF")
   sFile.close()

   fs.delete(saveFilename)
   fs.move(tmpFilename, saveFilename)
end


--
-- Initialize basic PID controller values
--
local function initControllerValues()
   local Tn = loopT
   local Tv = loopT * 10

   Ki = Kp / Tn
   Kd = Kp * Tv
end


--
-- Read number from file
--
-- Parameters:
--     sFile - opened file to read from
--
-- Return
--     the number of nil, if an error has occurred
--
local function readNumber(sFile)
   local s = sFile.readLine()
   if s == nil then
      return nil
   end
   return tonumber(s)
end

--
-- Restore last known controller state
--
-- Returns:
--     true, if the last saved state has successfully readed.
local function restoreControllerState()
   local tmpFilename = saveFilename .. ".tmp"
   local sFile = fs.open(saveFilename, "r")
   if sFile == nil and fs.exists(tmpFilename) then
      fs.move(tmpFilename, saveFilename)
      sFile = fs.open(saveFilename)
   end

   if sFile == nil then
      return false -- cannot read any file
   end

   local version = sFile.readLine()
   if version == nil then
      sFile.close()
      return false -- empty file
   end
   if version ~= "V0.1" then
      sFile.close()
      return false -- unknown version
   end

   local tSpeedNum = readNumber(sFile)
   if tSpeedNum == nil then
      sFile.close()
      return false -- cannot read target speed
   end

   local loopTNum = readNumber(sFile)
   if loopTNum == nil then
      sFile.close()
      return false -- cannot read loop speed
   end

   local KpNum = readNumber(sFile)
   if KpNum == nil then
      sFile.close()
      return false -- cannot read Kp
   end

   local errSumNum = readNumber(sFile)
   if errSumNum == nil then
      sFile.close()
      return false -- cannot read error sum
   end

   local errOldNum = readNumber(sFile)
   if errOldNum == nil then
      sFile.close()
      return false -- cannot read last error
   end

   local eofStr = sFile.readLine()
   if eofStr == nil or eofStr ~= "EOF" then
      sFile.close()
      return false -- EOF marker not found. File corrupted?
   end

   sFile.close()

   -- Restore saved values
   tSpeed = tSpeedNum
   loopT = loopTNum
   Kp = KpNum
   errSum = errSumNum
   errOld = errOldNum

   initControllerValues()

   if tSpeed == 0 then
      turbine.setActive(false)
   else
      turbine.setActive(true)
   end

   return true
end


--
-- Write text with colors, if possible (advance monitor)
--
-- Parameters:
--     mon   - handle of monitor
--     color - text color
--     text  - text to write
--
local function writeColor(mon, color, text)
   if mon.isColor() then
      mon.setTextColor(color)
   end
   mon.write(text)
   if mon.isColor() then
      mon.setTextColor(colors.white)
   end
end


--
-- Scale the monitor text size to needed size of output text.
--
-- This function try to scale the monitor text size, so that it is enoth for
-- "optHeight" lines with "optWidth" characters. If it is not possible
-- (text scale is not supported or the connected monitor is too small),
-- it also accept "minHeight" lines and "minWidth" characters.
--
-- Parameters:
--     mon        - handle of monitor.
--     minWidth   - Minimum number of columns needed.
--     optWidth   - Optimal number of columns desired.
--     minHeight  - Minimum number of rows needed.
--     optHeight  - Optimal number of rows desired.
--
-- Return:
--     Size of monitor after scaling: width, height.
--     If the monitor is too small, it returns nul,nil.
--
local function scaleMonitor(mon, minWidth, optWidth, minHeight, optHeight)
   if mon.setTextScale ~= nil then
       mon.setTextScale(1)
   end

   local width, height = mon.getSize()

   if mon.setTextScale == nil then
      -- Scale not available
      if width < minWidth or height < minHeight then
         return nil, nil -- too small
      else
         return width, height
      end
   end

   if width < optWidth or height < optHeight then
      -- too small: try to scale down.
      mon.setTextScale(0.5)

      width, height = mon.getSize()
      if width < minWidth or height < minHeight then
         return nil, nil -- still too small
      end
   else
      -- Huge monitors? Try to scale up, if possible (max scale=5).
      local scale = math.min(width / optWidth, height / optHeight, 5)
      scale = math.floor(scale * 2) / 2 -- multiple of 0.5

      if scale > 1 then
         mon.setTextScale(scale)
         width, height = mon.getSize()
      end
   end

   return width, height
end


-- Display turbine status to a monitor
--
-- Parameters:
--     mon     - Wraped handle of monitor
--     turbine - Wraped handle of turbine.
--     tSpeed  - Target speed.
--
local function displayStateOnMonitor(mon, turbine, tSpeed)

   -- scale it, if possible.
   local width, height = scaleMonitor(mon, 15, 16, 5, 5)

   if width == nil or height == nil then
      return -- Montitor is too small
   end

   mon.clear()

   mon.setCursorPos(1,1)
   mon.write("Turbine: ")
   if tSpeed == 0 then
      writeColor(mon, colors.red, "off")
   else
      writeColor(mon, colors.green, string.format("%d", tSpeed))
      if width > 16 then
         mon.write(" RPM")
      end
   end

   mon.setCursorPos(1,3)
   local speed = math.floor(turbine.getRotorSpeed()*10+0.5)/10
   mon.write("Speed: ")
   if (speed == tSpeed) then
      writeColor(mon, colors.green, speed)
   else
      writeColor(mon, colors.orange, speed)
   end
   if width > 16 then
       mon.write(" RPM")
   end

   local maxFlow = turbine.getFluidFlowRateMax()
   local actFlow = turbine.getFluidFlowRate()
   if width >= 16 then
      -- bigger monitor
       mon.setCursorPos(1,4)
       mon.write("MFlow: " .. string.format("%d", maxFlow) .. " mB/t")

       mon.setCursorPos(1,5)
       mon.write("AFlow: ")
       if actFlow < maxFlow then
          writeColor(mon, colors.red, string.format("%d", actFlow))
       else
          writeColor(mon, colors.green, string.format("%d", actFlow))
       end
       mon.write(" mB/t")
   else
      -- 1x1 monitor
       mon.setCursorPos(1,4)
       mon.write("Flow (act/max):")
       mon.setCursorPos(1,5)
       mon.write("(")

       if actFlow < maxFlow then
          writeColor(mon, colors.red, string.format("%d",actFlow))
       else
          writeColor(mon, colors.green, string.format("%d",actFlow))
       end

       mon.write("/")
       mon.write(string.format("%d", maxFlow))
       mon.write(" mB/t)")
   end

end


-- Display turbine status to any connected monitor and also to console.
--
-- Parameters:
--     turbine - Wraped handle of turbine.
--     tSpeed  - Target speed.
--
function displayState(turbine, tSpeed)
  displayStateOnMonitor(term, turbine, tSpeed)
  term.setCursorPos(1,7)
  term.write("* Keys: [o]ff, [m]edium (900), [f]ast (1800)")
  term.setCursorPos(1,8)

   local pList = peripheral.getNames()
   local i, name
   for i, name in pairs(pList) do
      if peripheral.getType(name) == "monitor" then
         -- found monitor as peripheral
         displayStateOnMonitor(peripheral.wrap(name), turbine, tSpeed)
      end
   end
end

--
-- Test the speedup time of the turbine.
--
-- Parameters:
--     turbine - Wraped handle of turbine.
--     loopT   - Loop timer.
--     tSpeed  - Target speed
local function testSpeedup(turbine, loopT, tSpeed)
   turbine.setFluidFlowRateMax(maxFRate)

   if turbine.setInductorEngaged then
      -- always engage coil
      turbine.setInductorEngaged(true)
   end

   local KpSum=0
   local nKp=0
   local oldSpeed=-1

   for i=0,5 do
      displayState(turbine, tSpeed)
      speed = turbine.getRotorSpeed()
      if oldSpeed >= 0 then
         KpSum = KpSum + (speed-oldSpeed)
         nKp = nKp + 1
      end
      oldSpeed = speed
      sleep(loopT)
   end

   if KpSum * loopT / nKp > 5 then
      -- Too fast: increase loop speed
      loopT = 5 * nKp / KpSum
      return 5, loopT
   else
      return (KpSum / nKp), loopT
   end
end


--
-- Main program
--

sleep(2) -- wait for 2s

-- wrap turbine
turbine = getTurbineHandle()
reactor = getReactorHandle()

searchAndOpenModems() -- search and open any modem.

if restoreControllerState() == false then
   -- restore of old values failed.
   tSpeed = 0
   Kp=0
end


maxFRate = turbine.getFluidFlowRateMaxMax()
while true do
	--reactor
	if turbine.getEnergyStored() > (maxRF / 2) then
			turbine.setActive(false)
			reactor.setActive(false)
			reactor.setAllControlRodLevels(100)
	else

			local active = tSpeed ~= 0

			turbine.setActive(active)
			reactor.setActive(active)
			reactor.setAllControlRodLevels(0)

			if reactor.getEnergyProducedLastTick() >= turbine.getFluidFlowRateMax() or reactor.getFuelTemperature() > 1000 then
				reactor.setAllControlRodLevels(100)
			end

	end

	--turbine
   displayState(turbine, tSpeed)

   if tSpeed ~= 0 then
      -- calculate PID controller
      local speed = turbine.getRotorSpeed()

      err = tSpeed - speed
      local errSumOld = errSum
      errSum = errSum + err

      if useDisengageCoils
         and floatRateChanged
         and err > 0
         and turbine.setInductorEngaged
      then
         -- Turbine startup: disengage coils
         turbine.setInductorEngaged(false)
      end

      if turbine.setInductorEngaged and err < 0 then
         -- speed too fast: engage coils
         turbine.setInductorEngaged(true)
      end

      local p = Kp * err
      local i = Ki * loopT * errSum
      local d = Kd * (err - errOld) * loopT

      if i < 0 or i > maxFRate then
         errSum=errSumOld -- error too heavy => reset to old value.
         i = Ki * loopT * errSum
      end

      local fRate = p + i + d
      errOld = err


      -- cut extreme flow rates.
      if fRate < 0 then
         fRate = 0
      elseif fRate > maxFRate then
         fRate = maxFRate
      end

      turbine.setFluidFlowRateMax(fRate)

      tID = os.startTimer(loopT) -- Wait for loopT secounds.
   else
      -- Turbine switched off:
      tID = os.startTimer(displayT) -- Wait for displayT secounds.
   end

   saveControllerState()
   floatRateChanged = false
   repeat
      -- Event loop
      local evt, p1, p2, p3, p4, p5 = os.pullEvent()
      if evt == "char" then
         -- character typed
         local oldTSpeed = tSpeed
         if p1 == "o" then -- off
            tSpeed = 0
            turbine.setActive(false)
            reactor.setActive(false)
            active = false
            saveControllerState()
         elseif p1 == "m" then -- medium speed = 900 RPM
            turbine.setActive(true)
            reactor.setActive(true)
            active = true
            tSpeed = 900
            floatRateChanged=true
         elseif p1 == "f" then -- fast speed = 1800 RPM
            turbine.setActive(true)
            reactor.setActive(true)
            active = true
            tSpeed = 1800
            floatRateChanged=true
         end

         if turbine.setInductorEngaged then
            -- engage coil by default
            turbine.setInductorEngaged(true)
         end


         if (p1 == "m" or p1 == "f") and tSpeed ~= oldTSpeed then
            -- Initialize PID controller values
            if Kp == 0 then
               Kp, loopT = testSpeedup(turbine, loopT, tSpeed)
            end

            initControllerValues()

            errSum = 0
            errOld = 0

            saveControllerState()
         end
      elseif evt == "modem_message"
         and stateRequestChannel >= 0
         and stateRequestChannel == p2
         and tostring(p4) == "BR_turbine_get_state"
      then
         -- Send status informations
         local cLabel = os.getComputerLabel()
         if cLabel == nil then
            -- No label: use coputer number (ID) as tio create a name
            cLabel = "ComputerID:" .. tostring(os.getComputerID())
         end

         if turbine.getInductorEngaged ~= nil then
            inductorEngaged = turbine.getInductorEngaged()
         else
            inductorEngaged = nil
         end

         -- State structure
         local rState = {
            version = "Turbine V0.1", -- Version of data structure
            label = cLabel,
            computerId = os.getComputerID(),
            remoteControl = remoteControl,
            active = turbine.getActive(),
            tSpeed = tSpeed,
            energyStored = turbine.getEnergyStored(),
            rotorSpeed = turbine.getRotorSpeed(),
            inputAmount = turbine.getInputAmount(),
            inputType = turbine.getInputType(),
            outputAmount = turbine.getOutputAmount(),
            outputType = turbine.getOutputType(),
            fluidAmountMax = turbine.getFluidAmountMax(),
            fluidFlowRate = turbine.getFluidFlowRate(),
            fluidFlowRateMax = turbine.getFluidFlowRateMax(),
            fluidFlowRateMaxMax = turbine.getFluidFlowRateMaxMax(),
            energyProducedLastTick = turbine.getEnergyProducedLastTick(),
            inductorEngaged = inductorEngaged
         }

         peripheral.call(p1, "transmit", p3, stateRequestChannel,
                         textutils.serialize(rState))
      elseif evt == "modem_message"
         and remoteControl
         and p2 == os.getComputerID()
         and string.sub(tostring(p4), 1, 21) == "BR_turbine_set_speed:"
      then
         -- Remote Request: Speed change
         local oldTSpeed = tSpeed
         tSpeed = tonumber(string.sub(tostring(p4), 22))
         if (tSpeed == 0) then
            turbine.setActive(false)
            saveControllerState()
         else
            turbine.setActive(true)
            floatRateChanged=true
         end

         if tSpeed ~= 0 and tSpeed ~= oldTSpeed then
            -- Initialize PID controller values
            if Kp == 0 then
               Kp = testSpeedup(turbine, loopT, tSpeed)
            end

            initControllerValues()

            errSum = 0
            errOld = 0

            saveControllerState()
         end

         if turbine.setInductorEngaged then
            -- engage coil by default
            turbine.setInductorEngaged(true)
         end
      elseif evt == "peripheral"
         and peripheral.getType(p1) == "modem"
         and stateRequestChannel >= 0
      then
         -- new modem connected
         peripheral.call(p1, "open", stateRequestChannel)
         peripheral.call(p1, "open", os.getComputerID())
      end

      -- exit loop on timer event or float rate change
   until (evt == "timer" and p1 == tID) or floatRateChanged
end

--
-- EOF
--