--
-- Test script for the MSP/SPORT bridge
--

-- Protocol version
SPORT_MSP_VERSION = 1

-- Sensor ID used by the local LUA script
LOCAL_SENSOR_ID  = 0x0D

-- Sensor ID used by the MSP server (BF, CF, MW, etc...)
REMOTE_SENSOR_ID = 0x1B

REQUEST_FRAME_ID = 0x30
REPLY_FRAME_ID   = 0x32

-- Sequence number for next MSP/SPORT packet
local sportMspSeq = 0
local sportMspRemoteSeq = 0

local mspRxBuf = {}
local mspRxIdx = 1
local mspRxCRC = 0
local mspStarted = false
local mspLastReq = 0

-- Stats
mspRequestsSent    = 0
mspRepliesReceived = 0
mspPkRxed = 0
mspErrorPk = 0
mspStartPk = 0
mspOutOfOrder = 0
mspCRCErrors = 0

local function mspResetStats()
   mspRequestsSent    = 0
   mspRepliesReceived = 0
   mspPkRxed = 0
   mspErrorPk = 0
   mspStartPk = 0
   mspOutOfOrderPk = 0
   mspCRCErrors = 0
end

local function mspSendRequest(cmd)

   local dataId = 0
   dataId = sportMspSeq                                -- sequence number
   dataId = dataId + bit32.lshift(1,4)                 -- start flag
   dataId = dataId + bit32.lshift(SPORT_MSP_VERSION,5) -- MSP/SPORT version
   -- size is 0 for now, no need to add it to dataId
   -- dataId = dataId + bit32.lshift(0,8)
   sportMspSeq = bit32.band(sportMspSeq + 1, 0x0F)
   
   local value = 0
   value = bit32.band(cmd,0xFF)        -- MSP command
   value = value + bit32.lshift(cmd,8) -- CRC

   mspLastReq = cmd
   mspRequestsSent = mspRequestsSent + 1
   return sportTelemetryPush(LOCAL_SENSOR_ID, REQUEST_FRAME_ID, dataId, value)
end

local function mspReceivedReply(payload)

   mspPkRxed = mspPkRxed + 1
   
   local idx      = 1
   local head     = payload[idx]
   local err_flag = (bit32.band(head,0x20) ~= 0)
   idx = idx + 1

   if err_flag then
      -- error flag set
      mspStarted = false

      mspErrorPk = mspErrorPk + 1

      -- return error
      -- CRC checking missing

      --return payload[idx]
      return nil
   end
   
   local start = (bit32.band(head,0x10) ~= 0)
   local seq   = bit32.band(head,0x0F)

   if start then
      -- start flag set
      mspRxIdx = 1
      mspRxBuf = {}

      mspRxSize = payload[idx]
      mspRxCRC  = bit32.bxor(mspRxSize,mspLastReq)
      idx = idx + 1
      mspStarted = true
      
      mspStartPk = mspStartPk + 1

   elseif not mspStarted then
      mspOutOfOrder = mspOutOfOrder + 1
      return nil

   elseif bit32.band(sportMspRemoteSeq + 1, 0x0F) ~= seq then
      mspOutOfOrder = mspOutOfOrder + 1
      mspStarted = false
      return nil
   end

   while (idx <= 6) and (mspRxIdx <= mspRxSize) do
      mspRxBuf[mspRxIdx] = payload[idx]
      mspRxCRC = bit32.bxor(mspRxCRC,payload[idx])
      mspRxIdx = mspRxIdx + 1
      idx = idx + 1
   end

   if idx > 6 then
      sportMspRemoteSeq = seq
      return
   end

   -- check CRC
   if mspRxCRC ~= payload[idx] then
      mspStarted = false
      mspCRCErrors = mspCRCErrors + 1
      return nil
   end

   mspRepliesReceived = mspRepliesReceived + 1
   mspStarted = false
   return mspRxBuf
end

local function mspPollReply()
   while true do
      local sensorId, frameId, dataId, value = sportTelemetryPop()
      if sensorId == REMOTE_SENSOR_ID and frameId == REPLY_FRAME_ID then

         local payload = {}
         payload[1] = bit32.band(dataId,0xFF)
         dataId = bit32.rshift(dataId,8)
         payload[2] = bit32.band(dataId,0xFF)

         payload[3] = bit32.band(value,0xFF)
         value = bit32.rshift(value,8)
         payload[4] = bit32.band(value,0xFF)
         value = bit32.rshift(value,8)
         payload[5] = bit32.band(value,0xFF)
         value = bit32.rshift(value,8)
         payload[6] = bit32.band(value,0xFF)

         return mspReceivedReply(payload)
      else
         break
      end
   end
end

local lastReqTS = 0

local function run(event)

   local now = getTime()

   if event == EVT_MINUS_FIRST or event == EVT_ROT_LEFT or event == EVT_MINUS_REPT then
      mspResetStats()
   end

   lcd.clear()
   lcd.drawText(41,1,"MSP/SPORT test script",INVERS)
   
   -- do we have valid telemetry data?
   if getValue("RSSI") > 0 then

      -- draw screen
      lcd.drawText(1,11,"Requests:",0)
      lcd.drawNumber(60,11,mspRequestsSent)
   
      lcd.drawText(1,21,"Replies:",0)
      lcd.drawNumber(60,21,mspRepliesReceived)

      lcd.drawText(1,31,"PkRxed:",0)
      lcd.drawNumber(60,31,mspPkRxed)

      lcd.drawText(1,41,"ErrorPk:",0)
      lcd.drawNumber(60,41,mspErrorPk)

      lcd.drawText(91,31,"StartPk:",0)
      lcd.drawNumber(160,31,mspStartPk)

      lcd.drawText(91,41,"OutOfOrder:",0)
      lcd.drawNumber(160,41,mspOutOfOrder)

      lcd.drawText(1,51,"CRCErrors:",0)
      lcd.drawNumber(60,51,mspCRCErrors)

      -- last request is at least 2s old
      if lastReqTS + 200 <= now then
         mspSendRequest(117) -- MSP_PIDNAMES
         lastReqTS = now
      end
   else
      lcd.drawText(15,20,"No telemetry signal", BLINK + DBLSIZE)
   end

   mspPollReply()
end

return {run=run}