.preload

-- Source code for the tutorial:
-- https://realtimelogic.com/articles/Your-First-Embedded-Single-Page-Application

-- Import and abreviate the string formatting function for later use.
local fmt=string.format

-- Table to keep track of connected SPA clients.
-- Key is the socket ('sock') and the value is a JSONS instance.
-- JSONS: https://realtimelogic.com/ba/doc/?url=lua.html#JSONS
local clients={}

-- Import the Serpent library for pretty-printing tables.
local serpent=require"serpent"
-- Print JSON message: name, payload, where payload is a Lua table
local function printMsg(msg,pl)
   tracep(false,5,msg,serpent.block(pl,{comment=false}))
end

-- If the 'esp32' global variable is not defined, simulate the GPIO for ESP32.
-- Used when running on the Mako Server.
if not esp32 then
   tracep(false,0,"Installing GPIO ESP32 simulator")

   local G={} -- G: GPIO API
   G.__index=G

   function G:close()
      tracep(false,5,"closing GPIO", self.pin)
   end

   -- Set or get the value of the simulated GPIO.
   function G:value(val)
      if val ~= nil then
         self.state=val
         tracep(false,5,"Set GPIO:value",self.pin,val)
         return true
      end
      return self.state
   end

   -- Create a simulated ESP32 environment.
   local esp32={}
   _G.esp32=esp32

   -- Simulate the GPIO pin creation for ESP32.
   function esp32.gpio(pin)
      return setmetatable({pin=pin},G)
   end
end

-- Send a message to one or all connected clients (SPAs)
-- msg: Message name
-- payload: string or table
-- js: JSONS instance. Used when sending a message to one client.
local function sendMsg(msg, payload, js)
   printMsg("Sending: "..msg,payload)
   local data={msg,payload}
   if js then -- unicast
      js:put(data)
   else -- multicast
      for sock,js in pairs(clients) do
         js:put(data)
      end
   end
end

-- Define the LED configurations used by the SPA for building the LED UI.
local ledsInfo={
   {
      name="LED1",
      id=1,
      color="red",
   },
   {
      name="LED2",
      id=2,
      color="green",
   },
   {
      name="LED3",
      id=3,
      color="blue",
   },
   {
      name="LED4",
      id=4,
      color="yellow",
   },
}

-- Function to configure a button with an interrupt driven callback.
local function cfgButton(pin,cb)
   local cfg={
      pulldown=true,
      type="POSEDGE",
      callback=cb
   }
   return esp32.gpio(pin,"IN", cfg)
end

-- Table to store LED data. Initialized below.
local ledsData

-- Called when a button is clicked; See ledsData below.
local function buttonClick(index, on)
   tracep(false,5,"Button",index)
   local ledObj = ledsData[index]
   if nil == on then -- if arg 'on' not provided
      ledObj.state = not ledObj.state -- toggle
   else
      ledObj.state = not on -- inverse
   end
   ledObj.led:value(ledObj.state) -- set LED
   sendMsg("setled", {id = index, on = not ledObj.state})
end

local function cfgLed(pin)
   local led=esp32.gpio(pin,"OUT")
   led:value(true) -- Set high: led off
   return led
end

-- Initialize the LED data.
ledsData={
   {
      state=true,
      button=cfgButton(9, function() buttonClick(1) end),
      led=cfgLed(1)
   },
   {
      state=true,
      button=cfgButton(8, function() buttonClick(2) end),
      led=cfgLed(2)
   },
   {
      state=true,
      button=cfgButton(7, function() buttonClick(3) end),
      led=cfgLed(3)
   },
   {
      state=true,
      button=cfgButton(44,function() buttonClick(4) end),
      led=cfgLed(4)
   },
}


-- Function to get the IO (Input/Output) interface.
-- If the 'mako' global variable is defined, use the 'home' IO,
-- otherwise use the 'disk' IO.
local function getIO()
   return mako and ba.openio"home" or  ba.openio"disk"
end

-- Function to hash a password using the SHA1 algorithm.
local function hashPwd(pwd)
   return ba.crypto.hash"sha1"(pwd)(true)
end

-- Function to retrieve stored credentials.
-- If no credentials are stored, return the default values root/password.
local function getCredentials()
   local fp <close> = getIO():open"credentials.json"
   if fp then
      local cred = ba.json.decode(fp:read"*a")
      if cred then return cred.uname,ba.b64decode(cred.pwd) end
   end
   -- Default
   return "root", hashPwd"password"
end

-- AJAX requests managed by server code
-- Tutorial: https://makoserver.net/articles/AJAX-over-WebSockets
local ajaxRequests={
   ["math/add"]=function(req)      return req[1] + req[2] end,
   ["math/subtract"]=function(req) return req[1] - req[2] end,
   ["math/mul"]=function(req)      return req[1] * req[2] end,
   ["math/div"]=function(req)
      if req[2] == 0 then return nil,"Divide by zero!" end
      return req[1] / req[2]
   end,
   ["auth/setcredentials"]=function(req)
      local uname, shaPwd = getCredentials()
      local reqUname, reqShaPwd = req[1], hashPwd(req[2])
      if uname==reqUname and shaPwd==reqShaPwd then
         local newUname, newShaPwd = req[3], hashPwd(req[4])
         local fp <close> = getIO():open("credentials.json","w")
         if fp then
            fp:write(ba.json.encode{uname=newUname,pwd=ba.b64encode(newShaPwd)})
            return true
         end
         return nil, "Cannot save credentials!"
      end
      return nil, "Incorrect account or password"
   end,
}

-- Find the AJAX request function in 'ajaxRequests' and call the function
local function ajax(msg)
   -- Ajax request name, AJAX response handle, payload
   local req,handle,pl=msg[1],msg[2],msg[3]
   -- payload is an array with two numbers
   if pl[1] == ba.json.null then pl[1]=0 end
   if pl[2] == ba.json.null then pl[2]=0 end
   -- Lookup and call AJAX function
   local rsp,err=ajaxRequests[req](pl)
   return "AJAX",{handle, rsp and {rsp=rsp} or {err=err}}
end

-- Called when a user clicks a LED button in the SPA
local function setled(msg)
   buttonClick(msg.id, msg.on)
end

-- Table with key (name: string) and value (SPA request handler: function)
-- Used by the "Main loop" below.
local requests={
   setled=setled,
   AJAX=ajax
}

-- Store the simulated temperature. Initialized in the 'tempManager' function.
local temperature
-- send the current temperature to client(s). All clients if js not provided.
local function sendTemperature(js)
   sendMsg("settemp", temperature, js)
end

-- Called when we receive a binary WebSocket frame. Binary messages
-- are used for uploading firmware.
local function recFirmware()
   local BinMsg_Upload <const> = 1
   local BinMsg_UploadEOF <const> = 2
   local io=getIO()
   local fp,ok,err,binMsg,frameCounter

   local function closeOnErr(js,err)
      tracep(false,0,"Firmware upload error:",err)
      -- Close socket, see internals in JSONS.lua
      js._sock:close()
      if fp then fp:close() fp=nil end
   end

   return function(data,bytesRead,frameLen,js)
      if not fp then
         tracep(false,5,"Opening FIRMWARE.bin")
         fp,err=io:open("FIRMWARE.bin","wb")
         if not fp then
            return closeOnErr(js,fmt("Cannot open %s: %s",io:realpath("FIRMWARE.bin", err)))
         end
         frameCounter,binMsg=0,nil
      end
      -- eom: end of message (websocket frame)
      local eom = not bytesRead or bytesRead == frameLen
      if not binMsg then
         binMsg=data:byte(1)
         data=data:sub(2,-1) -- remainder
      end
      ok,err=fp:write(data)
      if not ok then return closeOnErr(js,fmt("Writing failed: %s",err)) end
      frameCounter=frameCounter+1
      sendMsg("uploadack", frameCounter, js)
      if eom then
         if BinMsg_UploadEOF == binMsg then
            tracep(false,5,"Closing FIRMWARE.bin")
            fp:close()
            fp=nil
         end
         binMsg=nil -- Reset
      end
   end
end

-- Called by code in index.lsp when a new SPA client connects.
function newClient(sock)
   tracep(false,5,"New client", sock)

   local uname,shaPwd = getCredentials()
   -- JSONS: https://realtimelogic.com/ba/doc/?url=lua.html#JSONS
   local js,err = require("JSONS").create(sock, {
                                             maxsize=2048,
                                             bincb=recFirmware()
                                          })

   -- Designed for receiving JSON with: [message,payload]
   -- Returns: message,payload
   local function recMsg()
      local msg = js:get()
      if msg then -- msg is an array, where [1]=message name, [2]=payload
         printMsg("Received: "..msg[1],msg[2])
         return msg[1],msg[2]
      end
   end

   -- Sent to the SPA when it connects.
   local function sendLedInfo()
      sendMsg("ledinfo",{leds=ledsInfo}, js)
      for ix,ledObj in ipairs(ledsData) do
         sendMsg("setled", {id = ix, on = not ledObj.state}, js)
      end
   end

   sendMsg("devname",esp32 and "ESP32" or "simulator") -- First message
   local authenticated=false
   while not authenticated do -- Authentication loop
      local nonce = ba.rndbs(12)
      sendMsg("nonce",ba.b64encode(nonce), js)
      local msg,payload=recMsg()
      if not msg then break end
      if "auth" == msg and
         payload.name == uname and
         payload.hash == ba.crypto.hash"sha1"(shaPwd)(nonce)(true,"hex") then
         authenticated=true
         sendLedInfo()
         sendTemperature(js)
      else
         nonce = ba.rnds(12)
         sendMsg("nonce",ba.b64encode(nonce), js)
      end
   end
   
   clients[sock]=js -- Register SPA
   while true do -- Main loop
      local msg,payload=recMsg()
      if not msg then break end
      msg,payload=requests[msg](payload)
      -- Send unicast message if AJAX response
      if msg then sendMsg(msg, payload, "AJAX" == msg and js) end
   end
   clients[sock]=nil -- Deregister SPA
   tracep(false,5,"Closing client connection")
end

-- Timer coroutine used for simulating temperature.
local function tempManager()
   while true do
      temperature=0
      while true do
         sendTemperature()
         temperature = temperature + ba.rnd(5,100)
         if temperature > 1000 then break end
         coroutine.yield(true)
      end
      temperature=1000
      while true do
         sendTemperature()
         temperature = temperature - ba.rnd(5,200)
         if temperature < 0 then break end
         coroutine.yield(true)
      end
   end
end

tempTimer=ba.timer(tempManager)
tempTimer:set(5000)

-- Clean up resources when the script is unloaded.
function onunload()
   for ix,ledObj in ipairs(ledsData) do
      ledObj.button:close()
      ledObj.led:close()
   end
   for sock in pairs(clients) do
      sock:close()
   end
end