-- ********* Nest API communication Module Version 1.0 Created by Erwin van der Zwart ********* --
-- Resident script on 60 seconds, if you call the API faster you can get blocked due API limits --
-- *************************************** SET PARAMETERS ************************************* --

-- !! DO NOT KEEP THIS ON FOR EACH RUN !! Create access token, run once with this parameter on true and set to 'false' when you have the access token. !! DO NOT KEEP THIS ON FOR EACH RUN !!
Create_Token = false

-- See further down the device settings in your account

-- *************************************** END PARAMETERS ************************************* --
-- *************************** MODULE TO RECEIVE AUT TOKEN NEEDED ONCE ************************ --

-- Load modules
require('json')
require('ssl.https')

if Create_Token == true then
  
  -- First time actions:
  -- 1 Create a developer account on https://developer.nest.com, !! use the same email address and password from your normal NEST account on https://home.nest.com/ !!
  -- 2 Create a product on https://developer.nest.com/products
  -- 3 Select permissions on device you want to control (read or read/write) and keep the field Redirect URI empty! Because we need PIN based ..
  -- 4 Fill in the text like: "Allows homeLYnk to control the thermostat" or something like that ..
  -- 5 Create product and open the details after creation
  -- 6 On the right are Product ID, Product Secret, Authorization URL and Access Token URL
  -- 7 Change inside this URL the word CLIENT_ID with the Product ID from previous step:  https://home.nest.com/login/oauth2?client_id=CLIENT_ID&state=FOO
  -- 8 The URL would look something like this: https://home.nest.com/login/oauth2?client_id=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx&state=FOO
  -- 9 Past the new URL in the browser, accept the agreement and copy the PIN code from the page (the pincode is valid for 1 time, if you fail next steps you might need to create a new one)
  --10 Fill in the next parameters:
  --11 Add your products in your normal NEST account on https://home.nest.com/

  Product_ID = 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx' -- Change to your Product ID revieved in step 6
  Product_Secret = 'xxxxxxxxxxxxxxxxxxxxxxxxx' -- Change to your Product Secret revieved in step 6
  Pincode = 'XXXXXXXX' -- Change to your pincode revieved in step 9 !! Can be used once !! See text step 9
 
  -- Receive Authentication string
  response = {}
  res, stat, hdrs = ssl.https.request({
    url = "https://api.home.nest.com/oauth2/access_token?client_id=" .. Product_ID .. "&code=" .. Pincode .. "&client_secret=" .. Product_Secret .. "&grant_type=authorization_code", 
    method = 'POST',
    sink = ltn12.sink.table(response),
  }) 

  -- Handle response
  if stat == 400 then
    log("Error, Pincode, Product_ID or Product_Secret is not valid, try with new pincode and check Id en Secret")
  elseif stat == 200 then
    response_table = json.decode(response[1])
    Access_Token = response_table.access_token
    log(Access_Token)
  else
    log(stat)
  end
end

-- Copy your access token from the log and past it here between the '':
  Access_Token = 'c.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'

-- **************************** DON'T CHANGE ANYTHING UNDER THIS LINE ************************* --
-- ************************** SCROLL DOWN TO ENTER THE DEVICE PARAMETERS ********************** --

-- function to update only on change
grp.updatechange = function(addr, value, dpt)
  if not cacheupdate then
    cacheupdate = {}
	end
  if value ~= cacheupdate[ addr ] then
    cacheupdate[ addr ] = value
		grp.update(addr, value, dpt)
	end
end

-- function write only on change
grp.writechange = function(addr, value, dpt)
  if not cachewrite then
    cachewrite = {}
	end
  if value ~= cachewrite[ addr ] then
    cachewrite[ addr ] = value
    grp.write(addr, value, dpt)
	end
end

-- function changed object value to Nest when using grp.writechange
grp.checkwritechange = function(addr, devtype, id, object)
  value = grp.getvalue(addr)
  -- Safety check to avoid wrong value on thermostat
  if object == 'target_temperature_c' then
    if value < 9 then 
      value = 9 
    end
    if value > 32 then 
      value = 32 
    end
  end
  reply = 150
  if cachewrite then
    if value ~= cachewrite[ addr ] then
      body_value = {[object] = value}
      body_value = json.encode(body_value)
      res = set_device(devtype, id, body_value)
      if res[1] == body_value then
        reply = 200
        cachewrite[ addr ] = value
      else
        reply = 403
      end
    end
  else
    reply = 100
  end
  return reply
end

-- function changed object value to Nest when using grp.updatechange
grp.checkupdatechange = function(addr, devtype, id, object)
  value = grp.getvalue(addr)
  -- Safety check to avoid wrong value on thermostat
  if object == 'target_temperature_c' then
    if value < 9 then 
      value = 9 
    end
    if value > 32 then 
      value = 32 
    end
  end
  if object == 'away_temperature_low_c' then
    if value < 4 then 
      value = 4 
    end
    if value > 21 then 
      value = 21 
    end
  end
  reply = 150
  if cacheupdate then
    if value ~= cacheupdate[ addr ] then
      body_value = {[object] = value}
      body_value = json.encode(body_value)
      res = set_device(devtype, id, body_value)
      if res[1] == body_value then
        reply = 200
        cacheupdate[ addr ] = value
      else
        reply = 403
      end
    end
  else
    reply = 100
  end
  return reply
end

-- If URL is not declared then create it (this is needed for keeping redirect URL in next loop)
if Nest_Url == nil then
	Nest_Url = 'https://developer-api.nest.com/devices.json?auth=' .. Access_Token .. ''
end

-- If URL is not declared then create it (this is needed for keeping redirect URL in next loop)
if Nest_Url_Structures == nil then
  Nest_Url_Structures = 'https://developer-api.nest.com/structures.json?auth=' .. Access_Token .. ''
end

-- Fuction to get device data from your NEST account
function request_devices()
	local url, res, stat, hdrs
  -- Make API call on default URL
  res, stat, hdrs = ssl.https.request(Nest_Url)
  -- Check if there is a redirect request from NEST server
  if stat == 307 then
    -- Replace basic Nest URL with redirect URL received from NEST
    if Nest_Url ~= hdrs.location then
      Nest_Url = hdrs.location
    end
    -- Redirect and make API call with new URL 
    res = ssl.https.request(Nest_Url)
  end
  return json.decode(res)
end

-- Fuction to get structures data from your NEST account
function request_structures()
	local url, res, stat, hdrs
  -- Make API call on default URL
  res, stat, hdrs = ssl.https.request(Nest_Url_Structures)
  -- Check if there is a redirect request from NEST server
  if stat == 307 then
    -- Replace basic Nest URL with redirect URL received from NEST
    if Nest_Url_Structures ~= hdrs.location then
      Nest_Url_Structures = hdrs.location
    end
    -- Redirect and make API call with new URL 
     res = ssl.https.request(Nest_Url_Structures)
  end
  return json.decode(res)
end

--log(Nest_Url)
--log(Nest_Url_Structures)

-- Fuction to set device data to your NEST account
function set_device(device, device_id, body_value)
	Nest_Device_Url = "https://developer-api.nest.com/devices/" .. device .. "/" .. device_id .. "?auth=" .. Access_Token
  response = {}
  res, stat, hdrs = ssl.https.request({ 
  	url = Nest_Device_Url, 
  	method = 'PUT', 
  	sink = ltn12.sink.table(response), 
  	headers = { 
  	['content-length'] = #body_value, 
  	['content-type'] = 'application/json', 
  	}, 
  source = ltn12.source.string(body_value), 
  })

  if stat == 307 then
     -- Replace basic Nest device URL with redirect URL received from NEST
    if Nest_Device_Url ~= hdrs.location then
      Nest_Device_Url = hdrs.location
    end 
    res, stat, hdrs = ssl.https.request({   
    	url = Nest_Device_Url, 
    	method = 'PUT', 
    	sink = ltn12.sink.table(response), 
    	headers = { 
    	['content-length'] = #body_value, 
    	['content-type'] = 'application/json', 
    }, 
    source = ltn12.source.string(body_value), 
    })
  end
  return response
end

-- Get device data from your NEST account
res, devices_data = pcall(request_devices)

if devices_data ~= nil then
 log(devices_data)
  for index, devicesdata in pairs(devices_data) do
    if devicesdata == 'blocked' then
      message = 'Communication with nest is blocked (devices), probably because there are to many API calls, please lower your script interval speed to 60 seconds'
      log(message)
      --grp.update('8/0/0', message)
    else
      message = 'Communication with nest is OK'
      log(message)
      --grp.update('8/0/0', message)
    end
    if devicesdata ~= nil then
    	for index1, devicessubdata in pairs(devicesdata) do
        
-- **************************** DON'T CHANGE ANYTHING ABOVE THIS LINE ************************* --
-- **************************** ENTER HERE THE NEST DEVICE PARAMETERS ************************* --        
        
        --[[ DEVICE 1
        -- Setpoints Kantoor -- *************************************************************** --
        if devicessubdata.name == "Office (Kantoor)" then
          
          -- Make a read / write link to nest object target_temperature_c with update command to HL
          target_address = '8/0/1'
          res = grp.checkupdatechange(target_address, 'thermostats', devicessubdata.device_id, 'target_temperature_c')
          if res ~= 200 then
            grp.updatechange(target_address, devicessubdata.target_temperature_c, dt.float16)
          end
          
          -- Make a read only link to nest object devicessubdata.humidity with write command to HL
          grp.writechange('8/0/2', devicessubdata.ambient_temperature_c, dt.float16)
          
          -- Make a read only link to nest object devicessubdata.humidity with update command to HL
          grp.updatechange('8/0/3', devicessubdata.humidity, dt.scale)
          
          -- Make a read / write link to nest object away_temperature_low_c with write command to HL
          target_address = '8/0/4'
          res = grp.checkwritechange(target_address, 'thermostats', devicessubdata.device_id, 'away_temperature_low_c')
          if res ~= 200 then
            grp.writechange(target_address, devicessubdata.away_temperature_low_c, dt.float16)
          end
          
          -- Make a read only link to nest object devicessubdata.hvac_state with update command to HL
          grp.updatechange('8/0/5', devicessubdata.hvac_state, dt.string)
          
        end
        -- End Setpoints Kantoor -- *********************************************************** --
        
        -- DEVICE 2
        -- Setpoints Livingroom -- *************************************************************** --
        if devicessubdata.name == "Livingroom" then
          
          -- Make a read / write link to nest object target_temperature_c with update command to HL
          target_address = '8/0/11'
          res = grp.checkupdatechange(target_address, 'thermostats', devicessubdata.device_id, 'target_temperature_c')
          if res ~= 200 then
            grp.updatechange(target_address, devicessubdata.target_temperature_c, dt.float16)
          end
          
          -- Make a read only link to nest object devicessubdata.humidity with write command to HL
          grp.writechange('8/0/12', devicessubdata.ambient_temperature_c, dt.float16)
          
          -- Make a read only link to nest object devicessubdata.humidity with update command to HL
          grp.updatechange('8/0/13', devicessubdata.humidity, dt.scale)
          
          -- Make a read / write link to nest object away_temperature_low_c with write command to HL
          target_address = '8/0/14'
          res = grp.checkwritechange(target_address, 'thermostats', devicessubdata.device_id, 'away_temperature_low_c')
          if res ~= 200 then
            grp.writechange(target_address, devicessubdata.away_temperature_low_c, dt.float16)
          end
          
          -- Make a read only link to nest object devicessubdata.hvac_state with update command to HL
          grp.updatechange('8/0/15', devicessubdata.hvac_state, dt.string)
          
        end
        -- End Setpoints Kantoor -- *********************************************************** --
        
        -- DEVICE 3
        -- copy rules from above or create new ones, you can re-use the functions as above but check the function itself to be sure
        -- you don't write values that Nest can't handle
        ]]
-- **************************** DON'T CHANGE ANYTHING UNDER THIS LINE ************************* --        
      end
    end
  end
end

-- Get structures data from your NEST account
res, structures_data = pcall(request_structures)
--log(structures_data)
if structures_data ~= nil then
 --log(structures_data)
  for index, structuredata in pairs(structures_data) do
    if structuredata == 'blocked' then
      message = 'Communication with nest is blocked (structures), probably because there are to many API calls, please lower your script interval speed to 60 seconds'
      log(message)
      --grp.update('8/0/0', message)
    end
    if structuredata ~= nil then
      if structuredata.name == 'Woonkamer' then
        -- Make a read only link to nest object devicessubdata.hvac_state with update command to HL
          --grp.updatechange('8/0/6', structuredata.away, dt.string)
        log(structuredata.away, dt.string)
      end
      for index1, structuresubdata in pairs(structuredata) do
-- **************************** DON'T CHANGE ANYTHING ABOVE THIS LINE ************************* --
-- **************************** ENTER HERE THE NEST DEVICE PARAMETERS ************************* --   
      --log(structuresubdata)
      
-- **************************** DON'T CHANGE ANYTHING UNDER THIS LINE ************************* -- 
      end
    end
  end
end