#!/usr/bin/env python2
#
import time
import os
from GPIO import GPIO as GP
import urllib2

"""
This script is run via an SSH forced command that is tied to a
particular user and public/private key pair.

Commands are read using the original ssh command and are therefore
available to this script via the SSH_ORIGINAL_COMMAND environment
variable.

A set of valid commands are whitelisted and the passed command is
checked against this list using an if-formatted case pattern.
All commands result in a return of the new state of all LEDs (an
implied new status command).

LEDs are numbered 1, 2, 3, and 4 on the android app's user interface, 
so as to be user friendly.  Don't confuse the 0 based array index in
ledState with the LED number.

LED numbers are passed as an argument to the command.  There is
a space separating the command from its LED arguments.  The
LED argument is a comma delimited list of one or more numbers
representing the LEDs to operate on.  Examples:  

 3
 2,4
 1,2,3,4

The ALL argument can be used to have the command operate on
all LEDs.  It is a short cut way of specifying 1,2,3,4.

Commands are:

STATUS
 - return a pattern indicating LED state (on/off)
 - also returns a temperature and humidity from a networked
   arduino sensor.

The returned string is a JSON formatted array indicating
the state of each LED, 0 (LOW) respresenting OFF and 1 (HIGH) representing ON.
The array's first element represents the first LED which is usually
pin 21 on the beaglebone black (BBB).  The remaining elements are
the rest of the pins 22, 23, and 24 in order (i.e. LED numbers 1 
through 4).

A sample returned string is as follows (JSON array):

  [0, 1, 0, 0, 20, 25]
Above, the LED on pin 22 (LED 2) is lit up, while the other three LEDs are
off.  The temperature is 20C and the humidity is 25%.


OFF ALL
 - set all LEDs to off.

ON ALL
 - set all LEDs to on.

OFF n1[,n2,...]
 - set numbered LEDs to off.

ON n1[,n2,...]
 - set numbered LEDs to on.

"""

# The controller that has the 4 user LEDs is given the number 1 as in
# /dev/gpioc1

GPIO_CONTROLLER = 1
LOW = 0
HIGH = 1

leftBracket = "["
rightBracket = "]"

temperature = -999
humidity = -999

def JSONstate(leftDelimiter = "[", state_array = [], rightDelimiter = "]"):
  state_string = ", ".join([str(i) for i in state_array])
  return "".join([leftDelimiter, state_string, rightDelimiter])

def getSensorData():
    global temperature, humidity
    try:
        response = urllib2.urlopen('http://192.168.1.177/', timeout=1)
        html = response.read()
        temperature, humidity = html.split(" ")
    except urllib2.URLError, e:
        pass

pinBus = GP.GPIO(GPIO_CONTROLLER)
numPins = 4
ledPins = [21, 22, 23, 24]
ledNums = [1, 2, 3, 4]
ledState = [0, 0, 0, 0]

# Get the current state of the LEDs
for index, pin in enumerate(ledPins):
  ledState[index] = pinBus.pin_get(pin)

def get_pins_from_command(command):
  """
  Take the string command, split it on a single space, and then
  try and parse the LED number arguments.  Returns an empty list
  when things go wrong.  Ignores non numeric LED numbers.  
  The LED num argument is a comma separated list of LED numbers
  between 1 and 4 inclusive.  
  """
  command_parts = command.split(" ")
  if(len(command_parts) != 2):
    print("Command parts not equal to 2: ", command)
    return []  # bad arguments, bail, should complain TODO log

  else:
    possible_led_numbers = command_parts[1].split(",")
    num_led_args = len(possible_led_numbers)
    if (num_led_args <=0 or num_led_args > 4):
      print("Count of possible led numbers out of range: ", num_led_args)
      return []  # bad arguments, bail, should complain TODO log

    good_led_numbers = []

    for n in possible_led_numbers:
      try:
        num = int(n.strip())
      except ValueError:
        print("Value error on conversion of: ", n)
        continue
      if (num in ledNums):
        good_led_numbers.append(ledPins[num-1])

    return good_led_numbers

commandText = os.environ.get("SSH_ORIGINAL_COMMAND", "NONE")
#commandText = "STATUS"
#commandText = "OFF ALL"
#commandText = "ON ALL"
#commandText = "ON 1,4"

if (commandText == "STATUS" ):
  pass
     
elif (commandText == "ON ALL"):
  for index, pin in enumerate(ledPins):
    if (ledState[index] == LOW):
      pinBus.pin_set(pin, HIGH)

elif (commandText == "OFF ALL"):
  for index, pin in enumerate(ledPins):
    if (ledState[index] == HIGH):
      pinBus.pin_set(pin, LOW)

elif (commandText.startswith("ON ")):
  pin_args = get_pins_from_command(commandText)  # returns a list of pin numbers (21, ...)
  for index, pin in enumerate(pin_args):
    pinBus.pin_set(pin, HIGH)

elif (commandText.startswith("OFF ")):
  pin_args = get_pins_from_command(commandText)  # returns a list of pin numbers (21, ...)
  for index, pin in enumerate(pin_args):
    pinBus.pin_set(pin, LOW)

elif (commandText.startswith("VIDEO ")):
  print("Running video")
  exit()

else:
  pass # unknown command, this is a good item to log for security purposes TODO

getSensorData()

# Get the updated state of the LEDs
for index, pin in enumerate(ledPins):
  ledState[index] = pinBus.pin_get(pin)
ledState.append(temperature)
ledState.append(humidity)

# return the JSON status array to the android caller
print(JSONstate(leftBracket, ledState, rightBracket))