# Termi2 v0.5
# by Cameron Coward
# www.cameroncoward.com
# 11/10/22
#
# ESP32-based serial virtual assistant for TI Silent 700 terminals
# Ask questions, get answers!
# Utilizes Wolfram Alpha Simple Questions API

from machine import UART
from machine import Pin
import machine
import esp
import esp32
import urequests as requests
import os
import re
import time

reading_uart = False #becomes True when receiving bytes from UART
onboard_led = machine.Pin(2, machine.Pin.OUT) #LED for indicating WiFi connection
onboard_led.value(0) #start with LED off
uart2 = UART(2, baudrate=300, bits=7, parity=1, stop=1, timeout=5000, tx=17, rx=16, flow=0, txbuf=0, invert=UART.INV_TX | UART.INV_RX) #create UART

def do_connect():
    #open text file to pull network credentials, if they exist
    file = open("creds.txt")
    cred_string = file.read()
    creds = cred_string.split(",")
    file.close()
    
    #activate and config WLAN
    import network
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.config(reconnects=50)
    
    
    if (len(cred_string) > 2): #check if at least two characters were in file
        if not wlan.isconnected():
            wlan.connect(creds[0], creds[1])
    else:
        connect_failed()
    tries = 0 #reset connection attempt counter
    while not wlan.isconnected(): #loops until WiFi connection established or after 100 loops
        time.sleep(0.25) #wait a quarter second
        tries = tries + 1
        if tries > 100:
            connect_failed()
    
    onboard_led.value(1) #turns LED on to indicate WiFi connected
    enter_question() #let user ask a question

def ask_question(query):
    res = requests.get(url=query) #get results from Wolfram Alpha
    uart_output(res.text) #print results
    enter_question() #let user ask another question

def enter_question():
    question = uart_input("Ask Termi2: ") #get question string from user
    question = re.sub(r"[^a-zA-Z0-9 ]", "", question) #remove all special characters
    question = question.replace(' ', '+') #change to Wolfram Alpha API URL format
    # ****************** ENTER YOUR APP ID ON THE LINE BELOW!!! 
    query = 'http://api.wolframalpha.com/v1/result?appid=YOUR APP ID HERE&i=' + question #add question to API app URL... ENTER YOUR APP ID!
    ask_question(query) #pass query string to function for sending API request
    
def uart_input(prompt_str):
    uart_output(prompt_str) #print the passed string
    reading_uart = True
    uart_input_str = '' #start with an empty string
    while reading_uart == True:
        input_byte = uart2.read(1) #read a single byte
        
        if input_byte:
            cr_str = "\r" #carriage return
            cr_byte = cr_str.encode('utf-8') #encode carriage return as byte
            if input_byte == cr_byte: #check if the received byte is a carriage return
                reading_uart = False
            else:
                input_str = input_byte.decode('utf-8') #decode input byte
                uart_input_str = uart_input_str + input_str #add character to string with full input text

    return uart_input_str

def uart_output(message):
    uart2.write('   \n \n \r')
    line_count = 0
    for c in message:
        if line_count > 74:
            uart2.write('   \n \n \r')
            line_count = 0
        uart2.write(c)
        line_count+=1

    uart2.write('   \n \n \r')
    
def connect_failed():
    uart_output("Unable to connect to WiFi. Enter new credentials by opening creds.txt file in flash memory and format as 'SSID,password' ")
    pause_indefinitely = True
    blink_led_counter = 0
    while pause_indefinitely:
        blink_led_counter+=1
        time.sleep(0.1)
        if blink_led_counter < 5:
            onboard_led.value(1)
        elif blink_led_counter < 10:
            onboard_led.value(0)
        else:
            blink_led_counter = 0
    
do_connect()