backend.py

"""
Provides backend for GUI Smart Bin App
"""

from datetime import datetime
import sqlite3
import json
import uuid
import boto3
import RPi.GPIO as GPIO
from time import sleep
from config import (
    AWS_DYNAMODB_ENDPOINT,
    AWS_REGION,
    CREDENTIALS_FILE,
    OUTPUT_PINS,
    SQLITE_DB_LOCATION,
    SQLITE_INIT_FILE,
    TABLE_NAME,
)
from item import Item


class Backend:
    """Provides backend for GUI Smart Bin App"""

    # ============================ Private Methods ============================

    def __init__(self, gui):
        self.gui = gui

        # Setup Raspberry Pi Connection
        GPIO.setmode(GPIO.BCM)
        GPIO.setup(OUTPUT_PINS[0], GPIO.OUT)
        GPIO.setup(OUTPUT_PINS[1], GPIO.OUT)
        GPIO.setup(OUTPUT_PINS[2], GPIO.OUT)
        GPIO.setup(OUTPUT_PINS[3], GPIO.OUT)

        # Setup SQLite database
        self.db_connection = sqlite3.connect(SQLITE_DB_LOCATION)
        self.__init_db(SQLITE_INIT_FILE)

        # Setup DynamoDB connection

        f = open(CREDENTIALS_FILE, encoding="UTF8")
        aws_creds = json.load(f)
        f.close()

        self.dynamodb = boto3.resource(
            "dynamodb",
            region_name=AWS_REGION,
            #endpoint_url=AWS_DYNAMODB_ENDPOINT, Testing only
            aws_access_key_id=aws_creds["Access key ID"],
            aws_secret_access_key=aws_creds["Secret access key"],
        )
        self.__init_dynamodb()

    def __init_dynamodb(self):
        table_names = [table.name for table in self.dynamodb.tables.all()]

        if TABLE_NAME not in table_names:
            print("Creating DynamoDB table")
            self.dynamodb.create_table(
                TableName=TABLE_NAME,
                KeySchema=[{"AttributeName": "Id", "KeyType": "HASH"}],
                AttributeDefinitions=[
                    {"AttributeName": "Id", "AttributeType": "S"},
                ],
                ProvisionedThroughput={
                    "ReadCapacityUnits": 1,
                    "WriteCapacityUnits": 1,
                },
            )
            print("DynamoDB table created")

    def __init_db(self, init_file):

        # Load JSON
        f = open(init_file, encoding="UTF8")
        item_data = json.load(f)
        f.close()

        cursor = self.db_connection.cursor()

        # Create table
        cursor.execute(
            """CREATE TABLE items (
                name text,
                barcode text,
                notes text,
                bin integer
            )"""
        )
        self.db_connection.commit()

        # Iterate over items in item_data, inserting each item
        for item in item_data["items"]:
            self.__insert_item(
                item["name"], item["barcode"], item["notes"], item["bin"]
            )

    def __del__(self):
        print("Cleaning up backend...")

        print("CURRENT DATABASE DATA:")
        cursor = self.db_connection.cursor()
        cursor.execute("SELECT * FROM items")
        print(cursor.fetchall())

        self.db_connection.close()

    def __retrieve_item(self, item_input):
        cursor = self.db_connection.cursor()
        cursor.execute(
            f"SELECT * FROM items WHERE name LIKE '%{item_input.lower()}%' OR barcode='{item_input}'"
        )
        item = cursor.fetchone()

        if not item:
            return None

        return item

    def __insert_item(self, name="", barcode="", notes="", bin_number=-1):
        if bin_number == -1:
            raise Exception("Bin Number must be specified and within range 0-3")

        new_item = Item(
            name=name.lower(),
            barcode=barcode,
            notes=notes,
            bin_number=bin_number,
        )
        cursor = self.db_connection.cursor()
        cursor.execute(
            "INSERT INTO items VALUES (:name, :barcode, :notes, :bin)",
            {
                "name": new_item.name,
                "barcode": new_item.barcode,
                "notes": new_item.notes,
                "bin": new_item.bin,
            },
        )
        self.db_connection.commit()
    
    def __log_disposal(self, name, bin_number):
         table = self.dynamodb.Table(TABLE_NAME)
         
         table.put_item(Item={
             "Id": str(uuid.uuid4()),
             "Time": datetime.utcnow().isoformat(),
             "Name": name,
             "BinNumber": bin_number
         })

    def __highlight_bin(self, bin_number):
        if bin_number == 0:
            GPIO.output(OUTPUT_PINS[0], GPIO.HIGH)
            sleep(5)
            GPIO.output(OUTPUT_PINS[0], GPIO.LOW)
        elif bin_number == 1:
            GPIO.output(OUTPUT_PINS[1], GPIO.HIGH)
            sleep(5)
            GPIO.output(OUTPUT_PINS[1], GPIO.LOW)
        elif bin_number == 2:
            GPIO.output(OUTPUT_PINS[2], GPIO.HIGH)
            sleep(5)
            GPIO.output(OUTPUT_PINS[2], GPIO.LOW)
        elif bin_number == 3:
            GPIO.output(OUTPUT_PINS[3], GPIO.HIGH)
            sleep(5)
            GPIO.output(OUTPUT_PINS[3], GPIO.LOW)
        else:
            print(f'Error highlighting bin: Bin number "{bin_number}" does not exist.')

    def __clear_input(self):
        self.gui.input_box.delete(0, 'end')
    # ============================ Public Methods =============================

    def process_item(self, event=None):
        # Fetch text entry from input
        item_input = self.gui.input_text.get()
        item = self.__retrieve_item(item_input)
        if not item:
            print(f"Item corresponding to {item_input} does not exist")
            return

        self.__log_disposal(item[0], item[3])
        self.__highlight_bin(item[3])
        self.__clear_input()