import json
import datetime
import sys
import boto3
import decimal
from boto3.dynamodb.conditions import Key, Attr
dynamodb_client = boto3.resource('dynamodb')
import re
import os

class Product(object):
    def __init__(self, ProductId, Quantity,UnitPrice,Size, Color,State):
        self.ProductId = ProductId
        self.Quantity = Quantity
        self.UnitPrice = UnitPrice
        self.Size = Size
        self.Color = Color
        self.State = State
      
def lambda_handler(event, context):

    """Sample Lambda function which mocks the operation of business process post receiving price adjustment .

    For demonstration purposes, this Lambda function does not actually perform any
    actual transactions. It simply retrives the quantity and adds it to available quantity.

    Parameters
    ----------
    event: 
        Input product inventory event to the Lambda function

    context: object, required
        Lambda Context runtime methods and attributes

    Returns
    ------
        product_id, event json, timestamp and updated product json
    """
 
    inputEvent=event.get("ProductEvent")
    productId = inputEvent.get("productId")
    unitPrice = inputEvent.get("unitPrice")
    event_store_table=os.environ["EVENT_STORE_TABLE"]
   
    #check if record with input product_id already exists in the product event store
    table = dynamodb_client.Table(event_store_table)
    response = table.query(KeyConditionExpression=Key('Product_Id').eq(productId))
    items = response['Items']

    if items:
        for item in items:
            productDetails = item['Product_Details']
            productJson =json.loads (productDetails)
            productObject = Product(**productJson)
            productObject.UnitPrice=unitPrice
            newProductJson=json.dumps(productObject.__dict__)
    else:
        productObject = Product(inputEvent.get("productId"),inputEvent.get("quantity"),inputEvent.get("unitPrice"),inputEvent.get("size"),inputEvent.get("color"),"Available")
        newProductJson = json.dumps(productObject.__dict__)
        
   
    response = {
            "statusCode": 200,
            "Product_Id" : productId,
            "UpdatedProduct" : newProductJson,
            "Event" : str(inputEvent),
            "EventDateTime" : datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
            }

    return response