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lambda_handler.py
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lambda_handler.py
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import json
import cv2
import numpy as np
import paho.mqtt.client as mqtt
import boto3
from botocore.exceptions import ClientError
# jpeg layers color
BLUE, GREEN, RED = 0, 1, 2
# mqtt_broker_ip = "insert public ip of the broker"
def lambda_handler(event, context):
s3 = boto3.client('s3')
# read image from event object
file_meta = event['Records'][0]['s3']
event_image = file_meta['object']['key']
bucket_name = file_meta['bucket']['name']
image_local_path = "/tmp/"+event_image
s3.download_file(bucket_name, event_image, image_local_path)
img = cv2.imread(image_local_path)
if img is None:
return 1
# for each color compute the sum
red = np.sum(img[:, :, RED])
green = np.sum(img[:, :, GREEN])
blue = np.sum(img[:, :, BLUE])
del img # save some space
# total amount of color
base = (blue+green+red)
# percentage of each color in the image
red = int(red / base * 100)
green = int(green / base * 100)
blue = int(blue / base * 100)
# todo if the file doesn't exist then create it
# the json file contains the index of the images for each user
json_name="images.json"
json_path = "/tmp/"+json_name
json_images = {} # read the json file
# if the file exists, it is downloaded and loaded, otherwise it throws ClientError
# before it tries to open the file
try:
s3.download_file(bucket_name, "images.json", json_path)
with open(json_path, 'r') as fp:
json_images = json.load(fp)
except ClientError:
pass
user_code = event_image.split("_")[0]
img_data = {'name': event_image,
'red': red,
'green': green,
'blue': blue
}
stop = False
for users, macnames in json_images.items():
for macname in macnames.keys():
if user_code == macname: # append new data
json_images[users][user_code].append(img_data)
stop = True
break
# insert user for the first time if not already present
if not stop:
json_images['users'] = {user_code: [img_data]}
with open(json_path, 'w') as fp:
json.dump(json_images, fp)
# upload json file in the bucket
response = s3.upload_file(json_path, bucket_name, json_name)
client = mqtt.Client()
client.connect(mqtt_broker_ip)
client.publish(user_code, payload="{:02d}/{:02d}/{:02d}".format(red,green,blue))
return 0