AzureQueue.py

"""
A simple, lightweight library for communicating with the Azure Queue Storage REST API.
Author Tim Hanewich, github.com/TimHanewich
Find updates to this code: https://github.com/TimHanewich/MicroPython-Collection/tree/master/AzureQueue

MIT License
Copyright 2024 Tim Hanewich
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""

import requests

def urljoin(part1:str, part2:str) -> str:
    """Combines two portions into a single URL, being mindful of repeating slashes."""
    if len(part1) == 0:
        return part2
    elif len(part2) == 0:
        return part1
    
    # strip out trailing
    if part1[len(part1) - 1] == "/":
        part1 = part1[:-1]
    
    # strip out leading
    if part2[0] == "/":
        part2 = part2[1:]

    return part1 + "/" + part2

def get_xml_tag(body:str, tag_name:str) -> str:
    """Strips out a value from the body based on the XML tag name it resides in."""
    try:
        i1:int = body.index("<" + tag_name + ">")
        i1:int = body.index(">", i1 + 1)
        i2:int = body.index("<", i1 + 1)
        return body[i1+1:i2]
    except:
        raise Exception("Unable to find XML tag '" + tag_name + "' in provided body.")

class QueueMessage:
    def __init__(self):
        self._id:str = None
        self._pop:str = None
        self._txt:str = None

    @property
    def MessageId(self) -> str:
        return self._id
    
    @MessageId.setter
    def MessageId(self, value) -> None:
        self._id = value

    @property
    def PopReceipt(self) -> str:
        return self._pop
    
    @PopReceipt.setter
    def PopReceipt(self, value) -> None:
        self._pop = value

    @property
    def MessageText(self) -> str:
        return self._txt
    
    @MessageText.setter
    def MessageText(self, value) -> None:
        self._txt = value

    def __repr__(self):
        return str({"MessageId": self.MessageId, "PopReceipt": self.PopReceipt, "MessageText": self.MessageText})


class QueueService:
    """Brokers communication with the Azure Queue REST API"""

    def __init__(self, queue_url:str, sas_token:str):
        """
        Creates a new instance of the QueueService class, ready to communicate with a specific queue within a specific Azure Storage Account.
        
        Parameters:
        queue_url (str): The URL directly to the Azure Storage Queue, i.e. "https://mystorageaccount.queue.core.windows.net/myqueue"
        sas_token (str): The Shared Access Signature (SAS) you get when generating in the Azure Portal. i.e. "sv=2022-11-02&ss=bfqt&srt=c&sp=rwdlacupiytfx&se=2024-11-30T19:34:10Z&st=2024-11-30T11:34:10Z&spr=https&sig=%2FKxtw%2FTzD0lXqj2kGyMuJ9Y0cFb16javsQb7Pz4b6KM%3D"
        """

        # ensure the URL has an actual queue name in it
        if "/" not in queue_url.lower().replace("https://", "").replace("http://", "") or queue_url[len(queue_url) - 1] == "/":
            raise Exception("You did not provide the URL to a specific Queue in the URL you provided. Ensure the URL you are providing is not only to a specific storage account, but also to a specific queue (i.e. '/myqueue' at the end)!")


        self._url = queue_url
        self._token = sas_token

    def put(self, text:str) -> None:
        """Adds a new message to the queue."""
        
        # construct body
        body:str = "<QueueMessage><MessageText>" + text + "</MessageText></QueueMessage>"

        # Make POST request
        post_url:str = urljoin(self._url, "messages") + "?" + self._token
        headers = {"Content-Type": "application/xml"}
        response = requests.post(post_url, headers=headers, data=body)
        
        # handle code?
        if response.status_code != 201:
            raise Exception("POST request to Azure Queue Service to upload message returned status code '" + str(response.status_code) + "', not the successful '201 CREATED'!")
        
    def receive(self) -> QueueMessage:
        """Receives the next message from the queue, but does NOT delete it."""

        # make get request
        get_url:str = urljoin(self._url, "messages") + "?" + self._token
        response = requests.get(get_url)
        response_body:str = response.text

        # handle error
        if response.status_code != 200:
            raise Exception("GET request to receive queue message returned status code " + str(response.status_code) + "! Body: " + response_body)

        # if there was no queue messages left
        if "<QueueMessagesList />" in response_body: # an empty list
            return None
        
        # get data from response body
        ToReturn:QueueMessage = QueueMessage()
        ToReturn.MessageId = get_xml_tag(response_body, "MessageId")
        ToReturn.PopReceipt = get_xml_tag(response_body, "PopReceipt")
        ToReturn.MessageText = get_xml_tag(response_body, "MessageText")
        return ToReturn
    
    def delete(self, message_id:str, pop_receipt:str) -> None:
        """Deletes a message from the queue."""

        # make DELETE request
        delete_url:str = urljoin(urljoin(self._url, "messages"), message_id) + "?popreceipt=" + pop_receipt.replace("+", "%2B") + "&" + self._token
        response = requests.delete(delete_url)

        # handle error
        if response.status_code != 204: # when successful, it returns 204 NO CONTENT
            response_body:str = response.text
            raise Exception("Deletion of message '" + message_id + "' was unsuccessful! Status code '" + str(response.status_code) + "' was returned. Body: " + response_body)

    def clear(self) -> None:
        """Clears the queue of all messages"""

        # make DELETE request
        delete_url:str = urljoin(self._url, "messages") + "?" + self._token
        response = requests.delete(delete_url)

        # handle error
        if response.status_code != 204: # when successful, it returns 204 NO CONTENT
            response_body:str = response.text
            raise Exception("Clearing of queue was unsuccessful! Status code '" + str(response.status_code) + "' was returned. Body: " + response_body)