Take args from JSON post data

README.md

@@ -1,9 +1,47 @@
-# Merch Embedded 
-
+# Merch Embedded
 
 [![Join the chat at https://gitter.im/acm-uiuc/merch-development](https://badges.gitter.im/acm-uiuc/merch-development.svg)](https://gitter.im/acm-uiuc/merch-development?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
-Possible information sources:
+
+This repository contains all of the code related to controlling the underlying merch hardware (the vending machine).
+Merch runs an embedded webserver that can be accessed at merch.acm.illinois.edu.
+
+## API
+
+Requests to the device must contain a valid token in the Authorization Header for a request to be processed.
+As of now the only token will be given solely to the groot merch service, so if you wish to make merch requests go through groot.
+
+
+### Vend a location
+
+To vend a list of items, POST a request to `/vend`.
+The request is of the form
+```json
+{
+    "transaction_id": 1,
+    "items": ["A1", "B2", "C3"]
+}
+```
+
+The machine will respond with
+```json
+{
+    "transaction_id": 1,
+    "items": [
+        {"location": "A1", "error": null},
+        {"location": "B2", "error": "some sort of error"},
+        {"location": "C3", "error": null},
+
+    ]
+}
+```
+
+The errors that can take place while vending are currently:
+* `"Invalid location"`
+
+
+## Some related datasheets
+
 [http://bajavending.com/Manual-de-Operacion-BevMax.pdf](http://bajavending.com/Manual-de-Operacion-BevMax.pdf)
 * Has the right picture of the main controller board, no programming information though
 
@@ -18,15 +56,15 @@ has some useful info about what commands are sent
 
 ## License
 
-This project is licensed under the University of Illinois/NCSA Open Source License. For a full copy of this license take a look at the LICENSE file. 
+This project is licensed under the University of Illinois/NCSA Open Source License. For a full copy of this license take a look at the LICENSE file.
 
-When contributing new files to this project, preappend the following header to the file as a comment: 
+When contributing new files to this project, preappend the following header to the file as a comment:
 
 ```
 Copyright © 2017, ACM@UIUC
 
-This file is part of the Merch Project.  
- 
-The Merch Project is open source software, released under the University of Illinois/NCSA Open Source License. 
+This file is part of the Merch Project.
+
+The Merch Project is open source software, released under the University of Illinois/NCSA Open Source License.
 You should have received a copy of this license in a file with the distribution.
 ```

machine_controller/app.py

@@ -45,12 +45,28 @@
 def hello_world():
     if request.headers.get('TOKEN', '') != token_value:
         abort(401)
-    if 'item' not in request.args:
-        abort(400)
-    item = request.args['item']
-    merch.vend(item[0], int(item[1]))
-    return json.dumps({'success': True}), 200, {'ContentType': 'application/json'}
+    data = request.json()
+    items = data['items']
+    transaction_id = data['transaction_id']
+
+
+    statuses = []
+    for i, item in enumerate(items):
+        try:
+            merch.vend(item[0], int(item[1]))
+            statuses.append({'error': None, 'location': item})
+
+        except Exception as e:
+            # Some error occurred while vending
+            # I'd prefer to catch Merch.VendError's only, but if something else
+            # goes wrong, we still need to let the client know instead of
+            # throwing a 500
+            statuses.append({'error': str(e), 'location': item})
+
+    return jsonify(transaction_id=transaction_id, items=statuses)
 
 if __name__ == '__main__':
-    app.run(debug=True, host='0.0.0.0')
+    # Make sure flask runs in a single thread. Otherwise concurrent requests
+    # may cause problems with vending
+    app.run(debug=True, host='0.0.0.0', threaded=False)
 

machine_controller/vend.py

@@ -42,7 +42,12 @@ class Merch:
     ROW = [21, 20, 16]
     COL = [19, 13]
     MAX_LETTER = 'F'
-    MAX_NUMBER = '0'
+    MAX_NUMBER = 9
+
+    class VendError(Exception):
+        pass
+
+    InvalidLocationError = VendError("Invalid location")
 
     def __init__(self, debug=False):
         self.debug = debug
@@ -93,22 +98,20 @@ def vend(self, letter, number):
         try:
             char = ord(letter)
         except TypeError:
-            raise TypeError('Letter %s does not represent a character' %
-                            str(letter))
+            raise self.InvalidLocationError
 
         # Maybe we should use the actual keypad value?
-        if char < ord('A') or char > ord('Z'):
-            raise ValueError('Invalid Letter: %s' % str(letter))
+        if char < ord('A') or char > ord(self.MAX_LETTER):
+            raise self.InvalidLocationError
 
         num = 0
         try:
             num = int(number)
         except TypeError:
-            raise TypeError('Number %s is not convertible to an integer' %
-                            str(num))
+            raise self.InvalidLocationError
 
-        if num < 0 or num > 10:
-            raise ValueError('Number %d is not in the range 1-10' % num)
+        if num < 1 or num > MAX_NUMBER:
+            raise self.InvalidLocationError
 
         self.__vend(letter, str(number))