Add control codes app proof of concept

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/control_codes/classes.py

@@ -0,0 +1,101 @@
+from __future__ import unicode_literals
+
+import logging
+
+from PIL import Image
+from pyzbar.pyzbar import decode
+import qrcode
+
+from django.apps import apps
+from django.db import transaction
+
+from mayan.apps.common.serialization import yaml_dump, yaml_load
+from mayan.apps.documents.literals import DOCUMENT_IMAGE_TASK_TIMEOUT
+from mayan.apps.documents.tasks import task_generate_document_page_image
+
+CONTROL_CODE_MAGIC_NUMBER = 'MCTRL'
+CONTROL_CODE_SEPARATOR = ':'
+CONTROL_CODE_VERSION = '1'
+logger = logging.getLogger(__name__)
+
+
+class ControlCode(object):
+    _registry = {}
+    arguments = ()
+
+    @classmethod
+    def get(cls, name):
+        return cls._registry[name]
+
+    @classmethod
+    def process_document_version(cls, document_version):
+        logger.info(
+            'Starting processing document version: %s', document_version
+        )
+
+        for document_page in document_version.pages.all():
+            task = task_generate_document_page_image.apply_async(
+                kwargs=dict(
+                    document_page_id=document_page.pk
+                )
+            )
+
+            cache_filename = task.get(
+                timeout=DOCUMENT_IMAGE_TASK_TIMEOUT, disable_sync_subtasks=False
+            )
+
+            with document_page.cache_partition.get_file(filename=cache_filename).open() as file_object:
+                image = Image.open(file_object)
+                for code in decode(image):
+                    logger.debug('code found: %s', code)
+                    parts = code.data.split(CONTROL_CODE_SEPARATOR)
+
+                    if parts[0] == CONTROL_CODE_MAGIC_NUMBER:
+                        # Version
+                        if parts[1] == '1':
+                            try:
+                                control_code_class = ControlCode.get(name=parts[2])
+                            except KeyError:
+                                # Unknown control code name
+                                pass
+                            else:
+                                document_page.enabled = False
+                                document_page.save()
+                                arguments = CONTROL_CODE_SEPARATOR.join(parts[3:])
+                                control_code = control_code_class(
+                                    **yaml_load(arguments)
+                                )
+                                control_code.execute()
+
+    @classmethod
+    def register(cls, control_code):
+        cls._registry[control_code.name] = control_code
+
+    def __init__(self, **kwargs):
+        self.kwargs = {}
+        for argument_name in self.arguments:
+            setattr(self, argument_name, kwargs.get(argument_name))
+            self.kwargs[argument_name] = kwargs.get(argument_name)
+
+    @property
+    def image(self):
+        return qrcode.make(self.get_qrcode_string())
+
+    def get_qrcode_string(self):
+        result = []
+        result.append(CONTROL_CODE_MAGIC_NUMBER)
+        result.append(CONTROL_CODE_VERSION)
+        result.append(self.name)
+        result.append(
+            yaml_dump(
+                data=self.kwargs, allow_unicode=True, default_flow_style=True
+            )
+        )
+
+        return CONTROL_CODE_SEPARATOR.join(result)
+
+    def execute(self):
+        raise NotImplementedError(
+            'Your %s class has not defined the required '
+            'execue() method.' % self.__class__.__name__
+        )