Add new app to handle all dependencies

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/dependencies/algorithms.py

@@ -0,0 +1,64 @@
+from __future__ import print_function, unicode_literals
+
+import base64
+import hashlib
+
+from django.utils.encoding import force_text
+
+
+class HashAlgorithm(object):
+    DEFAULT_BLOCK_SIZE = 65535
+    _registry = {}
+    hash_factory = None
+
+    @classmethod
+    def get(cls, name):
+        return cls._registry[name]
+
+    @classmethod
+    def register(cls, algorithm_class):
+        cls._registry[algorithm_class.name] = algorithm_class
+
+    def __init__(self, file_object, block_size=None):
+        self.block_size = block_size or self.DEFAULT_BLOCK_SIZE
+        self.file_object = file_object
+        self.hash_object = self.hash_factory()
+
+    def calculate(self):
+        while (True):
+            data = self.file_object.read(self.block_size)
+            if not data:
+                break
+
+            self.hash_object.update(data)
+
+    def get_digest(self):
+        return force_text(self._get_digest())
+
+
+class SHA1Algorithm(HashAlgorithm):
+    hash_factory = hashlib.sha1
+    name = 'sha1'
+
+    def _get_digest(self):
+        return self.hash_object.hexdigest()
+
+
+class SHA256Algorithm(HashAlgorithm):
+    hash_factory = hashlib.sha256
+    name = 'sha256'
+
+    def _get_digest(self):
+        return base64.b64encode(
+            self.hash_object.digest()
+        )
+
+
+class SHA512Algorithm(SHA256Algorithm):
+    hash_factory = hashlib.sha512
+    name = 'sha512'
+
+
+HashAlgorithm.register(algorithm_class=SHA1Algorithm)
+HashAlgorithm.register(algorithm_class=SHA256Algorithm)
+HashAlgorithm.register(algorithm_class=SHA512Algorithm)