From 0f0d0473b1e21ade51c76d41a690b52bda8c57e7 Mon Sep 17 00:00:00 2001
From: Marsch Huynh <marsch.huynh@gmail.com>
Date: Sun, 20 Aug 2017 22:05:50 +0700
Subject: [PATCH] Support partial request for media resource

---
 docs/features.rst | 22 +++++++++++
 eve/endpoints.py  | 94 ++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 94 insertions(+), 22 deletions(-)

diff --git a/docs/features.rst b/docs/features.rst
index 8e8de04b4..8ba11f1ec 100644
--- a/docs/features.rst
+++ b/docs/features.rst
@@ -1776,6 +1776,28 @@ configuration. Enable ``AUTO_COLLAPSE_MULTI_KEYS`` and ``AUTO_CREATE_LISTS``
 to make this possible. This allows to send multiple values for one key in
 ``multipart/form-data`` requests and in this way upload a list of files.
 
+.. _partial_request:
+
+Partial request for media resource
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The partial request provides an ability to download a part of a file. 
+You can also pause and resume when you are downloading without restarting 
+your download. To use it, make sure you have ``Range`` in your request header.
+
+    .. code-block:: console
+
+        $ curl http://localhost/media/yourfilename -i -H "Range: bytes=0-10"
+        HTTP/1.1 206 PARTIAL CONTENT
+        Date: Sun, 20 Aug 2017 14:26:42 GMT
+        Content-Type: audio/mp4
+        Content-Length: 11
+        Connection: keep-alive
+        Content-Range: bytes 0-10/23671
+        Last-Modified: Sat, 19 Aug 2017 03:25:36 GMT
+        Accept-Ranges: bytes
+
+        ftypmp4%
+
 .. _geojson_feature:
 
 GeoJSON
diff --git a/eve/endpoints.py b/eve/endpoints.py
index fc598bfd3..eb5a750ca 100644
--- a/eve/endpoints.py
+++ b/eve/endpoints.py
@@ -11,6 +11,8 @@
     :copyright: (c) 2017 by Nicola Iarocci.
     :license: BSD, see LICENSE for more details.
 """
+import re
+
 from bson import tz_util
 from flask import abort, request, current_app as app, Response
 
@@ -175,28 +177,76 @@ def media_endpoint(_id):
 
     .. versionadded:: 0.6
     """
-    file_ = app.media.get(_id)
-    if file_ is None:
-        return abort(404)
-
-    if_modified_since = weak_date(request.headers.get('If-Modified-Since'))
-    if if_modified_since is not None:
-        if if_modified_since.tzinfo is None:
-            if_modified_since = if_modified_since.replace(
-                tzinfo=tz_util.utc)
-
-        if if_modified_since > file_.upload_date:
-            return Response(status=304)
-
-    headers = {
-        'Last-Modified': date_to_rfc1123(file_.upload_date),
-        'Content-Length': file_.length,
-    }
-
-    response = Response(file_, headers=headers, mimetype=file_.content_type,
-                        direct_passthrough=True)
-
-    return response
+    range_header = request.headers.get('Range', None)
+    if not range_header:
+        file_ = app.media.get(_id)
+        if file_ is None:
+            return abort(404)
+
+        if_modified_since = weak_date(request.headers.get('If-Modified-Since'))
+        if if_modified_since is not None:
+            if if_modified_since.tzinfo is None:
+                if_modified_since = if_modified_since.replace(
+                    tzinfo=tz_util.utc)
+
+            if if_modified_since > file_.upload_date:
+                return Response(status=304)
+
+        headers = {
+            'Last-Modified': date_to_rfc1123(file_.upload_date),
+            'Content-Length': file_.length,
+            'Accept-Ranges': 'bytes',
+        }
+
+        response = Response(
+            file_,
+            status=200,
+            headers=headers,
+            mimetype=file_.content_type,
+            direct_passthrough=True
+        )
+
+        return response
+    else:
+        file_ = app.media.get(_id)
+        size = file_.length
+        byte1, byte2 = 0, None
+
+        m = re.search('(\d+)-(\d*)', range_header)
+        g = m.groups()
+
+        if g[0]:
+            byte1 = int(g[0])
+        if g[1]:
+            byte2 = int(g[1])
+
+        length = size - byte1
+        if byte2 is not None:
+            length = byte2 - byte1 + 1
+
+        data = None
+        file_.seek(byte1)
+        data = file_.read(length)
+
+        headers = {
+            'Last-Modified': date_to_rfc1123(file_.upload_date),
+            'Content-Length': file_.length,
+            'Accept-Ranges': 'bytes',
+            'Content-Range': 'bytes {0}-{1}/{2}'.format(
+                byte1,
+                byte1 + length - 1,
+                size
+            ),
+        }
+
+        response = Response(
+            data,
+            206,
+            headers=headers,
+            mimetype=file_.content_type,
+            direct_passthrough=True)
+
+        return response
 
 
 @requires_auth('resource')