Add support for downloading patches and parsed diff data in the API.

This adds support for new mimetypes to FileDiffResource and DiffSetResource.
Both now support the text/x-patch mimetype, and will return the stored
patch. In the case of FileDiffResource, it's the patch for that particular
file, and for DiffSetResource, it's the patch for all files in the diff.

FileDiffResource also supports new
application/vnd.reviewboard.org.diff.data+json and
application/vnd.reviewboard.org.diff.data+xml mimetypes, which return
the parsed diff data in JSON or XML formats. This includes the
insert/delete/replace lines, move information, and more. It also supports a
?syntax-highlighting=1 parameter for returning data in a form that can
have CSS rules applied for syntax highlighting.

This new diff data resource should make it possible for third party
applications to render diffs without reimplementing Review Board's
diff viewer logic.

Reviewed at http://reviews.reviewboard.org/r/1642/

reviewboard/webapi/resources.py

@@ -1,5 +1,6 @@
 import logging
 import re
+import urllib
 
 import dateutil.parser
 from django.conf import settings
@@ -8,12 +9,15 @@
 from django.contrib.sites.models import Site
 from django.core.exceptions import PermissionDenied, ObjectDoesNotExist
 from django.db.models import Q
-from django.http import HttpResponseRedirect
+from django.http import HttpResponseRedirect, HttpResponse
 from django.template.defaultfilters import timesince
 from django.utils.translation import ugettext as _
 from djblets.siteconfig.models import SiteConfiguration
+from djblets.util.http import get_http_requested_mimetype, \
+                              set_last_modified
 from djblets.webapi.core import WebAPIResponseFormError, \
-                                WebAPIResponsePaginated
+                                WebAPIResponsePaginated, \
+                                WebAPIResponse
 from djblets.webapi.decorators import webapi_login_required, \
                                       webapi_request_fields
 from djblets.webapi.errors import DOES_NOT_EXIST, INVALID_FORM_DATA, \
@@ -26,6 +30,7 @@
 
 from reviewboard import get_version_string, get_package_version, is_release
 from reviewboard.accounts.models import Profile
+from reviewboard.diffviewer.diffutils import get_diff_files
 from reviewboard.diffviewer.forms import EmptyDiffError
 from reviewboard.reviews.errors import PermissionError
 from reviewboard.reviews.forms import UploadDiffForm, UploadScreenshotForm
@@ -48,6 +53,9 @@
                                       REPO_NOT_IMPLEMENTED
 
 
+CUSTOM_MIMETYPE_BASE = 'application/vnd.reviewboard.org'
+
+
 class WebAPIResource(DjbletsWebAPIResource):
     """A specialization of the Djblets WebAPIResource for Review Board."""
 
@@ -410,12 +418,86 @@ class FileDiffResource(WebAPIResource):
     uri_object_key = 'filediff_id'
     model_parent_key = 'diffset'
 
+    DIFF_DATA_MIMETYPE_BASE = CUSTOM_MIMETYPE_BASE + '.diff.data'
+
+    _supported_mimetypes = [
+        'application/json',
+        'application/xml',
+        'text/x-patch',
+        DIFF_DATA_MIMETYPE_BASE + '+json',
+        DIFF_DATA_MIMETYPE_BASE + '+xml',
+    ]
+
     def get_queryset(self, request, review_request_id, diff_revision,
                      *args, **kwargs):
         return self.model.objects.filter(
             diffset__history__review_request=review_request_id,
             diffset__revision=diff_revision)
 
+    @webapi_check_login_required
+    def get(self, request, *args, **kwargs):
+        mimetype = get_http_requested_mimetype(request,
+                                               self._supported_mimetypes)
+
+        if mimetype == 'text/x-patch':
+            return self._get_patch(request, *args, **kwargs)
+        elif mimetype.startswith(self.DIFF_DATA_MIMETYPE_BASE + "+"):
+            return self._get_diff_data(request, mimetype, *args, **kwargs)
+        else:
+            return super(FileDiffResource, self).get(request, *args, **kwargs)
+
+    def _get_patch(self, request, *args, **kwargs):
+        try:
+            review_request_resource.get_object(request, *args, **kwargs)
+            filediff = self.get_object(request, *args, **kwargs)
+        except ObjectDoesNotExist:
+            return DOES_NOT_EXIST
+
+        resp = HttpResponse(filediff.diff, mimetype='text/x-patch')
+        filename = '%s.patch' % urllib.quote(filediff.source_file)
+        resp['Content-Disposition'] = 'inline; filename=%s' % filename
+        set_last_modified(resp, filediff.diffset.timestamp)
+
+        return resp
+
+    def _get_diff_data(self, request, mimetype, *args, **kwargs):
+        try:
+            review_request_resource.get_object(request, *args, **kwargs)
+            filediff = self.get_object(request, *args, **kwargs)
+        except ObjectDoesNotExist:
+            return DOES_NOT_EXIST
+
+        highlighting = request.GET.get('syntax-highlighting', False)
+
+        files = get_diff_files(filediff.diffset, filediff,
+                               enable_syntax_highlighting=highlighting)
+
+        if not files:
+            # This may not be the right error here.
+            return DOES_NOT_EXIST
+
+        assert len(files) == 1
+        f = files[0]
+
+        payload = {
+            'diff_data': {
+                'binary': f['binary'],
+                'chunks': f['chunks'],
+                'num_changes': f['num_changes'],
+                'whitespace_only': f['whitespace_only'],
+                'changed_chunk_indexes': f['changed_chunk_indexes'],
+                'new_file': f['newfile'],
+            }
+        }
+
+        # XXX: Kind of a hack.
+        api_format = mimetype.split('+')[-1]
+
+        resp = WebAPIResponse(request, payload, api_format=api_format)
+        set_last_modified(resp, filediff.diffset.timestamp)
+
+        return resp
+
 filediff_resource = FileDiffResource()
 
 
@@ -432,6 +514,12 @@ class DiffSetResource(WebAPIResource):
     model_object_key = 'revision'
     model_parent_key = 'history'
 
+    _supported_mimetypes = [
+        'application/json',
+        'application/xml',
+        'text/x-patch'
+    ]
+
     def get_queryset(self, request, review_request_id, *args, **kwargs):
         return self.model.objects.filter(
             history__review_request=review_request_id)
@@ -449,6 +537,40 @@ def has_access_permissions(self, request, diffset, *args, **kwargs):
         review_request = diffset.history.review_request.get()
         return review_request.is_accessible_by(request.user)
 
+    @webapi_check_login_required
+    def get(self, request, *args, **kwargs):
+        mimetype = get_http_requested_mimetype(request,
+                                               self._supported_mimetypes)
+
+        if mimetype == 'text/x-patch':
+            return self._get_patch(request, *args, **kwargs)
+        else:
+            return super(DiffSetResource, self).get(request, *args, **kwargs)
+
+    def _get_patch(self, request, *args, **kwargs):
+        try:
+            review_request = \
+                review_request_resource.get_object(request, *args, **kwargs)
+            diffset = self.get_object(request, *args, **kwargs)
+        except ObjectDoesNotExist:
+            return DOES_NOT_EXIST
+
+        tool = review_request.repository.get_scmtool()
+        data = tool.get_parser('').raw_diff(diffset)
+
+        resp = HttpResponse(data, mimetype='text/x-patch')
+
+        if diffset.name == 'diff':
+            filename = 'bug%s.patch' % \
+                       review_request.bugs_closed.replace(',', '_')
+        else:
+            filename = diffset.name
+
+        resp['Content-Disposition'] = 'inline; filename=%s' % filename
+        set_last_modified(resp, diffset.timestamp)
+
+        return resp
+
     @webapi_login_required
     def create(self, request, *args, **kwargs):
         """Creates a new diffset by parsing an uploaded diff file.