metadata: allow `ndk:` to be str or list of release or revision

There are two version numbers used for NDKs: the "release" and the
"revision".  The "release" is used in the download URL and zipball and the
"revision" is used in the source.properties and the gradle ndkVersion field.

Also, there are some builds which need multiple NDKs installed, so this
makes it possible to have a list of release/revision entries in build.ndk.
This does not yet add full support since _fdroidserver/build.py_ will also
need changes.

fdroidserver/common.py

@@ -4021,6 +4021,32 @@ def auto_install_ndk(build):
     ndk = build.get('ndk')
     if not ndk:
         return
+    if isinstance(ndk, str):
+        _install_ndk(ndk)
+    elif isinstance(ndk, list):
+        for n in ndk:
+            _install_ndk(n)
+    else:
+        BuildException(_('Invalid ndk: entry in build: "{ndk}"')
+                       .format(ndk=str(ndk)))
+
+
+def _install_ndk(ndk):
+    """Install specified NDK if it is not already installed
+
+    Parameters
+    ----------
+
+    ndk
+        The NDK version to install, either in "release" form (r21e) or
+        "revision" form (21.4.7075529).
+    """
+    if re.match(r'[1-9][0-9.]+[0-9]', ndk):
+        for ndkdict in NDKS:
+            if ndk == ndkdict['revision']:
+                ndk = ndkdict['release']
+                break
+
     ndk_path = config.get(ndk)
     if ndk_path and os.path.isdir(ndk_path):
         return

fdroidserver/metadata.py

@@ -326,7 +326,11 @@ class Build(dict):
         return 'ant'
 
     def ndk_path(self):
-        return fdroidserver.common.config['ndk_paths'].get(self.ndk, '')
+        """Returns the path to the first configured NDK or an empty string"""
+        ndk = self.ndk
+        if isinstance(ndk, list):
+            ndk = self.ndk[0]
+        return fdroidserver.common.config['ndk_paths'].get(ndk, '')
 
 
 flagtypes = {

tests/common.TestCase

@@ -1796,6 +1796,42 @@ class CommonTest(unittest.TestCase):
             fdroidserver.common.metadata_find_developer_signing_files(appid, vc)
         )
 
+    def test_auto_install_ndk(self):
+        """Test all possible field data types for build.ndk"""
+        build = fdroidserver.metadata.Build()
+
+        none_entry = mock.Mock()
+        with mock.patch('fdroidserver.common._install_ndk', none_entry):
+            fdroidserver.common.auto_install_ndk(build)
+            none_entry.assert_not_called()
+
+        empty_list = mock.Mock()
+        build.ndk = []
+        with mock.patch('fdroidserver.common._install_ndk', empty_list):
+            fdroidserver.common.auto_install_ndk(build)
+            empty_list.assert_not_called()
+
+        release_entry = mock.Mock()
+        build.ndk = 'r21e'
+        with mock.patch('fdroidserver.common._install_ndk', release_entry):
+            fdroidserver.common.auto_install_ndk(build)
+            release_entry.assert_called_once_with('r21e')
+
+        revision_entry = mock.Mock()
+        build.ndk = '21.4.7075529'
+        with mock.patch('fdroidserver.common._install_ndk', revision_entry):
+            fdroidserver.common.auto_install_ndk(build)
+            revision_entry.assert_called_once_with('21.4.7075529')
+
+        list_entry = mock.Mock()
+        calls = []
+        build.ndk = ['11.0.2655954', 'r12b', 'r21e']
+        for n in build.ndk:
+            calls.append(mock.call(n))
+        with mock.patch('fdroidserver.common._install_ndk', list_entry):
+            fdroidserver.common.auto_install_ndk(build)
+            list_entry.assert_has_calls(calls)
+
 
 if __name__ == "__main__":
     os.chdir(os.path.dirname(__file__))