meson: Handle features detection for gst version in a script

Instead of having a big list of features in the meson.build file, we
reuse the information from the Cargo.toml files

This refactors the dependencies to handle that new use case

There were issue in previous handling and only activating the `webrtc`
plugin was failing because the list of features incorrect.

Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/issues/295

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1130>

dependencies.py

@@ -19,6 +19,8 @@ except ImportError:
 PARSER = ArgumentParser()
 PARSER.add_argument('src_dir', type=Path)
 PARSER.add_argument('plugins', nargs='*')
+PARSER.add_argument('--features', action="store_true", help="Get list of features to activate")
+PARSER.add_argument('--gst-version', help="Get list of features to activate")
 
 
 # Map plugin name to directory name, for those that does not match.
@@ -38,27 +40,73 @@ RENAMES = {
     'textwrap': 'wrap',
 }
 
+class CargoAnalyzer:
+    def __init__(self):
+        self.src_dir = None
+        self.plugins = None
+        self.features = False
+        self.gst_version = "1.18"
+
+    def extract_version(self, feature_name):
+        if feature_name.startswith('v'):
+            verindex = 1
+        elif feature_name.startswith('gst'):
+            verindex = 3
+        else:
+            return None
+
+        (majver, minver) = feature_name[verindex:].split("_")
+        return (int(majver), int(minver))
+
+    def extract_features(self, cargo_data):
+        features = cargo_data['features']
+        wanted_features = set()
+        gst_version_major = int(self.gst_version.split('.')[0])
+        gst_version_minor = int(self.gst_version.split('.')[1])
+        for (name, value) in features.items():
+            version = self.extract_version(name)
+
+            if version is None:
+                continue
+            (majver, minver) = version
+
+            if gst_version_major < majver or gst_version_minor < minver:
+                continue
+            wanted_features |= set(value)
+            if name.startswith("gst"):
+                # Required for some reason for rswebrtc which has a specific feature
+                wanted_features |= {f"{cargo_data['package']['name']}/{name}"}
+
+        return wanted_features
+
+    def run(self):
+        with (opts.src_dir / 'Cargo.toml').open('rb') as f:
+            crates = tomllib.load(f)['workspace']['members']
+        res = set()
+        for name in opts.plugins:
+            if name.startswith('gst'):
+                name = name[3:]
+
+            name = RENAMES.get(name, name)
+            crate_path = None
+            for crate in crates:
+                if Path(crate).name == name:
+                    crate_path = opts.src_dir / crate / 'Cargo.toml'
+            assert crate_path
+            with crate_path.open('rb') as f:
+                data = tomllib.load(f)
+                if opts.features:
+                    res |= self.extract_features(data)
+                else:
+                    try:
+                        requires = data['package']['metadata']['capi']['pkg_config']['requires_private']
+                    except KeyError:
+                        continue
+                    res.update([i.strip().replace('>', "|>").replace('<', "|<").replace("==", "|==") for i in requires.split(',')])
+        return res
 
 if __name__ == "__main__":
-    opts = PARSER.parse_args()
+    analyzer = CargoAnalyzer()
+    opts = PARSER.parse_args(namespace=analyzer)
 
-    with (opts.src_dir / 'Cargo.toml').open('rb') as f:
-        crates = tomllib.load(f)['workspace']['members']
-    deps = set()
-    for p in opts.plugins:
-        assert p.startswith('gst')
-        name = p[3:]
-        name = RENAMES.get(name, name)
-        crate_path = None
-        for crate in crates:
-            if Path(crate).name == name:
-                crate_path = opts.src_dir / crate / 'Cargo.toml'
-        assert crate_path
-        with crate_path.open('rb') as f:
-            data = tomllib.load(f)
-            try:
-                requires = data['package']['metadata']['capi']['pkg_config']['requires_private']
-            except KeyError:
-                continue
-            deps.update([i.strip().replace('>', "|>").replace('<', "|<").replace("==", "|==") for i in requires.split(',')])
-    print(','.join(deps))
+    print(','.join(analyzer.run()))

meson.build

@@ -315,28 +315,6 @@ if get_option('gtk4').allowed()
   endif
 endif
 
-if gst_dep.version().version_compare('>=1.21')
-  components = [
-    '', '-app', '-audio', '-base', '-check',
-    '-rtp', '-sdp', '-utils', '-video', '-webrtc',
-  ]
-  if get_option('tracers').allowed()
-    components += '-plugin-tracers'
-  endif
-  if get_option('threadshare').allowed()
-    components += '-net'
-  endif
-  if get_option('mp4').allowed() or get_option('fmp4').allowed()
-    components += '-pbutils'
-  endif
-  foreach c: components
-    features += f'gst@c@/v1_22'
-  endforeach
-  if get_option('webrtc').allowed()
-    features += 'gst-plugin-webrtc/gst1_22'
-  endif
-endif
-
 if get_option('rav1e').allowed() and find_program('nasm', required: false).found()
   features += 'gst-plugin-rav1e/asm'
 endif
@@ -359,6 +337,12 @@ foreach plugin_name, details: plugins
     if plugin_deps_found
       packages += f'gst-plugin-@plugin_name@'
       features += details.get('features', [])
+      extra_features = run_command('dependencies.py', meson.current_source_dir(), plugin_name,
+        '--feature', '--gst-version', gst_dep.version(), capture: true, check: true).stdout().strip()
+      if extra_features != ''
+        features += extra_features.split(',')
+      endif
+
       examples += details.get('examples', [])
       lib = details.get('library')
       if default_library in ['shared', 'both']