1 files changed, 158 insertions, 0 deletions
diff --git a/toolkit/components/nimbus/generate/generate_feature_manifest.py b/toolkit/components/nimbus/generate/generate_feature_manifest.py
new file mode 100644
index 0000000000..d4a3b71434
--- /dev/null
+++ b/toolkit/components/nimbus/generate/generate_feature_manifest.py
@@ -0,0 +1,158 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import json
+import sys
+from pathlib import Path
+
+import jsonschema
+import yaml
+
+HEADER_LINE = (
+    "// This file was generated by generate_feature_manifest.py from FeatureManifest.yaml."
+    " DO NOT EDIT.\n"
+)
+
+FEATURE_MANIFEST_SCHEMA = Path("schemas", "ExperimentFeatureManifest.schema.json")
+
+NIMBUS_FALLBACK_PREFS = (
+    "constexpr std::pair<nsLiteralCString, nsLiteralCString>"
+    "NIMBUS_FALLBACK_PREFS[]{{{}}};"
+)
+
+EXPORTED_SYMBOLS = 'const EXPORTED_SYMBOLS = ["{}"];'
+
+
+def write_fm_cpp_headers(fd):
+    fd.write(HEADER_LINE)
+
+
+def write_fm_js_headers(fd):
+    fd.write("\n".join([HEADER_LINE, EXPORTED_SYMBOLS.format("FeatureManifest")]))
+
+
+def validate_feature_manifest(schema_path, manifest_path, manifest):
+    with open(schema_path, "r") as f:
+        schema = json.load(f)
+
+    set_prefs = {}
+    fallback_prefs = {}
+
+    for feature, feature_def in manifest.items():
+        try:
+            jsonschema.validate(feature_def, schema)
+
+            for variable, variable_def in feature_def.get("variables", {}).items():
+                set_pref = variable_def.get("setPref")
+                if set_pref is not None:
+                    if set_pref in set_prefs:
+                        other_feature = set_prefs[set_pref][0]
+                        other_variable = set_prefs[set_pref][1]
+                        print("Multiple variables cannot declare the same setPref")
+                        print(
+                            f"{feature} variable {variable} wants to set pref {set_pref}"
+                        )
+                        print(
+                            f"{other_feature} variable {other_variable} wants to set pref "
+                            f"{set_pref}"
+                        )
+                        raise Exception("Set prefs are exclusive")
+
+                    set_prefs[set_pref] = (feature, variable)
+
+                fallback_pref = variable_def.get("fallbackPref")
+                if fallback_pref is not None:
+                    fallback_prefs[fallback_pref] = (feature, variable)
+
+                conflicts = [
+                    (
+                        "setPref",
+                        fallback_pref,
+                        "fallbackPref",
+                        set_prefs.get(fallback_pref),
+                    ),
+                    ("fallbackPref", set_pref, "setPref", fallback_prefs.get(set_pref)),
+                ]
+
+                for kind, pref, other_kind, conflict in conflicts:
+                    if conflict is not None:
+                        print(
+                            "The same pref cannot be specified in setPref and fallbackPref"
+                        )
+                        print(
+                            f"{feature} variable {variable} has specified {kind} {pref}"
+                        )
+                        print(
+                            f"{conflict[0]} variable {conflict[1]} has specified {other_kind} "
+                            f"{pref}"
+                        )
+                        raise Exception("Set prefs and fallback prefs cannot overlap")
+
+        except Exception as e:
+            print("Error while validating FeatureManifest.yaml")
+            print(f"On key: {feature}")
+            print(f"Input file: {manifest_path}")
+            raise e
+
+
+def generate_feature_manifest(fd, input_file):
+    write_fm_js_headers(fd)
+
+    try:
+        with open(input_file, "r", encoding="utf-8") as f:
+            manifest = yaml.safe_load(f)
+
+        validate_feature_manifest(
+            Path(input_file).parent / FEATURE_MANIFEST_SCHEMA, input_file, manifest
+        )
+
+        fd.write(f"const FeatureManifest = {json.dumps(manifest)};")
+    except (IOError) as e:
+        print(f"{input_file}: error:\n  {e}\n")
+        sys.exit(1)
+
+
+def platform_feature_manifest_array(features):
+    entries = []
+    for (feature, featureData) in features.items():
+        # Features have to be tagged isEarlyStartup to be accessible
+        # to Nimbus platform API
+        if not featureData.get("isEarlyStartup", False):
+            continue
+        entries.extend(
+            '{{ "{}_{}"_ns, "{}"_ns }}'.format(
+                feature, variable, variableData["fallbackPref"]
+            )
+            for (variable, variableData) in featureData.get("variables", {}).items()
+            if variableData.get("fallbackPref", False)
+        )
+    return NIMBUS_FALLBACK_PREFS.format(", ".join(entries))
+
+
+def generate_platform_feature_manifest(fd, input_file):
+    write_fm_cpp_headers(fd)
+
+    def file_structure(data):
+        return "\n".join(
+            [
+                "#ifndef mozilla_NimbusFeaturesManifest_h",
+                "#define mozilla_NimbusFeaturesManifest_h",
+                "#include <utility>",
+                '#include "mozilla/Maybe.h"',
+                '#include "nsStringFwd.h"',
+                "namespace mozilla {",
+                platform_feature_manifest_array(data),
+                '#include "./lib/NimbusFeatureManifest.inc.h"',
+                "}  // namespace mozilla",
+                "#endif  // mozilla_NimbusFeaturesManifest_h",
+            ]
+        )
+
+    try:
+        with open(input_file, "r", encoding="utf-8") as yaml_input:
+            data = yaml.safe_load(yaml_input)
+            fd.write(file_structure(data))
+    except (IOError) as e:
+        print("{}: error:\n  {}\n".format(input_file, e))
+        sys.exit(1)