hermes-engine: downloading prebuilt artifact takes precedence over bu…

…ilding from source

sdks/hermes-engine/hermes-engine.podspec

@@ -15,15 +15,12 @@ build_type = ENV['PRODUCTION'] == "1" ? :release : :debug
 package = JSON.parse(File.read(File.join(react_native_path, "package.json")))
 version = package['version']
 
-# sdks/.hermesversion
-hermestag_file = File.join(react_native_path, "sdks", ".hermesversion")
-isInCI = ENV['CI'] === 'true'
-
 source = {}
 git = "https://github.com/facebook/hermes.git"
 
-isInMain = version.include?('1000.0.0')
+isOnMain = version.include?('1000.0.0')
 isNightly = version.start_with?('0.0.0-')
+isOnStable = version.include?('-rc.')
 
 if ENV.has_key?('HERMES_ENGINE_TARBALL_PATH')
   if !File.exist?(ENV['HERMES_ENGINE_TARBALL_PATH'])
@@ -34,7 +31,7 @@ end
 if ENV.has_key?('HERMES_ENGINE_TARBALL_PATH')
   Pod::UI.puts "[Hermes] Using pre-built Hermes binaries from local path: #{ENV['HERMES_ENGINE_TARBALL_PATH']}".yellow if Object.const_defined?("Pod::UI")
   source[:http] = "file://#{ENV['HERMES_ENGINE_TARBALL_PATH']}"
-elsif isInMain
+elsif isOnMain
   Pod::UI.puts '[Hermes] Installing hermes-engine may take slightly longer, building Hermes compiler from source...'.yellow if Object.const_defined?("Pod::UI")
   source[:git] = git
   source[:commit] = `git ls-remote https://github.com/facebook/hermes main | cut -f 1`.strip
@@ -43,15 +40,22 @@ elsif isNightly
   destination_path = download_nightly_hermes(react_native_path, version)
   # set tarball as hermes engine
   source[:http] = "file://#{destination_path}"
-elsif File.exists?(hermestag_file) && isInCI
+elsif hermes_artifact_exists(version, build_type)
+  hermesArtifactURL = hermes_artifact_url(version, build_type)
+  Pod::UI.puts "[Hermes] Downloading artifact from #{hermesArtifactURL}".yellow if Object.const_defined?("Pod::UI")
+  source[:http] = hermesArtifactURL
+elsif isOnStable
+  # sdks/.hermesversion
+  hermestag_file = File.join(react_native_path, "sdks", ".hermesversion")
+  if !File.exists?(hermestag_file)
+    abort "[Hermes] .hermesversion file missing on stable branch."
+  end
   Pod::UI.puts '[Hermes] Detected that you are on a React Native release branch, building Hermes from source but fetched from tag...'.yellow if Object.const_defined?("Pod::UI")
   hermestag = File.read(hermestag_file).strip
   source[:git] = git
   source[:tag] = hermestag
 else
-  # Sample url from Maven:
-  # https://repo1.maven.org/maven2/com/facebook/react/react-native-artifacts/0.71.0/react-native-artifacts-0.71.0-hermes-ios-debug.tar.gz
-  source[:http] = "https://repo1.maven.org/maven2/com/facebook/react/react-native-artifacts/#{version}/react-native-artifacts-#{version}-hermes-ios-#{build_type.to_s}.tar.gz"
+  abort "[Hermes] Unable to determine source for hermes-engine."
 end
 
 Pod::Spec.new do |spec|

sdks/hermes-engine/hermes-utils.rb

@@ -24,3 +24,25 @@ def download_nightly_hermes(react_native_path, version)
     `mkdir -p "#{destination_folder}" && curl "#{tarball_url}" -Lo "#{destination_path}"`
     return destination_path
 end
+
+# This function builds Hermes artifact URL.
+# As of now it should point to the Maven repo.
+#
+# Parameters
+# - version: the version of React Native
+# - build_type: debug or release
+def hermes_artifact_url(version, build_type)
+    # Sample url from Maven:
+    # https://repo1.maven.org/maven2/com/facebook/react/react-native-artifacts/0.71.0/react-native-artifacts-0.71.0-hermes-ios-debug.tar.gz
+    return "https://repo1.maven.org/maven2/com/facebook/react/react-native-artifacts/#{version}/react-native-artifacts-#{version}-hermes-ios-#{build_type}.tar.gz"
+end
+
+# This function checks that Hermes artifact exists.
+# As of now it should check it on the Maven repo.
+#
+# Parameters
+# - version: the version of React Native
+# - build_type: debug or release
+def hermes_artifact_exists(version, build_type)
+    return (`curl -o /dev/null --silent -Iw '%{http_code}' #{hermes_artifact_url(version, build_type)}` == "200")
+end