Improve handling of latest extension versions in spec

[schlessera]

Multiple TODOs are still open in the ExtensionSpec template. These need to be resolved be generally improving the handling of latest versions of extensions.

• The spec will need to be adapted to be informed by https://github.com/ampproject/amphtml/blob/main/build-system/compile/bundles.config.extensions.json, where the latestVersion is stored with the spec (and the highest version is not always the same as latest), as well as any additional Bento metadata.
• There is one case where an extension lacks a 'latest' version, but maybe not for long. See ✨ Add latest version to amp-cache-url extension spec amphtml#34636.
• Why isn't the sorting done at ingestion time? Then getLatestVersion() could just be doing something like return self::LATEST_VERSION.

amp-toolbox-php/bin/src/Validator/SpecGenerator/Template/ExtensionSpec.php

Lines 29 to 67 in c680d60

	/**
	* Get the latest available version of the extension.
	*
	* phpcs:disable Generic.Files.LineLength.TooLong
	* @todo This will need to be adapted to be informed by <https://github.com/ampproject/amphtml/blob/main/build-system/compile/bundles.config.extensions.json>, where the latestVersion is stored with the spec (and the highest version is not always the same as latest), as well as any additional Bento metadata.
	* @return string Latest available version.
	*/
	public function getLatestVersion()
	{
	// @todo There is one case where an extension lacks a 'latest' version, but maybe not for long. See <https://github.com/ampproject/amphtml/pull/34636>.
	if (! array_key_exists(SpecRule::VERSION, self::EXTENSION_SPEC)) {
	return 'latest';
	}
	$versions = self::EXTENSION_SPEC[SpecRule::VERSION];
	// @todo Why isn't this sorting done at ingestion time? Then getLatestVersion could just be doing something like `return self::LATEST_VERSION`.
	// Sort versions in descending order so that the latest version ends up to be the first element in the array.
	usort(
	$versions,
	static function ($a, $b) {
	if ($a === $b) {
	return 0;
	}
	if ($a === 'latest') {
	return 1;
	}
	if ($b === 'latest') {
	return -1;
	}
	return version_compare($a, $b, '<');
	}
	);
	return $versions[0];
	}

[westonruter]

• The spec will need to be adapted to be informed by https://github.com/ampproject/amphtml/blob/main/build-system/compile/bundles.config.extensions.json, where the latestVersion is stored with the spec (and the highest version is not always the same as latest), as well as any additional Bento metadata.

See ampproject/amphtml#34838 for the latest on where the Bento information is stored.

[westonruter]

In order to determine which Bento versions are stable enough to be used, we have to cross-reference to make sure the version is among the versions which are present in the validator spec. See ampproject/amp-wp#6373.

[schlessera]

@ediamin Some of the above TODOs should already be solved by #297. Can you check in detail what was done, and what is still missing to update the issue description?

[ediamin]

Here are my findings about the current state of this issue:

1. The spec has adapted the bundles.config.extensions.json well from the ampproject/amphtml project. The latestVersion is stored with the spec as well as additional Bento metadata. It was handled in #297 .
2. The ampproject/amphtm#34636 PR is still open and need to be merged.
3. In PR#358 TagWithExtensionSpec was introduced. In which getLatestVersion() simply returns self::LATEST_VERSION.

[westonruter]

1. The spec has adapted the bundles.config.extensions.json well from the ampproject/amphtml project. The latestVersion is stored with the spec as well as additional Bento metadata. It was handled in #297 .

The Bento version is also now indicated in the validator spec via a bento_supported_version attribute: ampproject/amphtml#35757. The plugin is still using the version data in bundles.config.extensions.json, but I believe we could skip consuming that JSON file now that the validator has the data as well.