Rework the Search class and provide a search service

[Toflar]

This is a rough concept:

• SearchInterface
  • index(DocumentInterface $doc)
  • indexLazy(DocumentInterface $doc)
  • triggerLazyIndex()
  • search(QueryInterface $query)
  • etc.
• DocumentInterface
  • getUrl()
  • getContent()
  • getProtected()
  • etc.

Every Controller or Page type decides on its own whether to index something or not and does that by calling either $this->search->index() for immediate indexing or $this->search->indexLazy() for adding the content to the service and do a bulk insert when triggerLazyIndex() is called. The AddToSearchIndexListener executes $this->search->triggerLazyIndex().

Advantages to the current implementation:

• We get rid of one more "legacy" class (Search).
• The Search service can easily replaced by Elasticsearch and Co. All they need to do is implement our SearchInterface.
• It's possible to add content by different content providers for the same url.
• In theory, rebuilding the index can be sub requests instead of real requests.

[Toflar]

Also, drop the current getSearchablePages() behaviour in favour of a simple web crawler (see contao/core#6942). Note that it must update on a regular basis using a cronjob behaviour as well as manually in the back end somehow.

[Metis77]

+1

[HolyMacarony]

+1

[leofeyer]

This is a long running task, which will eventually result in the https://github.com/contao/search library.