URL generation/routing is only compatible with Hydrogen itself

[MadLittleMods]

Problem

If you use hydrogen-view-sdk to embed some Hydrogen pieces in your own app, the URL's throughout the Hydrogen UI only use a specific routing scheme and can't be changed.

Even if you supply your own urlCreator/urlRouter and Navigation, that only controls the base part of the URL and the rest of the path is just string interpolated on top, ex.

https://github.com/vector-im/hydrogen-web/blob/d9acc831826c14f311ff65bdb57756584448aab7/src/domain/session/room/timeline/tiles/BaseMessageTile.js#L61

Expected

In regards to my use case with https://github.com/matrix-org/matrix-public-archive

• For usernames/avatars: Either matrix.to or completely remove the link because I'm not interested in having a right-toolbar show the member.
• For the message timestamp: I want to replace them with matrix.to links or my own scheme for permalinking and highlighting. Also want to change the timezone to UTC but that's a slightly different problem.
• For the lightbox: Remove URL and pop the lightbox with no URL change
  • Solved via Add lightbox support and Hydrogen URL hashes relative to the room matrix-org/matrix-viewer#12 and More simple lightbox setup for SDK and compatible with custom History #749

Potential solutions

To be determined.

[MadLittleMods]

Spawning from a quick call with @bwindels. Discussed some ideas but our plan is for me to propose something and @bwindels can put some more thought and taste-making to make it Hydrogen.

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We could change the signature of URLRouter (also known as urlCreator in the views) to have a method for each type of URL (urlCreator.memberLink(matrixId), urlCreator.messagePermalink(matrixId)) similar to what we are already doing in matrix-public-archive for its own links. This allows SDK consumers to define their own URLRouter and override the methods they want to change throughout the app.

This doesn't solve all cases where you want to contextually replace some links but not others based on the component they are in or even the parent context (think avatar re-used in many different places). Say I want to replace the member links in the timeline, but not pills for example. We could introduce an extra context parameter which is just a string enum of discrete UI locations, urlCreator.memberLink(matrixId, { context: UILocation.Pill })

Better idea please 🙏

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As a note, urlCreator.urlForSegments([segments]) is more compatible than manually string interpolating with urlCreator.urlUntilSegment("room") because we are better able manage the # at the start. In the matrix-public-archive case, I don't want a dangling # on the end of the URL if there is nothing more to route from the room segment of the path. See pathAsUrl() logic in matrix-org/matrix-viewer#12

For the lightbox example, I decided that the hash URL representing the state of the lightbox open wasn't horrible. But I did make my own custom History instance so that we could make the hash relative to room #/lightbox/$17cgP6YBP9ny9xuU1vBmpOYFhRG4zpOe9SOgWi2Wxsk. All of the custom heavy lifting is in matrix-org/matrix-viewer#12. The changes in Hydrogen were more-so just making it easier as a SDK consumer to setup the lightbox, #749.

[bwindels]

I like the idea of having a dedicated method for every type of url (with a context param where needed to further differentiate). Would you be willing to draft this out in a PR to see what it looks like in practice?