Improve bookmark metadata formatting for Netscape exports

[virtualtam]

Changed

• When a bookmark's update date is set, set the LAST_MODIFIED attribute
• Ensure the PRIVATE attribute contains an integer value

Diff

Default bookmarks exported from the current master version (extract with <DT><A> elements):

<DT><A HREF="/shaare/f6PbvA" ADD_DATE="1654256014" PRIVATE="" TAGS="shaarli,help">Shaarli - The personal, minimalist, super-fast, database free, bookmarking service</A>
<DT><A HREF="/shaare/poWYsQ" ADD_DATE="1654256014" PRIVATE="1" TAGS="shaarli,help">Note: Shaare descriptions</A>
<DT><A HREF="https://www.youtube.com/watch?v=DVEUcbPkb-c" ADD_DATE="1654256014" PRIVATE="1" TAGS="shaarli,help,thumbnail">Calm Jazz Music - YouTube (private bookmark with thumbnail demo)</A>

Default bookmarks exported from the PR branch (extract with <DT><A> elements):

<DT><A HREF="/shaare/WJe-Cw" ADD_DATE="1654255845" PRIVATE="0" TAGS="shaarli,help">Shaarli - The personal, minimalist, super-fast, database free, bookmarking service</A>
<DT><A HREF="/shaare/gbH9Bg" ADD_DATE="1654255845" PRIVATE="1" TAGS="shaarli,help">Note: Shaare descriptions</A>
<DT><A HREF="https://www.youtube.com/watch?v=DVEUcbPkb-c" ADD_DATE="1654255845" LAST_MODIFIED="1654255845" PRIVATE="1" TAGS="shaarli,help,thumbnail">Calm Jazz Music - YouTube (private bookmark with thumbnail demo)</A>

[nodiscc]

Thanks!

• How does this affect re-importing bookmarks with LAST_MODIFIED attribute set into Shaarli? I don't think it is considered at all during import [1]), so no impact?
• How does this affect importing HTML exports to a web browser? For example does Firefox import this attribute/date as last modification time in its bookmarks db?

[virtualtam]

How does this affect re-importing bookmarks with LAST_MODIFIED attribute set into Shaarli?
I don't think it is considered at all during import [1]), so no impact?

AFAIK the LAST_MODIFIED field is mostly used by Web browsers, and is present in the test input data for NetscapeBookmarkParser:

• https://cs.github.com/shaarli/netscape-bookmark-parser?q=LAST_MODIFIED
• https://github.com/shaarli/netscape-bookmark-parser/blob/master/tests/input/scuttle.htm (as a folder title attribute)
• https://github.com/shaarli/netscape-bookmark-parser/blob/master/tests/input/firefox_nested.htm (as a bookmark attribute)

The parser itself (and as you mention, the Shaarli import utility) does not handle this attribute, so adding it to the Netscape-formatted exports would have no change when re-importing.

How does this affect importing HTML exports to a web browser? For example does Firefox import this attribute/date as last modification time in its bookmarks db?

My guess would be that this makes no difference from a user's point of view, as creation and update dates are not visible from eg Firefox's bookmark list. This would require some testing with different browsers though, as I'm not sure how metadata is handled when re-importing bookmarks.

[virtualtam]

Thanks for the reviews 👍