wikilinks: add .html more selectively

wikilinks.lua

@@ -3,8 +3,8 @@
 -- Obsidian's wiki linking where possible. It
 -- - replaces spaces with hyphens in the uri path and fragment
 -- - lower-cases the fragment
--- - adds ".html" to the path (preserving any fragment).
---   This is needed when the site is rendered locally, though not on hledger.org.
+-- - adds ".html" to the path when appropriate (preserving any fragment).
+--   This is not needed on hledger.org, but makes links work when rendered locally.
 -- Limitations: unlike Obsidian wikilinks,
 -- - these do not find files across folders - correct path is required
 -- - these are not aware of file existence - targets should exist
@@ -12,11 +12,15 @@
 function Link(elem)
    if elem.title == "wikilink" then
       t = elem.target .. "#"
-      t = string.gsub(t, " ", "-")
-      -- t = string.gsub(t, "'", "")
-      path, frag = string.match(t, "([^#]*)#([^#]*)")
+      t = t:gsub(" ", "-")
+      -- t = t:gsub(t, "'", "")
+      path, frag = t:match("([^#]*)#([^#]*)")
       t = path
-      if string.len(path) > 0 then
+      if path:len() > 0 and not (
+         path:match('%.html$') or
+         path:match('%.%.$') or
+         path:match('/$')
+      ) then
          t = t .. ".html"
       end
       if string.len(frag) > 0 then