site: wiki integration - render wiki pages within main site

The github wiki pages are now rendered as part of the website's static
content, like the main site pages (and using the same pandoc markdown).
Building the site now requires that a copy of the wiki is checked out
under wiki/.

Github wiki links are converted to suitable relative links,
in all pages (not just wiki pages).

`make site/index.md-push`, which updated the wiki links on the website
home page and committed/pushed it, is now `./Shake site/index.md`, and
doesn't commit/push.

Shake.hs now also depends on the `regex` package.

[ci skip]

Makefile

@@ -162,6 +162,7 @@ DOCSOURCEFILES:= \
 	$(MANUALSOURCEFILES) \
 	$(COMMANDHELPFILES) \
 	site/*.md \
+	wiki/*.md \
 
 # # file(s) which require recompilation for a build to have an up-to-date version string
 # VERSIONSOURCEFILE=hledger/Hledger/Cli/Version.hs
@@ -626,21 +627,6 @@ quickheap-%: hledgerprof samplejournals \
 ###############################################################################
 $(call def-help-subheading,DOCUMENTATION: (see also Shake.hs))
 
-site/index.md-push: \
-		$(call def-help,site/index.md-push, update home page with ./wiki/_Sidebar content and push if changed )
-	(sed -ne '1,/<!-- WIKICONTENT -->/ p'     site/index.md     ; \
-	 sed -ne '/^#.*Cookbook/,$$ p'            wiki/_Sidebar.md \
-	 | perl -p \
-	    -e 's/\[\[([^\|]*)\|([^\]]*)\]\]/[\1](https:\/\/github.com\/simonmichael\/hledger\/wiki\/\2)/g;' \
-	    -e 's/\[\[([^\]]*)\]\]/[\1](https:\/\/github.com\/simonmichael\/hledger\/wiki\/\1)/g;' \
-	    -e 's/^# >/##/;' \
-	 ; \
-	 sed -ne '/<!-- ENDWIKICONTENT -->/,$$ p' site/index.md     ) \
-	> site/_index.md.$$$$ && \
-	mv site/_index.md.$$$$ site/index.md
-	git diff --quiet site/index.md || \
-	  (git commit -q -m 'site: home: latest wiki links' -m '[ci skip]' site/index.md && git push)
-
 site-liverender: Shake \
 		$(call def-help,site-liverender, update the website html when source files are saved  )
 	ls $(DOCSOURCEFILES) | entr ./Shake website

Shake.hs

@@ -4,6 +4,7 @@
    --package base-prelude
    --package directory
    --package extra
+   --package regex
    --package safe
    --package shake
    --package time
@@ -41,7 +42,9 @@ not having to write :: Action ExitCode after a non-final cmd
 -}
 
 {-# LANGUAGE MultiWayIf #-}
+{-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE PackageImports #-}
+{-# LANGUAGE QuasiQuotes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
 import                Prelude ()
@@ -51,6 +54,8 @@ import "base"         Control.Exception as C
 import "directory"    System.Directory as S (getDirectoryContents)
 import "extra"        Data.List.Extra
 import "process"      System.Process
+import "regex"        Text.RE.TDFA.String
+import "regex"        Text.RE.Replace
 import "safe"         Safe
 import "shake"        Development.Shake
 import "shake"        Development.Shake.FilePath
@@ -70,6 +75,7 @@ usage = unlines
   ,""
   ,"./Shake mainpages                   build the web pages from the main repo"
   ,"./Shake wikipages                   build the web pages from the wiki repo"
+  -- ,"./Shake site/index.md               update wiki links on the website home page"
   ,"./Shake FILE                        build any individual file"
   ,"./Shake setversion                  update all packages from PKG/.version"
   ,"./Shake changelogs                  update the changelogs with any new commits"
@@ -368,28 +374,43 @@ main = do
     "site/_site/files/README" : [ "site/_site//*" <.> ext | ext <- webassetexts ] |%> \out -> do
         copyFile' ("site" </> dropDirectory2 out) out
 
+    -- embed the wiki's table of contents into the main site's home page
+    "site/index.md" %> \out -> do
+      wikicontent <- readFile' "wiki/_Sidebar.md"
+      old <- liftIO $ readFileStrictly "site/index.md"
+      let (startmarker, endmarker) = ("<!-- WIKICONTENT -->", "<!-- ENDWIKICONTENT -->")
+          (before, after') = break (startmarker `isPrefixOf`) $ lines old
+          (_, after)       = break (endmarker   `isPrefixOf`) $ after'
+          new = unlines $ concat [before, [startmarker], lines wikicontent, after]
+      liftIO $ writeFile out new
+
     -- render all web pages from the main repo (manuals, home, download, relnotes etc) as html, saved in site/_site/
     phony "mainpages" $ need mainpageshtml
 
     -- render all pages from the wiki as html, saved in site/_site/.
-    -- We assume there are no path collisions with mainrepopages.
+    -- We assume there are no filename collisions with mainpages.
     phony "wikipages" $ need wikipageshtml
 
-    -- render one website page as html, saved in sites/_site/
+    -- render one website page (main or wiki) as html, saved in sites/_site/.
+    -- In case it's a wiki page, we capture pandoc's output for final processing,
+    -- and hyperlink any github-style wikilinks.
     "site/_site//*.html" %> \out -> do
         let name = takeBaseName out
+            iswikipage = name `elem` wikipagenames
             source
-              | name `elem` wikipagenames = "wiki" </> name <.> "md"
+              | iswikipage = "wiki" </> name <.> "md"
               | otherwise  = "site" </> name <.> "md"
             template  = "site/site.tmpl"
             siteRoot  = if "site/_site/doc//*" ?== out then "../.." else "."
         need [source, template]
-        cmd Shell pandoc fromsrcmd "-t html" source
+        -- read markdown source, link any wikilinks, pipe it to pandoc, write html out
+        Stdin . wikify <$> (readFile' source) >>=
+          (cmd Shell pandoc fromsrcmd "-t html"
                            "--template"                template
                            ("--metadata=siteRoot:"  ++ siteRoot)
                            ("--metadata=title:"     ++ name)
-                         "--lua-filter"              "tools/pandoc-site.lua"
+                           "--lua-filter=tools/pandoc-site.lua"
-                         "--output"                  out
+                           "-o" out)
 
     -- render one wiki page as html, saved in site/_site/.
 
@@ -662,3 +683,47 @@ getCurrentDay :: IO Day
 getCurrentDay = do
   t <- getZonedTime
   return $ localDay (zonedTimeToLocalTime t)
+
+-- | Convert Github-style wikilinks to hledger website links.
+wikify :: String -> String
+wikify =
+  replaceBy wikilinkre         wikilinkReplace         .
+  replaceBy labelledwikilinkre labelledwikilinkReplace
+  
+-- couldn't figure out how to use match subgroups, so we don't
+-- wikilinkre         = [re|\[\[$([^]]+)]]|]                -- [[A]]
+-- labelledwikilinkre = [re|\[\[$([^(|)]+)\|$([^]]*)\]\]|]  -- [[A|B]]
+wikilinkre         = [re|\[\[[^]]+]]|]             -- [[A]]
+labelledwikilinkre = [re|\[\[[^(|)]+\|[^]]*\]\]|]  -- [[A|B]]. The | is parenthesised to avoid ending the quasiquoter
+
+-- wikilinkReplace _ loc@RELocation{locationCapture} cap@Capture{capturedText} =
+wikilinkReplace _ _ Capture{capturedText} =
+  -- trace (show (loc,cap)) $
+  Just $ "["++name++"]("++uri++")"
+  where
+    name = init $ init $ drop 2 capturedText
+    uri  = nameToUri name
+
+-- labelledwikilinkReplace _ loc@RELocation{locationCapture} cap@Capture{capturedText} =
+labelledwikilinkReplace _ _ Capture{capturedText} =
+  Just $ "["++label++"]("++uri++")"
+  where
+    [label,name] = take 2 $ (splitOn "|" $ init $ init $ drop 2 capturedText) ++ [""]
+    uri = nameToUri name
+
+nameToUri = (++".html") . intercalate "-" . words
+
+-- | Easier regex replace helper. Replaces each occurrence of a
+-- regular expression in src, by transforming each matched text with
+-- the given function.
+replaceBy re f src = replaceAllCaptures TOP f $ src *=~ re
+
+-- not powerful enough, saved for reference:
+-- wikify = (*=~/ wikilinkreplace) . (*=~/ labelledwikilinkreplace)
+--   where
+--     -- [[A]] -> [A](.../A)
+--     wikilinkreplace :: SearchReplace RE String
+--     wikilinkreplace = [ed|\[\[$([^]]+)]]///[$1]($1.html)|]
+--     -- [[A|B]] -> [A](.../B)
+--     labelledwikilinkreplace :: SearchReplace RE String
+--     labelledwikilinkreplace = [ed|\[\[$([^(|)]+)\|$([^]]*)\]\]///[$1]($2.html)|]