" Remark: Uses HTML syntax file
" Remark: I don't do anything with angle brackets (<>) because that would too easily
" easily conflict with HTML syntax
-" TODO: Do something appropriate with image syntax
" TODO: Handle stuff contained within stuff (e.g. headings within blockquotes)
syn region htmlItalic start=/\\\@<!\(^\|\A\)\@=\*\@<!\*\*\@!/ end=/\\\@<!\*\@<!\*\*\@!\($\|\A\)\@=/ contains=htmlBold,@Spell
syn region htmlBold start=/\\\@<!\(^\|\A\)\@=_\@<!___\@!/ end=/\\\@<!_\@<!___\@!\($\|\A\)\@=/ contains=htmlItalic,@Spell
syn region htmlItalic start=/\\\@<!\(^\|\A\)\@=_\@<!__\@!/ end=/\\\@<!_\@<!__\@!\($\|\A\)\@=/ contains=htmlBold,@Spell
-syn region htmlString start="]("ms=s+2 end=")"me=e-1
-syn region htmlLink start="\\\@<!\["ms=s+1 end="\\\@<!\]"me=e-1 contains=@Spell
-syn region htmlString start="\(\[.*]: *\)\@<=.*" end="$"
+
+" [link](URL) | [link][id] | [link][]
+syn region mkdLink matchgroup=mkdDelimiter start="\!\?\[" end="\]\ze\s*[[(]" contains=@Spell nextgroup=mkdURL,mkdID skipwhite oneline
+syn region mkdID matchgroup=mkdDelimiter start="\[" end="\]" contained
+syn region mkdURL matchgroup=mkdDelimiter start="(" end=")" contained
+
+" Link definitions: [id]: URL (Optional Title)
+" TODO handle automatic links without colliding with htmlTag (<URL>)
+syn region mkdLinkDef matchgroup=mkdDelimiter start="^ \{,3}\zs\[" end="]:" oneline nextgroup=mkdLinkDefTarget skipwhite
+syn region mkdLinkDefTarget start="<\?\zs\S" excludenl end="\ze[>[:space:]\n]" contained nextgroup=mkdLinkTitle,mkdLinkDef skipwhite skipnl oneline
+syn region mkdLinkTitle matchgroup=mkdDelimiter start=+"+ end=+"+ contained
+syn region mkdLinkTitle matchgroup=mkdDelimiter start=+'+ end=+'+ contained
+syn region mkdLinkTitle matchgroup=mkdDelimiter start=+(+ end=+)+ contained
"define Markdown groups
syn match mkdLineContinue ".$" contained
HtmlHiLink mkdListItem Identifier
HtmlHiLink mkdRule Identifier
HtmlHiLink mkdLineBreak Todo
+HtmlHiLink mkdLink htmlLink
+HtmlHiLink mkdURL htmlString
+HtmlHiLink mkdID Identifier
+HtmlHiLink mkdLinkDef mkdID
+HtmlHiLink mkdLinkDefTarget mkdURL
+HtmlHiLink mkdLinkTitle htmlString
+
+HtmlHiLink mkdDelimiter Delimiter
let b:current_syntax = "mkd"