" Customize highlight groups
hi link markdownCode Special
hi link markdownCodeDelimiter PreProc
hi link markdownHeadingDelimiter PreProc
hi link markdownLinkDelimiter PreProc
hi link markdownLinkTextDelimiter PreProc
hi link markdownUrl Include
hi link markdownError None

" Add match for GitHub style check boxes
syn match markdownCheckboxTick '\[\zsx\ze\]' contained
syn match markdownCheckboxDelimiter '\[[ x]\]' contained contains=markdownCheckboxTick
syn match markdownCheckbox '\s*\* \[[ x]\] ' contains=markdownCheckboxDelimiter,markdownListMarker
syn region markdownCheckboxDone start='\s*\* \ze\[x\] ' keepend end='\ze\(\n^\s*\*\|\n^\s*\n\)' contains=markdownCheckbox,@markdownCheckboxDoneInline

if has('conceal')
  setlocal conceallevel=0
  if get(g:, 'markdown_syntax_conceal', 1) == 1
    let s:concealends = ' concealends'
  endif
endif
exe 'syn region markdownCheckboxItalic matchgroup=markdownCheckboxItalicDelimiter start="\S\@<=\*\|\*\S\@=" end="\S\@<=\*\|\*\S\@=" keepend contains=markdownLineStart,@Spell contained' . s:concealends
exe 'syn region markdownCheckboxItalic matchgroup=markdownCheckboxItalicDelimiter start="\S\@<=_\|_\S\@=" end="\S\@<=_\|_\S\@=" keepend contains=markdownLineStart,@Spell contained' . s:concealends
exe 'syn region markdownCheckboxBold matchgroup=markdownCheckboxBoldDelimiter start="\S\@<=\*\*\|\*\*\S\@=" end="\S\@<=\*\*\|\*\*\S\@=" keepend contains=markdownLineStart,markdownItalic,@Spell contained' . s:concealends
exe 'syn region markdownCheckboxBold matchgroup=markdownCheckboxBoldDelimiter start="\S\@<=__\|__\S\@=" end="\S\@<=__\|__\S\@=" keepend contains=markdownLineStart,markdownItalic,@Spell contained' . s:concealends
exe 'syn region markdownCheckboxBoldItalic matchgroup=markdownCheckboxBoldItalicDelimiter start="\S\@<=\*\*\*\|\*\*\*\S\@=" end="\S\@<=\*\*\*\|\*\*\*\S\@=" keepend contains=markdownLineStart,@Spell contained' . s:concealends
exe 'syn region markdownCheckboxBoldItalic matchgroup=markdownCheckboxBoldItalicDelimiter start="\S\@<=___\|___\S\@=" end="\S\@<=___\|___\S\@=" keepend contains=markdownLineStart,@Spell contained' . s:concealends

syn region markdownCheckboxCode matchgroup=markdownCheckboxCodeDelimiter start="`" end="`" keepend contains=markdownLineStart contained
syn region markdownCheckboxCode matchgroup=markdownCheckboxCodeDelimiter start="`` \=" end=" \=``" keepend contains=markdownLineStart contained

syn cluster markdownInline contains=markdownLineBreak,markdownLinkText,markdownItalic,markdownBold,markdownCode,markdownEscape,@htmlTop,markdownError
syn cluster markdownCheckboxDoneInline contains=markdownLineBreak,markdownLinkText,markdownCheckboxItalic,markdownCheckboxBold,markdownCheckboxBoldItalic,markdownCheckboxCode,markdownEscape,@htmlTop,markdownError

hi link markdownCheckboxTick markdownListMarker
hi link markdownCheckboxDelimiter PreProc
hi link markdownCheckboxDone Comment
call CloneHighlightGroupWithAttributes('markdownCheckboxDone',
      \ 'markdownCheckboxItalic', 'italic')
hi link markdownCheckboxItalicDelimiter markdownCheckboxItalic
call CloneHighlightGroupWithAttributes('markdownCheckboxDone',
      \ 'markdownCheckboxBold', 'bold')
hi link markdownCheckboxBoldDelimiter markdownCheckboxBold
call CloneHighlightGroupWithAttributes('markdownCheckboxDone',
      \ 'markdownCheckboxBoldItalic', 'bold,italic')
hi link markdownCheckboxBoldItalicDelimiter markdownCheckboxBoldItalic
hi link markdownCheckboxCode SpecialComment
hi link markdownCheckboxCodeDelimiter PreProc

" yaml frontmatter
syn region markdownFrontmatter matchgroup=markdownFrontmatterDelimiter start='\%^---' keepend end='^---' contains=@markdownHighlightyaml
hi default link markdownFrontmatterDelimiter Special