" Read the HTML syntax to start with
if v:version < 600
  so <sfile>:p:h/html.vim
else
  runtime! syntax/html.vim

  if exists('b:current_syntax')
    unlet b:current_syntax
  endif
endif

if v:version < 600
  syntax clear
elseif exists('b:current_syntax')
  finish
endif

" don't use standard HiLink, it will not work with included syntax files
if v:version < 508
  command! -nargs=+ HtmlHiLink hi link <args>
else
  command! -nargs=+ HtmlHiLink hi def link <args>
endif

syn spell toplevel
syn case ignore
syn sync linebreaks=1

let s:conceal = ''
let s:concealends = ''
let s:concealcode = ''
if has('conceal') && get(g:, 'vim_markdown_conceal', 1)
  let s:conceal = ' conceal'
  let s:concealends = ' concealends'
endif
if has('conceal') && get(g:, 'vim_markdown_conceal_code_blocks', 1)
  let s:concealcode = ' concealends'
endif

" additions to HTML groups
if get(g:, 'vim_markdown_emphasis_multiline', 1)
    let s:oneline = ''
else
    let s:oneline = ' oneline'
endif
syn region mkdItalic matchgroup=mkdItalic start="\%(\*\|_\)"    end="\%(\*\|_\)"
syn region mkdBold matchgroup=mkdBold start="\%(\*\*\|__\)"    end="\%(\*\*\|__\)"
syn region mkdBoldItalic matchgroup=mkdBoldItalic start="\%(\*\*\*\|___\)"    end="\%(\*\*\*\|___\)"
execute 'syn region htmlItalic matchgroup=mkdItalic start="\%(^\|\s\)\zs\*\ze[^\\\*\t ]\%(\%([^*]\|\\\*\|\n\)*[^\\\*\t ]\)\?\*\_W" end="[^\\\*\t ]\zs\*\ze\_W" keepend contains=@Spell' . s:oneline . s:concealends
execute 'syn region htmlItalic matchgroup=mkdItalic start="\%(^\|\s\)\zs_\ze[^\\_\t ]" end="[^\\_\t ]\zs_\ze\_W" keepend contains=@Spell' . s:oneline . s:concealends
execute 'syn region htmlBold matchgroup=mkdBold start="\%(^\|\s\)\zs\*\*\ze\S" end="\S\zs\*\*" keepend contains=@Spell' . s:oneline . s:concealends
execute 'syn region htmlBold matchgroup=mkdBold start="\%(^\|\s\)\zs__\ze\S" end="\S\zs__" keepend contains=@Spell' . s:oneline . s:concealends
execute 'syn region htmlBoldItalic matchgroup=mkdBoldItalic start="\%(^\|\s\)\zs\*\*\*\ze\S" end="\S\zs\*\*\*" keepend contains=@Spell' . s:oneline . s:concealends
execute 'syn region htmlBoldItalic matchgroup=mkdBoldItalic start="\%(^\|\s\)\zs___\ze\S" end="\S\zs___" keepend contains=@Spell' . s:oneline . s:concealends

" [link](URL) | [link][id] | [link][] | ![image](URL)
syn region mkdFootnotes matchgroup=mkdDelimiter start="\[^"    end="\]"
execute 'syn region mkdID matchgroup=mkdDelimiter    start="\["    end="\]" contained oneline' . s:conceal
execute 'syn region mkdURL matchgroup=mkdDelimiter   start="("     end=")"  contained oneline' . s:conceal
execute 'syn region mkdLink matchgroup=mkdDelimiter  start="\\\@<!!\?\[\ze[^]\n]*\n\?[^]\n]*\][[(]" end="\]" contains=@mkdNonListItem,@Spell nextgroup=mkdURL,mkdID skipwhite' . s:concealends

" Autolink without angle brackets.
" mkd  inline links:      protocol     optional  user:pass@  sub/domain                    .com, .co.uk, etc         optional port   path/querystring/hash fragment
"                         ------------ _____________________ ----------------------------- _________________________ ----------------- __
syn match   mkdInlineURL /https\?:\/\/\(\w\+\(:\w\+\)\?@\)\?\([A-Za-z0-9][-_0-9A-Za-z]*\.\)\{1,}\(\w\{2,}\.\?\)\{1,}\(:[0-9]\{1,5}\)\?[^] \t]*/

" Autolink with parenthesis.
syn region  mkdInlineURL matchgroup=mkdDelimiter start="(\(https\?:\/\/\(\w\+\(:\w\+\)\?@\)\?\([A-Za-z0-9][-_0-9A-Za-z]*\.\)\{1,}\(\w\{2,}\.\?\)\{1,}\(:[0-9]\{1,5}\)\?[^] \t]*)\)\@=" end=")"

" Autolink with angle brackets.
syn region mkdInlineURL matchgroup=mkdDelimiter start="\\\@<!<\ze[a-z][a-z0-9,.-]\{1,22}:\/\/[^> ]*>" end=">"

" Link definitions: [id]: URL (Optional Title)
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

"HTML headings
syn region htmlH1       matchgroup=mkdHeading     start="^\s*#"                   end="$" contains=mkdLink,mkdInlineURL,@Spell
syn region htmlH2       matchgroup=mkdHeading     start="^\s*##"                  end="$" contains=mkdLink,mkdInlineURL,@Spell
syn region htmlH3       matchgroup=mkdHeading     start="^\s*###"                 end="$" contains=mkdLink,mkdInlineURL,@Spell
syn region htmlH4       matchgroup=mkdHeading     start="^\s*####"                end="$" contains=mkdLink,mkdInlineURL,@Spell
syn region htmlH5       matchgroup=mkdHeading     start="^\s*#####"               end="$" contains=mkdLink,mkdInlineURL,@Spell
syn region htmlH6       matchgroup=mkdHeading     start="^\s*######"              end="$" contains=mkdLink,mkdInlineURL,@Spell
syn match  htmlH1       /^.\+\n=\+$/ contains=mkdLink,mkdInlineURL,@Spell
syn match  htmlH2       /^.\+\n-\+$/ contains=mkdLink,mkdInlineURL,@Spell

"define Markdown groups
syn match  mkdLineBreak    /  \+$/
syn region mkdBlockquote   start=/^\s*>/                   end=/$/ contains=mkdLink,mkdInlineURL,mkdLineBreak,@Spell
execute 'syn region mkdCode matchgroup=mkdCodeDelimiter start=/\(\([^\\]\|^\)\\\)\@<!`/                     end=/`/'  . s:concealcode
execute 'syn region mkdCode matchgroup=mkdCodeDelimiter start=/\(\([^\\]\|^\)\\\)\@<!``/ skip=/[^`]`[^`]/   end=/``/' . s:concealcode
execute 'syn region mkdCode matchgroup=mkdCodeDelimiter start=/^\s*\z(`\{3,}\)[^`]*$/                       end=/^\s*\z1`*\s*$/'            . s:concealcode
execute 'syn region mkdCode matchgroup=mkdCodeDelimiter start=/\(\([^\\]\|^\)\\\)\@<!\~\~/  end=/\(\([^\\]\|^\)\\\)\@<!\~\~/'               . s:concealcode
execute 'syn region mkdCode matchgroup=mkdCodeDelimiter start=/^\s*\z(\~\{3,}\)\s*[0-9A-Za-z_+-]*\s*$/      end=/^\s*\z1\~*\s*$/'           . s:concealcode
execute 'syn region mkdCode matchgroup=mkdCodeDelimiter start="<pre\(\|\_s[^>]*\)\\\@<!>"                   end="</pre>"'                   . s:concealcode
execute 'syn region mkdCode matchgroup=mkdCodeDelimiter start="<code\(\|\_s[^>]*\)\\\@<!>"                  end="</code>"'                  . s:concealcode
syn region mkdFootnote     start="\[^"                     end="\]"
syn match  mkdCode         /^\s*\n\(\(\s\{8,}[^ ]\|\t\t\+[^\t]\).*\n\)\+/
syn match  mkdCode         /\%^\(\(\s\{4,}[^ ]\|\t\+[^\t]\).*\n\)\+/
syn match  mkdCode         /^\s*\n\(\(\s\{4,}[^ ]\|\t\+[^\t]\).*\n\)\+/ contained
syn match  mkdListItem     /^\s*\%([-*+]\|\d\+\.\)\ze\s\+/ contained nextgroup=mkdListItemCheckbox
syn match  mkdListItemCheckbox     /\[[xXoO ]\]\ze\s\+/ contained contains=mkdListItem
syn region mkdListItemLine start="^\s*\%([-*+]\|\d\+\.\)\s\+" end="$" oneline contains=@mkdNonListItem,mkdListItem,mkdListItemCheckbox,@Spell
syn region mkdNonListItemBlock start="\(\%^\(\s*\([-*+]\|\d\+\.\)\s\+\)\@!\|\n\(\_^\_$\|\s\{4,}[^ ]\|\t+[^\t]\)\@!\)" end="^\(\s*\([-*+]\|\d\+\.\)\s\+\)\@=" contains=@mkdNonListItem,@Spell
syn match  mkdRule         /^\s*\*\s\{0,1}\*\s\{0,1}\*\(\*\|\s\)*$/
syn match  mkdRule         /^\s*-\s\{0,1}-\s\{0,1}-\(-\|\s\)*$/
syn match  mkdRule         /^\s*_\s\{0,1}_\s\{0,1}_\(_\|\s\)*$/

" YAML frontmatter
if get(g:, 'vim_markdown_frontmatter', 0)
  syn include @yamlTop syntax/yaml.vim
  syn region Comment matchgroup=mkdDelimiter start="\%^---$" end="^\(---\|\.\.\.\)$" contains=@yamlTop keepend
  unlet! b:current_syntax
endif

if get(g:, 'vim_markdown_toml_frontmatter', 0)
  try
    syn include @tomlTop syntax/toml.vim
    syn region Comment matchgroup=mkdDelimiter start="\%^+++$" end="^+++$" transparent contains=@tomlTop keepend
    unlet! b:current_syntax
  catch /E484/
    syn region Comment matchgroup=mkdDelimiter start="\%^+++$" end="^+++$"
  endtry
endif

if get(g:, 'vim_markdown_json_frontmatter', 0)
  try
    syn include @jsonTop syntax/json.vim
    syn region Comment matchgroup=mkdDelimiter start="\%^{$" end="^}$" contains=@jsonTop keepend
    unlet! b:current_syntax
  catch /E484/
    syn region Comment matchgroup=mkdDelimiter start="\%^{$" end="^}$"
  endtry
endif

if get(g:, 'vim_markdown_math', 0)
  syn include @tex syntax/tex.vim
  syn region mkdMath start="\\\@<!\$" end="\$" skip="\\\$" contains=@tex keepend
  syn region mkdMath start="\\\@<!\$\$" end="\$\$" skip="\\\$" contains=@tex keepend
endif

" Strike through
if get(g:, 'vim_markdown_strikethrough', 0)
    execute 'syn region mkdStrike matchgroup=htmlStrike start="\%(\~\~\)" end="\%(\~\~\)"' . s:concealends
    HtmlHiLink mkdStrike        htmlStrike
endif

syn cluster mkdNonListItem contains=@htmlTop,htmlItalic,htmlBold,htmlBoldItalic,mkdFootnotes,mkdInlineURL,mkdLink,mkdLinkDef,mkdLineBreak,mkdBlockquote,mkdCode,mkdRule,htmlH1,htmlH2,htmlH3,htmlH4,htmlH5,htmlH6,mkdMath,mkdStrike

"highlighting for Markdown groups
HtmlHiLink mkdString           String
HtmlHiLink mkdCode             String
HtmlHiLink mkdCodeDelimiter    String
HtmlHiLink mkdCodeStart        String
HtmlHiLink mkdCodeEnd          String
HtmlHiLink mkdFootnote         Comment
HtmlHiLink mkdBlockquote       Comment
HtmlHiLink mkdListItem         Identifier
HtmlHiLink mkdListItemCheckbox Identifier
HtmlHiLink mkdRule             Identifier
HtmlHiLink mkdLineBreak        Visual
HtmlHiLink mkdFootnotes        htmlLink
HtmlHiLink mkdLink             htmlLink
HtmlHiLink mkdURL              htmlString
HtmlHiLink mkdInlineURL        htmlLink
HtmlHiLink mkdID               Identifier
HtmlHiLink mkdLinkDef          mkdID
HtmlHiLink mkdLinkDefTarget    mkdURL
HtmlHiLink mkdLinkTitle        htmlString
HtmlHiLink mkdDelimiter        Delimiter

let b:current_syntax = 'mkd'

delcommand HtmlHiLink
" vim: ts=8