" Function for commenting out blocks of text.

noremap cd <cmd>set operatorfunc=<sid>comment<cr>g@
nnoremap cdd <cmd>set operatorfunc=<sid>comment<cr>g@_
nnoremap cD <cmd>set operatorfunc=<sid>comment<cr>g@$

" Comment out the rest of the line and put the cursor into insert mode
nnoremap cdC  <cmd>call <sid>change_comment_obj('i')<cr>
nnoremap cdcc  <cmd>call <sid>change_comment_obj('I')<cr>

onoremap i/ <cmd>call <sid>comment_obj(v:operator, 'i')<cr>
vnoremap i/ <cmd>call <sid>comment_obj('', 'i')<cr>
onoremap a/ <cmd>call <sid>comment_obj(v:operator, 'a')<cr>
vnoremap a/ <cmd>call <sid>comment_obj('', 'a')<cr>

noremap czd <cmd>set operatorfunc=<sid>uncomment<cr>g@
nnoremap czdd <cmd>set operatorfunc=<sid>uncomment<cr>g@_

function! s:single_character_style(c)
  return {
      \         'block_start_regex': '\(^\s*\(\(\S\)\(' . a:c . '\)\@<!.*\|\S\n\)\_s\+\|\%^\)${as}' . a:c . '\s*${is}\S${ie}',
      \         'block_end_regex': a:c . '.*${is}.${ie}\(\n\s*\)*${as}\n\_s*\S' . a:c . '\@<!',
      \         'line': a:c
      \     }
endfunction
let s:default_style = s:single_character_style('#')


function! s:regex_combine(s1, s2) abort
  if a:s1 == ""
    return a:s2
  endif

  if a:s2 == ""
    return a:s1
  endif

  return printf('\(%s\)\|\(%s\)', a:s1, a:s2)
endfunction

function! s:comment_obj(op, iOrA)
  let style = get(s:comment_style, &ft, s:default_style)

  let start_regex = s:regex_combine(
        \ get(style, 'multi_start_regex', ''),
        \ get(style, 'block_start_regex', ''))
  let end_regex = s:regex_combine(
        \ get(style, 'multi_end_regex', ''),
        \ get(style, 'block_end_regex', ''))
        \
  if a:iOrA == 'i'
    let start_regex =
          \ substitute(
          \   substitute(start_regex, '\V${i\(\[se]\)}', '\\z\1', 'g'),
          \   '\V${a\(\[se]\)}', '', 'g')
    let end_regex =
          \ substitute(
          \   substitute(end_regex, '\V${i\(\[se]\)}', '\\z\1', 'g'),
          \   '\V${a\(\[se]\)}', '', 'g')
  else
    let start_regex =
          \ substitute(
          \   substitute(start_regex, '\V${a\(\[se]\)}', '\\z\1', 'g'),
          \   '\V${i\(\[se]\)}', '', 'g')
    let end_regex =
          \ substitute(
          \   substitute(end_regex, '\V${a\(\[se]\)}', '\\z\1', 'g'),
          \   '\V${i\(\[se]\)}', '', 'g')
  endif

  call search(end_regex, 'c')
  exec "normal! v\<esc>m>"
  call search(start_regex, 'bW')
  exec "normal! m<gv"

  let [_, sl, sc, _] = getpos("'<")
  let [_, el, ec, _] = getpos("'>")

  if getline(sl)[:sc - 2] =~ '^\s*$' && a:iOrA == 'a' && ec >= len(getline(el))
    exec "normal V"
  endif
endfunction

function! s:change_comment_obj(mv) abort
  let s = get(s:comment_style, &ft, s:default_style)
  " <C-g>U<Left> allows <Left>,<Right>,etc. to show up in the redo buff.
  call feedkeys(printf(
        \ "%s %s %s",
        \ a:mv,
        \ s.line,
        \ repeat("\<C-g>U\<left>", len(s.line) + 2)), 'n')
endfunction

let s:comment_style = {
      \ 'java,c,cpp,rust,go': {
      \         'multi_start_regex': '${as}\/\*\([*]\|\_s\)*${is}\S',
      \         'multi_end_regex': '${is}\S\_s*\*\/${as}',
      \         'block_start_regex': '\(^\s*\(\(\S\S\)\(\/\/\)\@<!.*\|\S\n\)\n*${as}\_s\+\|\%^${as}\)\/\/\+\s*${is}\S${ie}',
      \         'block_end_regex': '\/\/.*${is}.${ie}${as}\n\_s*\S\/\@<!',
      \         'line': '//',
      \         'multi_start': '/*',
      \         'multi_cont': ' *',
      \         'multi_end': ' */'
      \     },
      \ 'vim': s:single_character_style('"')
      \ }

let s:comment_style_new = {}
for [langs, i] in items(s:comment_style)
  for l in split(langs, ',')
    let s:comment_style_new[l] = i
  endfor
endfor
let s:comment_style = s:comment_style_new

function! s:uncomment(arg, ...) abort

  let s = get(s:comment_style, &ft, s:default_style)
  let l1 = line("'[")
  let l2 = line("']")

  if has_key(s, 'multi_start')
    silent exec printf(
          \ 'silent! %s,%s s/\V\zs%s\s\?\ze//', l1, l2, escape(s.multi_start, '/'))
    silent exec printf('silent! %s,%s s/\V\zs\s\?%s\ze//', l1, l2, escape(s.multi_end, '/'))
    silent exec printf('silent! %s,%s s/\V\^\s\*\zs%s\s\?\ze//', l1, l2, escape(s.multi_cont, '/'))
  endif

  silent exec printf('silent! %s,%s s/\V\^\s\*\zs%s\s\?\ze//', l1, l2, escape(s.line, '/'))
endfunction

function! s:comment(arg, ...) abort
  let cb = { 'arg': a:arg }
  normal! m`

  function! cb.operate(ls, t) dict abort
    let s = get(s:comment_style, &ft, s:default_style)
    let smallest = 100
    let ls = a:ls

    if self.arg == 'line' || len(ls) > 1
      for l in ls
        if ! (l =~ '^\s*$')
          let sz = match(l, '^\(\s\+\)\zs\S\ze') + 1
          if sz <= 0
            let sz = 1
          endif

          if sz < smallest && sz > 0
            let smallest = sz
          endif
        endif
      endfor

      if self.arg == 'line'
        let i = 0
        while i < len(ls)
          let ls[i] = substitute(ls[i], printf('\%%%dc', smallest), s.line . ' ', '')
          let i += 1
        endwhile
      else
        if self.arg != 'line' && !has_key(s, 'multi_start')
          throw "Inline comments not allowed"
        endif

        let ls[0] = substitute(ls[0], '^', s.multi_start . ' ', '')
        let ls[-1] = substitute(ls[-1], '$', ' ' . s.multi_end, '')
      endif
    else
      let l = getline('.')
      if l[len(l) - len(ls[0]):] ==# ls[0]
        let ls[0] = printf("%s %s", s.line, ls[0])
      else
        if !has_key(s, 'multi_start')
          throw "Inline comments not allowed"
        endif
        let ls[0] = printf("%s %s %s", s.multi_start, ls[0], s.multi_end)
      endif
    endif

    return ls
  endfunction

  call fieldmarshal#modifytext(a:arg, cb)
  norm ``
endfunction