" MIT License. Copyright (c) 2013-2018 Bailey Ling et al.
" vim: et ts=2 sts=2 sw=2

scriptencoding utf-8

let s:spc = g:airline_symbols.space
let s:current_bufnr = -1
let s:current_tabnr = -1
let s:current_modified = 0

function! airline#extensions#tabline#tabs#off()
  augroup airline_tabline_tabs
    autocmd!
  augroup END
endfunction

function! airline#extensions#tabline#tabs#on()
  augroup airline_tabline_tabs
    autocmd!
    autocmd BufDelete * call airline#extensions#tabline#tabs#invalidate()
  augroup END
endfunction

function! airline#extensions#tabline#tabs#invalidate()
  let s:current_bufnr = -1
endfunction

function! s:evaluate_tabline(tabline)
  let tabline = a:tabline
  let tabline = substitute(tabline, '%{\([^}]\+\)}', '\=eval(submatch(1))', 'g')
  let tabline = substitute(tabline, '%#[^#]\+#', '', 'g')
  let tabline = substitute(tabline, '%(\([^)]\+\)%)', '\1', 'g')
  let tabline = substitute(tabline, '%\d\+[TX]', '', 'g')
  let tabline = substitute(tabline, '%=', '', 'g')
  let tabline = substitute(tabline, '%\d*\*', '', 'g')
  return tabline
endfunction

function! s:get_title(tab_nr_type, i)
  let val = '%('

  if get(g:, 'airline#extensions#tabline#show_tab_nr', 1)
    let val .= airline#extensions#tabline#tabs#tabnr_formatter(a:tab_nr_type, a:i)
  endif

  return val.'%'.a:i.'T %{airline#extensions#tabline#title('.a:i.')} %)'
endfunction

" Compatibility wrapper for strchars, in case this vim version does not
" have it natively
function! s:strchars(str)
  if exists('*strchars')
    return strchars(a:str)
  else
    return strlen(substitute(a:str, '.', 'a', 'g'))
  endif
endfunction

function! airline#extensions#tabline#tabs#get()
  let curbuf = bufnr('%')
  let curtab = tabpagenr()
  try
    call airline#extensions#tabline#tabs#map_keys()
  catch
    " no-op
  endtry
  if curbuf == s:current_bufnr && curtab == s:current_tabnr && &columns == s:column_width
    if !g:airline_detect_modified || getbufvar(curbuf, '&modified') == s:current_modified
      return s:current_tabline
    endif
  endif

  let tab_nr_type = get(g:, 'airline#extensions#tabline#tab_nr_type', 0)
  let b = airline#extensions#tabline#new_builder()

  call airline#extensions#tabline#add_label(b, 'tabs')

  let tabs_position = b.get_position()

  call b.add_section('airline_tabfill', '')
  call b.split()
  call b.add_section('airline_tabfill', '')

  if get(g:, 'airline#extensions#tabline#show_close_button', 1)
    call b.add_section('airline_tab_right', ' %999X'.
          \ get(g:, 'airline#extensions#tabline#close_symbol', 'X').' ')
  endif

  if get(g:, 'airline#extensions#tabline#show_splits', 1) == 1
    let buffers = tabpagebuflist(curtab)
    for nr in buffers
      let group = airline#extensions#tabline#group_of_bufnr(buffers, nr) . "_right"
      call b.add_section_spaced(group, '%(%{airline#extensions#tabline#get_buffer_name('.nr.')}%)')
    endfor
    call airline#extensions#tabline#add_label(b, 'buffers')
  endif

  let b_tabline = s:evaluate_tabline(b.build())
  let num_tabs = tabpagenr('$')
  let left_tab = curtab - 1
  let right_tab = curtab + 1
  let left_position = tabs_position
  let right_position = tabs_position + 1
  let remaining_space = &columns - s:strchars(s:evaluate_tabline(b.build()))

  let left_sep_size = s:strchars(s:evaluate_tabline(b._context.left_sep))
  let left_alt_sep_size = s:strchars(s:evaluate_tabline(b._context.left_alt_sep))

  let skipped_tabs_marker = get(g:, 'airline#extensions#tabline#overflow_marker', g:airline_symbols.ellipsis)
  let skipped_tabs_marker_size = s:strchars(s:evaluate_tabline(skipped_tabs_marker))
  " The left marker will have left_alt_sep, and the right will have left_sep.
  let remaining_space -= 2 * skipped_tabs_marker_size + left_sep_size + left_alt_sep_size

  " Add the current tab
  let tab_title = s:get_title(tab_nr_type, curtab)
  let remaining_space -= s:strchars(s:evaluate_tabline(tab_title))
  " There are always two left_seps (either side of the selected tab) and all
  " other seperators are left_alt_seps.
  let remaining_space -= 2 * left_sep_size - left_alt_sep_size
  let group = 'airline_tabsel'
  if g:airline_detect_modified
    for bi in tabpagebuflist(curtab)
      if getbufvar(bi, '&modified')
        let group = 'airline_tabmod'
      endif
    endfor
  endif
  let s:current_modified = (group == 'airline_tabmod') ? 1 : 0
  call b.insert_section(group, tab_title, left_position)

  if get(g:, 'airline#extensions#tabline#current_first', 0)
    " always have current tabpage first
    let left_position += 1
  endif

  " Add the tab to the right
  if right_tab <= num_tabs
    let tab_title = s:get_title(tab_nr_type, right_tab)
    let remaining_space -= s:strchars(s:evaluate_tabline(tab_title)) + left_alt_sep_size
    call b.insert_section('airline_tab', tab_title, right_position)
    let right_position += 1
    let right_tab += 1
  endif

  while remaining_space > 0
    if left_tab > 0
      let tab_title = s:get_title(tab_nr_type, left_tab)
      let remaining_space -= s:strchars(s:evaluate_tabline(tab_title)) + left_alt_sep_size
      if remaining_space >= 0
        call b.insert_section('airline_tab', tab_title, left_position)
        let right_position += 1
        let left_tab -= 1
      endif
    elseif right_tab <= num_tabs
      let tab_title = s:get_title(tab_nr_type, right_tab)
      let remaining_space -= s:strchars(s:evaluate_tabline(tab_title)) + left_alt_sep_size
      if remaining_space >= 0
        call b.insert_section('airline_tab', tab_title, right_position)
        let right_position += 1
        let right_tab += 1
      endif
    else
      break
    endif
  endwhile

  if left_tab > 0
    if get(g:, 'airline#extensions#tabline#current_first', 0)
      let left_position -= 1
    endif
    call b.insert_raw('%#airline_tab#'.skipped_tabs_marker, left_position)
    let right_position += 1
  endif

  if right_tab <= num_tabs
    call b.insert_raw('%#airline_tab#'.skipped_tabs_marker, right_position)
  endif

  let s:current_bufnr = curbuf
  let s:current_tabnr = curtab
  let s:column_width = &columns
  let s:current_tabline = b.build()
  return s:current_tabline
endfunction

function! airline#extensions#tabline#tabs#map_keys()
  if exists("s:airline_tabline_map_key")
    return
  endif
  noremap <silent> <Plug>AirlineSelectTab1 :1tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab2 :2tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab3 :3tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab4 :4tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab5 :5tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab6 :6tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab7 :7tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab8 :8tabn<CR>
  noremap <silent> <Plug>AirlineSelectTab9 :9tabn<CR>
  noremap <silent> <Plug>AirlineSelectPrevTab gT
  " tabn {count} goes to count tab does not go {count} tab pages forward!
  noremap <silent> <Plug>AirlineSelectNextTab :<C-U>exe repeat(':tabn\|', v:count1)<cr>
  let s:airline_tabline_map_key = 1
endfunction

function! airline#extensions#tabline#tabs#tabnr_formatter(nr, i)
  let formatter = get(g:, 'airline#extensions#tabline#tabnr_formatter', 'tabnr')
  return airline#extensions#tabline#formatters#{formatter}#format(a:nr, a:i)
endfunction