" Remove trailing white space, see https://vi.stackexchange.com/a/456/15292
function! utils#StripTrailingWhitespaces() abort
  let l:save = winsaveview()
  " vint: next-line -ProhibitCommandRelyOnUser -ProhibitCommandWithUnintendedSideEffect
  keeppatterns %s/\v\s+$//e
  call winrestview(l:save)
endfunction

" Create command alias safely, see https://stackoverflow.com/q/3878692/6064933
" The following two functions are taken from answer below on SO:
" https://stackoverflow.com/a/10708687/6064933
function! utils#Cabbrev(key, value) abort
  execute printf('cabbrev <expr> %s (getcmdtype() == ":" && getcmdpos() <= %d) ? %s : %s',
        \ a:key, 1+len(a:key), <SID>Single_quote(a:value), <SID>Single_quote(a:key))
endfunction

function! s:Single_quote(str) abort
  return "'" . substitute(copy(a:str), "'", "''", 'g') . "'"
endfunction

" Check the syntax group in the current cursor position, see
" https://stackoverflow.com/q/9464844/6064933 and
" https://jordanelver.co.uk/blog/2015/05/27/working-with-vim-colorschemes/
function! utils#SynGroup() abort
  if !exists('*synstack')
    return
  endif
  echo map(synstack(line('.'), col('.')), 'synIDattr(v:val, "name")')
endfunction

" Check if a colorscheme exists in runtimepath.
" The following two functions are inspired by https://stackoverflow.com/a/5703164/6064933.
function! utils#HasColorscheme(name) abort
  let l:pat = printf('colors/%s.vim', a:name)
  return !empty(globpath(&runtimepath, l:pat))
endfunction

" Check if an Airline theme exists in runtimepath.
function! utils#HasAirlinetheme(name) abort
  let l:pat = printf('autoload/airline/themes/%s.vim', a:name)
  return !empty(globpath(&runtimepath, l:pat))
endfunction

" Generate random integers in the range [Low, High] in pure vim script,
" adapted from https://stackoverflow.com/a/12739441/6064933
function! utils#RandInt(Low, High) abort
  " Use lua to generate random int. It is faster. Ref: https://stackoverflow.com/a/20157671/6064933
  call v:lua.math.randomseed(localtime())
  return v:lua.math.random(a:Low, a:High)
endfunction

" Selection a random element from a sequence/list
function! utils#RandElement(seq) abort
  let l:idx = utils#RandInt(0, len(a:seq)-1)

  return a:seq[l:idx]
endfunction

" Custom fold expr, adapted from https://vi.stackexchange.com/a/9094/15292
function! utils#VimFolds(lnum) abort
  " get content of current line and the line below
  let l:cur_line = getline(a:lnum)
  let l:next_line = getline(a:lnum+1)

  if l:cur_line =~# '^"{'
    return '>' . (matchend(l:cur_line, '"{*') - 1)
  endif

  if l:cur_line ==# '' && (matchend(l:next_line, '"{*') - 1) == 1
    return 0
  endif

  return '='
endfunction

" Custom fold text, adapted from https://vi.stackexchange.com/a/3818/15292
" and https://vi.stackexchange.com/a/6608/15292
function! utils#MyFoldText() abort
  let l:line = getline(v:foldstart)
  let l:fold_line_num = v:foldend - v:foldstart
  let l:fold_text = substitute(l:line, '^"{\+', '', 'g')
  let l:fill_char_num = &textwidth - len(l:fold_text) - len(l:fold_line_num) - 10
  return printf('+%s%s %s (%s L)', repeat('-', 4), l:fold_text, repeat('-', l:fill_char_num), l:fold_line_num)
endfunction

" Toggle cursor column
function! utils#ToggleCursorCol() abort
  if &cursorcolumn
    set nocursorcolumn
    echo 'cursorcolumn: OFF'
  else
    set cursorcolumn
    echo 'cursorcolumn: ON'
  endif
endfunction

function! utils#SwitchLine(src_line_idx, direction) abort
  if a:direction ==# 'up'
    if a:src_line_idx == 1
        return
    endif
    move-2
  elseif a:direction ==# 'down'
    if a:src_line_idx == line('$')
        return
    endif
    move+1
  endif
endfunction

function! utils#MoveSelection(direction) abort
  " only do this if previous mode is visual line mode. Once we press some keys in
  " visual line mode, we will leave this mode. So the output of `mode()` will be
  " `n` instead of `V`. We can use `visualmode()` instead to check the previous
  " mode, see also https://stackoverflow.com/a/61486601/6064933
  if visualmode() !=# 'V'
    return
  endif

  let l:start_line = line("'<")
  let l:end_line = line("'>")
  let l:num_line = l:end_line - l:start_line + 1

  if a:direction ==# 'up'
    if l:start_line == 1
      " we can also directly use `normal gv`, see https://stackoverflow.com/q/9724123/6064933
      normal! gv
      return
    endif
    silent execute printf('%s,%smove-2', l:start_line, l:end_line)
    normal! gv
  elseif a:direction ==# 'down'
    if l:end_line == line('$')
      normal! gv
      return
    endif
    silent execute printf('%s,%smove+%s', l:start_line, l:end_line, l:num_line)
    normal! gv
  endif
endfunction


function! utils#Get_titlestr() abort
  let l:title_str = ''
  if g:is_linux
      let l:title_str = hostname() . '  '
  endif
  let l:title_str = l:title_str . expand('%:p:~') . '  '
  if &buflisted
    let l:title_str = l:title_str . strftime('%Y-%m-%d %H:%M',getftime(expand('%')))
  endif

  return l:title_str
endfunction

" Check if we are inside a Git repo.
function! utils#Inside_git_repo() abort
  let res = system('git rev-parse --is-inside-work-tree')
  if match(res, 'true') == -1
    return v:false
  else
    " Manually trigger a specical user autocmd InGitRepo (to use it for
    " lazyloading of fugitive by packer.nvim).
    " See also https://github.com/wbthomason/packer.nvim/discussions/534.
    doautocmd User InGitRepo
    return v:true
  endif
endfunction

function! utils#GetGitBranch()
  let l:res = systemlist('git rev-parse --abbrev-ref HEAD')[0]
  if match(l:res, 'fatal') != -1
    return ''
  else
    return l:res
  endif
endfunction

" Redirect command output to a register for later processing.
" Ref: https://stackoverflow.com/q/2573021/6064933 and https://unix.stackexchange.com/q/8101/221410 .
function! utils#CaptureCommandOutput(command) abort
  redir @m
  execute a:command
  redir END
  call v:lua.vim.notify("command output captured to register m", "info", {'title': 'nvim-config'}) 
endfunction

" Edit all files matching the given patterns.
function! utils#MultiEdit(patterns) abort
  for p in a:patterns
    for f in glob(p, 0, 1)
      execute 'edit ' . f
    endfor
  endfor
endfunction