vim-combo/plugin/vim-combo.vim

" COMBO Counter
" Choose combo file depending on extension

" Check for a .combo folder, make one if missing
if !isdirectory($HOME . '/.vim/.combo')
    silent !mkdir $HOME/.vim/.combo
endif
" Get extension, choose combo file
if strlen(expand("%:e")) > 0 
    let g:combo_file = $HOME . '/.vim/.combo/' . expand("%:e") . ".cmb"
else
    let g:combo_file = $HOME . '/.vim/.combo/none.cmb'
endif

" If file should be ignored, just set text, else continue with script
if g:disable_combo
	let g:combo = "N/A"
else
	" Find best score for current filetype. If none exists, start tracking
	if filereadable(g:combo_file)
		let g:best_combo = readfile(g:combo_file)
		let g:best_combo = g:best_combo[0]
	else
		silent exec '!echo 0 > ' . g:combo_file
		let g:best_combo = 0
	endif
	let g:best_last_combo = g:best_combo		" Used to revert

	" Configure variables
	let g:combo_counter = 0		" The actual combo variable
	let g:timeout = 1
	let g:combo = printf("[%d] 0", g:best_combo)
	let g:last_combo = reltime()	" Set current time as last combo time
	" Main check function, executed every time the file is changed
	function! UpdateCombo()
		if reltimefloat(reltime(g:last_combo)) > g:timeout
			call SaveCombo()
			let g:combo_counter = 1
		else
			let g:combo_counter +=1
		endif
		let g:combo = printf("[%d] %d", g:best_combo, g:combo_counter)
		let g:last_combo = reltime()
	endfunction
	" Checks if a new combo has been achieved and saves it to file
	function! SaveCombo()		" Should check inside because it can be called on InsertLeave
		if g:combo_counter > g:best_combo
			call writefile([g:combo_counter], g:combo_file)
			let g:best_last_combo = g:best_combo
			let g:best_combo = g:combo_counter
		endif
	endfunction

	autocmd TextChangedI * call UpdateCombo()	" Every time text is changed, call combo function
	autocmd InsertLeave * call SaveCombo()
	" In case you want to revert your last combo
	function! Cheated()
		let g:best_combo = g:best_last_combo
		let g:combo_counter = g:best_last_combo
		call writefile([g:combo_counter], g:combo_file)
	endfunction
	" This is only needed to avoid backspace cheating.
	function! Decrease()
		let g:combo_counter -= 1
		return "\<BS>"
	endfunction
	inoremap <expr> <BS> Decrease()
endif