fgrun

#!/usr/bin/env python

import os, sys, pathlib as pl, subprocess as sp

def main(args=None):
	dmenu_history_hwm = 10 * 2**10
	dmenu_history = pl.Path('~/.fgrun.history').expanduser()
	dmenu_cache = pl.Path('~/.fgrun.cache').expanduser()
	dmenu_cache_end = '-=puǝ=-'
	dmenu_args = ['-p', 'Run:', '-i', '-m', '2', '-fn', 'Luxi Sans-8:normal']

	# Read caches
	try:
		dmenu_cache_ts = dmenu_cache.stat().st_mtime
		dcache = dmenu_cache.read_text().split('\0')
		if dcache[-1] != dmenu_cache_end: raise OSError
		dcache = dict((s[0], s[1:]) for s in (s.split(' ') for s in dcache[:-1]))
	except OSError: dcache, dmenu_cache_ts = dict(), 0
	try: history = list(s for s in dmenu_history.read_text().splitlines() if s)
	except OSError: history = list()
	if os.environ.get('FGRUN_RECACHE'): dmenu_cache_ts = 0

	# Update caches
	dcache_update, paths = False, set()
	for s in os.environ.get('PATH', '').split(':'):
		if not s.strip(): continue
		try: p_mtime = (p := pl.Path(s).resolve(True)).stat().st_mtime
		except OSError: continue
		if (ps := str(p)) in paths: continue
		if ps not in dcache or p_mtime > dmenu_cache_ts:
			try: dcache[ps] = list(b for b in os.listdir(ps) if ' ' not in b)
			except OSError: continue
			dcache_update = True
		paths.add(ps)
	for ps in set(dcache).difference(paths):
		del dcache[ps]; dcache_update = True

	# Run dmenu
	dmenu_list = dict.fromkeys(reversed(history))
	for ext in dcache.values(): dmenu_list.update(dict.fromkeys(ext))
	dmenu_list[''] = None
	dmenu = sp.Popen(
		['dmenu'] + dmenu_args, stdin=sp.PIPE, stdout=sp.PIPE )
	dmenu.stdin.write('\n'.join(dmenu_list).encode())
	dmenu.stdin.close()
	run = dmenu.stdout.read().strip().decode()
	if dmenu.wait() != 0: run = None

	# Write caches, run app
	if dcache_update:
		(tmp := dmenu_cache.with_name(dmenu_cache.name + '.new')).write_text(
			'\0'.join([*(' '.join([k,*v]) for k,v in dcache.items()), dmenu_cache_end]) )
		tmp.rename(dmenu_cache)
	if not run: return
	try: hist_sz = dmenu_history.stat().st_size
	except OSError: pass
	history.append(run)
	if hist_sz >= dmenu_history_hwm: # deduplicate
		history = list(reversed(list(dict.fromkeys(reversed(history)))))
	history.append('')
	(tmp := dmenu_history.with_name(
		dmenu_history.name + '.new' )).write_text('\n'.join(history))
	tmp.rename(dmenu_history)
	os.execvp(run, [run] + sys.argv[1:])

if __name__ == '__main__': sys.exit(main())