#!/usr/bin/python -S
# Copyright (C) 2012  Roman Zimbelmann <romanz@lavabit.com>
# This software is distributed under the terms of the GNU GPL version 3.

"""
rifle, the file executor/opener of ranger

This can be used as a standalone program or can be embedded in python code.
When used together with ranger, it doesn't have to be installed to $PATH.

Example usage:

	rifle = Rifle("rilfe.conf")
	rifle.reload_config()
	rifle.execute(["file1", "file2"])
"""

import os.path
import re
from subprocess import Popen, PIPE
import sys

DEFAULT_PAGER = 'less'
DEFAULT_EDITOR = 'nano'
ENCODING = 'utf-8'

try:
	from ranger.ext.get_executables import get_executables
except ImportError:
	_cached_executables = None

	def get_executables():
		"""
		Return all executable files in $PATH + Cache them.
		"""
		global _cached_executables
		if _cached_executables is not None:
			return _cached_executables

		if 'PATH' in os.environ:
			paths = os.environ['PATH'].split(':')
		else:
			paths = ['/usr/bin', '/bin']

		from stat import S_IXOTH, S_IFREG
		paths_seen = set()
		_cached_executables = set()
		for path in paths:
			if path in paths_seen:
				continue
			paths_seen.add(path)
			try:
				content = listdir(path)
			except:
				continue
			for item in content:
				abspath = path + '/' + item
				try:
					filestat = stat(abspath)
				except:
					continue
				if filestat.st_mode & (S_IXOTH | S_IFREG):
					_cached_executables.add(item)
		return _cached_executables


def _is_terminal():
	# Check if stdin (file descriptor 0), stdout (fd 1) and
	# stderr (fd 2) are connected to a terminal
	try:
		os.ttyname(0)
		os.ttyname(1)
		os.ttyname(2)
	except:
		return False
	return True


def squash_flags(flags):
	"""
	Remove lowercase flags if the respective uppercase flag exists

	>>> squash_flags('abc')
	'abc'
	>>> squash_flags('abcC')
	'ab'
	>>> squash_flags('CabcAd')
	'bd'
	"""
	exclude = ''.join(f.upper() + f.lower() for f in flags if f == f.upper())
	return ''.join(f for f in flags if f not in exclude)


class Rifle(object):
	delimiter1 = '='
	delimiter2 = ','

	def hook_before_executing(self, command, mimetype, flags):
		pass

	def hook_after_executing(self, command, mimetype, flags):
		pass

	def hook_command_preprocessing(self, command):
		return command

	def hook_command_postprocessing(self, command):
		return command

	def hook_environment(self, env):
		return env

	def hook_logger(self, string):
		sys.stderr.write(string + "\n")

	def __init__(self, config_file):
		self.config_file = config_file
		self._app_flags = ''
		self._app_label = None

	def reload_config(self, config_file=None):
		"""Replace the current configuration with the one in config_file"""
		if config_file is None:
			config_file = self.config_file
		f = open(config_file, 'r')
		self.rules = []
		lineno = 1
		for line in f:
			if line.startswith('#') or line == '\n':
				continue
			line = line.strip()
			try:
				if self.delimiter1 not in line:
					raise Exception("Line without delimiter")
				tests, command = line.split(self.delimiter1, 1)
				tests = tests.split(self.delimiter2)
				tests = tuple(tuple(f.strip().split(None, 1)) for f in tests)
				command = command.strip()
				self.rules.append((command, tests))
			except Exception as e:
				self.hook_logger("Syntax error in %s line %d (%s)" % \
					(config_file, lineno, str(e)))
			lineno += 1
		f.close()

	def _eval_condition(self, condition, files, label):
		# Handle the negation of conditions starting with an exclamation mark,
		# then pass on the arguments to _eval_condition2().

		if not condition:
			return True
		if condition[0].startswith('!'):
			new_condition = tuple([condition[0][1:]]) + tuple(condition[1:])
			return not self._eval_condition2(new_condition, files, label)
		return self._eval_condition2(condition, files, label)

	def _eval_condition2(self, rule, files, label):
		# This function evaluates the condition, after _eval_condition() handled
		# negation of conditions starting with a "!".

		if not files:
			return False

		function = rule[0]
		argument = rule[1] if len(rule) > 1 else ''

		if function == 'ext':
			extension = os.path.basename(files[0]).rsplit('.', 1)[-1]
			return bool(re.search('^(' + argument + ')$', extension))
		elif function == 'name':
			return bool(re.search(argument, os.path.basename(files[0])))
		elif function == 'match':
			return bool(re.search(argument, files[0]))
		elif function == 'file':
			return os.path.isfile(files[0])
		elif function == 'directory':
			return os.path.isdir(files[0])
		elif function == 'path':
			return bool(re.search(argument, os.path.abspath(files[0])))
		elif function == 'mime':
			return bool(re.search(argument, self._get_mimetype(files[0])))
		elif function == 'has':
			return argument in get_executables()
		elif function == 'terminal':
			return _is_terminal()
		elif function == 'number':
			if argument.isdigit():
				self._skip = int(argument)
			return True
		elif function == 'label':
			self._app_label = argument
			if label:
				return argument == label
			return True
		elif function == 'flag':
			self._app_flags = argument
			return True
		elif function == 'X':
			return 'DISPLAY' in os.environ
		elif function == 'else':
			return True

	def _get_mimetype(self, fname):
		# Spawn "file" to determine the mime-type of the given file.
		if self._mimetype:
			return self._mimetype
		process = Popen(["file", "--mime-type", "-Lb", fname],
				stdout=PIPE, stderr=PIPE)
		mimetype, _ = process.communicate()
		self._mimetype = mimetype.decode(ENCODING)
		return self._mimetype

	def _build_command(self, files, action, flags):
		# Get the flags
		if isinstance(flags, str):
			self._app_flags += flags
		self._app_flags = squash_flags(self._app_flags)
		flags = self._app_flags

		_filenames = "' '".join(f.replace("'", "'\\\''") for f in files
				if "\x00" not in f)
		command = "set -- '%s'" % _filenames + '\n'

		# Apply flags
		command += self._apply_flags(action, flags)
		return command

	def _apply_flags(self, action, flags):
		# FIXME: Flags do not work properly when pipes are in the command.
		# NOTE: "r" flag is handled in execute()
		if 't' in flags:
			if 'TERMCMD' not in os.environ:
				term = os.environ['TERM']
				if term.startswith('rxvt-unicode'):
					term = 'urxvt'
				if term not in get_executables():
					self.hook_logger("Can not determine terminal command.  "
						"Please set $TERMCMD manually.")
				os.environ['TERMCMD'] = term
			action = "$TERMCMD -e %s" % action
		if 'f' in flags:
			if 'setsid' in get_executables():
				action = "setsid %s > /dev/null 2> /dev/null &" % action
			else:
				action = "nohup %s > /dev/null 2> /dev/null &" % action
		return action

	def list_commands(self, files, mimetype=None):
		"""
		Returns one 4-tuple for all currently applicable commands
		The 4-tuple contains (count, command, label, flags).
		count is the index, counted from 0 upwards,
		command is the command that will be executed.
		label and flags are the label and flags specified in the rule.
		"""
		self._mimetype = mimetype
		count = -1
		for cmd, tests in self.rules:
			self._skip = None
			self._app_flags = ''
			self._app_label = None
			for test in tests:
				if not self._eval_condition(test, files, None):
					break
			else:
				if self._skip is None:
					count += 1
				else:
					count = self._skip
				yield (count, cmd, self._app_label, self._app_flags)

	def execute(self, files, number=0, label=None, flags="", mimetype=None):
		"""
		Executes the given list of files.

		By default, this executes the first command where all conditions apply,
		but by specifying number=N you can run the 1+Nth command.

		If a label is specified, only rules with this label will be considered.

		If you specify the mimetype, rifle will not try to determine it itself.

		By specifying a flag, you extend the flag that is defined in the rule.
		Uppercase flags negate the respective lowercase flags.
		For example: if the flag in the rule is "pw" and you specify "Pf", then
		the "p" flag is negated and the "f" flag is added, resulting in "wf".
		"""
		command = None
		found_at_least_one = None

		# Determine command
		for count, cmd, lbl, flgs in self.list_commands(files, mimetype):
			if label and label == lbl or not label and count == number:
				cmd = self.hook_command_preprocessing(cmd)
				command = self._build_command(files, cmd, flags + flgs)
				break
			else:
				found_at_least_one = True
		else:
			if label and label in get_executables():
				cmd = '%s "$@"' % label
				command = self._build_command(files, cmd, flags)

		# Execute command
		if command is None:
			if found_at_least_one:
				if label:
					self.hook_logger("Label '%s' is undefined" % label)
				else:
					self.hook_logger("Method number %d is undefined." % number)
			else:
				self.hook_logger("No action found.")
		else:
			if 'PAGER' not in os.environ:
				os.environ['PAGER'] = DEFAULT_PAGER
			if 'EDITOR' not in os.environ:
				os.environ['EDITOR'] = DEFAULT_EDITOR
			command = self.hook_command_postprocessing(command)
			self.hook_before_executing(command, self._mimetype, self._app_flags)
			try:
				if 'r' in flags:
					p = Popen(['sudo', '-E', 'su', '-mc', command],
							env=self.hook_environment(os.environ), shell=False)
				else:
					p = Popen(command, env=self.hook_environment(os.environ), shell=True)
				p.wait()
			finally:
				self.hook_after_executing(command, self._mimetype, self._app_flags)


def main():
	"""The main function which is run when you start this program direectly."""
	import sys

	# Find configuration file path
	if 'XDG_CONFIG_HOME' in os.environ and os.environ['XDG_CONFIG_HOME']:
		conf_path = os.environ['XDG_CONFIG_HOME'] + '/ranger/rifle.conf'
	else:
		conf_path = os.path.expanduser('~/.config/ranger/rifle.conf')
	if not os.path.isfile(conf_path):
		conf_path = os.path.normpath(os.path.join(os.path.dirname(__file__),
			'../defaults/rifle.conf'))

	# Evaluate arguments
	from optparse import OptionParser
	parser = OptionParser(usage="%prog [-fhlpw] [files]")
	parser.add_option('-f', type="string", default="", metavar="FLAGS",
			help="use additional flags: f=fork, r=root, t=terminal. "
			"Uppercase flag negates respective lowercase flags.")
	parser.add_option('-l', action="store_true",
			help="list possible ways to open the files (id:label:flags:command)")
	parser.add_option('-p', type='string', default='0', metavar="KEYWORD",
			help="pick a method to open the files.  KEYWORD is either the "
			"number listed by 'rifle -l' or a string that matches a label in "
			"the configuration file")
	parser.add_option('-w', type='string', default=None, metavar="PROGRAM",
			help="open the files with PROGRAM")
	options, positional = parser.parse_args()
	if not positional:
		parser.print_help()
		raise SystemExit(1)

	if options.p.isdigit():
		number = int(options.p)
		label = None
	else:
		number = 0
		label = options.p

	if options.w is not None and not options.l:
		p = Popen([options.w] + list(positional))
		p.wait()
	else:
		# Start up rifle
		rifle = Rifle(conf_path)
		rifle.reload_config()
		#print(rifle.list_commands(sys.argv[1:]))
		if options.l:
			for count, cmd, label, flags in rifle.list_commands(positional):
				print("%d:%s:%s:%s" % (count, label or '', flags, cmd))
		else:
			rifle.execute(positional, number=number, label=label, flags=options.f)


if __name__ == '__main__':
	if 'RANGER_DOCTEST' in os.environ:
		import doctest
		doctest.testmod()
	else:
		main()