# Copyright 1999-2012 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

from _emerge.AsynchronousLock import AsynchronousLock

import portage
from portage import os
from portage.exception import PortageException
from portage.util.SlotObject import SlotObject

class EbuildBuildDir(SlotObject):

	__slots__ = ("scheduler", "settings",
		"locked", "_catdir", "_lock_obj")

	def __init__(self, **kwargs):
		SlotObject.__init__(self, **kwargs)
		self.locked = False

	def lock(self):
		"""
		This raises an AlreadyLocked exception if lock() is called
		while a lock is already held. In order to avoid this, call
		unlock() or check whether the "locked" attribute is True
		or False before calling lock().
		"""
		if self._lock_obj is not None:
			raise self.AlreadyLocked((self._lock_obj,))

		dir_path = self.settings.get('PORTAGE_BUILDDIR')
		if not dir_path:
			raise AssertionError('PORTAGE_BUILDDIR is unset')
		catdir = os.path.dirname(dir_path)
		self._catdir = catdir

		try:
			portage.util.ensure_dirs(os.path.dirname(catdir),
				gid=portage.portage_gid,
				mode=0o70, mask=0)
		except PortageException:
			if not os.path.isdir(os.path.dirname(catdir)):
				raise
		catdir_lock = AsynchronousLock(path=catdir, scheduler=self.scheduler)
		catdir_lock.start()
		catdir_lock.wait()
		self._assert_lock(catdir_lock)

		try:
			try:
				portage.util.ensure_dirs(catdir,
					gid=portage.portage_gid,
					mode=0o70, mask=0)
			except PortageException:
				if not os.path.isdir(catdir):
					raise
			builddir_lock = AsynchronousLock(path=dir_path,
				scheduler=self.scheduler)
			builddir_lock.start()
			builddir_lock.wait()
			self._assert_lock(builddir_lock)
			self._lock_obj = builddir_lock
			self.settings['PORTAGE_BUILDDIR_LOCKED'] = '1'
		finally:
			self.locked = self._lock_obj is not None
			catdir_lock.unlock()

	def _assert_lock(self, async_lock):
		if async_lock.returncode != os.EX_OK:
			# TODO: create a better way to propagate this error to the caller
			raise AssertionError("AsynchronousLock failed with returncode %s" \
				% (async_lock.returncode,))

	def clean_log(self):
		"""Discard existing log. The log will not be be discarded
		in cases when it would not make sense, like when FEATURES=keepwork
		is enabled."""
		settings = self.settings
		if 'keepwork' in settings.features:
			return
		log_file = settings.get('PORTAGE_LOG_FILE')
		if log_file is not None and os.path.isfile(log_file):
			try:
				os.unlink(log_file)
			except OSError:
				pass

	def unlock(self):
		if self._lock_obj is None:
			return

		self._lock_obj.unlock()
		self._lock_obj = None
		self.locked = False
		self.settings.pop('PORTAGE_BUILDDIR_LOCKED', None)
		catdir_lock = AsynchronousLock(path=self._catdir, scheduler=self.scheduler)
		catdir_lock.start()
		if catdir_lock.wait() == os.EX_OK:
			try:
				os.rmdir(self._catdir)
			except OSError:
				pass
			finally:
				catdir_lock.unlock()

	class AlreadyLocked(portage.exception.PortageException):
		pass