from base import Submodule, UpdateProgress
from util import (
					find_first_remote_branch
				)
from git.exc import InvalidGitRepositoryError
import git

import sys

__all__ = ["RootModule", "RootUpdateProgress"]


class RootUpdateProgress(UpdateProgress):
	"""Utility class which adds more opcodes to the UpdateProgress"""
	REMOVE, PATHCHANGE, BRANCHCHANGE, URLCHANGE = [1 << x for x in range(UpdateProgress._num_op_codes, UpdateProgress._num_op_codes+4)]
	_num_op_codes = UpdateProgress._num_op_codes+4
	
	__slots__ = tuple()

BEGIN = RootUpdateProgress.BEGIN
END = RootUpdateProgress.END
REMOVE = RootUpdateProgress.REMOVE
BRANCHCHANGE = RootUpdateProgress.BRANCHCHANGE
URLCHANGE = RootUpdateProgress.URLCHANGE
PATHCHANGE = RootUpdateProgress.PATHCHANGE

class RootModule(Submodule):
	"""A (virtual) Root of all submodules in the given repository. It can be used
	to more easily traverse all submodules of the master repository"""
	
	__slots__ = tuple()
	
	k_root_name = '__ROOT__'
	
	def __init__(self, repo):
		# repo, binsha, mode=None, path=None, name = None, parent_commit=None, url=None, ref=None)
		super(RootModule, self).__init__(
										repo, 
										binsha = self.NULL_BIN_SHA, 
										mode = self.k_default_mode, 
										path = '', 
										name = self.k_root_name, 
										parent_commit = repo.head.commit,
										url = '',
										branch_path = git.Head.to_full_path(self.k_head_default)
										)
		
	
	def _clear_cache(self):
		"""May not do anything"""
		pass
	
	#{ Interface 
	
	def update(self, previous_commit=None, recursive=True, force_remove=False, init=True, 
					to_latest_revision=False, progress=None, dry_run=False):
		"""Update the submodules of this repository to the current HEAD commit.
		This method behaves smartly by determining changes of the path of a submodules
		repository, next to changes to the to-be-checked-out commit or the branch to be 
		checked out. This works if the submodules ID does not change.
		Additionally it will detect addition and removal of submodules, which will be handled
		gracefully.
		
		:param previous_commit: If set to a commit'ish, the commit we should use 
			as the previous commit the HEAD pointed to before it was set to the commit it points to now. 
			If None, it defaults to HEAD@{1} otherwise
		:param recursive: if True, the children of submodules will be updated as well
			using the same technique
		:param force_remove: If submodules have been deleted, they will be forcibly removed.
			Otherwise the update may fail if a submodule's repository cannot be deleted as 
			changes have been made to it (see Submodule.update() for more information)
		:param init: If we encounter a new module which would need to be initialized, then do it.
		:param to_latest_revision: If True, instead of checking out the revision pointed to 
			by this submodule's sha, the checked out tracking branch will be merged with the 
			newest remote branch fetched from the repository's origin
		:param progress: RootUpdateProgress instance or None if no progress should be sent
		:param dry_run: if True, operations will not actually be performed. Progress messages
			will change accordingly to indicate the WOULD DO state of the operation."""
		if self.repo.bare:
			raise InvalidGitRepositoryError("Cannot update submodules in bare repositories")
		# END handle bare
		
		if progress is None:
			progress = RootUpdateProgress()
		#END assure progress is set
		
		prefix = ''
		if dry_run:
			prefix = 'DRY-RUN: '
		
		repo = self.repo
		
		# SETUP BASE COMMIT
		###################
		cur_commit = repo.head.commit
		if previous_commit is None:
			try:
				previous_commit = repo.commit(repo.head.log_entry(-1).oldhexsha)
				if previous_commit.binsha == previous_commit.NULL_BIN_SHA:
					raise IndexError
				#END handle initial commit
			except IndexError:
				# in new repositories, there is no previous commit
				previous_commit = cur_commit
			#END exception handling
		else:
			previous_commit = repo.commit(previous_commit)	 # obtain commit object 
		# END handle previous commit
		
		
		psms = self.list_items(repo, parent_commit=previous_commit)
		sms = self.list_items(repo)
		spsms = set(psms)
		ssms = set(sms)
		
		# HANDLE REMOVALS
		###################
		rrsm = (spsms - ssms)
		len_rrsm = len(rrsm)
		for i, rsm in enumerate(rrsm):
			op = REMOVE
			if i == 0:
				op |= BEGIN
			#END handle begin
			
			# fake it into thinking its at the current commit to allow deletion
			# of previous module. Trigger the cache to be updated before that
			progress.update(op, i, len_rrsm, prefix+"Removing submodule %r at %s" % (rsm.name, rsm.abspath))
			rsm._parent_commit = repo.head.commit
			if not dry_run:
				rsm.remove(configuration=False, module=True, force=force_remove)
			#END handle dry-run
			
			if i == len_rrsm-1:
				op |= END
			#END handle end
			progress.update(op, i, len_rrsm, prefix+"Done removing submodule %r" % rsm.name)
		# END for each removed submodule
		
		# HANDLE PATH RENAMES
		#####################
		# url changes + branch changes
		csms = (spsms & ssms)
		len_csms = len(csms)
		for i, csm in enumerate(csms):
			psm = psms[csm.name]
			sm = sms[csm.name]
			
			#PATH CHANGES
			##############
			if sm.path != psm.path and psm.module_exists():
				progress.update(BEGIN|PATHCHANGE, i, len_csms, prefix+"Moving repository of submodule %r from %s to %s" % (sm.name, psm.abspath, sm.abspath))  
				# move the module to the new path
				if not dry_run:
					psm.move(sm.path, module=True, configuration=False)
				#END handle dry_run
				progress.update(END|PATHCHANGE, i, len_csms, prefix+"Done moving repository of submodule %r" % sm.name)
			# END handle path changes
			
			if sm.module_exists():
				# HANDLE URL CHANGE
				###################
				if sm.url != psm.url:
					# Add the new remote, remove the old one
					# This way, if the url just changes, the commits will not 
					# have to be re-retrieved
					nn = '__new_origin__'
					smm = sm.module()
					rmts = smm.remotes
					
					# don't do anything if we already have the url we search in place
					if len([r for r in rmts if r.url == sm.url]) == 0:
						progress.update(BEGIN|URLCHANGE, i, len_csms, prefix+"Changing url of submodule %r from %s to %s" % (sm.name, psm.url, sm.url))
						
						if not dry_run:
							assert nn not in [r.name for r in rmts]
							smr = smm.create_remote(nn, sm.url)
							smr.fetch(progress=progress)
							
							# If we have a tracking branch, it should be available
							# in the new remote as well.
							if len([r for r in smr.refs if r.remote_head == sm.branch_name]) == 0:
								raise ValueError("Submodule branch named %r was not available in new submodule remote at %r" % (sm.branch_name, sm.url))
							# END head is not detached
							
							# now delete the changed one
							rmt_for_deletion = None
							for remote in rmts:
								if remote.url == psm.url:
									rmt_for_deletion = remote
									break
								# END if urls match
							# END for each remote
							
							# if we didn't find a matching remote, but have exactly one, 
							# we can safely use this one
							if rmt_for_deletion is None:
								if len(rmts) == 1:
									rmt_for_deletion = rmts[0]
								else:
									# if we have not found any remote with the original url
									# we may not have a name. This is a special case, 
									# and its okay to fail here
									# Alternatively we could just generate a unique name and leave all
									# existing ones in place
									raise InvalidGitRepositoryError("Couldn't find original remote-repo at url %r" % psm.url)
								#END handle one single remote
							# END handle check we found a remote
							
							orig_name = rmt_for_deletion.name
							smm.delete_remote(rmt_for_deletion)
							# NOTE: Currently we leave tags from the deleted remotes
							# as well as separate tracking branches in the possibly totally 
							# changed repository ( someone could have changed the url to 
							# another project ). At some point, one might want to clean
							# it up, but the danger is high to remove stuff the user
							# has added explicitly
							
							# rename the new remote back to what it was
							smr.rename(orig_name)
							
							# early on, we verified that the our current tracking branch
							# exists in the remote. Now we have to assure that the 
							# sha we point to is still contained in the new remote
							# tracking branch.
							smsha = sm.binsha
							found = False
							rref = smr.refs[self.branch_name]
							for c in rref.commit.traverse():
								if c.binsha == smsha:
									found = True
									break
								# END traverse all commits in search for sha
							# END for each commit
							
							if not found:
								# adjust our internal binsha to use the one of the remote
								# this way, it will be checked out in the next step
								# This will change the submodule relative to us, so 
								# the user will be able to commit the change easily
								print >> sys.stderr, "WARNING: Current sha %s was not contained in the tracking branch at the new remote, setting it the the remote's tracking branch" % sm.hexsha
								sm.binsha = rref.commit.binsha
							#END reset binsha
							
							#NOTE: All checkout is performed by the base implementation of update
						#END handle dry_run
						progress.update(END|URLCHANGE, i, len_csms, prefix+"Done adjusting url of submodule %r" % (sm.name))
					# END skip remote handling if new url already exists in module
				# END handle url
				
				# HANDLE PATH CHANGES
				#####################
				if sm.branch_path != psm.branch_path:
					# finally, create a new tracking branch which tracks the 
					# new remote branch
					progress.update(BEGIN|BRANCHCHANGE, i, len_csms, prefix+"Changing branch of submodule %r from %s to %s" % (sm.name, psm.branch_path, sm.branch_path))
					if not dry_run:
						smm = sm.module()
						smmr = smm.remotes
						try:
							tbr = git.Head.create(smm, sm.branch_name, logmsg='branch: Created from HEAD')
						except OSError:
							# ... or reuse the existing one
							tbr = git.Head(smm, sm.branch_path)
						#END assure tracking branch exists
						
						tbr.set_tracking_branch(find_first_remote_branch(smmr, sm.branch_name))
						# figure out whether the previous tracking branch contains
						# new commits compared to the other one, if not we can 
						# delete it.
						try:
							tbr = find_first_remote_branch(smmr, psm.branch_name)
							if len(smm.git.cherry(tbr, psm.branch)) == 0:
								psm.branch.delete(smm, psm.branch)
							#END delete original tracking branch if there are no changes
						except InvalidGitRepositoryError:
							# ignore it if the previous branch couldn't be found in the
							# current remotes, this just means we can't handle it
							pass
						# END exception handling
						
						#NOTE: All checkout is done in the base implementation of update
					#END handle dry_run
					
					progress.update(END|BRANCHCHANGE, i, len_csms, prefix+"Done changing branch of submodule %r" % sm.name)
				#END handle branch
			#END handle 
		# END for each common submodule 
		
		# FINALLY UPDATE ALL ACTUAL SUBMODULES
		######################################
		for sm in sms:
			# update the submodule using the default method
			sm.update(recursive=False, init=init, to_latest_revision=to_latest_revision, 
						progress=progress, dry_run=dry_run)
			
			# update recursively depth first - question is which inconsitent 
			# state will be better in case it fails somewhere. Defective branch
			# or defective depth. The RootSubmodule type will never process itself, 
			# which was done in the previous expression
			if recursive:
				# the module would exist by now if we are not in dry_run mode
				if sm.module_exists():
					type(self)(sm.module()).update(	recursive=True, force_remove=force_remove, 
													init=init, to_latest_revision=to_latest_revision,
													progress=progress, dry_run=dry_run)
				#END handle dry_run
			#END handle recursive
		# END for each submodule to update

	def module(self):
		""":return: the actual repository containing the submodules"""
		return self.repo
	#} END interface
#} END classes
