#!/usr/bin/env python2
# Thanks to Zac Medico <zmedico@gentoo.org> for working example of using an api

import portage
from portage.dep import Atom

# to not use own emerge option parser. Options may change but I hope 
# parse_opts function will always be there
from _emerge.main import parse_opts

# TODO: check if actions always here
try:
  from _emerge import actions, Package
  from _emerge.create_depgraph_params import create_depgraph_params
  from _emerge.depgraph import backtrack_depgraph, resume_depgraph, depgraph
except ImportError, Err: # non-critical, just print warning(TODO: strerr)
  print "Error while loading modules: %s" % Err.message

class portage_api:
  """ class for accessing the portage api """
  def __init__(self):
	""" test """
	settings,trees,mtimedb=actions.load_emerge_config()

	#import pdb; pdb.set_trace()
	self.settings=settings
	self.trees=trees
	self.mtimedb=mtimedb
	self.vartree=trees[portage.root]['vartree']
	self.vardb=self.vartree.dbapi
	self.portdb=portage.portdb
	self.metadata_keys = [
	  k for k in portage.auxdbkeys if not k.startswith("UNUSED_")]
	self.use=self.settings["USE"]

  # This function is from portage and almost unchanged
  # It is here because old versions of portage not have this function
  def expand_new_virt(self,atom):
	"""
	Iterate over the recursively expanded RDEPEND atoms of
	a new-style virtual. If atom is not a new-style virtual
	or it does not match an installed package then it is
	yielded without any expansion.
	"""
	vardb=self.vartree.dbapi
	
	if not isinstance(atom, Atom):
		atom = Atom(atom)

	if not atom.cp.startswith("virtual/"):
		yield atom
		return

	traversed = set()
	stack = [atom]

	while stack:
		atom = stack.pop()
		if atom.blocker or \
			not atom.cp.startswith("virtual/"):
			yield atom
			continue

		matches = vardb.match(atom)
		if not (matches and matches[-1].startswith("virtual/")):
			yield atom
			continue

		virt_cpv = matches[-1]
		if virt_cpv in traversed:
			continue

		traversed.add(virt_cpv)
		eapi, iuse, rdepend, use = vardb.aux_get(virt_cpv,
			["EAPI", "IUSE", "RDEPEND", "USE"])
		if not portage.eapi_is_supported(eapi):
			yield atom
			continue

		iuse_defaults=[
		  u[1:] for u in iuse.split() if u.startswith("+")]

		use=use.split()

		for u in iuse_defaults:
		  if u not in use:
			use.append(u)

		success, atoms = portage.dep_check(rdepend,
			None, vardb.settings, myuse=use,
			myroot=vardb.root, trees={vardb.root:{"porttree":vardb.vartree,
			"vartree":vardb.vartree}})

		if success:
			stack.extend(atoms)
		else:
			yield atom


  def get_best_visible_pkg(self,pkg,db="portdb"):
	"""
	Gets best candidate on installing. Returns empty string if no found

	:param pkg: package name
	:param db: name of db to look. Can be "vardb" or "portdb"  
	"""
	try:
	  if db=="portdb":
		return self.portdb.xmatch("bestmatch-visible", pkg)
	  elif db=="vardb":
		return self.vardb.match(pkg)[0]
	  else:
		return ''
	except:
	  return ''

  # trying to repeat action_build(...) logic in _emerge/actions.py
  def get_merge_list(self,emergeargs):
	"""
	Gets list of packages that emerge with emergeargs-arguments will merge
	This function uses very internal functions of portage so 
	it may be unreliable in various portage versions
	
	:param emergeargs: list of raw args of emerge, for example, ['-1','bash']
	
	"""

	try:
	  action, opts, files = parse_opts(emergeargs, silent=True)

	  resume = False
	  if "--resume" in opts and \
		("resume" in self.mtimedb or "resume_backup" in self.mtimedb):
		resume = True
		if "resume" not in self.mtimedb:
		  self.mtimedb["resume"] = self.mtimedb["resume_backup"]
		# "opts" is a list for backward compatibility.
		resume_opts = self.mtimedb["resume"].get("myopts", [])
		if isinstance(resume_opts, list):
		  resume_opts = dict((k,True) for k in resume_opts)
		for opt in ("--ask", "--color", "--skipfirst", "--tree"):
		  resume_opts.pop(opt, None)

		# Current options always override resume_opts.
		resume_opts.update(opts)
		opts.clear()
		opts.update(resume_opts)
	  
	  
	  params=create_depgraph_params(opts,action)

	  if resume:
		success, mydepgraph, dropped_tasks = resume_depgraph(
		  self.settings, self.trees, self.mtimedb, opts, params, None)
		if not success:
		  return []
	  else:
		success, mydepgraph, favorites = backtrack_depgraph(
		  self.settings, self.trees, opts, params, action, files, None)
		if not success:
		  return []
	  
	  ret=[]
	  for pkg in mydepgraph.altlist():
		if type(pkg) is Package.Package:
		  ret.append(pkg.cpv)
	  return ret
	  
	except:
	  return []

  # non-recursive dependency getter
  def get_dep(self,pkg,dep_type=["RDEPEND","DEPEND"],db="portdb"):
	"""
	Gets current dependencies of a package. Looks in portage db by default
	
	:param pkg: name of package
	:param dep_type: type of dependencies to recurse. Can be ["DEPEND"] or 
	  ["RDEPEND", "DEPEND"]
	:param db: name of db to look. Can be "vardb" or "portdb"  
	:returns: **set** of packages names
	"""
  
	ret=set()
	
	pkg = self.get_best_visible_pkg(pkg,db)	
	if not pkg:
	  return ret
		
	# we found the best visible match in common tree
	#import pdb; pdb.set_trace()

	if db=="portdb":
	  aux_get=self.portdb.aux_get
	elif db=="vardb":
	  aux_get=self.vardb.aux_get
	else:
	  return ret
	
	metadata = dict(zip(self.metadata_keys, aux_get(pkg, self.metadata_keys)))
	dep_str = " ".join(metadata[k] for k in dep_type)

	# the IUSE default are very important for us
	iuse_defaults=[
	  u[1:] for u in metadata.get("IUSE",'').split() if u.startswith("+")]

	use=self.use.split()

	for u in iuse_defaults:
	  if u not in use:
		use.append(u)
			
  
	success, atoms = portage.dep_check(dep_str, None, self.settings, 
	  myuse=use, trees=portage.db, myroot=self.settings["ROOT"])
	if not success:
	  return ret
	  
	for atom in atoms:
	  atomname = self.vartree.dep_bestmatch(atom)

	  if not atomname:
		continue
	
	  for unvirt_pkg in self.expand_new_virt('='+atomname):
		for pkg in self.vartree.dep_match(unvirt_pkg):
		  ret.add(pkg)

	return ret
	
  # recursive dependency getter
  def get_deps(self,pkg,dep_type=["RDEPEND","DEPEND"],db="portdb"):
	""" 
	Gets current dependencies of a package on any depth 
	All dependencies **must** be installed
	
	:param pkg: name of package
	:param dep_type: type of dependencies to recurse. Can be ["DEPEND"] or 
	  ["RDEPEND", "DEPEND"]
	:param db: name of db to look. Can be "vardb" or "portdb"  
	:returns: **set** of packages names
	"""
	
	ret=set()

    # get porttree dependencies on the first package

	pkg = self.get_best_visible_pkg(pkg,db)
	if not pkg:
	  return ret
	#print "doing",pkg

	known_packages=set()
	unknown_packages=self.get_dep(pkg,dep_type,db)
	ret=ret.union(unknown_packages)
	
	while unknown_packages:
	  p=unknown_packages.pop()
	  #print "proceeding "+p
	  if p in known_packages:
		continue
	  known_packages.add(p)

	  current_deps=self.get_dep(p,dep_type,'vardb')
	  unknown_packages=unknown_packages.union(current_deps)
	  ret=ret.union(current_deps)

	return ret

  def get_deps_for_package_building(self, pkg):
	""" 
	  returns buildtime dependencies of current package and 
	  all runtime dependencies of that buildtime dependencies
	"""
	buildtime_deps=self.get_dep(pkg, ["DEPEND"],"portdb")
	runtime_deps=set()
	for dep in buildtime_deps:
	  runtime_deps|=self.get_deps(dep,["RDEPEND","PDEPEND"],"vardb")

	ret = buildtime_deps | runtime_deps

	
	return ret

  def get_system_packages_list(self):
	""" 
	returns all packages from system set. They are always implicit dependencies
	
	:returns: **list** of package names
	"""
	ret=[]
	for atom in self.settings.packages:
	  for pre_pkg in self.vartree.dep_match(atom):
		for unvirt_pkg in self.expand_new_virt('='+pre_pkg):
		  for pkg in self.vartree.dep_match(unvirt_pkg):
			ret.append(pkg)
	return ret

  def get_system_packages_rdeps(self):
	"""
	returns runtime dependencies of packages from system set
	
	:returns: **list** of package names
	"""
	ret=set()
	
	for pkg in self.get_system_packages_list():
	  ret=ret.union(self.get_deps(pkg,["RDEPEND"]))
	return list(ret)

  def parse_emerge_args(self,args):
	""" 
	call emerge arguments parser 
	
	:param args: arguments passed to emerge
	:returns: **tuple** (action string, options dictionary, files or atoms 
	  list)
	"""
	action, opts, files = parse_opts(args, silent=True)
	return action, opts, files