# Copyright: 2005 Gentoo Foundation
# Author(s): Brian Harring (ferringb@gentoo.org)
# License: GPL2
# $Id: sql_template.py 6934 2007-06-22 02:50:33Z zmedico $

from cache import template, cache_errors
from cache.template import reconstruct_eclasses

class SQLDatabase(template.database):
	"""template class for RDBM based caches
	
	This class is designed such that derivatives don't have to change much code, mostly constant strings.
	_BaseError must be an exception class that all Exceptions thrown from the derived RDBMS are derived
	from.

	SCHEMA_INSERT_CPV_INTO_PACKAGE should be modified dependant on the RDBMS, as should SCHEMA_PACKAGE_CREATE-
	basically you need to deal with creation of a unique pkgid.  If the dbapi2 rdbms class has a method of 
	recovering that id, then modify _insert_cpv to remove the extra select.

	Creation of a derived class involves supplying _initdb_con, and table_exists.
	Additionally, the default schemas may have to be modified.
	"""
	
	SCHEMA_PACKAGE_NAME	= "package_cache"
	SCHEMA_PACKAGE_CREATE 	= "CREATE TABLE %s (\
		pkgid INTEGER PRIMARY KEY, label VARCHAR(255), cpv VARCHAR(255), UNIQUE(label, cpv))" % SCHEMA_PACKAGE_NAME
	SCHEMA_PACKAGE_DROP	= "DROP TABLE %s" % SCHEMA_PACKAGE_NAME

	SCHEMA_VALUES_NAME	= "values_cache"
	SCHEMA_VALUES_CREATE	= "CREATE TABLE %s ( pkgid integer references %s (pkgid) on delete cascade, \
		key varchar(255), value text, UNIQUE(pkgid, key))" % (SCHEMA_VALUES_NAME, SCHEMA_PACKAGE_NAME)
	SCHEMA_VALUES_DROP	= "DROP TABLE %s" % SCHEMA_VALUES_NAME
	SCHEMA_INSERT_CPV_INTO_PACKAGE	= "INSERT INTO %s (label, cpv) VALUES(%%s, %%s)" % SCHEMA_PACKAGE_NAME

	_BaseError = ()
	_dbClass = None

	autocommits = False
#	cleanse_keys = True

	# boolean indicating if the derived RDBMS class supports replace syntax
	_supports_replace = False

	def __init__(self, location, label, auxdbkeys, *args, **config):
		"""initialize the instance.
		derived classes shouldn't need to override this"""

		super(SQLDatabase, self).__init__(location, label, auxdbkeys, *args, **config)

		config.setdefault("host","127.0.0.1")
		config.setdefault("autocommit", self.autocommits)
		self._initdb_con(config)

		self.label = self._sfilter(self.label)


	def _dbconnect(self, config):
		"""should be overridden if the derived class needs special parameters for initializing
		the db connection, or cursor"""
		self.db = self._dbClass(**config)
		self.con = self.db.cursor()


	def _initdb_con(self,config):
		"""ensure needed tables are in place.
		If the derived class needs a different set of table creation commands, overload the approriate
		SCHEMA_ attributes.  If it needs additional execution beyond, override"""

		self._dbconnect(config)
		if not self._table_exists(self.SCHEMA_PACKAGE_NAME):
			if self.readonly:
				raise cache_errors.ReadOnlyRestriction("table %s doesn't exist" % \
					self.SCHEMA_PACKAGE_NAME)
			try:	self.con.execute(self.SCHEMA_PACKAGE_CREATE)
			except  self._BaseError, e:
				raise cache_errors.InitializationError(self.__class__, e)

		if not self._table_exists(self.SCHEMA_VALUES_NAME):
			if self.readonly:
				raise cache_errors.ReadOnlyRestriction("table %s doesn't exist" % \
					self.SCHEMA_VALUES_NAME)
			try:	self.con.execute(self.SCHEMA_VALUES_CREATE)
			except	self._BaseError, e:
				raise cache_errors.InitializationError(self.__class__, e)


	def _table_exists(self, tbl):
		"""return true if a table exists
		derived classes must override this"""
		raise NotImplementedError


	def _sfilter(self, s):
		"""meta escaping, returns quoted string for use in sql statements"""
		return "\"%s\"" % s.replace("\\","\\\\").replace("\"","\\\"")


	def _getitem(self, cpv):
		try:	self.con.execute("SELECT key, value FROM %s NATURAL JOIN %s "
			"WHERE label=%s AND cpv=%s" % (self.SCHEMA_PACKAGE_NAME, self.SCHEMA_VALUES_NAME,
			self.label, self._sfilter(cpv)))
		except self._BaseError, e:
			raise cache_errors.CacheCorruption(self, cpv, e)

		rows = self.con.fetchall()

		if len(rows) == 0:
			raise KeyError(cpv)

		vals = dict([(k,"") for k in self._known_keys])
		vals.update(dict(rows))
		return vals


	def _delitem(self, cpv):
		"""delete a cpv cache entry
		derived RDBM classes for this *must* either support cascaded deletes, or 
		override this method"""
		try:
			try:	
				self.con.execute("DELETE FROM %s WHERE label=%s AND cpv=%s" % \
				(self.SCHEMA_PACKAGE_NAME, self.label, self._sfilter(cpv)))
				if self.autocommits:
					self.commit()
			except self._BaseError, e:
				raise cache_errors.CacheCorruption(self, cpv, e)
			if self.con.rowcount <= 0:
				raise KeyError(cpv)
		except Exception:
			if not self.autocommits:
				self.db.rollback()
				# yes, this can roll back a lot more then just the delete.  deal.
			raise

	def __del__(self):
		# just to be safe.
		if "db" in self.__dict__ and self.db != None:
			self.commit()
			self.db.close()

	def _setitem(self, cpv, values):

		try:
			# insert.
			try:	pkgid = self._insert_cpv(cpv)
			except self._BaseError, e:
				raise cache_errors.CacheCorruption(cpv, e)

			# __getitem__ fills out missing values, 
			# so we store only what's handed to us and is a known key
			db_values = []
			for key in self._known_keys:
				if values.has_key(key) and values[key] != '':
					db_values.append({"key":key, "value":values[key]})

			if len(db_values) > 0:
				try:	self.con.executemany("INSERT INTO %s (pkgid, key, value) VALUES(\"%s\", %%(key)s, %%(value)s)" % \
					(self.SCHEMA_VALUES_NAME, str(pkgid)), db_values)
				except self._BaseError, e:
					raise cache_errors.CacheCorruption(cpv, e)
			if self.autocommits:
				self.commit()

		except Exception:
			if not self.autocommits:
				try:	self.db.rollback()
				except self._BaseError: pass
			raise


	def _insert_cpv(self, cpv):
		"""uses SCHEMA_INSERT_CPV_INTO_PACKAGE, which must be overloaded if the table definition
		doesn't support auto-increment columns for pkgid.
		returns the cpvs new pkgid
		note this doesn't commit the transaction.  The caller is expected to."""
		
		cpv = self._sfilter(cpv)
		if self._supports_replace:
			query_str = self.SCHEMA_INSERT_CPV_INTO_PACKAGE.replace("INSERT","REPLACE",1)
		else:
			# just delete it.
			try:	del self[cpv]
			except	(cache_errors.CacheCorruption, KeyError):	pass
			query_str = self.SCHEMA_INSERT_CPV_INTO_PACKAGE
		try:
			self.con.execute(query_str % (self.label, cpv))
		except self._BaseError:
			self.db.rollback()
			raise
		self.con.execute("SELECT pkgid FROM %s WHERE label=%s AND cpv=%s" % \
			(self.SCHEMA_PACKAGE_NAME, self.label, cpv))
			
		if self.con.rowcount != 1:
			raise cache_error.CacheCorruption(cpv, "Tried to insert the cpv, but found "
				" %i matches upon the following select!" % len(rows))
		return self.con.fetchone()[0]


	def __contains__(self, cpv):
		if not self.autocommits:
			try:	self.commit()
			except self._BaseError, e:
				raise cache_errors.GeneralCacheCorruption(e)

		try:	self.con.execute("SELECT cpv FROM %s WHERE label=%s AND cpv=%s" % \
				(self.SCHEMA_PACKAGE_NAME, self.label, self._sfilter(cpv)))
		except self._BaseError, e:
			raise cache_errors.GeneralCacheCorruption(e)
		return self.con.rowcount > 0


	def __iter__(self):
		if not self.autocommits:
			try:	self.commit()
			except self._BaseError, e:
				raise cache_errors.GeneralCacheCorruption(e)

		try:	self.con.execute("SELECT cpv FROM %s WHERE label=%s" % 
				(self.SCHEMA_PACKAGE_NAME, self.label))
		except self._BaseError, e:
			raise cache_errors.GeneralCacheCorruption(e)
#		return [ row[0] for row in self.con.fetchall() ]
		for x in self.con.fetchall():
			yield x[0]

	def iteritems(self):
		try:	self.con.execute("SELECT cpv, key, value FROM %s NATURAL JOIN %s "
			"WHERE label=%s" % (self.SCHEMA_PACKAGE_NAME, self.SCHEMA_VALUES_NAME,
			self.label))
		except self._BaseError, e:
			raise cache_errors.CacheCorruption(self, cpv, e)
		
		oldcpv = None
		l = []
		for x, y, v in self.con.fetchall():
			if oldcpv != x:
				if oldcpv != None:
					d = dict(l)
					if "_eclasses_" in d:
						d["_eclasses_"] = reconstruct_eclasses(oldcpv, d["_eclasses_"])
					yield cpv, d
				l.clear()
				oldcpv = x
			l.append((y,v))
		if oldcpv != None:
			d = dict(l)
			if "_eclasses_" in d:
				d["_eclasses_"] = reconstruct_eclasses(oldcpv, d["_eclasses_"])
			yield cpv, d			

	def commit(self):
		self.db.commit()

	def get_matches(self,match_dict):
		query_list = []
		for k,v in match_dict.items():
			if k not in self._known_keys:
				raise cache_errors.InvalidRestriction(k, v, "key isn't known to this cache instance")
			v = v.replace("%","\\%")
			v = v.replace(".*","%")
			query_list.append("(key=%s AND value LIKE %s)" % (self._sfilter(k), self._sfilter(v)))

		if len(query_list):
			query = " AND "+" AND ".join(query_list)
		else:
			query = ''

		print "query = SELECT cpv from package_cache natural join values_cache WHERE label=%s %s" % (self.label, query)
		try:	self.con.execute("SELECT cpv from package_cache natural join values_cache WHERE label=%s %s" % \
				(self.label, query))
		except self._BaseError, e:
			raise cache_errors.GeneralCacheCorruption(e)

		return [ row[0] for row in self.con.fetchall() ]

