"""Support for the Oracle database via the zxjdbc JDBC connector.

JDBC Driver
-----------

The official Oracle JDBC driver is at
http://www.oracle.com/technology/software/tech/java/sqlj_jdbc/index.html.

"""
import decimal
import re

from sqlalchemy import sql, types as sqltypes, util
from sqlalchemy.connectors.zxJDBC import ZxJDBCConnector
from sqlalchemy.dialects.oracle.base import OracleCompiler, OracleDialect, OracleExecutionContext
from sqlalchemy.engine import base, default
from sqlalchemy.sql import expression

SQLException = zxJDBC = None

class _ZxJDBCDate(sqltypes.Date):

    def result_processor(self, dialect, coltype):
        def process(value):
            if value is None:
                return None
            else:
                return value.date()
        return process


class _ZxJDBCNumeric(sqltypes.Numeric):

    def result_processor(self, dialect, coltype):
        #XXX: does the dialect return Decimal or not???
        # if it does (in all cases), we could use a None processor as well as
        # the to_float generic processor
        if self.asdecimal:
            def process(value):
                if isinstance(value, decimal.Decimal):
                    return value
                else:
                    return decimal.Decimal(str(value))
        else:
            def process(value):
                if isinstance(value, decimal.Decimal):
                    return float(value)
                else:
                    return value
        return process


class OracleCompiler_zxjdbc(OracleCompiler):

    def returning_clause(self, stmt, returning_cols):
        self.returning_cols = list(expression._select_iterables(returning_cols))

        # within_columns_clause=False so that labels (foo AS bar) don't render
        columns = [self.process(c, within_columns_clause=False, result_map=self.result_map)
                   for c in self.returning_cols]

        if not hasattr(self, 'returning_parameters'):
            self.returning_parameters = []

        binds = []
        for i, col in enumerate(self.returning_cols):
            dbtype = col.type.dialect_impl(self.dialect).get_dbapi_type(self.dialect.dbapi)
            self.returning_parameters.append((i + 1, dbtype))

            bindparam = sql.bindparam("ret_%d" % i, value=ReturningParam(dbtype))
            self.binds[bindparam.key] = bindparam
            binds.append(self.bindparam_string(self._truncate_bindparam(bindparam)))

        return 'RETURNING ' + ', '.join(columns) +  " INTO " + ", ".join(binds)


class OracleExecutionContext_zxjdbc(OracleExecutionContext):

    def pre_exec(self):
        if hasattr(self.compiled, 'returning_parameters'):
            # prepare a zxJDBC statement so we can grab its underlying
            # OraclePreparedStatement's getReturnResultSet later
            self.statement = self.cursor.prepare(self.statement)

    def get_result_proxy(self):
        if hasattr(self.compiled, 'returning_parameters'):
            rrs = None
            try:
                try:
                    rrs = self.statement.__statement__.getReturnResultSet()
                    rrs.next()
                except SQLException, sqle:
                    msg = '%s [SQLCode: %d]' % (sqle.getMessage(), sqle.getErrorCode())
                    if sqle.getSQLState() is not None:
                        msg += ' [SQLState: %s]' % sqle.getSQLState()
                    raise zxJDBC.Error(msg)
                else:
                    row = tuple(self.cursor.datahandler.getPyObject(rrs, index, dbtype)
                                for index, dbtype in self.compiled.returning_parameters)
                    return ReturningResultProxy(self, row)
            finally:
                if rrs is not None:
                    try:
                        rrs.close()
                    except SQLException:
                        pass
                self.statement.close()

        return base.ResultProxy(self)

    def create_cursor(self):
        cursor = self._connection.connection.cursor()
        cursor.datahandler = self.dialect.DataHandler(cursor.datahandler)
        return cursor


class ReturningResultProxy(base.FullyBufferedResultProxy):

    """ResultProxy backed by the RETURNING ResultSet results."""

    def __init__(self, context, returning_row):
        self._returning_row = returning_row
        super(ReturningResultProxy, self).__init__(context)

    def _cursor_description(self):
        ret = []
        for c in self.context.compiled.returning_cols:
            if hasattr(c, 'name'):
                ret.append((c.name, c.type))
            else:
                ret.append((c.anon_label, c.type))
        return ret

    def _buffer_rows(self):
        return [self._returning_row]


class ReturningParam(object):

    """A bindparam value representing a RETURNING parameter.

    Specially handled by OracleReturningDataHandler.
    """

    def __init__(self, type):
        self.type = type

    def __eq__(self, other):
        if isinstance(other, ReturningParam):
            return self.type == other.type
        return NotImplemented

    def __ne__(self, other):
        if isinstance(other, ReturningParam):
            return self.type != other.type
        return NotImplemented

    def __repr__(self):
        kls = self.__class__
        return '<%s.%s object at 0x%x type=%s>' % (kls.__module__, kls.__name__, id(self),
                                                   self.type)


class OracleDialect_zxjdbc(ZxJDBCConnector, OracleDialect):
    jdbc_db_name = 'oracle'
    jdbc_driver_name = 'oracle.jdbc.OracleDriver'

    statement_compiler = OracleCompiler_zxjdbc
    execution_ctx_cls = OracleExecutionContext_zxjdbc

    colspecs = util.update_copy(
        OracleDialect.colspecs,
        {
            sqltypes.Date : _ZxJDBCDate,
            sqltypes.Numeric: _ZxJDBCNumeric
        }
    )

    def __init__(self, *args, **kwargs):
        super(OracleDialect_zxjdbc, self).__init__(*args, **kwargs)
        global SQLException, zxJDBC
        from java.sql import SQLException
        from com.ziclix.python.sql import zxJDBC
        from com.ziclix.python.sql.handler import OracleDataHandler
        class OracleReturningDataHandler(OracleDataHandler):

            """zxJDBC DataHandler that specially handles ReturningParam."""

            def setJDBCObject(self, statement, index, object, dbtype=None):
                if type(object) is ReturningParam:
                    statement.registerReturnParameter(index, object.type)
                elif dbtype is None:
                    OracleDataHandler.setJDBCObject(self, statement, index, object)
                else:
                    OracleDataHandler.setJDBCObject(self, statement, index, object, dbtype)
        self.DataHandler = OracleReturningDataHandler

    def initialize(self, connection):
        super(OracleDialect_zxjdbc, self).initialize(connection)
        self.implicit_returning = connection.connection.driverversion >= '10.2'

    def _create_jdbc_url(self, url):
        return 'jdbc:oracle:thin:@%s:%s:%s' % (url.host, url.port or 1521, url.database)

    def _get_server_version_info(self, connection):
        version = re.search(r'Release ([\d\.]+)', connection.connection.dbversion).group(1)
        return tuple(int(x) for x in version.split('.'))

dialect = OracleDialect_zxjdbc
