# Copyright 2017 Dimitri Capitaine
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import re
import sys

import phoenixdb
import sqlalchemy

from sqlalchemy import types
from sqlalchemy.engine.default import DefaultDialect, DefaultExecutionContext
from sqlalchemy.exc import CompileError
from sqlalchemy.sql.compiler import DDLCompiler
from sqlalchemy.types import BIGINT, BOOLEAN, CHAR, DATE, DECIMAL, FLOAT, INTEGER, NUMERIC,\
    SMALLINT, TIME, TIMESTAMP, VARBINARY, VARCHAR

if sys.version_info.major == 3:
    from urllib.parse import urlunsplit, SplitResult, urlencode
else:
    from urllib import urlencode
    from urlparse import urlunsplit, SplitResult


class PhoenixDDLCompiler(DDLCompiler):

    def visit_primary_key_constraint(self, constraint):
        if constraint.name is None:
            raise CompileError("Can't create primary key without a name.")
        return DDLCompiler.visit_primary_key_constraint(self, constraint)


AUTOCOMMIT_REGEXP = re.compile(
    r"\s*(?:UPDATE|UPSERT|CREATE|DELETE|DROP|ALTER)", re.I | re.UNICODE
)


if sqlalchemy.__version__.startswith('1.3'):
    def _get_dbapi(connectable):
        return connectable.connect().connection.connection
else:
    def _get_dbapi(connectable):
        return connectable.connection


class PhoenixExecutionContext(DefaultExecutionContext):

    def should_autocommit_text(self, statement):
        return AUTOCOMMIT_REGEXP.match(statement)


class PhoenixDialect(DefaultDialect):
    '''Phoenix dialect

    dialect:: phoenix
    :name: Phoenix

    note::

    The Phoenix dialect for SQLAlchemy is incomplete. It implements the functions required by Hue
    for basic operation, but little else.

    Connecting
    ----------

    The connection URL has the format of phoenix://host:port

    This format does not allow for specifying the http scheme, or the URL path the the server uses.
    Setting tls=True sets the server URL scheme to https.
    If the path arg is set , it used as the path of the server URL.

    The phoenix-specific authentication options can be set via the standard connect_args argument.

    Connecting to an unsecure server::

        create_engine('phoenix://localhost:8765')

    Connecting to a secure server via SPNEGO (after kinit)::

        create_engine('phoenix://localhost:8765', tls=True, connect_args={'authentication': 'SPNEGO'})

    Connecting to a secure server via Knox::

        create_engine('phoenix://localhost:8765', tls=True, path='/gateway/avatica/'\
        connect_args={'authentication':'BASIC', 'avatica_user':'user', 'avatica_password':'password'})
    '''

    name = "phoenix"

    driver = "phoenixdb"

    supports_statement_cache = False  # We only implement textual SQL anyway

    ddl_compiler = PhoenixDDLCompiler

    execution_ctx_cls = PhoenixExecutionContext

    def __init__(self, tls=False, path='/', **opts):
        '''
        :param tls:
            If True, then use https for connecting, otherwise use http

        :param path:
            The path component of the connection URL
        '''
        # There is no way to pass these via the SqlAlchemy url object
        self.tls = tls
        self.path = path
        super(PhoenixDialect, self).__init__(**opts)

    @classmethod
    def import_dbapi(cls):
        return phoenixdb

    @classmethod
    def dbapi(cls):
        return phoenixdb

    def create_connect_args(self, url):
        connect_args = dict()
        if url.username is not None:
            connect_args['user'] = url.username
            if url.password is not None:
                connect_args['password'] = url.username
        phoenix_url = urlunsplit(SplitResult(
            scheme='https' if self.tls else 'http',
            netloc='{}:{}'.format(url.host, 8765 if url.port is None else url.port),
            path=self.path,
            query=urlencode(url.query),
            fragment='',
        ))
        return [phoenix_url], connect_args

    def has_table(self, connection, table_name, schema=None, **kw):
        if schema is None:
            schema = ''
        return bool(_get_dbapi(connection).meta().get_tables(
            tableNamePattern=table_name,
            schemaPattern=schema,
            typeList=('TABLE', 'SYSTEM_TABLE')))

    def get_schema_names(self, connection, **kw):
        schemas = _get_dbapi(connection).meta().get_schemas()
        schema_names = [schema['TABLE_SCHEM'] for schema in schemas]
        # Phoenix won't return the default schema if there aren't any tables in it
        if '' not in schema_names:
            schema_names.insert(0, '')
        return schema_names

    def get_table_names(self, connection, schema=None, order_by=None, **kw):
        '''order_by is ignored'''
        if schema is None:
            schema = ''
        tables = _get_dbapi(connection).meta().get_tables(
            schemaPattern=schema, typeList=('TABLE', 'SYSTEM TABLE'))
        return [table['TABLE_NAME'] for table in tables]

    def get_view_names(self, connection, schema=None, **kw):
        if schema is None:
            schema = ''
        views = _get_dbapi(connection).meta().get_tables(schemaPattern=schema, typeList=('VIEW',))
        return [view['TABLE_NAME'] for view in views]

    def get_columns(self, connection, table_name, schema=None, **kw):
        if schema is None:
            schema = ''
        raw = _get_dbapi(connection).meta().get_columns(
            schemaPattern=schema, tableNamePattern=table_name)
        return [self._map_column(row) for row in raw]

    def get_pk_constraint(self, connection, table_name, schema=None, **kw):
        if schema is None:
            schema = ''
        raw = _get_dbapi(connection).meta().get_primary_keys(
            schema=schema, table=table_name)
        cooked = {
            'constrained_columns': []
        }
        if raw:
            cooked['name'] = raw[0]['PK_NAME']
            for row in raw:
                cooked['constrained_columns'].insert(row['KEY_SEQ'] - 1, row['COLUMN_NAME'])
        return cooked

    def get_indexes(self, connection, table_name, schema=None, **kw):
        if schema is None:
            schema = ''
        raw = _get_dbapi(connection).meta().get_index_info(schema=schema, table=table_name)
        # We know that Phoenix returns the rows ordered by INDEX_NAME and ORDINAL_POSITION
        cooked = []
        current = None
        for row in raw:
            if current is None or row['INDEX_NAME'] != current['name']:
                current = {
                    'name': row['INDEX_NAME'],
                    'unique': not row['NON_UNIQUE'] is False,
                    'column_names': [],
                }
                cooked.append(current)
            # Phoenix returns the column names in its internal representation here
            # Remove the default CF prefix
            canonical_name = row['INDEX_NAME']
            if canonical_name.startswith('0:'):
                canonical_name = canonical_name[len(':0')]
            if canonical_name.startswith(':'):
                canonical_name = canonical_name[len(':')]
            current['column_names'].append(canonical_name)
        return cooked

    def get_foreign_keys(self, conn, table_name, schema=None, **kw):
        '''Foreign keys are a foreign concept to Phoenix,
        and SqlAlchemy cannot parse the DB schema if it's not implemented '''
        return []

    def _map_column(self, raw):
        cooked = {}
        cooked['name'] = raw['COLUMN_NAME']
        cooked['type'] = COLUMN_DATA_TYPE[raw['TYPE_ID']]
        cooked['nullable'] = bool(raw['IS_NULLABLE'])
        cooked['autoincrement'] = bool(raw['IS_AUTOINCREMENT'])
        cooked['comment'] = raw['REMARKS']
        cooked['default'] = None  # Not apparent how to get this from the metatdata
        return cooked


class TINYINT(types.Integer):
    __visit_name__ = "SMALLINT"


class UNSIGNED_TINYINT(types.Integer):
    __visit_name__ = "SMALLINT"


class UNSIGNED_INTEGER(types.Integer):
    __visit_name__ = "INTEGER"


class DOUBLE(types.FLOAT):
    __visit_name__ = "FLOAT"


class UNSIGNED_DOUBLE(types.FLOAT):
    __visit_name__ = "FLOAT"


class UNSIGNED_FLOAT(types.FLOAT):
    __visit_name__ = "FLOAT"


class UNSIGNED_LONG(types.BIGINT):
    __visit_name__ = "BIGINT"


class UNSIGNED_TIME(types.TIME):
    __visit_name__ = "TIME"


class UNSIGNED_DATE(types.DATE):
    __visit_name__ = "DATE"


class UNSIGNED_TIMESTAMP(types.TIMESTAMP):
    __visit_name__ = "TIMESTAMP"


class ROWID (types.String):
    __visit_name__ = "VARCHAR"


COLUMN_DATA_TYPE = {
    -6: TINYINT,
    -5: BIGINT,
    -3: VARBINARY,
    1: CHAR,
    2: NUMERIC,
    3: DECIMAL,
    4: INTEGER,
    5: SMALLINT,
    6: FLOAT,
    8: DOUBLE,
    9: UNSIGNED_INTEGER,
    10: UNSIGNED_LONG,
    11: UNSIGNED_TINYINT,
    12: VARCHAR,
    13: ROWID,
    14: UNSIGNED_FLOAT,
    15: UNSIGNED_DOUBLE,
    16: BOOLEAN,
    18: UNSIGNED_TIME,
    19: UNSIGNED_DATE,
    20: UNSIGNED_TIMESTAMP,
    91: DATE,
    92: TIME,
    93: TIMESTAMP
}