##########################################################################
#
# pgAdmin 4 - PostgreSQL Tools
#
# Copyright (C) 2013 - 2018, The pgAdmin Development Team
# This software is released under the PostgreSQL Licence
#
##########################################################################

""" Implements Index Node """

import simplejson as json
from functools import wraps

import pgadmin.browser.server_groups.servers.databases as database
from flask import render_template, request, jsonify
from flask_babel import gettext
from pgadmin.browser.collection import CollectionNodeModule
from pgadmin.browser.utils import PGChildNodeView
from pgadmin.utils.ajax import make_json_response, internal_server_error, \
    make_response as ajax_response, gone
from pgadmin.utils.driver import get_driver
from config import PG_DEFAULT_DRIVER
from pgadmin.utils import IS_PY2
# If we are in Python3
if not IS_PY2:
    unicode = str


class IndexesModule(CollectionNodeModule):
    """
     class IndexesModule(CollectionNodeModule)

        A module class for Index node derived from CollectionNodeModule.

    Methods:
    -------
    * __init__(*args, **kwargs)
      - Method is used to initialize the Index and it's base module.

    * get_nodes(gid, sid, did, scid, tid)
      - Method is used to generate the browser collection node.

    * node_inode()
      - Method is overridden from its base class to make the node as leaf node.

    * script_load()
      - Load the module script for schema, when any of the server node is
        initialized.
    """

    NODE_TYPE = 'index'
    COLLECTION_LABEL = gettext("Indexes")

    def __init__(self, *args, **kwargs):
        """
        Method is used to initialize the IndexModule and it's base module.

        Args:
            *args:
            **kwargs:
        """
        self.min_ver = None
        self.max_ver = None
        super(IndexesModule, self).__init__(*args, **kwargs)

    def BackendSupported(self, manager, **kwargs):
        """
        Load this module if vid is view, we will not load it under
        material view
        """
        if super(IndexesModule, self).BackendSupported(manager, **kwargs):
            conn = manager.connection(did=kwargs['did'])

            # In case of partitioned table return false.
            if 'tid' in kwargs and manager.version >= 100000:
                partition_path = 'partition/sql/#{0}#'.format(manager.version)
                SQL = render_template(
                    "/".join([partition_path, 'backend_support.sql']),
                    tid=kwargs['tid']
                )
                status, res = conn.execute_scalar(SQL)

                # check if any errors
                if not status:
                    return internal_server_error(errormsg=res)
                return not res

            if 'vid' not in kwargs:
                return True

            template_path = 'index/sql/#{0}#'.format(manager.version)
            SQL = render_template(
                "/".join([template_path, 'backend_support.sql']),
                vid=kwargs['vid']
            )
            status, res = conn.execute_scalar(SQL)

            # check if any errors
            if not status:
                return internal_server_error(errormsg=res)
            # Check vid is view not material view
            # then true, othewise false
            return res

    def get_nodes(self, gid, sid, did, scid, **kwargs):
        """
        Generate the collection node
        """
        assert ('tid' in kwargs or 'vid' in kwargs)
        yield self.generate_browser_collection_node(
            kwargs['tid'] if 'tid' in kwargs else kwargs['vid']
        )

    @property
    def script_load(self):
        """
        Load the module script for server, when any of the server-group node is
        initialized.
        """
        return database.DatabaseModule.NODE_TYPE

    @property
    def node_inode(self):
        """
        Load the module node as a leaf node
        """
        return False

    @property
    def module_use_template_javascript(self):
        """
        Returns whether Jinja2 template is used for generating the javascript
        module.
        """
        return False


blueprint = IndexesModule(__name__)


class IndexesView(PGChildNodeView):
    """
    This class is responsible for generating routes for Index node

    Methods:
    -------
    * __init__(**kwargs)
      - Method is used to initialize the IndexView and it's base view.

    * module_js()
      - This property defines (if javascript) exists for this node.
        Override this property for your own logic

    * check_precondition()
      - This function will behave as a decorator which will checks
        database connection before running view, it will also attaches
        manager,conn & template_path properties to self

    * list()
      - This function is used to list all the Index nodes within that
      collection.

    * nodes()
      - This function will used to create all the child node within that
        collection, Here it will create all the Index node.

    * node()
      - This function will used to create the child node within that
        collection, Here it will create specific the Index node.

    * properties(gid, sid, did, scid, tid, idx)
      - This function will show the properties of the selected Index node

    * create(gid, sid, did, scid, tid)
      - This function will create the new Index object

    * update(gid, sid, did, scid, tid, idx)
      - This function will update the data for the selected Index node

    * delete(self, gid, sid, scid, tid, idx):
      - This function will drop the Index object

    * msql(gid, sid, did, scid, tid, idx)
      - This function is used to return modified SQL for the selected
        Index node

    * get_sql(data, scid, tid)
      - This function will generate sql from model data

    * sql(gid, sid, did, scid):
      - This function will generate sql to show it in sql pane for the
        selected Index node.

    * dependency(gid, sid, did, scid):
      - This function will generate dependency list show it in dependency
        pane for the selected Index node.

    * dependent(gid, sid, did, scid):
      - This function will generate dependent list to show it in dependent
        pane for the selected Index node.
    """

    node_type = blueprint.node_type

    parent_ids = [
        {'type': 'int', 'id': 'gid'},
        {'type': 'int', 'id': 'sid'},
        {'type': 'int', 'id': 'did'},
        {'type': 'int', 'id': 'scid'},
        {'type': 'int', 'id': 'tid'}
    ]
    ids = [
        {'type': 'int', 'id': 'idx'}
    ]

    operations = dict({
        'obj': [
            {'get': 'properties', 'delete': 'delete', 'put': 'update'},
            {'get': 'list', 'post': 'create'}
        ],
        'delete': [{'delete': 'delete'}],
        'children': [{'get': 'children'}],
        'nodes': [{'get': 'node'}, {'get': 'nodes'}],
        'sql': [{'get': 'sql'}],
        'msql': [{'get': 'msql'}, {'get': 'msql'}],
        'stats': [{'get': 'statistics'}, {'get': 'statistics'}],
        'dependency': [{'get': 'dependencies'}],
        'dependent': [{'get': 'dependents'}],
        'module.js': [{}, {}, {'get': 'module_js'}],
        'get_collations': [{'get': 'get_collations'},
                           {'get': 'get_collations'}],
        'get_access_methods': [{'get': 'get_access_methods'},
                               {'get': 'get_access_methods'}],
        'get_op_class': [{'get': 'get_op_class'},
                         {'get': 'get_op_class'}]
    })

    def check_precondition(f):
        """
        This function will behave as a decorator which will checks
        database connection before running view, it will also attaches
        manager,conn & template_path properties to self
        """

        @wraps(f)
        def wrap(*args, **kwargs):
            # Here args[0] will hold self & kwargs will hold gid,sid,did
            self = args[0]
            self.manager = get_driver(PG_DEFAULT_DRIVER).connection_manager(
                kwargs['sid']
            )
            self.conn = self.manager.connection(did=kwargs['did'])
            # We need datlastsysoid to check if current index is system index
            self.datlastsysoid = self.manager.db_info[
                kwargs['did']
            ]['datlastsysoid'] if self.manager.db_info is not None and \
                kwargs['did'] in self.manager.db_info else 0

            # we will set template path for sql scripts
            self.template_path = 'index/sql/#{0}#'.format(self.manager.version)

            # We need parent's name eg table name and schema name
            # when we create new index in update we can fetch it using
            # property sql
            SQL = render_template(
                "/".join([self.template_path, 'get_parent.sql']),
                tid=kwargs['tid']
            )
            status, rset = self.conn.execute_2darray(SQL)
            if not status:
                return internal_server_error(errormsg=rset)

            for row in rset['rows']:
                self.schema = row['schema']
                self.table = row['table']

            return f(*args, **kwargs)

        return wrap

    @check_precondition
    def get_collations(self, gid, sid, did, scid, tid, idx=None):
        """
        This function will return list of collation available
        via AJAX response
        """
        res = [{'label': '', 'value': ''}]
        try:
            SQL = render_template(
                "/".join([self.template_path, 'get_collations.sql'])
            )
            status, rset = self.conn.execute_2darray(SQL)
            if not status:
                return internal_server_error(errormsg=res)

            for row in rset['rows']:
                res.append(
                    {'label': row['collation'],
                     'value': row['collation']}
                )
            return make_json_response(
                data=res,
                status=200
            )

        except Exception as e:
            return internal_server_error(errormsg=str(e))

    @check_precondition
    def get_access_methods(self, gid, sid, did, scid, tid, idx=None):
        """
        This function will return list of access methods available
        via AJAX response
        """
        res = [{'label': '', 'value': ''}]
        try:
            SQL = render_template("/".join([self.template_path, 'get_am.sql']))
            status, rset = self.conn.execute_2darray(SQL)
            if not status:
                return internal_server_error(errormsg=res)

            for row in rset['rows']:
                res.append(
                    {'label': row['amname'],
                     'value': row['amname']}
                )
            return make_json_response(
                data=res,
                status=200
            )

        except Exception as e:
            return internal_server_error(errormsg=str(e))

    @check_precondition
    def get_op_class(self, gid, sid, did, scid, tid, idx=None):
        """
        This function will return list of op_class method
        for each access methods available via AJAX response
        """
        res = dict()
        try:
            # Fetching all the access methods
            SQL = render_template("/".join([self.template_path, 'get_am.sql']))
            status, rset = self.conn.execute_2darray(SQL)
            if not status:
                return internal_server_error(errormsg=res)

            for row in rset['rows']:
                # Fetching all the op_classes for each access method
                SQL = render_template(
                    "/".join([self.template_path, 'get_op_class.sql']),
                    oid=row['oid']
                )
                status, result = self.conn.execute_2darray(SQL)
                if not status:
                    return internal_server_error(errormsg=res)

                op_class_list = [{'label': '', 'value': ''}]

                for r in result['rows']:
                    op_class_list.append({'label': r['opcname'],
                                          'value': r['opcname']})

                # Append op_class list in main result as collection
                res[row['amname']] = op_class_list

            return make_json_response(
                data=res,
                status=200
            )

        except Exception as e:
            return internal_server_error(errormsg=str(e))

    @check_precondition
    def list(self, gid, sid, did, scid, tid):
        """
        This function is used to list all the schema nodes within that collection.

        Args:
            gid: Server group ID
            sid: Server ID
            did: Database ID
            scid: Schema ID
            tid: Table ID

        Returns:
            JSON of available schema nodes
        """

        SQL = render_template(
            "/".join([self.template_path, 'nodes.sql']), tid=tid
        )
        status, res = self.conn.execute_dict(SQL)

        if not status:
            return internal_server_error(errormsg=res)
        return ajax_response(
            response=res['rows'],
            status=200
        )

    @check_precondition
    def node(self, gid, sid, did, scid, tid, idx):
        """
        This function will used to create all the child node within that collection.
        Here it will create all the schema node.

        Args:
            gid: Server Group ID
            sid: Server ID
            did: Database ID
            scid: Schema ID
            tid: Table ID
            idx: Index ID

        Returns:
            JSON of available schema child nodes
        """
        SQL = render_template(
            "/".join([self.template_path, 'nodes.sql']),
            tid=tid, idx=idx
        )
        status, rset = self.conn.execute_2darray(SQL)
        if not status:
            return internal_server_error(errormsg=rset)

        if len(rset['rows']) == 0:
            return gone(gettext("""Could not find the index in the table."""))

        res = self.blueprint.generate_browser_node(
                rset['rows'][0]['oid'],
                tid,
                rset['rows'][0]['name'],
                icon="icon-index"
            )

        return make_json_response(
            data=res,
            status=200
        )

    @check_precondition
    def nodes(self, gid, sid, did, scid, tid):
        """
        This function will used to create all the child node within that collection.
        Here it will create all the schema node.

        Args:
            gid: Server Group ID
            sid: Server ID
            did: Database ID
            scid: Schema ID
            tid: Table ID

        Returns:
            JSON of available schema child nodes
        """
        res = []
        SQL = render_template(
            "/".join([self.template_path, 'nodes.sql']), tid=tid
        )
        status, rset = self.conn.execute_2darray(SQL)
        if not status:
            return internal_server_error(errormsg=rset)

        for row in rset['rows']:
            res.append(
                self.blueprint.generate_browser_node(
                    row['oid'],
                    tid,
                    row['name'],
                    icon="icon-index"
                ))

        return make_json_response(
            data=res,
            status=200
        )

    def _column_details(self, idx, data, mode='properties'):
        """
        This functional will fetch list of column details for index

        Args:
            idx: Index OID
            data: Properties data

        Returns:
            Updated properties data with column details
        """

        SQL = render_template(
            "/".join([self.template_path, 'column_details.sql']), idx=idx
        )
        status, rset = self.conn.execute_2darray(SQL)
        if not status:
            return internal_server_error(errormsg=rset)
        # 'attdef' comes with quotes from query so we need to strip them
        # 'options' we need true/false to render switch ASC(false)/DESC(true)
        columns = []
        cols = []
        for row in rset['rows']:
            # We need all data as collection for ColumnsModel
            # we will not strip down colname when using in SQL to display
            cols_data = {
                'colname': row['attdef'] if mode == 'create' else
                row['attdef'].strip('"'),
                'collspcname': row['collnspname'],
                'op_class': row['opcname'],
            }
            if row['options'][0] == 'DESC':
                cols_data['sort_order'] = True
            columns.append(cols_data)

            # We need same data as string to display in properties window
            # If multiple column then separate it by colon
            cols_str = row['attdef']
            if row['collnspname']:
                cols_str += ' COLLATE ' + row['collnspname']
            if row['opcname']:
                cols_str += ' ' + row['opcname']
            if row['options'][0] == 'DESC':
                cols_str += ' DESC'
            cols.append(cols_str)

        # Push as collection
        data['columns'] = columns
        # Push as string
        data['cols'] = ', '.join(cols)

        return data

    @check_precondition
    def properties(self, gid, sid, did, scid, tid, idx):
        """
        This function will show the properties of the selected schema node.

        Args:
            gid: Server Group ID
            sid: Server ID
            did:  Database ID
            scid: Schema ID
            scid: Schema ID
            tid: Table ID
            idx: Index ID

        Returns:
            JSON of selected schema node
        """

        SQL = render_template(
            "/".join([self.template_path, 'properties.sql']),
            did=did, tid=tid, idx=idx, datlastsysoid=self.datlastsysoid
        )

        status, res = self.conn.execute_dict(SQL)

        if not status:
            return internal_server_error(errormsg=res)

        if len(res['rows']) == 0:
            return gone(gettext("""Could not find the index in the table."""))

        # Making copy of output for future use
        data = dict(res['rows'][0])

        # Add column details for current index
        data = self._column_details(idx, data)

        return ajax_response(
            response=data,
            status=200
        )

    @check_precondition
    def create(self, gid, sid, did, scid, tid):
        """
        This function will creates new the schema object

         Args:
           gid: Server Group ID
           sid: Server ID
           did: Database ID
           scid: Schema ID
           tid: Table ID
        """
        data = request.form if request.form else json.loads(
            request.data, encoding='utf-8'
        )

        for k, v in data.items():
            try:
                data[k] = json.loads(v, encoding='utf-8')
            except (ValueError, TypeError, KeyError):
                data[k] = v

        required_args = {
            'name': 'Name',
            'columns': 'Columns'
        }

        for arg in required_args:
            err_msg = None
            if arg == 'columns' and len(data['columns']) < 1:
                err_msg = "You must provide one or more column to create index"

            if arg not in data:
                err_msg = "Could not find the required parameter (%s)." % \
                          required_args[arg]
                # Check if we have at least one column
            if err_msg is not None:
                return make_json_response(
                    status=410,
                    success=0,
                    errormsg=gettext(err_msg)
                )

        # Adding parent into data dict, will be using it while creating sql
        data['schema'] = self.schema
        data['table'] = self.table

        try:
            # Start transaction.
            self.conn.execute_scalar("BEGIN;")
            SQL = render_template(
                "/".join([self.template_path, 'create.sql']),
                data=data, conn=self.conn, mode='create'
            )
            status, res = self.conn.execute_scalar(SQL)
            if not status:
                # End transaction.
                self.conn.execute_scalar("END;")
                return internal_server_error(errormsg=res)

            # If user chooses concurrent index then we cannot run it along
            # with other alter statements so we will separate alter index part
            SQL = render_template(
                "/".join([self.template_path, 'alter.sql']),
                data=data, conn=self.conn
            )
            SQL = SQL.strip('\n').strip(' ')
            if SQL != '':
                status, res = self.conn.execute_scalar(SQL)
                if not status:
                    # End transaction.
                    self.conn.execute_scalar("END;")
                    return internal_server_error(errormsg=res)

            # we need oid to to add object in tree at browser
            SQL = render_template(
                "/".join([self.template_path, 'get_oid.sql']),
                tid=tid, data=data
            )
            status, idx = self.conn.execute_scalar(SQL)
            if not status:
                # End transaction.
                self.conn.execute_scalar("END;")
                return internal_server_error(errormsg=tid)

            # End transaction.
            self.conn.execute_scalar("END;")
            return jsonify(
                node=self.blueprint.generate_browser_node(
                    idx,
                    tid,
                    data['name'],
                    icon="icon-index"
                )
            )
        except Exception as e:
            # End transaction.
            self.conn.execute_scalar("END;")
            return internal_server_error(errormsg=str(e))

    @check_precondition
    def delete(self, gid, sid, did, scid, tid, idx):
        """
        This function will updates existing the schema object

         Args:
           gid: Server Group ID
           sid: Server ID
           did: Database ID
           scid: Schema ID
           tid: Table ID
           idx: Index ID
        """
        # Below will decide if it's simple drop or drop with cascade call
        if self.cmd == 'delete':
            # This is a cascade operation
            cascade = True
        else:
            cascade = False

        try:
            # We will first fetch the index name for current request
            # so that we create template for dropping index
            SQL = render_template(
                "/".join([self.template_path, 'properties.sql']),
                did=did, tid=tid, idx=idx, datlastsysoid=self.datlastsysoid
            )

            status, res = self.conn.execute_dict(SQL)
            if not status:
                return internal_server_error(errormsg=res)

            if not res['rows']:
                return make_json_response(
                    success=0,
                    errormsg=gettext(
                        'Error: Object not found.'
                    ),
                    info=gettext(
                        'The specified index could not be found.\n'
                    )
                )

            data = dict(res['rows'][0])

            SQL = render_template(
                "/".join([self.template_path, 'delete.sql']),
                data=data, conn=self.conn, cascade=cascade
            )
            status, res = self.conn.execute_scalar(SQL)
            if not status:
                return internal_server_error(errormsg=res)

            return make_json_response(
                success=1,
                info=gettext("Index is dropped"),
                data={
                    'id': idx,
                    'tid': tid
                }
            )

        except Exception as e:
            return internal_server_error(errormsg=str(e))

    @check_precondition
    def update(self, gid, sid, did, scid, tid, idx):
        """
        This function will updates existing the schema object

         Args:
           gid: Server Group ID
           sid: Server ID
           did: Database ID
           scid: Schema ID
           tid: Table ID
           idx: Index ID
        """
        data = request.form if request.form else json.loads(
            request.data, encoding='utf-8'
        )
        data['schema'] = self.schema
        data['table'] = self.table
        try:
            SQL, name = self.get_sql(did, scid, tid, idx, data)
            if not isinstance(SQL, (str, unicode)):
                return SQL
            SQL = SQL.strip('\n').strip(' ')
            status, res = self.conn.execute_scalar(SQL)
            if not status:
                return internal_server_error(errormsg=res)

            return jsonify(
                node=self.blueprint.generate_browser_node(
                    idx,
                    tid,
                    name,
                    icon="icon-%s" % self.node_type
                )
            )
        except Exception as e:
            return internal_server_error(errormsg=str(e))

    @check_precondition
    def msql(self, gid, sid, did, scid, tid, idx=None):
        """
        This function will generates modified sql for schema object

         Args:
           gid: Server Group ID
           sid: Server ID
           did: Database ID
           scid: Schema ID
           tid: Table ID
           idx: Index ID (When working with existing index)
        """
        data = dict()
        for k, v in request.args.items():
            try:
                data[k] = json.loads(v, encoding='utf-8')
            except ValueError:
                data[k] = v

        # Adding parent into data dict, will be using it while creating sql
        data['schema'] = self.schema
        data['table'] = self.table

        try:
            sql, name = self.get_sql(did, scid, tid, idx, data, mode='create')
            if not isinstance(sql, (str, unicode)):
                return sql
            sql = sql.strip('\n').strip(' ')
            if sql == '':
                sql = "--modified SQL"
            return make_json_response(
                data=sql,
                status=200
            )
        except Exception as e:
            return internal_server_error(errormsg=str(e))

    def get_sql(self, did, scid, tid, idx, data, mode=None):
        """
        This function will genrate sql from model data
        """
        if idx is not None:
            SQL = render_template(
                "/".join([self.template_path, 'properties.sql']),
                did=did, tid=tid, idx=idx, datlastsysoid=self.datlastsysoid
            )

            status, res = self.conn.execute_dict(SQL)
            if not status:
                return internal_server_error(errormsg=res)
            if len(res['rows']) == 0:
                return gone(gettext("""Could not find the index in the table."""))

            old_data = dict(res['rows'][0])

            # If name is not present in data then
            # we will fetch it from old data, we also need schema & table name
            if 'name' not in data:
                data['name'] = old_data['name']

            SQL = render_template(
                "/".join([self.template_path, 'update.sql']),
                data=data, o_data=old_data, conn=self.conn
            )
        else:
            required_args = {
                'name': 'Name',
                'columns': 'Columns'
            }
            for arg in required_args:
                err = False
                if arg == 'columns' and len(data['columns']) < 1:
                    err = True

                if arg not in data:
                    err = True
                    # Check if we have at least one column
                if err:
                    return gettext('-- definition incomplete')

            # If the request for new object which do not have did
            SQL = render_template(
                "/".join([self.template_path, 'create.sql']),
                data=data, conn=self.conn, mode=mode
            )
            SQL += "\n"
            SQL += render_template(
                "/".join([self.template_path, 'alter.sql']),
                data=data, conn=self.conn
            )

        return SQL, data['name'] if 'name' in data else old_data['name']

    @check_precondition
    def sql(self, gid, sid, did, scid, tid, idx):
        """
        This function will generates reverse engineered sql for schema object

         Args:
           gid: Server Group ID
           sid: Server ID
           did: Database ID
           scid: Schema ID
           tid: Table ID
           idx: Index ID
        """

        SQL = render_template(
            "/".join([self.template_path, 'properties.sql']),
            did=did, tid=tid, idx=idx, datlastsysoid=self.datlastsysoid
        )

        status, res = self.conn.execute_dict(SQL)
        if not status:
            return internal_server_error(errormsg=res)
        if len(res['rows']) == 0:
            return gone(gettext("""Could not find the index in the table."""))

        data = dict(res['rows'][0])
        # Adding parent into data dict, will be using it while creating sql
        data['schema'] = self.schema
        data['table'] = self.table

        # Add column details for current index
        data = self._column_details(idx, data, 'create')

        SQL, name = self.get_sql(did, scid, tid, None, data)
        if not isinstance(SQL, (str, unicode)):
            return SQL
        sql_header = u"-- Index: {0}\n\n-- ".format(data['name'])

        sql_header += render_template(
            "/".join([self.template_path, 'delete.sql']),
            data=data, conn=self.conn
        )

        SQL = sql_header + '\n\n' + SQL

        return ajax_response(response=SQL)

    @check_precondition
    def dependents(self, gid, sid, did, scid, tid, idx):
        """
        This function get the dependents and return ajax response
        for the schema node.

        Args:
            gid: Server Group ID
            sid: Server ID
            did: Database ID
            scid: Schema ID
            tid: Table ID
            idx: Index ID
        """
        dependents_result = self.get_dependents(
            self.conn, idx
        )

        return ajax_response(
            response=dependents_result,
            status=200
        )

    @check_precondition
    def dependencies(self, gid, sid, did, scid, tid, idx):
        """
        This function get the dependencies and return ajax response
        for the schema node.

        Args:
            gid: Server Group ID
            sid: Server ID
            did: Database ID
            scid: Schema ID
            tid: Table ID
            idx: Index ID

        """
        dependencies_result = self.get_dependencies(
            self.conn, idx
        )

        return ajax_response(
            response=dependencies_result,
            status=200
        )

    @check_precondition
    def statistics(self, gid, sid, did, scid, tid, idx=None):
        """
        Statistics

        Args:
            gid: Server Group Id
            sid: Server Id
            did: Database Id
            scid: Schema Id
            tid: Table Id
            idx: Index Id

        Returns the statistics for a particular object if idx is specified
        else return all indexes
        """

        if idx is not None:
            # Individual index

            # Check if pgstattuple extension is already created?
            # if created then only add extended stats
            status, is_pgstattuple = self.conn.execute_scalar("""
            SELECT (count(extname) > 0) AS is_pgstattuple
            FROM pg_extension
            WHERE extname='pgstattuple'
            """)
            if not status:
                return internal_server_error(errormsg=is_pgstattuple)

            if is_pgstattuple:
                # Fetch index details only if extended stats available
                SQL = render_template(
                    "/".join([self.template_path, 'properties.sql']),
                    did=did, tid=tid, idx=idx,
                    datlastsysoid=self.datlastsysoid
                )
                status, res = self.conn.execute_dict(SQL)
                if not status:
                    return internal_server_error(errormsg=res)
                if len(res['rows']) == 0:
                    return gone(
                        gettext("""Could not find the index in the table.""")
                    )

                data = dict(res['rows'][0])
                index = data['name']
            else:
                index = None

            status, res = self.conn.execute_dict(
                render_template(
                    "/".join([self.template_path, 'stats.sql']),
                    conn=self.conn, schema=self.schema,
                    index=index, idx=idx, is_pgstattuple=is_pgstattuple
                )
            )

        else:
            status, res = self.conn.execute_dict(
                render_template(
                    "/".join([self.template_path, 'coll_stats.sql']),
                    conn=self.conn, schema=self.schema,
                    table=self.table
                )
            )

        if not status:
            return internal_server_error(errormsg=res)

        return make_json_response(
            data=res,
            status=200
        )


IndexesView.register_node_view(blueprint)
