# Copyright (C) 2013 Ipsilon project Contributors, for license see COPYING

import cherrypy
import datetime
from ipsilon.util.log import Log
from sqlalchemy import create_engine
from sqlalchemy import MetaData, Table, Column, Text
from sqlalchemy.pool import QueuePool, SingletonThreadPool
from sqlalchemy.sql import select, and_
import ConfigParser
import os
import uuid
import logging


CURRENT_SCHEMA_VERSION = 1
OPTIONS_COLUMNS = ['name', 'option', 'value']
UNIQUE_DATA_COLUMNS = ['uuid', 'name', 'value']


class SqlStore(Log):
    __instances = {}

    @classmethod
    def get_connection(cls, name):
        if name not in cls.__instances:
            if cherrypy.config.get('db.conn.log', False):
                logging.debug('SqlStore new: %s', name)
            cls.__instances[name] = SqlStore(name)
        return cls.__instances[name]

    def __init__(self, name):
        self.db_conn_log = cherrypy.config.get('db.conn.log', False)
        self.debug('SqlStore init: %s' % name)
        self.name = name
        engine_name = name
        if '://' not in engine_name:
            engine_name = 'sqlite:///' + engine_name
        # This pool size is per configured database. The minimum needed,
        #  determined by binary search, is 23. We're using 25 so we have a bit
        #  more playroom, and then the overflow should make sure things don't
        #  break when we suddenly need more.
        pool_args = {'poolclass': QueuePool,
                     'pool_size': 25,
                     'max_overflow': 50}
        if engine_name.startswith('sqlite://'):
            # It's not possible to share connections for SQLite between
            #  threads, so let's use the SingletonThreadPool for them
            pool_args = {'poolclass': SingletonThreadPool}
        self._dbengine = create_engine(engine_name, **pool_args)
        self.is_readonly = False

    def debug(self, fact):
        if self.db_conn_log:
            super(SqlStore, self).debug(fact)

    def engine(self):
        return self._dbengine

    def connection(self):
        self.debug('SqlStore connect: %s' % self.name)
        conn = self._dbengine.connect()

        def cleanup_connection():
            self.debug('SqlStore cleanup: %s' % self.name)
            conn.close()
        cherrypy.request.hooks.attach('on_end_request', cleanup_connection)
        return conn


def SqlAutotable(f):
    def at(self, *args, **kwargs):
        self.create()
        return f(self, *args, **kwargs)
    return at


class SqlQuery(Log):

    def __init__(self, db_obj, table, columns, trans=True):
        self._db = db_obj
        self._con = self._db.connection()
        self._trans = self._con.begin() if trans else None
        self._table = self._get_table(table, columns)

    def _get_table(self, name, columns):
        table = Table(name, MetaData(self._db.engine()))
        for c in columns:
            table.append_column(Column(c, Text()))
        return table

    def _where(self, kvfilter):
        where = None
        if kvfilter is not None:
            for k in kvfilter:
                w = self._table.columns[k] == kvfilter[k]
                if where is None:
                    where = w
                else:
                    where = where & w
        return where

    def _columns(self, columns=None):
        cols = None
        if columns is not None:
            cols = []
            for c in columns:
                cols.append(self._table.columns[c])
        else:
            cols = self._table.columns
        return cols

    def rollback(self):
        self._trans.rollback()

    def commit(self):
        self._trans.commit()

    def create(self):
        self._table.create(checkfirst=True)

    def drop(self):
        self._table.drop(checkfirst=True)

    @SqlAutotable
    def select(self, kvfilter=None, columns=None):
        return self._con.execute(select(self._columns(columns),
                                        self._where(kvfilter)))

    @SqlAutotable
    def insert(self, values):
        self._con.execute(self._table.insert(values))

    @SqlAutotable
    def update(self, values, kvfilter):
        self._con.execute(self._table.update(self._where(kvfilter), values))

    @SqlAutotable
    def delete(self, kvfilter):
        self._con.execute(self._table.delete(self._where(kvfilter)))


class FileStore(Log):

    def __init__(self, name):
        self._filename = name
        self.is_readonly = True
        self._timestamp = None
        self._config = None

    def get_config(self):
        try:
            stat = os.stat(self._filename)
        except OSError, e:
            self.error("Unable to check config file %s: [%s]" % (
                self._filename, e))
            self._config = None
            raise
        timestamp = stat.st_mtime
        if self._config is None or timestamp > self._timestamp:
            self._config = ConfigParser.RawConfigParser()
            self._config.optionxform = str
            self._config.read(self._filename)
        return self._config


class FileQuery(Log):

    def __init__(self, fstore, table, columns, trans=True):
        self._fstore = fstore
        self._config = fstore.get_config()
        self._section = table
        if len(columns) > 3 or columns[-1] != 'value':
            raise ValueError('Unsupported configuration format')
        self._columns = columns

    def rollback(self):
        return

    def commit(self):
        return

    def create(self):
        raise NotImplementedError

    def drop(self):
        raise NotImplementedError

    def select(self, kvfilter=None, columns=None):
        if self._section not in self._config.sections():
            return []

        opts = self._config.options(self._section)

        prefix = None
        prefix_ = ''
        if self._columns[0] in kvfilter:
            prefix = kvfilter[self._columns[0]]
            prefix_ = prefix + ' '

        name = None
        if len(self._columns) == 3 and self._columns[1] in kvfilter:
            name = kvfilter[self._columns[1]]

        value = None
        if self._columns[-1] in kvfilter:
            value = kvfilter[self._columns[-1]]

        res = []
        for o in opts:
            if len(self._columns) == 3:
                # 3 cols
                if prefix and not o.startswith(prefix_):
                    continue

                col1, col2 = o.split(' ', 1)
                if name and col2 != name:
                    continue

                col3 = self._config.get(self._section, o)
                if value and col3 != value:
                    continue

                r = [col1, col2, col3]
            else:
                # 2 cols
                if prefix and o != prefix:
                    continue
                r = [o, self._config.get(self._section, o)]

            if columns:
                s = []
                for c in columns:
                    s.append(r[self._columns.index(c)])
                res.append(s)
            else:
                res.append(r)

        self.debug('SELECT(%s, %s, %s) -> %s' % (self._section,
                                                 repr(kvfilter),
                                                 repr(columns),
                                                 repr(res)))
        return res

    def insert(self, values):
        raise NotImplementedError

    def update(self, values, kvfilter):
        raise NotImplementedError

    def delete(self, kvfilter):
        raise NotImplementedError


class Store(Log):
    def __init__(self, config_name=None, database_url=None):
        if config_name is None and database_url is None:
            raise ValueError('config_name or database_url must be provided')
        if config_name:
            if config_name not in cherrypy.config:
                raise NameError('Unknown database %s' % config_name)
            name = cherrypy.config[config_name]
        else:
            name = database_url
        if name.startswith('configfile://'):
            _, filename = name.split('://')
            self._db = FileStore(filename)
            self._query = FileQuery
        else:
            self._db = SqlStore.get_connection(name)
            self._query = SqlQuery
        self._upgrade_database()

    def _upgrade_database(self):
        if self.is_readonly:
            # If the database is readonly, we cannot do anything to the
            #  schema. Let's just return, and assume people checked the
            #  upgrade notes
            return
        current_version = self.load_options('dbinfo').get('scheme', None)
        if current_version is None or 'version' not in current_version:
            # No version stored, storing current version
            self.save_options('dbinfo', 'scheme',
                              {'version': CURRENT_SCHEMA_VERSION})
            current_version = CURRENT_SCHEMA_VERSION
        else:
            current_version = int(current_version['version'])
        if current_version != CURRENT_SCHEMA_VERSION:
            self.debug('Upgrading database schema from %i to %i' % (
                       current_version, CURRENT_SCHEMA_VERSION))
            self._upgrade_database_from(current_version)

    def _upgrade_database_from(self, old_schema_version):
        # Insert code here to upgrade from old_schema_version to
        #  CURRENT_SCHEMA_VERSION
        raise Exception('Unable to upgrade database to current schema'
                        ' version: version %i is unknown!' %
                        old_schema_version)

    @property
    def is_readonly(self):
        return self._db.is_readonly

    def _row_to_dict_tree(self, data, row):
        name = row[0]
        if len(row) > 2:
            if name not in data:
                data[name] = dict()
            d2 = data[name]
            self._row_to_dict_tree(d2, row[1:])
        else:
            value = row[1]
            if name in data:
                if data[name] is list:
                    data[name].append(value)
                else:
                    v = data[name]
                    data[name] = [v, value]
            else:
                data[name] = value

    def _rows_to_dict_tree(self, rows):
        data = dict()
        for r in rows:
            self._row_to_dict_tree(data, r)
        return data

    def _load_data(self, table, columns, kvfilter=None):
        rows = []
        try:
            q = self._query(self._db, table, columns, trans=False)
            rows = q.select(kvfilter)
        except Exception, e:  # pylint: disable=broad-except
            self.error("Failed to load data for table %s: [%s]" % (table, e))
        return self._rows_to_dict_tree(rows)

    def load_config(self):
        table = 'config'
        columns = ['name', 'value']
        return self._load_data(table, columns)

    def load_options(self, table, name=None):
        kvfilter = dict()
        if name:
            kvfilter['name'] = name
        options = self._load_data(table, OPTIONS_COLUMNS, kvfilter)
        if name and name in options:
            return options[name]
        return options

    def save_options(self, table, name, options):
        curvals = dict()
        q = None
        try:
            q = self._query(self._db, table, OPTIONS_COLUMNS)
            rows = q.select({'name': name}, ['option', 'value'])
            for row in rows:
                curvals[row[0]] = row[1]

            for opt in options:
                if opt in curvals:
                    q.update({'value': options[opt]},
                             {'name': name, 'option': opt})
                else:
                    q.insert((name, opt, options[opt]))

            q.commit()
        except Exception, e:  # pylint: disable=broad-except
            if q:
                q.rollback()
            self.error("Failed to save options: [%s]" % e)
            raise

    def delete_options(self, table, name, options=None):
        kvfilter = {'name': name}
        q = None
        try:
            q = self._query(self._db, table, OPTIONS_COLUMNS)
            if options is None:
                q.delete(kvfilter)
            else:
                for opt in options:
                    kvfilter['option'] = opt
                    q.delete(kvfilter)
            q.commit()
        except Exception, e:  # pylint: disable=broad-except
            if q:
                q.rollback()
            self.error("Failed to delete from %s: [%s]" % (table, e))
            raise

    def new_unique_data(self, table, data):
        newid = str(uuid.uuid4())
        q = None
        try:
            q = self._query(self._db, table, UNIQUE_DATA_COLUMNS)
            for name in data:
                q.insert((newid, name, data[name]))
            q.commit()
        except Exception, e:  # pylint: disable=broad-except
            if q:
                q.rollback()
            self.error("Failed to store %s data: [%s]" % (table, e))
            raise
        return newid

    def get_unique_data(self, table, uuidval=None, name=None, value=None):
        kvfilter = dict()
        if uuidval:
            kvfilter['uuid'] = uuidval
        if name:
            kvfilter['name'] = name
        if value:
            kvfilter['value'] = value
        return self._load_data(table, UNIQUE_DATA_COLUMNS, kvfilter)

    def save_unique_data(self, table, data):
        q = None
        try:
            q = self._query(self._db, table, UNIQUE_DATA_COLUMNS)
            for uid in data:
                curvals = dict()
                rows = q.select({'uuid': uid}, ['name', 'value'])
                for r in rows:
                    curvals[r[0]] = r[1]

                datum = data[uid]
                for name in datum:
                    if name in curvals:
                        if datum[name] is None:
                            q.delete({'uuid': uid, 'name': name})
                        else:
                            q.update({'value': datum[name]},
                                     {'uuid': uid, 'name': name})
                    else:
                        if datum[name] is not None:
                            q.insert((uid, name, datum[name]))

            q.commit()
        except Exception, e:  # pylint: disable=broad-except
            if q:
                q.rollback()
            self.error("Failed to store data in %s: [%s]" % (table, e))
            raise

    def del_unique_data(self, table, uuidval):
        kvfilter = {'uuid': uuidval}
        try:
            q = self._query(self._db, table, UNIQUE_DATA_COLUMNS, trans=False)
            q.delete(kvfilter)
        except Exception, e:  # pylint: disable=broad-except
            self.error("Failed to delete data from %s: [%s]" % (table, e))

    def _reset_data(self, table):
        q = None
        try:
            q = self._query(self._db, table, UNIQUE_DATA_COLUMNS)
            q.drop()
            q.create()
            q.commit()
        except Exception, e:  # pylint: disable=broad-except
            if q:
                q.rollback()
            self.error("Failed to erase all data from %s: [%s]" % (table, e))


class AdminStore(Store):

    def __init__(self):
        super(AdminStore, self).__init__('admin.config.db')

    def get_data(self, plugin, idval=None, name=None, value=None):
        return self.get_unique_data(plugin+"_data", idval, name, value)

    def save_data(self, plugin, data):
        return self.save_unique_data(plugin+"_data", data)

    def new_datum(self, plugin, datum):
        table = plugin+"_data"
        return self.new_unique_data(table, datum)

    def del_datum(self, plugin, idval):
        table = plugin+"_data"
        return self.del_unique_data(table, idval)

    def wipe_data(self, plugin):
        table = plugin+"_data"
        self._reset_data(table)


class UserStore(Store):

    def __init__(self, path=None):
        super(UserStore, self).__init__('user.prefs.db')

    def save_user_preferences(self, user, options):
        self.save_options('users', user, options)

    def load_user_preferences(self, user):
        return self.load_options('users', user)

    def save_plugin_data(self, plugin, user, options):
        self.save_options(plugin+"_data", user, options)

    def load_plugin_data(self, plugin, user):
        return self.load_options(plugin+"_data", user)


class TranStore(Store):

    def __init__(self, path=None):
        super(TranStore, self).__init__('transactions.db')


class SAML2SessionStore(Store):

    def __init__(self, database_url):
        super(SAML2SessionStore, self).__init__(database_url=database_url)
        self.table = 'sessions'
        # pylint: disable=protected-access
        table = SqlQuery(self._db, self.table, UNIQUE_DATA_COLUMNS)._table
        table.create(checkfirst=True)

    def _get_unique_id_from_column(self, name, value):
        """
        The query is going to return only the column in the query.
        Use this method to get the uuidval which can be used to fetch
        the entire entry.

        Returns None or the uuid of the first value found.
        """
        data = self.get_unique_data(self.table, name=name, value=value)
        count = len(data)
        if count == 0:
            return None
        elif count != 1:
            raise ValueError("Multiple entries returned")
        return data.keys()[0]

    def remove_expired_sessions(self):
        # pylint: disable=protected-access
        table = SqlQuery(self._db, self.table, UNIQUE_DATA_COLUMNS)._table
        sel = select([table.columns.uuid]). \
            where(and_(table.c.name == 'expiration_time',
                       table.c.value <= datetime.datetime.now()))
        # pylint: disable=no-value-for-parameter
        d = table.delete().where(table.c.uuid.in_(sel))
        d.execute()

    def get_data(self, idval=None, name=None, value=None):
        return self.get_unique_data(self.table, idval, name, value)

    def new_session(self, datum):
        if 'supported_logout_mechs' in datum:
            datum['supported_logout_mechs'] = ','.join(
                datum['supported_logout_mechs']
            )
        return self.new_unique_data(self.table, datum)

    def get_session(self, session_id=None, request_id=None):
        if session_id:
            uuidval = self._get_unique_id_from_column('session_id', session_id)
        elif request_id:
            uuidval = self._get_unique_id_from_column('request_id', request_id)
        else:
            raise ValueError("Unable to find session")
        if not uuidval:
            return None, None
        data = self.get_unique_data(self.table, uuidval=uuidval)
        return uuidval, data[uuidval]

    def get_user_sessions(self, user):
        """
        Return a list of all sessions for a given user.
        """
        rows = self.get_unique_data(self.table, name='user', value=user)

        # We have a list of sessions for this user, now get the details
        logged_in = []
        for r in rows:
            data = self.get_unique_data(self.table, uuidval=r)
            data[r]['supported_logout_mechs'] = data[r].get(
                'supported_logout_mechs', '').split(',')
            logged_in.append(data)

        return logged_in

    def update_session(self, datum):
        self.save_unique_data(self.table, datum)

    def remove_session(self, uuidval):
        self.del_unique_data(self.table, uuidval)

    def wipe_data(self):
        self._reset_data(self.table)