import os 
import ldap
import time
import bcrypt
import urlparse
import traceback

from datetime import datetime
from flask.ext.login import AnonymousUserMixin

from app import app, db
from lib import utils
from lib.log import logger
logging = logger('MODEL', app.config['LOG_LEVEL'], app.config['LOG_FILE']).config()

LDAP_URI = app.config['LDAP_URI']
LDAP_USERNAME = app.config['LDAP_USERNAME']
LDAP_PASSWORD = app.config['LDAP_PASSWORD']
LDAP_SEARCH_BASE = app.config['LDAP_SEARCH_BASE']

PDNS_STATS_URL = app.config['PDNS_STATS_URL']
PDNS_API_KEY = app.config['PDNS_API_KEY']


class Anonymous(AnonymousUserMixin):
  def __init__(self):
    self.username = 'Anonymous'


class User(db.Model):

    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), index=True, unique=True)
    password = db.Column(db.String(64))
    firstname = db.Column(db.String(64))
    lastname = db.Column(db.String(64))
    email = db.Column(db.String(128))
    avatar = db.Column(db.String(128))
    role_id = db.Column(db.Integer, db.ForeignKey('role.id'))

    def __init__(self, id=None, username=None, password=None, plain_text_password=None, firstname=None, lastname=None, role_id=None, email=None, avatar=None, reload_info=True):
        self.id = id
        self.username = username
        self.password = password
        self.plain_text_password = plain_text_password
        self.firstname = firstname
        self.lastname = lastname
        self.role_id = role_id
        self.email = email
        self.avatar = avatar

        if reload_info:
            user_info = self.get_user_info_by_id() if id else self.get_user_info_by_username()

            if user_info:
                self.id = user_info.id
                self.username = user_info.username
                self.firstname = user_info.firstname
                self.lastname = user_info.lastname
                self.email = user_info.email
                self.role_id = user_info.role_id

    def is_authenticated(self):
        return True
 
    def is_active(self):
        return True
 
    def is_anonymous(self):
        return False

    def get_id(self):
        try:
            return unicode(self.id)  # python 2
        except NameError:
            return str(self.id)  # python 3

    def __repr__(self):
        return '<User %r>' % (self.username)

    def get_hashed_password(self, plain_text_password=None):
        # Hash a password for the first time
        #   (Using bcrypt, the salt is saved into the hash itself)
        pw = plain_text_password if plain_text_password else self.plain_text_password
        return bcrypt.hashpw(pw, bcrypt.gensalt())

    def check_password(self, hashed_password):        
        # Check hased password. Useing bcrypt, the salt is saved into the hash itself
        return bcrypt.checkpw(self.plain_text_password, hashed_password)

    def get_user_info_by_id(self):
        user_info = User.query.get(int(self.id))
        return user_info

    def get_user_info_by_username(self):
        user_info = User.query.filter(User.username == self.username).first()
        return user_info

    def ldap_search(self, searchFilter, baseDN):
        searchScope = ldap.SCOPE_SUBTREE
        retrieveAttributes = None

        try:
            ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)
            l = ldap.initialize(LDAP_URI)
            l.set_option(ldap.OPT_REFERRALS, 0)
            l.set_option(ldap.OPT_PROTOCOL_VERSION, 3)
            l.set_option(ldap.OPT_X_TLS,ldap.OPT_X_TLS_DEMAND)
            l.set_option( ldap.OPT_X_TLS_DEMAND, True )
            l.set_option( ldap.OPT_DEBUG_LEVEL, 255 )
            l.protocol_version = ldap.VERSION3

            l.simple_bind_s(LDAP_USERNAME, LDAP_PASSWORD)
            ldap_result_id = l.search(baseDN, searchScope, searchFilter, retrieveAttributes)
            result_set = []
            while 1:
                result_type, result_data = l.result(ldap_result_id, 0)
                if (result_data == []):
                    break
                else:
                    if result_type == ldap.RES_SEARCH_ENTRY:
                        result_set.append(result_data)
            return result_set

        except ldap.LDAPError, e:
            logging.error(e)
            raise

    def is_validate(self, method):
        """
        Validate user credential
        """
        if method == 'LOCAL':
            user_info = User.query.filter(User.username == self.username).first()

            if user_info:
                if self.check_password(user_info.password):
                    logging.info('User "%s" logged in successfully' % self.username)
                    return True
                else:
                    logging.error('User "%s" input a wrong password' % self.username)
                    return False
            else:
                logging.warning('User "%s" does not exist' % self.username)
                return False

        elif method == 'LDAP':
            searchFilter = "cn=%s" % self.username
            try:
                result = self.ldap_search(searchFilter, LDAP_SEARCH_BASE)
            except Exception, e:
                raise

            if not result:
                logging.warning('User "%s" does not exist' % self.username)
                return False
            else:
                ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)
                l = ldap.initialize(LDAP_URI)
                l.set_option(ldap.OPT_REFERRALS, 0)
                l.set_option(ldap.OPT_PROTOCOL_VERSION, 3)
                l.set_option(ldap.OPT_X_TLS,ldap.OPT_X_TLS_DEMAND)
                l.set_option( ldap.OPT_X_TLS_DEMAND, True )
                l.set_option( ldap.OPT_DEBUG_LEVEL, 255 )
                l.protocol_version = ldap.VERSION3

                try:
                    ldap_username = result[0][0][0]
                    l.simple_bind_s(ldap_username, self.password)
                    logging.info('User "%s" logged in successfully' % self.username)
                    
                    # create user if not exist in the db
                    if User.query.filter(User.username == self.username).first() == None:
                        try:
                            # try to get user's firstname & lastname from LDAP
                            # this might be changed in the future
                            self.firstname = result[0][0][1]['givenName'][0]
                            self.lastname = result[0][0][1]['sn'][0]
                        except:
                            self.firstname = self.username
                            self.lastname = ''

                        self.role_id = 2
                        self.create_user()
                        logging.info('Created user "%s" in the DB' % self.username)
                    return True
                except:
                    logging.error('User "%s" input a wrong password' % self.username)
                    return False
        else:
            logging.error('Unsupported authentication method')
            return False

    def create_user(self):
        """
        If user logged in successfully via LDAP in the first time
        We will create a local user (in DB) in order to manage user
        profile such as name, roles,...
        """
        user = User(username=self.username, firstname=self.firstname, lastname=self.lastname, role_id=self.role_id)
        db.session.add(user)
        db.session.commit()
        # assgine user_id to current_user after create in the DB
        self.id = user.id

    def create_local_user(self):
        """
        Create local user witch stores username / password in the DB
        """
        # check if username existed
        user = User.query.filter(User.username == self.username).first()
        if user:
            return 'Username already existed'

        # check if email existed
        user = User.query.filter(User.email == self.email).first()
        if user:
            return 'Email already existed'

        try:
            self.role_id = 2
            user = User(username=self.username, firstname=self.firstname, lastname=self.lastname, role_id=self.role_id, email=self.email, password=self.get_hashed_password(self.plain_text_password))
            db.session.add(user)
            db.session.commit()
            return True
        except Exception, e:
            raise

    def update_profile(self):
        """
        Update user profile
        """
        user = User.query.filter(User.username == self.username).first()
        if user:
            if self.firstname:
                user.firstname = self.firstname
            if self.lastname:
                user.lastname = self.lastname
            if self.email:
                user.email = self.email
            if self.plain_text_password:
                user.password = self.get_hashed_password(self.plain_text_password)
            if self.avatar:
                user.avatar = self.avatar

            try:
                db.session.commit()
                return True
            except:
                db.session.rollback()
                return False

    def get_domain(self):
        """
        Get domains which user has permission to
        access
        """
        user_domains = []
        query = db.session.query(User, DomainUser, Domain).filter(User.id==self.id).filter(User.id==DomainUser.user_id).filter(Domain.id==DomainUser.domain_id).all()
        for q in query:
            user_domains.append(q[2])
        return user_domains

    def delete(self):
        """
        Delete a user
        """
        # revoke all user privileges first
        self.revoke_privilege()

        try:
            User.query.filter(User.username == self.username).delete()
            db.session.commit()
            return True
        except:
            db.session.rollback()
            logging.error('Cannot delete user %s from DB' % self.username)
            return False

    def revoke_privilege(self):
        """
        Revoke all privielges from a user
        """
        user = User.query.filter(User.username == self.username).first()
        
        if user:
            user_id = user.id
            try:
                DomainUser.query.filter(DomainUser.user_id == user_id).delete()
                db.session.commit()
                return True
            except:
                db.session.rollback()
                logging.error('Cannot revoke user %s privielges.' % self.username)
                return False
        return False

    def set_admin(self, is_admin):
        """
        Set role for a user:
            is_admin == True  => Administrator
            is_admin == False => User
        """
        user_role_name = 'Administrator' if is_admin else 'User'
        role = Role.query.filter(Role.name==user_role_name).first()

        try:
            if role:
                user = User.query.filter(User.username==self.username).first()
                user.role_id = role.id
                db.session.commit()
                return True
            else:
                return False
        except:
            db.session.roleback()
            logging.error('Cannot change user role in DB')
            logging.debug(traceback.format_exc())
            return False


class Role(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    name = db.Column(db.String(64), index=True, unique=True)
    description = db.Column(db.String(128))
    users = db.relationship('User', backref='role', lazy='dynamic')

    def __int__(self, id=None, name=None, description=None):
        self.id = id
        self.name = name
        self.description = description

    def __repr__(self):
        return '<Role %r>' % (self.name)


class Domain(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    name = db.Column(db.String(255), index=True, unique=True)
    master = db.Column(db.String(128))
    type = db.Column(db.String(6), nullable = False)
    serial = db.Column(db.Integer)
    notified_serial = db.Column(db.Integer)
    last_check = db.Column(db.Integer)

    def __int__(self, id=None, name=None, master=None, type='NATIVE', serial=None, notified_serial=None, last_check=None):
        self.id = id
        self.name = name
        self.master = master
        self.type = type
        self.serial = serial
        self.notified_serial = notified_serial
        self.last_check = last_check

    def __repr__(self):
        return '<Domain %r>' % (self.name)

    def get_domains(self):
        """
        Get all domains which has in PowerDNS
        jdata example:
            [
              {
                "id": "example.org.",
                "url": "/servers/localhost/zones/example.org.",
                "name": "example.org",
                "kind": "Native",
                "dnssec": false,
                "account": "",
                "masters": [],
                "serial": 2015101501,
                "notified_serial": 0,
                "last_check": 0
              }
            ]
        """
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones'), headers=headers)
        return jdata

    def get_id_by_name(self, name):
        """
        Return domain id
        """
        domain = Domain.query.filter(Domain.name==name).first()
        return domain.id 

    def update(self):
        """
        Fetch zones (domains) from PowerDNS and update into DB
        """
        db_domain = Domain.query.all()
        list_db_domain = [d.name for d in db_domain]

        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones'), headers=headers)
            list_jdomain = [d['name'] for d in jdata]

            try:
                # domains should remove from db since it doesn't exist in powerdns anymore
                should_removed_db_domain = list(set(list_db_domain).difference(list_jdomain))
                for d in should_removed_db_domain:
                    # revoke permission before delete domain
                    domain = Domain.query.filter(Domain.name==d).first()
                    domain_user = DomainUser.query.filter(DomainUser.domain_id==domain.id)
                    if domain_user:
                        domain_user.delete()
                        db.session.commit()

                    # then remove domain
                    Domain.query.filter(Domain.name == d).delete()
                    db.session.commit()
            except:
                logging.error('Can not delete domain from DB')
                logging.debug(traceback.format_exc())
                db.session.rollback()

            # update/add new domain
            for data in jdata:
                d = Domain.query.filter(Domain.name == data['name']).first()
                if d:
                    #update exist domain
                    d.master = str(data['masters'])
                    d.type = data['kind']
                    d.serial = data['serial']
                    d.notified_serial = data['notified_serial']
                    d.last_check = data['last_check']
                else:
                    # add new domain
                    d = Domain()
                    d.name = data['name']
                    d.master = str(data['masters'])
                    d.type = data['kind']
                    d.serial = data['serial']
                    d.notified_serial = data['notified_serial']
                    d.last_check = data['last_check']
                    db.session.add(d)
                try:
                    db.session.commit()
                except:
                    db.session.rollback()
            return {'status': 'ok', 'msg': 'Domain table has been updated successfully'}
        except Exception, e:
            logging.error('Can not update domain table.' + str(e))
            return {'status': 'error', 'msg': 'Can not update domain table'}

    def add(self, domain_name, domain_type, domain_ns=[], domain_master_ips=[]):
        """
        Add a domain to power dns
        """
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        post_data = {
                        "name": domain_name,
                        "kind": domain_type,
                        "masters": domain_master_ips,
                        "nameservers": domain_ns
                    }
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones'), headers=headers, method='POST', data=post_data)
            if 'error' in jdata.keys():
                logging.error(jdata['error'])
                return {'status': 'error', 'msg': jdata['error']}
            else:
                logging.info('Added domain %s successfully' % domain_name)
                return {'status': 'ok', 'msg': 'Added domain successfully'}
        except Exception, e:
            print traceback.format_exc()
            logging.error('Cannot add domain %s' % domain_name)
            logging.debug(str(e))
            return {'status': 'error', 'msg': 'Cannot add this domain.'}


    def delete(self, domain_name):
        """
        Delete a single domain name from powerdns
        """
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones/%s' % domain_name), headers=headers, method='DELETE')
            logging.info('Delete domain %s successfully' % domain_name)
            return {'status': 'ok', 'msg': 'Delete domain successfully'}
        except Exception, e:
            print traceback.format_exc()
            logging.error('Cannot delete domain %s' % domain_name)
            logging.debug(str(e))
            return {'status': 'error', 'msg': 'Cannot delete domain'}

    def get_user(self):
        """
        Get users (id) who have access to this domain name
        """
        user_ids = []
        query = db.session.query(DomainUser, Domain).filter(User.id==DomainUser.user_id).filter(Domain.id==DomainUser.domain_id).filter(Domain.name==self.name).all()
        for q in query:
            user_ids.append(q[0].user_id)
        return user_ids

    def grant_privielges(self, new_user_list):
        """
        Reconfigure domain_user table
        """

        domain_id = self.get_id_by_name(self.name)
        
        domain_user_ids = self.get_user()
        new_user_ids = [u.id for u in User.query.filter(User.username.in_(new_user_list)).all()] if new_user_list else []
        
        removed_ids = list(set(domain_user_ids).difference(new_user_ids))
        added_ids = list(set(new_user_ids).difference(domain_user_ids))

        try:
            for uid in removed_ids:
                DomainUser.query.filter(DomainUser.user_id == uid).filter(DomainUser.domain_id==domain_id).delete()
                db.session.commit()
        except:
            db.session.rollback()
            logging.error('Cannot revoke user privielges on domain %s' % self.name)

        try:
            for uid in added_ids:
                du = DomainUser(domain_id, uid)
                db.session.add(du)
                db.session.commit()
        except:
            db.session.rollback()
            logging.error('Cannot grant user privielges to domain %s' % self.name)


    def update_from_master(self, domain_name):
        """
        Update records from Master DNS server
        """
        domain = Domain.query.filter(Domain.name == domain_name).first()
        if domain:
            headers = {}
            headers['X-API-Key'] = PDNS_API_KEY
            try:
                jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones/%s/axfr-retrieve' % domain), headers=headers, method='PUT')
                return {'status': 'ok', 'msg': 'Update from Master successfully'}
            except:
                return {'status': 'error', 'msg': 'There was something wrong, please contact administrator'}
        else:
            return {'status': 'error', 'msg': 'This domain doesnot exist'}

class DomainUser(db.Model):
    __tablename__ = 'domain_user'
    id = db.Column(db.Integer, primary_key = True)
    domain_id = db.Column(db.Integer, db.ForeignKey('domain.id'), nullable = False)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable = False)

    def __init__(self, domain_id, user_id):
        self.domain_id = domain_id
        self.user_id = user_id

    def __repr__(self):
        return '<Domain_User %r %r>' % (self.domain_id, self.user_id)


class Record(object):
    """
    This is not a model, it's just an object
    which be assigned data from PowerDNS API
    """

    def __init__(self, name=None, type=None, status=None, ttl=None, data=None):
        self.name = name
        self.type = type
        self.status = status
        self.ttl = ttl
        self.data = data

    def get_record_data(self, domain):
        """
        Query domain's DNS records via API
        """
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones/%s' % domain), headers=headers)
        except:
            logging.error("Cannot fetch domain's record data from remote powerdns api")
            return False
        return jdata

    def add(self, domain):
        """
        Add a record to domain
        """
        # validate record first
        r = self.get_record_data(domain)
        records = r['records']
        check = filter(lambda check: check['name'] == self.name, records)
        if check:
            r = check[0]
            if r['type'] in ('A', 'AAAA' ,'CNAME'):
                return {'status': 'error', 'msg': 'Record might was already exist with type "A", "AAAA", "CNAME"'}

        # continue if the record is ready to be added
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        data = {"rrsets": [
                    {
                        "name": self.name,
                        "type": self.type,
                        "changetype": "REPLACE",
                        "records": [ 
                            {
                                "content": self.data,
                                "disabled": self.status,
                                "name": self.name,
                                "ttl": self.ttl,
                                "type": self.type
                            } 
                        ]
                    }
                ]
            }
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones/%s' % domain), headers=headers, method='PATCH', data=data)
            logging.debug(jdata)
            return {'status': 'ok', 'msg': 'Record was added successfully'}
        except Exception, e:
            logging.error("Cannot add record %s/%s/%s to domain %s. DETAIL: %s" % (self.name, self.type, self.data, domain, str(e)))
            return {'status': 'error', 'msg': 'There was something wrong, please contact administrator'}


    def compare(self, domain_name, new_records):
        """
        Compare new records with current powerdns record data
        Input is a list of hashes (records)
        """
        # get list of current records we have in powerdns
        current_records = self.get_record_data(domain_name)['records']
        
        # convert them to list of list (just has [name, type]) instead of list of hash
        # to compare easier
        list_current_records = [[x['name'],x['type']] for x in current_records]
        list_new_records = [[x['name'],x['type']] for x in new_records]

        # get list of deleted records
        # they are the records which exist in list_current_records but not in list_new_records
        list_deleted_records = [x for x in list_current_records if x not in list_new_records]

        # convert back to list of hash
        deleted_records = [x for x in current_records if [x['name'],x['type']] in list_deleted_records and x['type'] in app.config['RECORDS_ALLOW_EDIT']]

        # return a tuple
        return deleted_records, new_records


    def apply(self, domain, post_records):
        """
        Apply record changes to domain
        """
        deleted_records, new_records = self.compare(domain, post_records)

        records = []
        for r in deleted_records:
            record = {
                        "name": r['name'],
                        "type": r['type'],
                        "changetype": "DELETE",
                        "records": [
                        ]
                    }
            records.append(record)
        postdata_for_delete = {"rrsets": records}

        records = []
        for r in new_records:
            record = {
                        "name": r['name'],
                        "type": r['type'],
                        "changetype": "REPLACE",
                        "records": [
                            {
                                "content": r['content'],
                                "disabled": r['disabled'],
                                "name": r['name'],
                                "ttl": r['ttl'],
                                "type": r['type'],
                            }
                        ]
                    }
            records.append(record)
        postdata_for_new = {"rrsets": records}

        try:
            headers = {}
            headers['X-API-Key'] = PDNS_API_KEY
            jdata1 = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones/%s' % domain), headers=headers, method='PATCH', data=postdata_for_delete)
            #logging.debug(jdata1)

            jdata2 = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones/%s' % domain), headers=headers, method='PATCH', data=postdata_for_new)
            #logging.debug(jdata2)

            if 'error' in jdata2.keys():
                logging.error('Cannot apply record changes.')
                logging.debug(jdata2['error'])
                return {'status': 'error', 'msg': jdata2['error']}
            else:
                logging.info('Record was applied successfully.')
                return {'status': 'ok', 'msg': 'Record was applied successfully'}
        except Exception, e:
            logging.error("Cannot apply record changes to domain %s. DETAIL: %s" % (str(e), domain))
            return {'status': 'error', 'msg': 'There was something wrong, please contact administrator'}


    def delete(self, domain):
        """
        Delete a record from domain
        """
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        data = {"rrsets": [
                    {
                        "name": self.name,
                        "type": self.type,
                        "changetype": "DELETE",
                        "records": [ 
                            {
                                "name": self.name,
                                "type": self.type
                            } 
                        ]
                    }
                ]
            }
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/localhost/zones/%s' % domain), headers=headers, method='PATCH', data=data)
            logging.debug(jdata)
            return {'status': 'ok', 'msg': 'Record was removed successfully'}
        except:
            logging.error("Cannot remove record %s/%s/%s from domain %s" % (self.name, self.type, self.data, domain))
            return {'status': 'error', 'msg': 'There was something wrong, please contact administrator'}

    def is_allowed(self):
        """
        Check if record is allowed to edit/removed
        """
        return self.type in app.config['RECORDS_ALLOW_EDIT']


class Server(object):
    """
    This is not a model, it's just an object
    which be assigned data from PowerDNS API
    """

    def __init__(self, server_id=None, server_config=None):
        self.server_id = server_id
        self.server_config = server_config

    def get_config(self):
        """
        Get server config
        """
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/%s/config' % self.server_id), headers=headers, method='GET')
            return jdata
        except:
            logging.error("Can not get server configuration.")
            logging.debug(traceback.format_exc())
            return []

    def get_statistic(self):
        """
        Get server statistics
        """
        headers = {}
        headers['X-API-Key'] = PDNS_API_KEY
        
        try:
            jdata = utils.fetch_json(urlparse.urljoin(PDNS_STATS_URL, '/servers/%s/statistics' % self.server_id), headers=headers, method='GET')
            return jdata
        except:
            logging.error("Can not get server statistics.")
            logging.debug(traceback.format_exc())
            return []


class History(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    msg = db.Column(db.String(256))
    detail = db.Column(db.Text())
    created_by = db.Column(db.String(128))
    created_on = db.Column(db.DateTime, default=datetime.utcnow)

    def __init__(self, id=None, msg=None, detail=None, created_by=None):
        self.id = id
        self.msg = msg
        self.detail = detail
        self.created_by = created_by

    def __repr__(self):
        return '<History %r>' % (self.msg)

    def add(self):
        """
        Add an event to history table
        """
        h = History()
        h.msg = self.msg
        h.detail = self.detail
        h.created_by = self.created_by
        db.session.add(h)
        db.session.commit()

    def remove_all(self):
        """
        Remove all history from DB
        """
        try:
            num_rows_deleted = db.session.query(History).delete()
            db.session.commit()
            logging.info("Removed all history")
            return True
        except:
            db.session.rollback()
            logging.error("Cannot remove history")
            logging.debug(traceback.format_exc())
            return False

class Setting(db.Model):
    id = db.Column(db.Integer, primary_key = True)
    name = db.Column(db.String(64))
    value = db.Column(db.String(256))

    def __init__(self, id=None, name=None, value=None):
        self.id = id
        self.name = name
        self.value = value

    def set_mainteance(self, mode):
        """
        mode = True/False
        """
        mode = str(mode)
        maintenance = Setting.query.filter(Setting.name=='maintenance').first()
        try:
            if maintenance:
                if maintenance.value != mode:
                    maintenance.value = mode
                    db.session.commit()
                return True
            else:
                s = Setting(name='maintenance', value=mode)
                db.session.add(s)
                db.session.commit()
                return True
        except:
            logging.error('Cannot set maintenance to %s' % mode)
            logging.debug(traceback.format_exc())
            db.session.rollback()
            return False