# -*- coding: utf-8 -*-

from sqlalchemy import create_engine, MetaData, asc, desc
from sqlalchemy.ext.automap import automap_base
from sqlalchemy.orm import Session, scoped_session, sessionmaker

class Project():
    """ A helper class representing a Citavi project. """
    def __init__(self, sqlite_file):
        """ Constructor to get absolute path to sqlite. """
        self.sqlite_file = sqlite_file
        self._is_open = False
        self._is_error = False
        self._sa = {}  # Object namespace for sqlalchemy related objects

    def __del__(self):
        """ Destructor to close the citavi file. """
        self.close()

    def is_valid(self):
        """ This method returns False in case the given sqlite file is not a valid Citavi project. """
        return self._is_open and not self._is_error

    def get_persons(self):
        """ Returns all persons from the Citavi project. """
        try:
            person_class = self._sa_sqlite_autobase.classes.Person
            citavi_persons = self._sa_sqlite_session.query(person_class).order_by(asc('ID')).all()
            return citavi_persons
        except Exception, e:
            print e
            self._is_error = True
            # TODO: better error handling!
            print str(u"An error occured within a get_persons call!")
            return False

    def get_person_by_uuid(self, uuid):
        """ Returns a person from the Citavi project by their uuid. """
        try:
            person_class = self._sa_sqlite_autobase.classes.Person
            citavi_person = self._sa_sqlite_session.query(person_class).filter(u'ID=\'' + unicode(uuid) + u'\'').all()
            return citavi_person[0]
        except Exception, e:
            print e
            self._is_error = True
            # TODO: better error handling!
            print str(u"An error occured within a get_person_by_uuid call!")
            return False

    def open(self):
        """ Public method to open a citavi project file. """
        if not self._is_open:
            self._open()

    def close(self):
        """ Public method to close a citavi project file. """
        if self._is_open:
            self._close()

    def _open(self):
        """ Internal method to open a citavi project file. """
        try:
            self._sa_sqlite_engine = create_engine(u'sqlite+pysqlite:///' + self.sqlite_file)
            self._sa_sqlite_session = scoped_session(sessionmaker(bind=self._sa_sqlite_engine))  # Caution: SQLAlchemy Sessions are per thread!
            self._sa_sqlite_meta = MetaData(bind=self._sa_sqlite_engine)
            self._sa_sqlite_meta.reflect()
            self._sa_sqlite_autobase = automap_base()
            self._sa_sqlite_autobase.prepare(self._sa_sqlite_engine, reflect=True)
            self._is_open = True
        except:
            self._is_error = True
            self._is_open = False

    def _close(self):
        """ Internal method to actually close a citavi project file. """
        try:
            del self._sa.sqlite_engine
            del self._sa.sqlite_session
            del self._sa.sqlite_meta
            del self._sa.sqlite_autobase
            del self._sa.sqlite_engine
            self._is_open = False
        except:
            self._is_error = True
            self._is_open = True


class ProjectManager():
    """ A backend to provide fast access to Citavi identity data. """

    def __init__(self):
        """ Constructor initializing dictionary for instances of Project. """
        self._projects = {}

    def __del__(self):
        """ Destructor making sure all Project instances are properly deconstructed. """
        self._projects.clear()

    def get_path_for_project_id(self, project_id):
        return u'media/citavi/project_' + unicode(project_id) + u'.ctt4'

    def _add_project(self, project_id):
        """ Internal method to add a Project instance if not existing. """
        if project_id not in self._projects:
            self._projects[project_id] = Project(self.get_path_for_project_id(project_id))
            self._projects[project_id].open()

    def get_person_by_uuid(self, project_id, uuid):
        """ Returns the person matching the given uuid. """
        self._add_project(project_id)
        return self._projects[project_id].get_person_by_uuid(uuid)

    def get_persons_from_project(self, project_id):
        """ Returns all person from a projects. """
        self._add_project(project_id)
        return self._projects[project_id].get_persons()