from datetime import datetime
from flask import current_app
from flask_login import UserMixin, AnonymousUserMixin
from itsdangerous import BadSignature, TimedJSONWebSignatureSerializer
from werkzeug.security import generate_password_hash, check_password_hash
from werkzeug.utils import secure_filename
from . import db, login_manager


class Permission:
    '''
    Defines User permissions as integers by the power of 2. User permission
    can be evaluated using the bitwise operator &. 3 equals to CREATE_JOB and
    DELETE_JOB and so on.
    '''
    MANAGE_CORPORA = 1
    MANAGE_JOBS = 2
    # PERMISSION_NAME = 4
    # PERMISSION_NAME = 8
    ADMIN = 16


class Role(db.Model):
    '''
    Model for the different roles Users can have. Is a one-to-many
    relationship. A Role can be associated with many User rows.
    '''
    __tablename__ = 'roles'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Fields
    default = db.Column(db.Boolean, default=False, index=True)
    name = db.Column(db.String(64), unique=True)
    permissions = db.Column(db.BigInteger)
    # Relationships
    users = db.relationship('User', backref='role', lazy='dynamic')

    def to_dict(self):
        return {'id': self.id,
                'default': self.default,
                'name': self.name,
                'permissions': self.permissions}

    def __init__(self, **kwargs):
        super(Role, self).__init__(**kwargs)
        if self.permissions is None:
            self.permissions = 0

    def __repr__(self):
        '''
        String representation of the Role. For human readability.
        '''
        return '<Role {role_name}>'.format(role_name=self.name)

    def add_permission(self, perm):
        '''
        Add new permission to Role. Input is a Permission.
        '''
        if not self.has_permission(perm):
            self.permissions += perm

    def remove_permission(self, perm):
        '''
        Removes permission from a Role. Input a Permission.
        '''
        if self.has_permission(perm):
            self.permissions -= perm

    def reset_permissions(self):
        '''
        Resets permissions to zero. Zero equals no permissions at all.
        '''
        self.permissions = 0

    def has_permission(self, perm):
        '''
        Checks if a Role has a specific Permission. Does this with the bitwise
        operator.
        '''
        return self.permissions & perm == perm

    @staticmethod
    def insert_roles():
        '''
        Inserts roles into the database. This has to be executed befor Users
        are added to the database. Otherwiese Users will not have a Role
        assigned to them. Order of the roles dictionary determines the ID of
        each role. Users have the ID 1 and Administrators have the ID 2.
        '''
        roles = {'User': [Permission.MANAGE_CORPORA, Permission.MANAGE_JOBS],
                 'Administrator': [Permission.MANAGE_CORPORA,
                                   Permission.MANAGE_JOBS, Permission.ADMIN]}
        default_role = 'User'
        for r in roles:
            role = Role.query.filter_by(name=r).first()
            if role is None:
                role = Role(name=r)
            role.reset_permissions()
            for perm in roles[r]:
                role.add_permission(perm)
            role.default = (role.name == default_role)
            db.session.add(role)
        db.session.commit()


class User(UserMixin, db.Model):
    '''
    Model for Users that are registered to Opaque.
    '''
    __tablename__ = 'users'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign keys
    role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))
    # Fields
    confirmed = db.Column(db.Boolean, default=False)
    email = db.Column(db.String(254), unique=True, index=True)
    last_seen = db.Column(db.DateTime(), default=datetime.utcnow)
    member_since = db.Column(db.DateTime(), default=datetime.utcnow)
    password_hash = db.Column(db.String(128))
    setting_dark_mode = db.Column(db.Boolean, default=False)
    setting_job_status_mail_notifications = db.Column(db.String(16),
                                                      default='end')
    setting_job_status_site_notifications = db.Column(db.String(16),
                                                      default='all')
    username = db.Column(db.String(64), unique=True, index=True)
    # Relationships
    corpora = db.relationship('Corpus', backref='creator', lazy='dynamic',
                              cascade='save-update, merge, delete')
    jobs = db.relationship('Job', backref='creator', lazy='dynamic',
                           cascade='save-update, merge, delete')

    def to_dict(self):
        return {'id': self.id,
                'role_id': self.role_id,
                'confirmed': self.confirmed,
                'email': self.email,
                'last_seen': self.last_seen.timestamp(),
                'member_since': self.member_since.timestamp(),
                'username': self.username,
                'settings': {'dark_mode': self.setting_dark_mode,
                             'job_status_mail_notifications':
                                 self.setting_job_status_mail_notifications,
                             'job_status_site_notifications':
                                 self.setting_job_status_site_notifications},
                'corpora': {corpus.id: corpus.to_dict()
                            for corpus in self.corpora},
                'jobs': {job.id: job.to_dict() for job in self.jobs}}

    def __repr__(self):
        '''
        String representation of the User. For human readability.
        '''
        return '<User {username}>'.format(username=self.username)

    def __init__(self, **kwargs):
        super(User, self).__init__(**kwargs)
        if self.role is None:
            if self.email == current_app.config['NOPAQUE_ADMIN']:
                self.role = Role.query.filter_by(name='Administrator').first()
            if self.role is None:
                self.role = Role.query.filter_by(default=True).first()

    def generate_confirmation_token(self, expiration=3600):
        '''
        Generates a confirmation token for user confirmation via email.
        '''
        s = TimedJSONWebSignatureSerializer(current_app.config['SECRET_KEY'],
                                            expiration)
        return s.dumps({'confirm': self.id}).decode('utf-8')

    def generate_reset_token(self, expiration=3600):
        '''
        Generates a reset token for password reset via email.
        '''
        s = TimedJSONWebSignatureSerializer(current_app.config['SECRET_KEY'],
                                            expiration)
        return s.dumps({'reset': self.id}).decode('utf-8')

    def confirm(self, token):
        '''
        Confirms User if the given token is valid and not expired.
        '''
        s = TimedJSONWebSignatureSerializer(current_app.config['SECRET_KEY'])
        try:
            data = s.loads(token.encode('utf-8'))
        except BadSignature:
            return False
        if data.get('confirm') != self.id:
            return False
        self.confirmed = True
        db.session.add(self)
        return True

    @staticmethod
    def reset_password(token, new_password):
        '''
        Resets password for User if the given token is valid and not expired.
        '''
        s = TimedJSONWebSignatureSerializer(current_app.config['SECRET_KEY'])
        try:
            data = s.loads(token.encode('utf-8'))
        except BadSignature:
            return False
        user = User.query.get(data.get('reset'))
        if user is None:
            return False
        user.password = new_password
        db.session.add(user)
        return True

    @property
    def password(self):
        raise AttributeError('password is not a readable attribute')

    @password.setter
    def password(self, password):
        self.password_hash = generate_password_hash(password)

    def verify_password(self, password):
        return check_password_hash(self.password_hash, password)

    def can(self, perm):
        '''
        Checks if a User with its current role can doe something. Checks if the
        associated role actually has the needed Permission.
        '''
        return self.role is not None and self.role.has_permission(perm)

    def is_administrator(self):
        '''
        Checks if User has Admin permissions.
        '''
        return self.can(Permission.ADMIN)

    def ping(self):
        self.last_seen = datetime.utcnow()
        db.session.add(self)

    def delete(self):
        '''
        Delete the user and its corpora and jobs from database and filesystem.
        '''
        for job in self.jobs:
            job.delete()
        for corpus in self.corpora:
            corpus.delete()
        db.session.delete(self)
        db.session.commit()


class AnonymousUser(AnonymousUserMixin):
    '''
    Model replaces the default AnonymousUser.
    '''

    def can(self, permissions):
        return False

    def is_administrator(self):
        return False


class JobInput(db.Model):
    '''
    Class to define JobInputs.
    '''
    __tablename__ = 'job_inputs'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign keys
    job_id = db.Column(db.Integer, db.ForeignKey('jobs.id'))
    # Fields
    dir = db.Column(db.String(255))
    filename = db.Column(db.String(255))

    def __repr__(self):
        '''
        String representation of the JobInput. For human readability.
        '''
        return '<JobInput {filename}>'.format(filename=self.filename)

    def to_dict(self):
        return {'id': self.id,
                'job_id': self.job_id,
                'filename': self.filename}


class JobResult(db.Model):
    '''
    Class to define JobResults.
    '''
    __tablename__ = 'job_results'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign keys
    job_id = db.Column(db.Integer, db.ForeignKey('jobs.id'))
    # Fields
    dir = db.Column(db.String(255))
    filename = db.Column(db.String(255))

    def __repr__(self):
        '''
        String representation of the JobResult. For human readability.
        '''
        return '<JobResult {filename}>'.format(filename=self.filename)

    def to_dict(self):
        return {'id': self.id,
                'job_id': self.job_id,
                'filename': self.filename}


class Job(db.Model):
    '''
    Class to define Jobs.
    '''
    __tablename__ = 'jobs'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign keys
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    # Fields
    creation_date = db.Column(db.DateTime(), default=datetime.utcnow)
    description = db.Column(db.String(255))
    end_date = db.Column(db.DateTime())
    mem_mb = db.Column(db.Integer)
    n_cores = db.Column(db.Integer)
    secure_filename = db.Column(db.String(32))
    service = db.Column(db.String(64))
    '''
    ' Service specific arguments as string list.
    ' Example: ["-l eng", "--keep-intermediates", "--skip-binarization"]
    '''
    service_args = db.Column(db.String(255))
    service_version = db.Column(db.String(16))
    status = db.Column(db.String(16))
    title = db.Column(db.String(32))
    # Relationships
    inputs = db.relationship('JobInput', backref='job', lazy='dynamic',
                             cascade='save-update, merge, delete')
    results = db.relationship('JobResult', backref='job', lazy='dynamic',
                              cascade='save-update, merge, delete')
    notification_data = db.relationship('NotificationData',
                                        cascade='save-update, merge, delete',
                                        uselist=False,
                                        back_populates='job')  # One-to-One relationship
    notification_email_data = db.relationship('NotificationEmailData',
                                              cascade='save-update, merge, delete',
                                              back_populates='job')

    def __repr__(self):
        '''
        String representation of the Job. For human readability.
        '''
        return '<Job {job_title}>'.format(job_title=self.title)

    def create_secure_filename(self):
        '''
        Takes the job.title string nad cratesa a secure filename from this.
        '''
        self.secure_filename = secure_filename(self.title)

    def delete(self):
        '''
        Delete the job and its inputs and results from the database.
        '''
        for input in self.inputs:
            db.session.delete(input)
        for result in self.results:
            db.session.delete(result) # TODO: shouldn't this happen through the cascade option?
        db.session.delete(self)
        db.session.commit()

    def to_dict(self):
        return {'id': self.id,
                'user_id': self.user_id,
                'creation_date': self.creation_date.timestamp(),
                'description': self.description,
                'end_date': (self.end_date.timestamp() if self.end_date else
                             None),
                'inputs': {input.id: input.to_dict() for input in self.inputs},
                'mem_mb': self.mem_mb,
                'n_cores': self.n_cores,
                'results': {result.id: result.to_dict()
                            for result in self.results},
                'service': self.service,
                'service_args': self.service_args,
                'service_version': self.service_version,
                'status': self.status,
                'title': self.title}


class NotificationData(db.Model):
    '''
    Class to define notification data used for sending a notification mail with
    nopaque_notify.
    '''
    __tablename__ = 'notification_data'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign Key
    job_id = db.Column(db.Integer, db.ForeignKey('jobs.id'))
    # relationships
    job = db.relationship('Job', back_populates='notification_data')
    # Fields
    notified_on = db.Column(db.String(16), default=None)

    def __repr__(self):
        '''
        String representation of the NotificationData. For human readability.
        '''
        return '<NotificationData {id}>'.format(id=self.id)

    def to_dict(self):
        return {'id': self.id,
                'job_id': self.job_id,
                'job': self.job,
                'notified': self.notified}


class NotificationEmailData(db.Model):
    '''
    Class to define data that will be used to send a corresponding Notification
    via email.
    '''
    __tablename__ = 'notification_email_data'
    # Primary Key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign Key
    job_id = db.Column(db.Integer, db.ForeignKey('jobs.id'))
    # relationships
    job = db.relationship('Job', back_populates='notification_email_data')
    notify_status = db.Column(db.String(16), default=None)
    creation_date = db.Column(db.DateTime(), default=datetime.utcnow)

    def __repr__(self):
        '''
        String representation of the NotificationEmailData. For human readability.
        '''
        return '<NotificationData {id}>'.format(id=self.id)

    def to_dict(self):
        return {'id': self.id,
                'job_id': self.job_id,
                'job': self.job,
                'notify_status': self.notify_status,
                'creation_date': self.creation_date}


class CorpusFile(db.Model):
    '''
    Class to define Files.
    '''
    __tablename__ = 'corpus_files'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign keys
    corpus_id = db.Column(db.Integer, db.ForeignKey('corpora.id'))
    # Fields
    address = db.Column(db.String(255))
    author = db.Column(db.String(255))
    booktitle = db.Column(db.String(255))
    chapter = db.Column(db.String(255))
    dir = db.Column(db.String(255))
    editor = db.Column(db.String(255))
    filename = db.Column(db.String(255))
    institution = db.Column(db.String(255))
    journal = db.Column(db.String(255))
    pages = db.Column(db.String(255))
    publisher = db.Column(db.String(255))
    publishing_year = db.Column(db.Integer)
    school = db.Column(db.String(255))
    title = db.Column(db.String(255))

    def delete(self):
        self.corpus.status = 'unprepared'
        db.session.delete(self)
        db.session.commit()

    def to_dict(self):
        return {'id': self.id,
                'corpus_id': self.corpus_id,
                'address': self.address,
                'author': self.author,
                'booktitle': self.booktitle,
                'chapter': self.chapter,
                'editor': self.editor,
                'filename': self.filename,
                'institution': self.institution,
                'journal': self.journal,
                'pages': self.pages,
                'publisher': self.publisher,
                'publishing_year': self.publishing_year,
                'school': self.school,
                'title': self.title}


class Corpus(db.Model):
    '''
    Class to define a corpus.
    '''
    __tablename__ = 'corpora'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign keys
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    # Fields
    creation_date = db.Column(db.DateTime(), default=datetime.utcnow)
    current_nr_of_tokens = db.Column(db.BigInteger, default=0)
    description = db.Column(db.String(255))
    last_edited_date = db.Column(db.DateTime(), default=datetime.utcnow)
    max_nr_of_tokens = db.Column(db.BigInteger, default=2147483647)
    status = db.Column(db.String(16))
    title = db.Column(db.String(32))
    # Relationships
    files = db.relationship('CorpusFile', backref='corpus', lazy='dynamic',
                            cascade='save-update, merge, delete')

    def to_dict(self):
        return {'id': self.id,
                'user_id': self.user_id,
                'creation_date': self.creation_date.timestamp(),
                'description': self.description,
                'status': self.status,
                'last_edited_date': self.last_edited_date.timestamp(),
                'title': self.title,
                'files': {file.id: file.to_dict() for file in self.files}}

    def delete(self):
        for corpus_file in self.files:
            db.session.delete(corpus_file)
        db.session.delete(self)
        db.session.commit()

    def __repr__(self):
        '''
        String representation of the corpus. For human readability.
        '''
        return '<Corpus {corpus_title}>'.format(corpus_title=self.title)


'''
' Flask-Login is told to use the application’s custom anonymous user by setting
' its class in the login_manager.anonymous_user attribute.
'''
login_manager.anonymous_user = AnonymousUser


@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))