from datetime import datetime, timedelta
from flask import current_app, url_for
from flask_login import UserMixin
from itsdangerous import BadSignature, TimedJSONWebSignatureSerializer
from time import sleep
from werkzeug.security import generate_password_hash, check_password_hash
import xml.etree.ElementTree as ET
from . import db, hashids, login
import base64
import enum
import os
import shutil


class HashidMixin:
    @property
    def hashid(self):
        return hashids.encode(self.id)


class FileMixin:
    creation_date = db.Column(db.DateTime, default=datetime.utcnow)
    filename = db.Column(db.String(256))
    last_edited_date = db.Column(db.DateTime, default=datetime.utcnow)
    mimetype = db.Column(db.String(255))

    def file_mixin_to_dict(self, backrefs=False, relationships=False):
        return {
            'creation_date': self.creation_date.isoformat() + 'Z',
            'filename': self.filename,
            'last_edited_date': self.last_edited_date.isoformat() + 'Z',
            'mimetype': self.mimetype
        }


class Permission(enum.IntEnum):
    '''
    Defines User permissions as integers by the power of 2. User permission
    can be evaluated using the bitwise operator &.
    '''
    ADMINISTRATE = 1
    USE_API = 2


class Role(HashidMixin, db.Model):
    __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.Integer)
    # Relationships
    users = db.relationship('User', backref='role', lazy='dynamic')

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

    def __repr__(self):
        return f'<Role {self.name}>'

    def add_permission(self, permission):
        if not self.has_permission(permission):
            self.permissions += permission

    def has_permission(self, permission):
        return self.permissions & permission == permission

    def remove_permission(self, permission):
        if self.has_permission(permission):
            self.permissions -= permission

    def reset_permissions(self):
        self.permissions = 0

    def to_dict(self, backrefs=False, relationships=False):
        dict_role = {
            'id': self.hashid,
            'default': self.default,
            'name': self.name,
            'permissions': self.permissions
        }
        if relationships:
            dict_role['users']: {
                x.to_dict(backrefs=False, relationships=True)
                for x in self.users
            }
        return dict_role

    @staticmethod
    def insert_roles():
        roles = {
            'User': [],
            'Administrator': [Permission.USE_API, Permission.ADMINISTRATE]
        }
        default_role_name = 'User'
        for role_name, permissions in roles.items():
            role = Role.query.filter_by(name=role_name).first()
            if role is None:
                role = Role(name=role_name)
            role.reset_permissions()
            for permission in permissions:
                role.add_permission(permission)
            role.default = role.name == default_role_name
            db.session.add(role)
        db.session.commit()


class User(HashidMixin, UserMixin, db.Model):
    __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))
    token = db.Column(db.String(32), index=True, unique=True)
    token_expiration = db.Column(db.DateTime)
    username = db.Column(db.String(64), unique=True, index=True)
    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')
    # Backrefs: role: Role
    # Relationships
    corpora = db.relationship(
        'Corpus',
        backref='user',
        cascade='all, delete-orphan',
        lazy='dynamic'
    )
    jobs = db.relationship(
        'Job',
        backref='user',
        cascade='all, delete-orphan',
        lazy='dynamic'
    )
    query_results = db.relationship(
        'QueryResult',
        backref='user',
        cascade='all, delete-orphan',
        lazy='dynamic'
    )

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        if self.role is not None:
            return
        if self.email == current_app.config['NOPAQUE_ADMIN']:
            self.role = Role.query.filter_by(name='Administrator').first()
        else:
            self.role = Role.query.filter_by(default=True).first()

    def __repr__(self):
        return f'<User {self.username}>'

    @property
    def jsonpatch_path(self):
        return f'/users/{self.hashid}'

    @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)

    @property
    def path(self):
        return os.path.join(
            current_app.config.get('NOPAQUE_DATA_DIR'), str(self.id))

    def can(self, permission):
        return self.role.has_permission(permission)

    def confirm(self, token):
        s = TimedJSONWebSignatureSerializer(current_app.config['SECRET_KEY'])
        try:
            data = s.loads(token.encode('utf-8'))
        except BadSignature:
            return False
        if data.get('confirm') != self.hashid:
            return False
        self.confirmed = True
        db.session.add(self)
        return True

    def delete(self):
        shutil.rmtree(self.path, ignore_errors=True)
        db.session.delete(self)

    def generate_confirmation_token(self, expiration=3600):
        s = TimedJSONWebSignatureSerializer(
            current_app.config['SECRET_KEY'], expiration)
        return s.dumps({'confirm': self.hashid}).decode('utf-8')

    def generate_reset_token(self, expiration=3600):
        s = TimedJSONWebSignatureSerializer(
            current_app.config['SECRET_KEY'], expiration)
        return s.dumps({'reset': self.hashid}).decode('utf-8')

    def get_token(self, expires_in=3600):
        now = datetime.utcnow()
        if self.token and self.token_expiration > now + timedelta(seconds=60):
            return self.token
        self.token = base64.b64encode(os.urandom(24)).decode('utf-8')
        self.token_expiration = now + timedelta(seconds=expires_in)
        db.session.add(self)
        return self.token

    def is_administrator(self):
        return self.can(Permission.ADMINISTRATE)

    def revoke_token(self):
        self.token_expiration = datetime.utcnow() - timedelta(seconds=1)

    def to_dict(self, backrefs=False, relationships=False):
        dict_user = {
            'id': self.hashid,
            'role_id': self.role.hashid,
            'confirmed': self.confirmed,
            'email': self.email,
            'last_seen': self.last_seen.isoformat() + 'Z',
            'member_since': self.member_since.isoformat() + 'Z',
            '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
            }
        }
        if backrefs:
            dict_user['role'] = self.role.to_dict(
                backrefs=True, relationships=False)
        if relationships:
            dict_user['corpora'] = {
                x.hashid: x.to_dict(backrefs=False, relationships=True)
                for x in self.corpora
            }
            dict_user['jobs'] = {
                x.hashid: x.to_dict(backrefs=False, relationships=True)
                for x in self.jobs
            }
            dict_user['query_results'] = {
                x.hashid: x.to_dict(backrefs=False, relationships=True)
                for x in self.query_results
            }
        return dict_user

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

    @staticmethod
    def check_token(token):
        user = User.query.filter_by(token=token).first()
        if user is None or user.token_expiration < datetime.utcnow():
            return None
        return user

    @staticmethod
    def reset_password(token, new_password):
        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


class JobInput(FileMixin, HashidMixin, db.Model):
    __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'))
    # Backrefs: job: Job

    def __repr__(self):
        return f'<JobInput {self.filename}>'

    @property
    def download_url(self):
        return url_for(
            'jobs.download_job_input',
            job_id=self.job.id,
            job_input_id=self.id
        )

    @property
    def jsonpatch_path(self):
        return f'{self.job.jsonpatch_path}/inputs/{self.hashid}'

    @property
    def path(self):
        return os.path.join(self.job.path, self.filename)

    def to_dict(self, backrefs=False, relationships=False):
        dict_job_input = {
            'id': self.hashid,
            'job_id': self.job.hashid,
            'download_url': self.download_url,
            'url': self.url,
            **self.file_mixin_to_dict()
        }
        if backrefs:
            dict_job_input['job'] = self.job.to_dict(
                backrefs=True, relationships=False)
        return dict_job_input

    @property
    def url(self):
        return url_for(
            'jobs.job',
            job_id=self.job_id,
            _anchor=f'job-{self.job.hashid}-input-{self.hashid}'
        )

    @property
    def user_hashid(self):
        return self.job.user.hashid

    @property
    def user_id(self):
        return self.job.user_id


class JobResult(FileMixin, HashidMixin, db.Model):
    __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'))
    # Backrefs: job: Job

    def __repr__(self):
        return f'<JobResult {self.filename}>'

    @property
    def download_url(self):
        return url_for(
            'jobs.download_job_result',
            job_id=self.job_id,
            job_result_id=self.id
        )

    @property
    def jsonpatch_path(self):
        return f'{self.job.jsonpatch_path}/results/{self.hashid}'

    @property
    def path(self):
        return os.path.join(self.job.path, 'output', self.filename)

    def to_dict(self, backrefs=False, relationships=False):
        dict_job_result = {
            'id': self.hashid,
            'job_id': self.job.hashid,
            'download_url': self.download_url,
            'url': self.url,
            **self.file_mixin_to_dict(
                backrefs=backrefs, relationships=relationships)
        }
        if backrefs:
            dict_job_result['job'] = self.job.to_dict(
                backrefs=True, relationships=False)
        return dict_job_result

    @property
    def url(self):
        return url_for(
            'jobs.job',
            job_id=self.job_id,
            _anchor=f'job-{self.job.hashid}-result-{self.hashid}'
        )

    @property
    def user_hashid(self):
        return self.job.user.hashid

    @property
    def user_id(self):
        return self.job.user_id


class Job(HashidMixin, 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())
    service = db.Column(db.String(64))
    '''
    ' Service specific arguments as string list.
    ' Example: ["-l eng", "--binarize"]
    '''
    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))
    # Backrefs: user: User
    # Relationships
    inputs = db.relationship(
        'JobInput',
        backref='job',
        cascade='all, delete-orphan',
        lazy='dynamic'
    )
    results = db.relationship(
        'JobResult',
        backref='job',
        cascade='all, delete-orphan',
        lazy='dynamic'
    )

    def __repr__(self):
        return f'<Job {self.title}>'

    @property
    def jsonpatch_path(self):
        return f'{self.user.jsonpatch_path}/jobs/{self.hashid}'

    @property
    def path(self):
        return os.path.join(self.user.path, 'jobs', str(self.id))

    @property
    def url(self):
        return url_for('jobs.job', job_id=self.id)

    @property
    def user_hashid(self):
        return self.user.hashid

    def delete(self):
        '''
        Delete the job and its inputs and results from the database.
        '''
        if self.status not in ['complete', 'failed']:
            self.status = 'canceling'
            db.session.commit()
            while self.status != 'canceled':
                # In case the daemon handled a job in any way
                if self.status != 'canceling':
                    self.status = 'canceling'
                    db.session.commit()
                sleep(1)
                db.session.refresh(self)
        shutil.rmtree(self.path, ignore_errors=True)
        db.session.delete(self)

    def restart(self):
        '''
        Restart a job - only if the status is complete or failed
        '''

        if self.status not in ['complete', 'failed']:
            raise Exception('Could not restart job: status is not "complete/failed"')  # noqa
        shutil.rmtree(os.path.join(self.path, 'output'), ignore_errors=True)
        shutil.rmtree(os.path.join(self.path, 'pyflow.data'), ignore_errors=True)  # noqa
        for result in self.results:
            db.session.delete(result)
        self.end_date = None
        self.status = 'submitted'

    def to_dict(self, backrefs=False, relationships=False):
        dict_job = {
            'id': self.hashid,
            'user_id': self.user.hashid,
            'creation_date': self.creation_date.isoformat() + 'Z',
            'description': self.description,
            'end_date': None if self.end_date is None else f'{self.end_date.isoformat()}Z',  # noqa
            'service': self.service,
            'service_args': self.service_args,
            'service_version': self.service_version,
            'status': self.status,
            'title': self.title,
            'url': self.url
        }
        if backrefs:
            dict_job['user'] = self.user.to_dict(
                backrefs=True, relationships=False)
        if relationships:
            dict_job['inputs'] = {
                x.hashid: x.to_dict(backrefs=False, relationships=True)
                for x in self.inputs
            }
            dict_job['results'] = {
                x.hashid: x.to_dict(backrefs=False, relationships=True)
                for x in self.results
            }
        return dict_job


class CorpusFile(FileMixin, HashidMixin, db.Model):
    __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))
    editor = 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))
    # Backrefs: corpus: Corpus

    @property
    def download_url(self):
        return url_for(
            'corpora.download_corpus_file',
            corpus_id=self.corpus_id,
            corpus_file_id=self.id
        )

    @property
    def jsonpatch_path(self):
        return f'{self.corpus.jsonpatch_path}/files/{self.hashid}'

    @property
    def path(self):
        return os.path.join(self.corpus.path, self.filename)

    @property
    def url(self):
        return url_for(
            'corpora.corpus_file',
            corpus_id=self.corpus_id,
            corpus_file_id=self.id
        )

    @property
    def user_hashid(self):
        return self.corpus.user.hashid

    @property
    def user_id(self):
        return self.corpus.user_id

    def delete(self):
        try:
            os.remove(self.path)
        except OSError:
            current_app.logger.error(
                'Removing {} led to an OSError!'.format(self.path)
            )
            pass
        db.session.delete(self)
        self.corpus.status = 'unprepared'

    def to_dict(self, backrefs=False, relationships=False):
        dict_corpus_file = {
            'id': self.hashid,
            'corpus_id': self.corpus.hashid,
            'download_url': self.download_url,
            'url': self.url,
            'address': self.address,
            'author': self.author,
            'booktitle': self.booktitle,
            'chapter': self.chapter,
            'editor': self.editor,
            'institution': self.institution,
            'journal': self.journal,
            'pages': self.pages,
            'publisher': self.publisher,
            'publishing_year': self.publishing_year,
            'school': self.school,
            'title': self.title,
            **self.file_mixin_to_dict(
                backrefs=backrefs, relationships=relationships)
        }
        if backrefs:
            dict_corpus_file['corpus'] = self.corpus.to_dict(
                backrefs=True, relationships=False)
        return dict_corpus_file


class Corpus(HashidMixin, 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)
    description = db.Column(db.String(255))
    last_edited_date = db.Column(db.DateTime(), default=datetime.utcnow)
    status = db.Column(db.String(16), default='unprepared')
    title = db.Column(db.String(32))
    num_analysis_sessions = db.Column(db.Integer, default=0)
    num_tokens = db.Column(db.Integer, default=0)
    archive_file = db.Column(db.String(255))
    # Backrefs: user: User
    # Relationships
    files = db.relationship(
        'CorpusFile',
        backref='corpus',
        lazy='dynamic',
        cascade='all, delete-orphan'
    )
    # Python class variables
    max_num_tokens = 2147483647

    def __repr__(self):
        return f'<Corpus {self.title}>'

    @property
    def analysis_url(self):
        return url_for('corpora.analyse_corpus', corpus_id=self.id)

    @property
    def jsonpatch_path(self):
        return f'{self.user.jsonpatch_path}/corpora/{self.hashid}'

    @property
    def path(self):
        return os.path.join(self.user.path, 'corpora', str(self.id))

    @property
    def url(self):
        return url_for('corpora.corpus', corpus_id=self.id)

    @property
    def user_hashid(self):
        return self.user.hashid

    def build(self):
        output_dir = os.path.join(self.path, 'merged')
        shutil.rmtree(output_dir, ignore_errors=True)
        os.mkdir(output_dir)
        output_file = os.path.join(output_dir, 'corpus.vrt')
        corpus_element = ET.fromstring('<corpus>\n</corpus>')
        for corpus_file in self.files:
            element_tree = ET.parse(corpus_file.path)
            text_node = element_tree.find('text')
            text_node.set('address', corpus_file.address or 'NULL')
            text_node.set('author', corpus_file.author)
            text_node.set('booktitle', corpus_file.booktitle or 'NULL')
            text_node.set('chapter', corpus_file.chapter or 'NULL')
            text_node.set('editor', corpus_file.editor or 'NULL')
            text_node.set('institution', corpus_file.institution or 'NULL')
            text_node.set('journal', corpus_file.journal or 'NULL')
            text_node.set('pages', corpus_file.pages or 'NULL')
            text_node.set('publisher', corpus_file.publisher or 'NULL')
            text_node.set('publishing_year', str(corpus_file.publishing_year))
            text_node.set('school', corpus_file.school or 'NULL')
            text_node.set('title', corpus_file.title)
            corpus_element.insert(1, text_node)
        ET.ElementTree(corpus_element).write(output_file, encoding='utf-8')
        self.last_edited_date = datetime.utcnow()
        self.status = 'submitted'

    def delete(self):
        shutil.rmtree(self.path, ignore_errors=True)
        db.session.delete(self)

    def to_dict(self, backrefs=False, relationships=False):
        dict_corpus = {
            'id': self.hashid,
            'user_id': self.user.hashid,
            'analysis_url': self.analysis_url,
            'url': self.url,
            'creation_date': self.creation_date.isoformat() + 'Z',
            'description': self.description,
            'max_num_tokens': self.max_num_tokens,
            'num_analysis_sessions': self.num_analysis_sessions,
            'num_tokens': self.num_tokens,
            'status': self.status,
            'last_edited_date': self.last_edited_date.isoformat() + 'Z',
            'title': self.title
        }
        if backrefs:
            dict_corpus['user'] = self.user.to_dict(
                backrefs=True, relationships=False)
        if relationships:
            dict_corpus['files'] = {
                x.hashid: x.to_dict(backrefs=False, relationships=True)
                for x in self.files
            }
        return dict_corpus


class QueryResult(FileMixin, HashidMixin, db.Model):
    __tablename__ = 'query_results'
    # Primary key
    id = db.Column(db.Integer, primary_key=True)
    # Foreign keys
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    # Fields
    description = db.Column(db.String(255))
    query_metadata = db.Column(db.JSON())
    title = db.Column(db.String(32))
    # Backrefs: user: User

    def __repr__(self):
        '''
        String representation of the QueryResult. For human readability.
        '''
        return f'<QueryResult {self.title}>'

    @property
    def download_url(self):
        return url_for(
            'corpora.download_query_result', query_result_id=self.id)

    @property
    def jsonpatch_path(self):
        return f'{self.user.jsonpatch_path}/query_results/{self.hashid}'

    @property
    def path(self):
        return os.path.join(
            self.user.path, 'query_results', str(self.id), self.filename)

    @property
    def url(self):
        return url_for('corpora.query_result', query_result_id=self.id)

    @property
    def user_hashid(self):
        return self.user.hashid

    def delete(self):
        shutil.rmtree(self.path, ignore_errors=True)
        db.session.delete(self)

    def to_dict(self, backrefs=False, relationships=False):
        dict_query_result = {
            'id': self.hashid,
            'user_id': self.user.hashid,
            'download_url': self.download_url,
            'url': self.url,
            'corpus_title': self.query_metadata['corpus_name'],
            'description': self.description,
            'filename': self.filename,
            'query': self.query_metadata['query'],
            'query_metadata': self.query_metadata,
            'title': self.title,
            **self.file_mixin_to_dict(
                backrefs=backrefs, relationships=relationships)
        }
        if backrefs:
            dict_query_result['user'] = self.user.to_dict(
                backrefs=True, relationships=False)


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