from datetime import datetime
from enum import IntEnum
from flask import current_app, url_for
from flask_hashids import HashidMixin
from sqlalchemy.ext.associationproxy import association_proxy
from typing import Union
from pathlib import Path
import shutil
import xml.etree.ElementTree as ET
from app import db
from app.converters.vrt import normalize_vrt_file
from app.extensions.sqlalchemy import IntEnumColumn
from .corpus_follower_association import CorpusFollowerAssociation


class CorpusStatus(IntEnum):
    UNPREPARED = 1
    SUBMITTED = 2
    QUEUED = 3
    BUILDING = 4
    BUILT = 5
    FAILED = 6
    STARTING_ANALYSIS_SESSION = 7
    RUNNING_ANALYSIS_SESSION = 8
    CANCELING_ANALYSIS_SESSION = 9

    @staticmethod
    def get(corpus_status: Union['CorpusStatus', int, str]) -> 'CorpusStatus':
        if isinstance(corpus_status, CorpusStatus):
            return corpus_status
        if isinstance(corpus_status, int):
            return CorpusStatus(corpus_status)
        if isinstance(corpus_status, str):
            return CorpusStatus[corpus_status]
        raise TypeError('corpus_status must be CorpusStatus, int, or str')


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))
    status = db.Column(
        IntEnumColumn(CorpusStatus),
        default=CorpusStatus.UNPREPARED
    )
    title = db.Column(db.String(32))
    num_analysis_sessions = db.Column(db.Integer, default=0)
    num_tokens = db.Column(db.Integer, default=0)
    is_public = db.Column(db.Boolean, default=False)
    # Relationships
    files = db.relationship(
        'CorpusFile',
        back_populates='corpus',
        lazy='dynamic',
        cascade='all, delete-orphan'
    )
    corpus_follower_associations = db.relationship(
        'CorpusFollowerAssociation',
        back_populates='corpus',
        cascade='all, delete-orphan'
    )
    followers = association_proxy(
        'corpus_follower_associations',
        'follower',
        creator=lambda u: CorpusFollowerAssociation(follower=u)
    )
    user = db.relationship('User', back_populates='corpora')
    # "static" attributes
    max_num_tokens = 2_147_483_647

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

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

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

    @property
    def path(self) -> Path:
        return self.user.path / 'corpora' / f'{self.id}'

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

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

    @staticmethod
    def create(**kwargs):
        corpus = Corpus(**kwargs)
        db.session.add(corpus)
        db.session.flush(objects=[corpus])
        db.session.refresh(corpus)
        corpus_files_dir = corpus.path / 'files'
        corpus_cwb_dir = corpus.path / 'cwb'
        corpus_cwb_data_dir = corpus_cwb_dir / 'data'
        corpus_cwb_registry_dir = corpus_cwb_dir / 'registry'
        try:
            corpus.path.mkdir()
            corpus_files_dir.mkdir()
            corpus_cwb_dir.mkdir()
            corpus_cwb_data_dir.mkdir()
            corpus_cwb_registry_dir.mkdir()
        except OSError as e:
            # TODO: Potential leftover cleanup
            current_app.logger.error(e)
            db.session.rollback()
            raise
        return corpus

    def build(self):
        corpus_cwb_dir = self.path / 'cwb'
        corpus_cwb_data_dir = corpus_cwb_dir / 'data'
        corpus_cwb_registry_dir = corpus_cwb_dir / 'registry'
        try:
            shutil.rmtree(corpus_cwb_dir, ignore_errors=True)
            corpus_cwb_dir.mkdir()
            corpus_cwb_data_dir.mkdir()
            corpus_cwb_registry_dir.mkdir()
        except OSError as e:
            current_app.logger.error(e)
            self.status = CorpusStatus.FAILED
            raise
        corpus_element = ET.fromstring('<corpus>\n</corpus>')
        for corpus_file in self.files:
            normalized_vrt_path = corpus_cwb_dir / f'{corpus_file.id}.norm.vrt'
            try:
                normalize_vrt_file(corpus_file.path, normalized_vrt_path)
            except:
                self.status = CorpusStatus.FAILED
                return
            element_tree = ET.parse(normalized_vrt_path)
            text_element = element_tree.getroot()
            text_element.set('author', corpus_file.author)
            text_element.set('title', corpus_file.title)
            text_element.set(
                'publishing_year',
                f'{corpus_file.publishing_year}'
            )
            text_element.set('address', corpus_file.address or 'NULL')
            text_element.set('booktitle', corpus_file.booktitle or 'NULL')
            text_element.set('chapter', corpus_file.chapter or 'NULL')
            text_element.set('editor', corpus_file.editor or 'NULL')
            text_element.set('institution', corpus_file.institution or 'NULL')
            text_element.set('journal', corpus_file.journal or 'NULL')
            text_element.set('pages', f'{corpus_file.pages}' or 'NULL')
            text_element.set('publisher', corpus_file.publisher or 'NULL')
            text_element.set('school', corpus_file.school or 'NULL')
            text_element.tail = '\n'
            # corpus_element.insert(1, text_element)
            corpus_element.append(text_element)
        ET.ElementTree(corpus_element).write(
            corpus_cwb_dir / 'corpus.vrt',
            encoding='utf-8'
        )
        self.status = CorpusStatus.SUBMITTED

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

    def to_json_serializeable(self, backrefs=False, relationships=False):
        json_serializeable = {
            'id': self.hashid,
            'creation_date': f'{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.name,
            'title': self.title,
            'is_public': self.is_public
        }
        if backrefs:
            json_serializeable['user'] = \
                self.user.to_json_serializeable(backrefs=True)
        if relationships:
            json_serializeable['corpus_follower_associations'] = {
                x.hashid: x.to_json_serializeable()
                for x in self.corpus_follower_associations
            }
            json_serializeable['files'] = {
                x.hashid: x.to_json_serializeable(relationships=True)
                for x in self.files
            }
        return json_serializeable