from datetime import datetime
from enum import IntEnum
from flask import current_app, url_for
from flask_hashids import HashidMixin
from time import sleep
from typing import Union
from pathlib import Path
import shutil
from app import db
from app.extensions.sqlalchemy import ContainerColumn, IntEnumColumn


class JobStatus(IntEnum):
    INITIALIZING = 1
    SUBMITTED = 2
    QUEUED = 3
    RUNNING = 4
    CANCELING = 5
    CANCELED = 6
    COMPLETED = 7
    FAILED = 8

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


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_args = db.Column(ContainerColumn(dict, 255))
    service_version = db.Column(db.String(16))
    status = db.Column(
        IntEnumColumn(JobStatus),
        default=JobStatus.INITIALIZING
    )
    title = db.Column(db.String(32))
    # Relationships
    inputs = db.relationship(
        'JobInput',
        back_populates='job',
        cascade='all, delete-orphan',
        lazy='dynamic'
    )
    results = db.relationship(
        'JobResult',
        back_populates='job',
        cascade='all, delete-orphan',
        lazy='dynamic'
    )
    user = db.relationship(
        'User',
        back_populates='jobs'
    )

    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) -> Path:
        return self.user.path / 'jobs' / f'{self.id}'

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

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

    @staticmethod
    def create(**kwargs):
        job = Job(**kwargs)
        db.session.add(job)
        db.session.flush(objects=[job])
        db.session.refresh(job)
        job_inputs_dir = job.path / 'inputs'
        job_pipeline_data_dir = job.path / 'pipeline_data'
        job_results_dir = job.path / 'results'
        try:
            job.path.mkdir()
            job_inputs_dir.mkdir()
            job_pipeline_data_dir.mkdir()
            job_results_dir.mkdir()
        except OSError as e:
            # TODO: Potential leftover cleanup
            current_app.logger.error(e)
            db.session.rollback()
            raise
        return job

    def delete(self):
        ''' Delete the job and its inputs and results from the database. '''
        if self.status not in [JobStatus.COMPLETED, JobStatus.FAILED]:  # noqa
            self.status = JobStatus.CANCELING
            db.session.commit()
            while self.status != JobStatus.CANCELED:
                # In case the daemon handled a job in any way
                if self.status != JobStatus.CANCELING:
                    self.status = JobStatus.CANCELING
                    db.session.commit()
                sleep(1)
                db.session.refresh(self)
        try:
            shutil.rmtree(self.path)
        except OSError as e:
            current_app.logger.error(e)
            db.session.rollback()
            raise e
        db.session.delete(self)

    def restart(self):
        ''' Restart a job - only if the status is failed '''
        if self.status != JobStatus.FAILED:
            raise Exception('Job status is not "failed"')
        shutil.rmtree(self.path / 'results', ignore_errors=True)
        shutil.rmtree(self.path / 'pyflow.data', ignore_errors=True)
        for result in self.results:
            db.session.delete(result)
        self.end_date = None
        self.status = JobStatus.SUBMITTED

    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,
            'end_date': (
                None if self.end_date is None
                else f'{self.end_date.isoformat()}Z'
            ),
            'service': self.service,
            'service_args': self.service_args,
            'service_version': self.service_version,
            'status': self.status.name,
            'title': self.title
        }
        if backrefs:
            json_serializeable['user'] = \
                self.user.to_json_serializeable(backrefs=True)
        if relationships:
            json_serializeable['inputs'] = {
                x.hashid: x.to_json_serializeable(relationships=True)
                for x in self.inputs
            }
            json_serializeable['results'] = {
                x.hashid: x.to_json_serializeable(relationships=True)
                for x in self.results
            }
        return json_serializeable