# Copyright (C) 2017 the Software Heritage developers
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

import binascii
from collections import defaultdict
import datetime

from sqlalchemy import (
    Boolean,
    Column,
    DateTime,
    Enum,
    ForeignKey,
    Integer,
    LargeBinary,
    String,
    Table,
    UniqueConstraint,
)

try:
    from sqlalchemy import JSON
except ImportError:
    # SQLAlchemy < 1.1
    from sqlalchemy.dialects.postgresql import JSONB as JSON

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship

SQLBase = declarative_base()


class Distribution(SQLBase):
    """A distribution (e.g. Debian, Ubuntu, Fedora, ...)"""
    __tablename__ = 'distribution'

    id = Column(Integer, primary_key=True)
    name = Column(String, unique=True, nullable=False)
    type = Column(Enum('deb', 'rpm', name='distribution_types'),
                  nullable=False)
    mirror_uri = Column(String, nullable=False)

    areas = relationship('Area', back_populates='distribution')

    def origin_for_package(self, package_name, package_versions):
        """Return the origin dictionary for the given package"""
        return {
            'type': self.type,
            'url': '%s://%s/packages/%s' % (
                self.type, self.name, package_name
            ),
        }

    def __repr__(self):
        return 'Distribution(%s (%s) on %s)' % (
            self.name,
            self.type,
            self.mirror_uri,
        )


class Area(SQLBase):
    __tablename__ = 'area'
    __table_args__ = (
        UniqueConstraint('distribution_id', 'name'),
    )

    id = Column(Integer, primary_key=True)
    distribution_id = Column(Integer, ForeignKey('distribution.id'),
                             nullable=False)
    name = Column(String, nullable=False)
    active = Column(Boolean, nullable=False, default=True)

    distribution = relationship('Distribution', back_populates='areas')

    def index_uris(self):
        """Get possible URIs for this component's package index"""
        if self.distribution.type == 'deb':
            compression_exts = ('xz', 'bz2', 'gz', None)
            base_uri = '%s/dists/%s/source/Sources' % (
                self.distribution.mirror_uri,
                self.name,
            )
            for ext in compression_exts:
                if ext:
                    yield (base_uri + '.' + ext, ext)
                else:
                    yield (base_uri, None)

        raise NotImplementedError(
            'Do not know how to build index URI for Distribution type %s' %
            self.distribution.type
        )

    def __repr__(self):
        return 'Area(%s of %s)' % (
            self.name,
            self.distribution.name,
        )


class Package(SQLBase):
    __tablename__ = 'package'
    __table_args__ = (
        UniqueConstraint('area_id', 'name', 'version'),
    )

    id = Column(Integer, primary_key=True)
    area_id = Column(Integer, ForeignKey('area.id'), nullable=False)
    name = Column(String, nullable=False)
    version = Column(String, nullable=False)
    directory = Column(String, nullable=False)
    files = Column(JSON, nullable=False)

    origin_id = Column(Integer)
    task_id = Column(Integer)

    revision_id = Column(LargeBinary(20))

    area = relationship('Area')

    @property
    def distribution(self):
        return self.area.distribution

    def fetch_uri(self, filename):
        """Get the URI to fetch the `filename` file associated with the
        package"""
        if self.distribution.type == 'deb':
            return '%s/%s/%s' % (
                self.distribution.mirror_uri,
                self.directory,
                filename,
            )
        else:
            raise NotImplementedError(
                'Do not know how to build fetch URI for Distribution type %s' %
                self.distribution.type
            )

    def loader_dict(self):
        ret = {
            'id': self.id,
            'name': self.name,
            'version': self.version,
        }
        if self.revision_id:
            ret['revision_id'] = binascii.hexlify(self.revision_id).decode()
        else:
            files = {
                name: checksums.copy()
                for name, checksums in self.files.items()
            }
            for name in files:
                files[name]['uri'] = self.fetch_uri(name)

            ret.update({
                'revision_id': None,
                'files': files,
            })
        return ret

    def __repr__(self):
        return 'Package(%s_%s of %s %s)' % (
            self.name,
            self.version,
            self.distribution.name,
            self.area.name,
        )


class DistributionSnapshot(SQLBase):
    __tablename__ = 'distribution_snapshot'

    id = Column(Integer, primary_key=True)
    date = Column(DateTime, nullable=False, index=True)
    distribution_id = Column(Integer,
                             ForeignKey('distribution.id'),
                             nullable=False)

    distribution = relationship('Distribution')
    areas = relationship('AreaSnapshot', back_populates='snapshot')

    def task_for_package(self, package_name, package_versions):
        """Return the task dictionary for the given list of package versions"""
        origin = self.distribution.origin_for_package(
            package_name, package_versions,
        )

        return {
            'policy': 'oneshot',
            'type': 'load-%s-package' % self.distribution.type,
            'next_run': datetime.datetime.now(tz=datetime.timezone.utc),
            'arguments': {
                'args': [],
                'kwargs': {
                    'origin': origin,
                    'date': self.date.isoformat(),
                    'packages': package_versions,
                },
            }
        }

    def get_packages(self):
        packages = defaultdict(dict)
        for area_snapshot in self.areas:
            area_name = area_snapshot.area.name
            for package in area_snapshot.packages:
                ref_name = '%s/%s' % (area_name, package.version)
                packages[package.name][ref_name] = package.loader_dict()

        return packages


area_snapshot_package_assoc = Table(
    'area_snapshot_package', SQLBase.metadata,
    Column('area_snapshot_id', Integer, ForeignKey('area_snapshot.id'),
           nullable=False),
    Column('package_id', Integer, ForeignKey('package.id'),
           nullable=False),
)


class AreaSnapshot(SQLBase):
    __tablename__ = 'area_snapshot'

    id = Column(Integer, primary_key=True)
    snapshot_id = Column(Integer,
                         ForeignKey('distribution_snapshot.id'),
                         nullable=False)
    area_id = Column(Integer,
                     ForeignKey('area.id'),
                     nullable=False)

    snapshot = relationship('DistributionSnapshot', back_populates='areas')
    area = relationship('Area')
    packages = relationship('Package', secondary=area_snapshot_package_assoc)


class TempPackage(SQLBase):
    __tablename__ = 'temp_package'
    __table_args__ = {
        'prefixes': ['TEMPORARY'],
    }

    id = Column(Integer, primary_key=True)
    area_id = Column(Integer)
    name = Column(String)
    version = Column(String)