# Copyright (C) 2015  The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

import datetime
import numbers


DEFAULT_AUTHOR = {
    'name': b'',
    'email': b'',
}

DEFAULT_DATE = {
    'timestamp': None,
    'offset': 0,
}


def author_to_db(author):
    """Convert a swh-model author to its DB representation.

    Args: a swh-model compatible author
    Returns:
        a dict containing two keys: author and email
    """
    if author is None:
        return DEFAULT_AUTHOR

    return author


def db_to_author(name, email):
    """Convert the DB representation of an author to a swh-model author.

    Args:
        name (bytes): the author's name
        email (bytes): the author's email

    Returns:
        a dict with two keys: author and email.
    """

    return {
        'name': name,
        'email': email,
    }


def db_to_date(date, offset):
    """Convert the DB representation of a date to a swh-model compatible date.

    Args:
        date (datetime.datetime): a date pulled out of the database
        offset (int): an integer number of minutes representing an UTC offset

    Returns:
        a datetime.datetime object, using a timezone with the proper offset.
    """

    if date is None:
        return None

    new_tz = datetime.timezone(datetime.timedelta(minutes=offset))
    return date.astimezone(tz=new_tz)


def date_to_db(date_offset):
    """Convert a swh-model date_offset to its DB representation.

    Args: a swh-model compatible date_offset
    Returns:
        a dict containing a numeric timestamp and an integer offset

    """

    if date_offset is None:
        return DEFAULT_DATE

    if isinstance(date_offset, numbers.Real):
        date_offset = datetime.datetime.fromtimestamp(date_offset,
                                                      tz=datetime.timezone.utc)

    if isinstance(date_offset, datetime.datetime):
        timestamp = date_offset
        utcoffset = date_offset.utcoffset()
        offset = int(utcoffset.total_seconds()) // 60
    else:
        if isinstance(date_offset['timestamp'], numbers.Real):
            timestamp = datetime.datetime.fromtimestamp(
                date_offset['timestamp'], tz=datetime.timezone.utc)
        else:
            timestamp = date_offset['timestamp']
        offset = date_offset['offset']

    return {
        'timestamp': timestamp.isoformat(),
        'offset': offset,
    }


def revision_to_db(revision):
    """Convert a swh-model revision to its database representation.
    """

    author = author_to_db(revision['author'])
    date = date_to_db(revision['date'])
    committer = author_to_db(revision['committer'])
    committer_date = date_to_db(revision['committer_date'])

    return {
        'id': revision['id'],
        'author_name': author['name'],
        'author_email': author['email'],
        'date': date['timestamp'],
        'date_offset': date['offset'],
        'committer_name': committer['name'],
        'committer_email': committer['email'],
        'committer_date': committer_date['timestamp'],
        'committer_date_offset': committer_date['offset'],
        'type': revision['type'],
        'directory': revision['directory'],
        'message': revision['message'],
        'metadata': revision['metadata'],
        'synthetic': revision['synthetic'],
        'parents': [
            {
                'id': revision['id'],
                'parent_id': parent,
                'parent_rank': i,
            } for i, parent in enumerate(revision['parents'])
        ],
    }


def db_to_revision(db_revision):
    """Convert a database representation of a revision to its swh-model
    representation."""

    author = db_to_author(
        db_revision['author_name'],
        db_revision['author_email'],
    )
    date = db_to_date(db_revision['date'], db_revision['date_offset'])

    committer = db_to_author(
        db_revision['committer_name'],
        db_revision['committer_email'],
    )
    committer_date = db_to_date(
        db_revision['committer_date'],
        db_revision['committer_date_offset'],
    )

    parents = []
    if 'parents' in db_revision:
        for parent in db_revision['parents']:
            if parent:
                parents.append(parent)

    return {
        'id': db_revision['id'],
        'author': author,
        'date': date,
        'committer': committer,
        'committer_date': committer_date,
        'type': db_revision['type'],
        'directory': db_revision['directory'],
        'message': db_revision['message'],
        'metadata': db_revision['metadata'],
        'synthetic': db_revision['synthetic'],
        'parents': parents,
    }


def release_to_db(release):
    """Convert a swh-model release to its database representation.
    """

    author = author_to_db(release['author'])
    date = date_to_db(release['date'])

    return {
        'id': release['id'],
        'author_name': author['name'],
        'author_email': author['email'],
        'date': date['timestamp'],
        'date_offset': date['offset'],
        'name': release['name'],
        'target': release['target'],
        'target_type': release['target_type'],
        'comment': release['message'],
        'synthetic': release['synthetic'],
    }


def db_to_release(db_release):
    """Convert a database representation of a release to its swh-model
    representation.
    """

    author = db_to_author(
        db_release['author_name'],
        db_release['author_email'],
    )
    date = db_to_date(db_release['date'], db_release['date_offset'])

    return {
        'author': author,
        'date': date,
        'id': db_release['id'],
        'name': db_release['name'],
        'message': db_release['comment'],
        'synthetic': db_release['synthetic'],
        'target': db_release['target'],
        'target_type': db_release['target_type'],
    }