# -*- coding: utf-8 -*-

##########################################################################
# OpenLP - Open Source Lyrics Projection                                 #
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# Copyright (c) 2008-2023 OpenLP Developers                              #
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# This program is free software: you can redistribute it and/or modify   #
# it under the terms of the GNU General Public License as published by   #
# the Free Software Foundation, either version 3 of the License, or      #
# (at your option) any later version.                                    #
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# This program is distributed in the hope that it will be useful,        #
# but WITHOUT ANY WARRANTY; without even the implied warranty of         #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          #
# GNU General Public License for more details.                           #
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# You should have received a copy of the GNU General Public License      #
# along with this program.  If not, see <https://www.gnu.org/licenses/>. #
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"""
The :mod:`db` module provides the database and schema that is the backend for
the Songs plugin


The song database contains the following tables:

    * authors
    * authors_songs
    * media_files
    * media_files_songs
    * song_books
    * songs
    * songs_songbooks
    * songs_topics
    * topics

**authors** Table
    This table holds the names of all the authors. It has the following
    columns:

    * id
    * first_name
    * last_name
    * display_name

**authors_songs Table**
    This is a bridging table between the *authors* and *songs* tables, which
    serves to create a many-to-many relationship between the two tables. It
    has the following columns:

    * author_id
    * song_id
    * author_type

**media_files Table**
    * id
    * file_path
    * file_hash
    * type
    * weight

**song_books Table**
    The *song_books* table holds a list of books that a congregation gets
    their songs from, or old hymnals now no longer used. This table has the
    following columns:

    * id
    * name
    * publisher

**songs Table**
    This table contains the songs, and each song has a list of attributes.
    The *songs* table has the following columns:

    * id
    * title
    * alternate_title
    * lyrics
    * verse_order
    * copyright
    * comments
    * ccli_number
    * theme_name
    * search_title
    * search_lyrics

**songs_songsbooks Table**
    This is a mapping table between the *songs* and the *song_books* tables. It has the following columns:

    * songbook_id
    * song_id
    * entry  # The song number, like 120 or 550A

**songs_topics Table**
    This is a bridging table between the *songs* and *topics* tables, which
    serves to create a many-to-many relationship between the two tables. It
    has the following columns:

    * song_id
    * topic_id

**topics Table**
    The topics table holds a selection of topics that songs can cover. This
    is useful when a worship leader wants to select songs with a certain
    theme. This table has the following columns:

    * id
    * name
"""
from typing import Optional

from sqlalchemy import Column, ForeignKey, MetaData, Table
from sqlalchemy.ext.hybrid import hybrid_property
from sqlalchemy.orm import reconstructor, relationship
from sqlalchemy.sql.expression import func, text
from sqlalchemy.types import Boolean, DateTime, Integer, Unicode, UnicodeText

# Maintain backwards compatibility with older versions of SQLAlchemy while supporting SQLAlchemy 1.4+
try:
    from sqlalchemy.orm import declarative_base
except ImportError:
    from sqlalchemy.ext.declarative import declarative_base

from openlp.core.common.i18n import get_natural_key, translate
from openlp.core.lib.db import PathType, init_db


Base = declarative_base(MetaData())


songs_topics_table = Table(
    'songs_topics', Base.metadata,
    Column('song_id', Integer, ForeignKey('songs.id'), primary_key=True),
    Column('topic_id', Integer, ForeignKey('topics.id'), primary_key=True)
)


class AuthorType(object):
    """
    Enumeration for Author
    They are defined by OpenLyrics: http://openlyrics.info/dataformat.html#authors

    The 'words+music' type is not an official type, but is provided for convenience.
    """
    NoType = ''
    Words = 'words'
    Music = 'music'
    WordsAndMusic = 'words+music'
    Translation = 'translation'
    Types = {
        NoType: '',
        Words: translate('SongsPlugin.AuthorType', 'Words', 'Author who wrote the lyrics of a song'),
        Music: translate('SongsPlugin.AuthorType', 'Music', 'Author who wrote the music of a song'),
        WordsAndMusic: translate('SongsPlugin.AuthorType', 'Words and Music',
                                 'Author who wrote both lyrics and music of a song'),
        Translation: translate('SongsPlugin.AuthorType', 'Translation', 'Author who translated the song')
    }
    SortedTypes = [
        NoType,
        Words,
        Music,
        WordsAndMusic,
        Translation
    ]
    TranslatedTypes = [
        Types[NoType],
        Types[Words],
        Types[Music],
        Types[WordsAndMusic],
        Types[Translation]
    ]

    @staticmethod
    def from_translated_text(translated_type):
        """
        Get the AuthorType from a translated string.
        :param translated_type: Translated Author type.
        """
        for key, value in AuthorType.Types.items():
            if value == translated_type:
                return key
        return AuthorType.NoType


class Author(Base):
    """
    Author model
    """
    __tablename__ = 'authors'

    id = Column(Integer, primary_key=True)
    first_name = Column(Unicode(128))
    last_name = Column(Unicode(128))
    display_name = Column(Unicode(255), index=True, nullable=False)

    authors_songs = relationship('AuthorSong', back_populates='author')

    def get_display_name(self, author_type: Optional[str] = None) -> str:
        if author_type:
            return "{name} ({author})".format(name=self.display_name, author=AuthorType.Types[author_type])
        return self.display_name


class AuthorSong(Base):
    """
    Relationship between Authors and Songs (many to many).
    Need to define this relationship table explicit to get access to the
    Association Object (author_type).
    http://docs.sqlalchemy.org/en/latest/orm/relationships.html#association-object
    """
    __tablename__ = 'authors_songs'

    author_id = Column(Integer, ForeignKey('authors.id'), primary_key=True)
    song_id = Column(Integer, ForeignKey('songs.id'), primary_key=True)
    author_type = Column(Unicode(255), primary_key=True, nullable=False, server_default=text('""'))

    author = relationship('Author', back_populates='authors_songs')
    song = relationship('Song', back_populates='authors_songs')


class SongBook(Base):
    """
    SongBook model
    """
    __tablename__ = 'song_books'

    id = Column(Integer, primary_key=True)
    name = Column(Unicode(128), nullable=False)
    publisher = Column(Unicode(128))

    songbook_entries = relationship('SongBookEntry', back_populates='songbook')

    @property
    def songs(self):
        """
        A property to return the songs associated with this book.
        """
        return [sbe.song for sbe in self.songbook_entries]

    def __repr__(self):
        return f'<SongBook id="{self.id}" name="{self.name}" publisher="{self.publisher}">'


class MediaFile(Base):
    """
    MediaFile model
    """
    __tablename__ = 'media_files'

    id = Column(Integer, primary_key=True)
    song_id = Column(Integer, ForeignKey('songs.id'), default=None)
    file_path = Column(PathType, nullable=False)
    file_hash = Column(Unicode(128), nullable=False)
    type = Column(Unicode(64), nullable=False, default='audio')
    weight = Column(Integer, default=0)

    songs = relationship('Song', back_populates='media_files')


class Song(Base):
    """
    Song model
    """
    __tablename__ = 'songs'
    id = Column(Integer, primary_key=True)
    title = Column(Unicode(255), nullable=False)
    alternate_title = Column(Unicode(255))
    lyrics = Column(UnicodeText, nullable=False)
    verse_order = Column(Unicode(128))
    copyright = Column(Unicode(255))
    comments = Column(UnicodeText)
    ccli_number = Column(Unicode(64))
    theme_name = Column(Unicode(128))
    search_title = Column(Unicode(255), index=True, nullable=False)
    search_lyrics = Column(UnicodeText, nullable=False)
    create_date = Column(DateTime, default=func.now())
    last_modified = Column(DateTime, default=func.now(), onupdate=func.now())
    temporary = Column(Boolean, default=False)

    authors_songs = relationship('AuthorSong', back_populates='song', cascade='all, delete-orphan')
    media_files = relationship('MediaFile', back_populates='songs', order_by='MediaFile.weight')
    songbook_entries = relationship('SongBookEntry', back_populates='song', cascade='all, delete-orphan')
    topics = relationship('Topic', back_populates='songs', secondary=songs_topics_table)

    @hybrid_property
    def authors(self):
        return [author_song.author for author_song in self.authors_songs]

    @reconstructor
    def init_on_load(self):
        """
        Precompute a natural sorting, locale aware sorting key.

        Song sorting is performance sensitive operation.
        To get maximum speed lets precompute the sorting key.
        """
        self.sort_key = get_natural_key(self.title)

    def add_author(self, author, author_type=None):
        """
        Add an author to the song if it not yet exists

        :param author: Author object
        :param author_type: AuthorType constant or None
        """
        for author_song in self.authors_songs:
            if author_song.author == author and author_song.author_type == author_type:
                return
        new_author_song = AuthorSong(author=author, author_type=author_type)
        new_author_song.author = author
        new_author_song.author_type = author_type
        self.authors_songs.append(new_author_song)

    def remove_author(self, author, author_type=None):
        """
        Remove an existing author from the song

        :param author: Author object
        :param author_type: AuthorType constant or None
        """
        for author_song in self.authors_songs:
            if author_song.author == author and author_song.author_type == author_type:
                self.authors_songs.remove(author_song)
                return

    def add_songbook_entry(self, songbook, entry):
        """
        Add a Songbook Entry to the song if it not yet exists

        :param songbook: Name of the Songbook.
        :param entry: Entry in the Songbook (usually a number)
        """
        for songbook_entry in self.songbook_entries:
            if songbook_entry.songbook.name == songbook.name and songbook_entry.entry == entry:
                return

        new_songbook_entry = SongBookEntry()
        new_songbook_entry.songbook = songbook
        new_songbook_entry.entry = entry
        self.songbook_entries.append(new_songbook_entry)


class SongBookEntry(Base):
    """
    SongBookEntry model
    """
    __tablename__ = 'songs_songbooks'

    songbook_id = Column(Integer, ForeignKey('song_books.id'), primary_key=True)
    song_id = Column(Integer, ForeignKey('songs.id'), primary_key=True)
    entry = Column(Unicode(255), primary_key=True, nullable=False)

    songbook = relationship('SongBook', back_populates='songbook_entries')
    song = relationship('Song', back_populates='songbook_entries')

    def __repr__(self):
        return SongBookEntry.get_display_name(self.songbook.name, self.entry)

    @staticmethod
    def get_display_name(songbook_name, entry):
        if entry:
            return "{name} #{entry}".format(name=songbook_name, entry=entry)
        return songbook_name


class Topic(Base):
    """
    Topic model
    """
    __tablename__ = 'topics'
    id = Column(Integer, primary_key=True)
    name = Column(Unicode(128), index=True, nullable=False)

    songs = relationship('Song', back_populates='topics', secondary=songs_topics_table)


def init_schema(url):
    """
    Setup the songs database connection and initialise the database schema.

    :param url: The database to setup

    """
    session, metadata = init_db(url, base=Base)
    metadata.create_all(checkfirst=True)
    return session