# This file is part of beets.
# Copyright 2015, Adrian Sampson.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

"""A Web interface to beets."""
from __future__ import (division, absolute_import, print_function,
                        unicode_literals)

from beets.plugins import BeetsPlugin
from beets import ui
from beets import util
import beets.library
import flask
from flask import g
from werkzeug.routing import BaseConverter, PathConverter
import os
import json


# Utilities.

def _rep(obj, expand=False):
    """Get a flat -- i.e., JSON-ish -- representation of a beets Item or
    Album object. For Albums, `expand` dictates whether tracks are
    included.
    """
    out = dict(obj)

    if isinstance(obj, beets.library.Item):
        del out['path']

        # Get the size (in bytes) of the backing file. This is useful
        # for the Tomahawk resolver API.
        try:
            out['size'] = os.path.getsize(util.syspath(obj.path))
        except OSError:
            out['size'] = 0

        return out

    elif isinstance(obj, beets.library.Album):
        del out['artpath']
        if expand:
            out['items'] = [_rep(item) for item in obj.items()]
        return out


def json_generator(items, root):
    """Generator that dumps list of beets Items or Albums as JSON

    :param root:  root key for JSON
    :param items: list of :class:`Item` or :class:`Album` to dump
    :returns:     generator that yields strings
    """
    yield '{"%s":[' % root
    first = True
    for item in items:
        if first:
            first = False
        else:
            yield ','
        yield json.dumps(_rep(item))
    yield ']}'


def resource(name):
    """Decorates a function to handle RESTful HTTP requests for a resource.
    """
    def make_responder(retriever):
        def responder(ids):
            entities = [retriever(id) for id in ids]
            entities = [entity for entity in entities if entity]

            if len(entities) == 1:
                return flask.jsonify(_rep(entities[0]))
            elif entities:
                return app.response_class(
                    json_generator(entities, root=name),
                    mimetype='application/json'
                )
            else:
                return flask.abort(404)
        responder.__name__ = b'get_%s' % name.encode('utf8')
        return responder
    return make_responder


def resource_query(name):
    """Decorates a function to handle RESTful HTTP queries for resources.
    """
    def make_responder(query_func):
        def responder(queries):
            return app.response_class(
                json_generator(query_func(queries), root='results'),
                mimetype='application/json'
            )
        responder.__name__ = b'query_%s' % name.encode('utf8')
        return responder
    return make_responder


def resource_list(name):
    """Decorates a function to handle RESTful HTTP request for a list of
    resources.
    """
    def make_responder(list_all):
        def responder():
            return app.response_class(
                json_generator(list_all(), root=name),
                mimetype='application/json'
            )
        responder.__name__ = b'all_%s' % name.encode('utf8')
        return responder
    return make_responder


class IdListConverter(BaseConverter):
    """Converts comma separated lists of ids in urls to integer lists.
    """

    def to_python(self, value):
        ids = []
        for id in value.split(','):
            try:
                ids.append(int(id))
            except ValueError:
                pass
        return ids

    def to_url(self, value):
        return ','.join(value)


class QueryConverter(PathConverter):
    """Converts slash separated lists of queries in the url to string list.
    """

    def to_python(self, value):
        return value.split('/')

    def to_url(self, value):
        return ','.join(value)


# Flask setup.

app = flask.Flask(__name__)
app.url_map.converters['idlist'] = IdListConverter
app.url_map.converters['query'] = QueryConverter


@app.before_request
def before_request():
    g.lib = app.config['lib']


# Items.

@app.route('/item/<idlist:ids>')
@resource('items')
def get_item(id):
    return g.lib.get_item(id)


@app.route('/item/')
@app.route('/item/query/')
@resource_list('items')
def all_items():
    return g.lib.items()


@app.route('/item/<int:item_id>/file')
def item_file(item_id):
    item = g.lib.get_item(item_id)
    response = flask.send_file(item.path, as_attachment=True,
                               attachment_filename=os.path.basename(item.path))
    response.headers['Content-Length'] = os.path.getsize(item.path)
    return response


@app.route('/item/query/<query:queries>')
@resource_query('items')
def item_query(queries):
    return g.lib.items(queries)


# Albums.

@app.route('/album/<idlist:ids>')
@resource('albums')
def get_album(id):
    return g.lib.get_album(id)


@app.route('/album/')
@app.route('/album/query/')
@resource_list('albums')
def all_albums():
    return g.lib.albums()


@app.route('/album/query/<query:queries>')
@resource_query('albums')
def album_query(queries):
    return g.lib.albums(queries)


@app.route('/album/<int:album_id>/art')
def album_art(album_id):
    album = g.lib.get_album(album_id)
    return flask.send_file(album.artpath)


# Artists.

@app.route('/artist/')
def all_artists():
    with g.lib.transaction() as tx:
        rows = tx.query("SELECT DISTINCT albumartist FROM albums")
    all_artists = [row[0] for row in rows]
    return flask.jsonify(artist_names=all_artists)


# Library information.

@app.route('/stats')
def stats():
    with g.lib.transaction() as tx:
        item_rows = tx.query("SELECT COUNT(*) FROM items")
        album_rows = tx.query("SELECT COUNT(*) FROM albums")
    return flask.jsonify({
        'items': item_rows[0][0],
        'albums': album_rows[0][0],
    })


# UI.

@app.route('/')
def home():
    return flask.render_template('index.html')


# Plugin hook.

class WebPlugin(BeetsPlugin):
    def __init__(self):
        super(WebPlugin, self).__init__()
        self.config.add({
            'host': u'127.0.0.1',
            'port': 8337,
            'cors': '',
        })

    def commands(self):
        cmd = ui.Subcommand('web', help='start a Web interface')
        cmd.parser.add_option('-d', '--debug', action='store_true',
                              default=False, help='debug mode')

        def func(lib, opts, args):
            args = ui.decargs(args)
            if args:
                self.config['host'] = args.pop(0)
            if args:
                self.config['port'] = int(args.pop(0))

            app.config['lib'] = lib
            # Enable CORS if required.
            if self.config['cors']:
                self._log.info('Enabling CORS with origin: {0}',
                               self.config['cors'])
                from flask.ext.cors import CORS
                app.config['CORS_ALLOW_HEADERS'] = "Content-Type"
                app.config['CORS_RESOURCES'] = {
                    r"/*": {"origins": self.config['cors'].get(str)}
                }
                CORS(app)
            # Start the web application.
            app.run(host=self.config['host'].get(unicode),
                    port=self.config['port'].get(int),
                    debug=opts.debug, threaded=True)
        cmd.func = func
        return [cmd]