beets/beetsplug/web/__init__.py

# This file is part of beets.
# Copyright 2016, 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."""

import base64
import json
import os
import typing as t

import flask
from flask import jsonify
from unidecode import unidecode
from werkzeug.routing import BaseConverter, PathConverter

import beets.library
from beets import ui, util
from beets.dbcore.query import PathQuery
from beets.plugins import BeetsPlugin

# Type checking hacks

if t.TYPE_CHECKING:

    class LibraryCtx(flask.ctx._AppCtxGlobals):
        lib: beets.library.Library

    g = LibraryCtx()
else:
    from flask import g

# 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):
        if app.config.get("INCLUDE_PATHS", False):
            out["path"] = util.displayable_path(out["path"])
        else:
            del out["path"]

        # Filter all bytes attributes and convert them to strings.
        for key, value in out.items():
            if isinstance(out[key], bytes):
                out[key] = base64.b64encode(value).decode("ascii")

        # 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):
        if app.config.get("INCLUDE_PATHS", False):
            out["artpath"] = util.displayable_path(out["artpath"])
        else:
            del out["artpath"]
        if expand:
            out["items"] = [_rep(item) for item in obj.items()]
        return out


def json_generator(items, root, expand=False):
    """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
    :param expand: If true every :class:`Album` contains its items in the json
                   representation
    :returns:     generator that yields strings
    """
    yield f'{{"{root}":['
    first = True
    for item in items:
        if first:
            first = False
        else:
            yield ","
        yield json.dumps(_rep(item, expand=expand))
    yield "]}"


def is_expand():
    """Returns whether the current request is for an expanded response."""

    return flask.request.args.get("expand") is not None


def is_delete():
    """Returns whether the current delete request should remove the selected
    files.
    """

    return flask.request.args.get("delete") is not None


def get_method():
    """Returns the HTTP method of the current request."""
    return flask.request.method


def resource(name, patchable=False):
    """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 get_method() == "DELETE":
                if app.config.get("READONLY", True):
                    return flask.abort(405)

                for entity in entities:
                    entity.remove(delete=is_delete())

                return flask.make_response(jsonify({"deleted": True}), 200)

            elif get_method() == "PATCH" and patchable:
                if app.config.get("READONLY", True):
                    return flask.abort(405)

                for entity in entities:
                    entity.update(flask.request.get_json())
                    entity.try_sync(True, False)  # write, don't move

                if len(entities) == 1:
                    return flask.jsonify(_rep(entities[0], expand=is_expand()))
                elif entities:
                    return app.response_class(
                        json_generator(entities, root=name),
                        mimetype="application/json",
                    )

            elif get_method() == "GET":
                if len(entities) == 1:
                    return flask.jsonify(_rep(entities[0], expand=is_expand()))
                elif entities:
                    return app.response_class(
                        json_generator(entities, root=name),
                        mimetype="application/json",
                    )
                else:
                    return flask.abort(404)

            else:
                return flask.abort(405)

        responder.__name__ = f"get_{name}"

        return responder

    return make_responder


def resource_query(name, patchable=False):
    """Decorates a function to handle RESTful HTTP queries for resources."""

    def make_responder(query_func):
        def responder(queries):
            entities = query_func(queries)

            if get_method() == "DELETE":
                if app.config.get("READONLY", True):
                    return flask.abort(405)

                for entity in entities:
                    entity.remove(delete=is_delete())

                return flask.make_response(jsonify({"deleted": True}), 200)

            elif get_method() == "PATCH" and patchable:
                if app.config.get("READONLY", True):
                    return flask.abort(405)

                for entity in entities:
                    entity.update(flask.request.get_json())
                    entity.try_sync(True, False)  # write, don't move

                return app.response_class(
                    json_generator(entities, root=name),
                    mimetype="application/json",
                )

            elif get_method() == "GET":
                return app.response_class(
                    json_generator(
                        entities, root="results", expand=is_expand()
                    ),
                    mimetype="application/json",
                )

            else:
                return flask.abort(405)

        responder.__name__ = f"query_{name}"

        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, expand=is_expand()),
                mimetype="application/json",
            )

        responder.__name__ = f"all_{name}"
        return responder

    return make_responder


def _get_unique_table_field_values(model, field, sort_field):
    """retrieve all unique values belonging to a key from a model"""
    if field not in model.all_keys() or sort_field not in model.all_keys():
        raise KeyError
    with g.lib.transaction() as tx:
        rows = tx.query(
            f"SELECT DISTINCT {field} FROM {model._table} ORDER BY {sort_field}"
        )
    return [row[0] for row in rows]


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(str(v) for v in value)


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

    def to_python(self, value):
        queries = value.split("/")
        """Do not do path substitution on regex value tests"""
        return [
            query if "::" in query else query.replace("\\", os.sep)
            for query in queries
        ]

    def to_url(self, value):
        return "/".join([v.replace(os.sep, "\\") for v in value])


class EverythingConverter(PathConverter):
    part_isolating = False
    regex = ".*?"


# Flask setup.

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


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


# Items.


@app.route("/item/<idlist:ids>", methods=["GET", "DELETE", "PATCH"])
@resource("items", patchable=True)
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)

    item_path = util.syspath(item.path)
    base_filename = os.path.basename(item_path)

    try:
        # Imitate http.server behaviour
        base_filename.encode("latin-1", "strict")
    except UnicodeError:
        safe_filename = unidecode(base_filename)
    else:
        safe_filename = base_filename

    response = flask.send_file(
        item_path, as_attachment=True, download_name=safe_filename
    )
    return response


@app.route("/item/query/<query:queries>", methods=["GET", "DELETE", "PATCH"])
@resource_query("items", patchable=True)
def item_query(queries):
    return g.lib.items(queries)


@app.route("/item/path/<everything:path>")
def item_at_path(path):
    query = PathQuery("path", path.encode("utf-8"))
    item = g.lib.items(query).get()
    if item:
        return flask.jsonify(_rep(item))
    else:
        return flask.abort(404)


@app.route("/item/values/<string:key>")
def item_unique_field_values(key):
    sort_key = flask.request.args.get("sort_key", key)
    try:
        values = _get_unique_table_field_values(
            beets.library.Item, key, sort_key
        )
    except KeyError:
        return flask.abort(404)
    return flask.jsonify(values=values)


# Albums.


@app.route("/album/<idlist:ids>", methods=["GET", "DELETE"])
@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>", methods=["GET", "DELETE"])
@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)
    if album and album.artpath:
        return flask.send_file(album.artpath.decode())
    else:
        return flask.abort(404)


@app.route("/album/values/<string:key>")
def album_unique_field_values(key):
    sort_key = flask.request.args.get("sort_key", key)
    try:
        values = _get_unique_table_field_values(
            beets.library.Album, key, sort_key
        )
    except KeyError:
        return flask.abort(404)
    return flask.jsonify(values=values)


# 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().__init__()
        self.config.add(
            {
                "host": "127.0.0.1",
                "port": 8337,
                "cors": "",
                "cors_supports_credentials": False,
                "reverse_proxy": False,
                "include_paths": False,
                "readonly": True,
            }
        )

    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 = args
            if args:
                self.config["host"] = args.pop(0)
            if args:
                self.config["port"] = int(args.pop(0))

            app.config["lib"] = lib
            # Normalizes json output
            app.config["JSONIFY_PRETTYPRINT_REGULAR"] = False

            app.config["INCLUDE_PATHS"] = self.config["include_paths"]
            app.config["READONLY"] = self.config["readonly"]

            # Enable CORS if required.
            if self.config["cors"]:
                self._log.info(
                    "Enabling CORS with origin: {}", self.config["cors"]
                )
                from flask_cors import CORS

                app.config["CORS_ALLOW_HEADERS"] = "Content-Type"
                app.config["CORS_RESOURCES"] = {
                    r"/*": {"origins": self.config["cors"].get(str)}
                }
                CORS(
                    app,
                    supports_credentials=self.config[
                        "cors_supports_credentials"
                    ].get(bool),
                )

            # Allow serving behind a reverse proxy
            if self.config["reverse_proxy"]:
                app.wsgi_app = ReverseProxied(app.wsgi_app)

            # Start the web application.
            app.run(
                host=self.config["host"].as_str(),
                port=self.config["port"].get(int),
                debug=opts.debug,
                threaded=True,
            )

        cmd.func = func
        return [cmd]


class ReverseProxied:
    """Wrap the application in this middleware and configure the
    front-end server to add these headers, to let you quietly bind
    this to a URL other than / and to an HTTP scheme that is
    different than what is used locally.

    In nginx:
    location /myprefix {
        proxy_pass http://192.168.0.1:5001;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Scheme $scheme;
        proxy_set_header X-Script-Name /myprefix;
        }

    From: http://flask.pocoo.org/snippets/35/

    :param app: the WSGI application
    """

    def __init__(self, app):
        self.app = app

    def __call__(self, environ, start_response):
        script_name = environ.get("HTTP_X_SCRIPT_NAME", "")
        if script_name:
            environ["SCRIPT_NAME"] = script_name
            path_info = environ["PATH_INFO"]
            if path_info.startswith(script_name):
                environ["PATH_INFO"] = path_info[len(script_name) :]

        scheme = environ.get("HTTP_X_SCHEME", "")
        if scheme:
            environ["wsgi.url_scheme"] = scheme
        return self.app(environ, start_response)