Implement /NP

This queries the system for the current song being played. This uses
DBus & MPRIS/xesam.

The priority is any player in playing state > any player in paused
state.

Only players in the playing or paused state, with a valid song title are
considered.

4 files changed, 101 insertions, 0 deletions

diff --git a/commands.go b/commands.go
index 55582a0..5a2c71b 100644
--- a/commands.go
+++ b/commands.go
@@ -3,6 +3,7 @@ package senpai
 import (
 	"errors"
 	"fmt"
+	"net/url"
 	"sort"
 	"strconv"
 	"strings"
@@ -11,6 +12,8 @@ import (
 	"git.sr.ht/~taiite/senpai/irc"
 	"git.sr.ht/~taiite/senpai/ui"
 	"github.com/gdamore/tcell/v2"
+	"github.com/godbus/dbus/v5"
+	"golang.org/x/net/context"
 )
 
 var (
@@ -57,6 +60,11 @@ func init() {
 			Desc:      "send an action (reply to last query if sent from home)",
 			Handle:    commandDoMe,
 		},
+		"NP": {
+			AllowHome: true,
+			Desc:      "send the current song that is being played on the system",
+			Handle:    commandDoNP,
+		},
 		"MSG": {
 			AllowHome: true,
 			MinArgs:   2,
@@ -343,6 +351,14 @@ func commandDoMe(app *App, args []string) (err error) {
 	return nil
 }
 
+func commandDoNP(app *App, args []string) (err error) {
+	song := getSong()
+	if song == "" {
+		return fmt.Errorf("no song was detected")
+	}
+	return commandDoMe(app, []string{fmt.Sprintf("np: %s", song)})
+}
+
 func commandDoMsg(app *App, args []string) (err error) {
 	target := args[0]
 	content := args[1]
@@ -775,3 +791,81 @@ func (app *App) handleInput(buffer, content string) error {
 
 	return cmd.Handle(app, args)
 }
+
+func getSong() string {
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+
+	bus, err := dbus.ConnectSessionBus(dbus.WithContext(ctx))
+	if err != nil {
+		return ""
+	}
+	defer bus.Close()
+
+	var names []string
+	if err := bus.BusObject().CallWithContext(ctx, "org.freedesktop.DBus.ListNames", 0).Store(&names); err != nil {
+		return ""
+	}
+	song := ""
+	for _, name := range names {
+		if !strings.HasPrefix(name, "org.mpris.MediaPlayer2.") {
+			continue
+		}
+		var playing bool
+		o := bus.Object(name, "/org/mpris/MediaPlayer2")
+		var status string
+		if err := o.CallWithContext(ctx, "org.freedesktop.DBus.Properties.Get", 0, "org.mpris.MediaPlayer2.Player", "PlaybackStatus").Store(&status); err != nil {
+			continue
+		}
+		switch status {
+		case "Playing":
+			playing = true
+		case "Paused":
+			playing = false
+		default:
+			continue
+		}
+		var metadata map[string]dbus.Variant
+		if err := o.CallWithContext(ctx, "org.freedesktop.DBus.Properties.Get", 0, "org.mpris.MediaPlayer2.Player", "Metadata").Store(&metadata); err != nil {
+			continue
+		}
+		var trackURL string
+		var title string
+		var album string
+		var artist string
+		if e, ok := metadata["xesam:title"].Value().(string); ok {
+			title = e
+		}
+		if e, ok := metadata["xesam:album"].Value().(string); ok {
+			album = e
+		}
+		if e, ok := metadata["xesam:url"].Value().(string); ok {
+			trackURL = e
+		}
+		if e, ok := metadata["xesam:artist"].Value().([]string); ok && len(e) > 0 {
+			artist = e[0]
+		}
+		if title == "" {
+			continue
+		}
+		var sb strings.Builder
+		fmt.Fprintf(&sb, "\x02%s\x02", title)
+		if artist != "" {
+			fmt.Fprintf(&sb, " by \x02%s\x02", artist)
+		}
+		if album != "" {
+			fmt.Fprintf(&sb, " from \x02%s\x02", album)
+		}
+		if u, err := url.Parse(trackURL); err == nil {
+			switch u.Scheme {
+			case "http", "https":
+				fmt.Fprintf(&sb, " — %s", trackURL)
+			}
+		}
+		song = sb.String()
+		if playing {
+			return song
+		}
+	}
+	return song
+}
diff --git a/doc/senpai.1.scd b/doc/senpai.1.scd
index d58e55a..20befac 100644
--- a/doc/senpai.1.scd
+++ b/doc/senpai.1.scd
@@ -165,6 +165,10 @@ _name_ is matched case-insensitively.  It can be one of the following:
 	Send a message prefixed with your nick (a user action). If sent from home,
 	reply to the last person who sent a private message.
 
+*NP*
+	Send the current song that is being played on the system. Uses DBus/MPRIS
+	internally.
+
 *QUOTE* <raw message>
 	Send _raw message_ verbatim.
 
diff --git a/go.mod b/go.mod
index 2c304cd..8cfff1b 100644
--- a/go.mod
+++ b/go.mod
@@ -6,6 +6,7 @@ require (
 	git.sr.ht/~emersion/go-scfg v0.0.0-20201019143924-142a8aa629fc
 	github.com/delthas/go-localeinfo v0.0.0-20221115102303-5a7785a1acc1
 	github.com/gdamore/tcell/v2 v2.5.4-0.20221017224006-ede1dd5ee680
+	github.com/godbus/dbus/v5 v5.1.0
 	github.com/mattn/go-runewidth v0.0.14
 	golang.org/x/net v0.0.0-20220722155237-a158d28d115b
 	golang.org/x/term v0.0.0-20210927222741-03fcf44c2211
diff --git a/go.sum b/go.sum
index afa9274..b421a96 100644
--- a/go.sum
+++ b/go.sum
@@ -8,6 +8,8 @@ github.com/gdamore/encoding v1.0.0 h1:+7OoQ1Bc6eTm5niUzBa0Ctsh6JbMW6Ra+YNuAtDBdk
 github.com/gdamore/encoding v1.0.0/go.mod h1:alR0ol34c49FCSBLjhosxzcPHQbf2trDkoo5dl+VrEg=
 github.com/gdamore/tcell/v2 v2.5.4-0.20221017224006-ede1dd5ee680 h1:bCjGvZsZNvhzJZ+gDmXpKdDPyf358nSPqepaTI1AsMQ=
 github.com/gdamore/tcell/v2 v2.5.4-0.20221017224006-ede1dd5ee680/go.mod h1:XmCynGHvvGG7UFI6az9zzoEHBvZB1PGf5APwOJMFUyE=
+github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
+github.com/godbus/dbus/v5 v5.1.0/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 h1:El6M4kTTCOh6aBiKaUGG7oYTSPP8MxqL4YI3kZKwcP4=
 github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=