soumya92/barista

// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package pulseaudio

import (
    "fmt"
    "os"

    "barista.run/base/value"
    "barista.run/modules/volume"

    "github.com/jfreymuth/pulse/proto"
)

type deviceType int

const (
    // SinkDevice represents devices used for audio output, e.g. headphones.
    SinkDevice deviceType = iota
    // SourceDevice represents devices used for audio input, e.g. microphones.
    SourceDevice
)

func (deviceType deviceType) String() string {
    return ([]string{"Sink", "Source"})[deviceType]
}

// PulseAudio implementation.
type paModule struct {
    deviceName string
    deviceType deviceType
}

func openPulseAudio() (*proto.Client, error) {
    client, _, err := proto.Connect("")
    return client, err
}

// Device creates a PulseAduio volume module for a named device that can either be a sink or a source.
func Device(deviceName string, deviceType deviceType) volume.Provider {
    return &paModule{deviceName: deviceName, deviceType: deviceType}
}

// Sink creates a PulseAudio volume module for a named sink.
func Sink(sinkName string) volume.Provider {
    return Device(sinkName, SinkDevice)
}

// DefaultSink creates a PulseAudio volume module that follows the default sink.
func DefaultSink() volume.Provider {
    return Sink("@DEFAULT_SINK@")
}

// Source creates a PulseAudio volume module for a named source.
func Source(sourceName string) volume.Provider {
    return Device(sourceName, SourceDevice)
}

// DefaultSource creates a PulseAudio volume module that follows the default source.
func DefaultSource() volume.Provider {
    return Source("@DEFAULT_SOURCE@")
}

type sinkController struct {
    client     *proto.Client
    deviceName string
}

type sourceController struct {
    client     *proto.Client
    deviceName string
}

func (c *sinkController) SetVolume(newVol int64) (err error) {
    return c.client.Request(&proto.SetSinkVolume{
        SinkIndex:      proto.Undefined,
        SinkName:       c.deviceName,
        ChannelVolumes: proto.ChannelVolumes{uint32(newVol)},
    }, nil)
}

func (c *sourceController) SetVolume(newVol int64) (err error) {
    return c.client.Request(&proto.SetSourceVolume{
        SourceIndex:    proto.Undefined,
        SourceName:     c.deviceName,
        ChannelVolumes: proto.ChannelVolumes{uint32(newVol)},
    }, nil)
}

func (c *sinkController) SetMuted(muted bool) (err error) {
    return c.client.Request(&proto.SetSinkMute{
        SinkIndex: proto.Undefined,
        SinkName:  c.deviceName,
        Mute:      muted,
    }, nil)
}

func (c *sourceController) SetMuted(muted bool) (err error) {
    return c.client.Request(&proto.SetSourceMute{
        SourceIndex: proto.Undefined,
        SourceName:  c.deviceName,
        Mute:        muted,
    }, nil)
}

func getVolume(client *proto.Client, deviceName string, deviceType deviceType) (vol volume.Volume, err error) {
    switch deviceType {
    case SinkDevice:
        return getVolumeSink(client, deviceName)
    case SourceDevice:
        return getVolumeSource(client, deviceName)
    default:
        panic(fmt.Sprintf("unexpected device type %v", int(deviceType)))
    }
}

func getVolumeSink(client *proto.Client, deviceName string) (vol volume.Volume, err error) {
    repl := proto.GetSinkInfoReply{}
    err = client.Request(&proto.GetSinkInfo{SinkIndex: proto.Undefined, SinkName: deviceName}, &repl)
    if err != nil {
        return
    }
    return makeVolume(repl.ChannelVolumes, repl.Mute, &sinkController{client, deviceName}), nil
}

func getVolumeSource(client *proto.Client, deviceName string) (vol volume.Volume, err error) {
    repl := proto.GetSourceInfoReply{}
    err = client.Request(&proto.GetSourceInfo{SourceIndex: proto.Undefined, SourceName: deviceName}, &repl)
    if err != nil {
        return
    }
    return makeVolume(repl.ChannelVolumes, repl.Mute, &sourceController{client, deviceName}), nil
}

func makeVolume(channelVolumes proto.ChannelVolumes, mute bool, controller volume.Controller) volume.Volume {
    // Take the volume as the average across all channels.
    var totalVol int64
    for _, ch := range channelVolumes {
        totalVol += int64(ch)
    }
    currentVol := totalVol / int64(len(channelVolumes))
    return volume.MakeVolume(0, int64(proto.VolumeNorm), currentVol, mute, controller)
}

func (m *paModule) Worker(s *value.ErrorValue) {
    client, conn, err := proto.Connect("")
    if s.Error(err) {
        return
    }
    defer conn.Close()

    ch := make(chan struct{}, 1)

    client.Callback = func(val interface{}) {
        switch val.(type) {
        case *proto.SubscribeEvent:
            // When PulseAudio server notifies us about sink/source change,
            // refresh the volume.
            //
            // It's okay if we lose notification something due to channel
            // being full though: this means that refresh is already pending.
            select {
            case ch <- struct{}{}:
            default:
            }
        }
    }

    props := proto.PropList{
        "application.name":           proto.PropListString("barista"),
        "application.process.binary": proto.PropListString(os.Args[0]),
        "application.process.id":     proto.PropListString(fmt.Sprintf("%d", os.Getpid())),
    }

    err = client.Request(&proto.SetClientName{Props: props}, nil)
    if s.Error(err) {
        return
    }

    var mask proto.SubscriptionMask
    switch m.deviceType {
    case SinkDevice:
        mask |= proto.SubscriptionMaskSink
    case SourceDevice:
        mask |= proto.SubscriptionMaskSource
    }
    err = client.Request(&proto.Subscribe{Mask: mask}, nil)
    if s.Error(err) {
        return
    }

    for {
        vol, err := getVolume(client, m.deviceName, m.deviceType)
        // Ignore ErrNoSuchEntity because devices may easily go away.
        if err != proto.ErrNoSuchEntity {
            if s.SetOrError(vol, err) {
                return
            }
        }
        <-ch
    }
}