From 112d9ab28e49856653f999fae1ae8b3c5ffded5b Mon Sep 17 00:00:00 2001
From: Unlock Music Dev <dev@unlock-music.dev>
Date: Fri, 25 Nov 2022 04:29:59 +0800
Subject: [PATCH] feat(qmc): allow retrieve metadata online

---
 algo/qmc/qmc.go            | 11 ++++--
 algo/qmc/qmc_meta.go       | 73 ++++++++++++++++++++++++++++++++++++--
 internal/ffmpeg/ffprobe.go |  4 +++
 3 files changed, 83 insertions(+), 5 deletions(-)

diff --git a/algo/qmc/qmc.go b/algo/qmc/qmc.go
index 7e8597f..0ea6c81 100644
--- a/algo/qmc/qmc.go
+++ b/algo/qmc/qmc.go
@@ -34,8 +34,10 @@ type Decoder struct {
 	albumMediaID  string
 
 	// cache
-	meta  common.AudioMeta
-	cover []byte
+	meta          common.AudioMeta
+	cover         []byte
+	embeddedCover bool          // embeddedCover is true if the cover is embedded in the file
+	probeBuf      *bytes.Buffer // probeBuf is the buffer for sniffing metadata
 
 	// provider
 	logger *zap.Logger
@@ -48,6 +50,8 @@ func (d *Decoder) Read(p []byte) (int, error) {
 	if n > 0 {
 		d.cipher.Decrypt(p[:n], d.offset)
 		d.offset += n
+
+		_, _ = d.probeBuf.Write(p[:n]) // bytes.Buffer.Write never return error
 	}
 	return n, err
 }
@@ -89,6 +93,9 @@ func (d *Decoder) Validate() error {
 	}
 	d.audio = io.LimitReader(d.raw, int64(d.audioLen))
 
+	// prepare for sniffing metadata
+	d.probeBuf = bytes.NewBuffer(make([]byte, 0, d.audioLen))
+
 	return nil
 }
 
diff --git a/algo/qmc/qmc_meta.go b/algo/qmc/qmc_meta.go
index 23493be..6a93b32 100644
--- a/algo/qmc/qmc_meta.go
+++ b/algo/qmc/qmc_meta.go
@@ -4,9 +4,14 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io"
+	"strings"
+
+	"github.com/samber/lo"
 
 	"unlock-music.dev/cli/algo/common"
 	"unlock-music.dev/cli/algo/qmc/client"
+	"unlock-music.dev/cli/internal/ffmpeg"
 )
 
 func (d *Decoder) GetAudioMeta(ctx context.Context) (common.AudioMeta, error) {
@@ -15,10 +20,27 @@ func (d *Decoder) GetAudioMeta(ctx context.Context) (common.AudioMeta, error) {
 	}
 
 	if d.songID != 0 {
-		return d.meta, d.getMetaBySongID(ctx)
+		if err := d.getMetaBySongID(ctx); err != nil {
+			return nil, err
+		}
+		return d.meta, nil
 	}
 
-	return nil, errors.New("qmc[GetAudioMeta] not implemented")
+	embedMeta, err := ffmpeg.ProbeReader(ctx, d.probeBuf)
+	if err != nil {
+		return nil, fmt.Errorf("qmc[GetAudioMeta] probe reader: %w", err)
+	}
+	d.meta = embedMeta
+	d.embeddedCover = embedMeta.HasAttachedPic()
+
+	if !d.embeddedCover && embedMeta.HasMetadata() {
+		if err := d.searchMetaOnline(ctx, embedMeta); err != nil {
+			return nil, err
+		}
+		return d.meta, nil
+	}
+
+	return d.meta, nil
 }
 
 func (d *Decoder) getMetaBySongID(ctx context.Context) error {
@@ -38,12 +60,56 @@ func (d *Decoder) getMetaBySongID(ctx context.Context) error {
 	return nil
 }
 
+func (d *Decoder) searchMetaOnline(ctx context.Context, original common.AudioMeta) error {
+	c := client.NewQQMusicClient() // todo: use global client
+	keyword := lo.WithoutEmpty(append(
+		[]string{original.GetTitle(), original.GetAlbum()},
+		original.GetArtists()...),
+	)
+	if len(keyword) == 0 {
+		return errors.New("qmc[searchMetaOnline] no keyword")
+	}
+
+	trackList, err := c.Search(ctx, strings.Join(keyword, " "))
+	if err != nil {
+		return fmt.Errorf("qmc[searchMetaOnline] search: %w", err)
+	}
+
+	if len(trackList) == 0 {
+		return errors.New("qmc[searchMetaOnline] no result")
+	}
+
+	meta := trackList[0]
+	d.meta = meta
+	d.albumID = meta.Album.Id
+	if meta.Album.Pmid == "" {
+		d.albumMediaID = meta.Album.Pmid
+	} else {
+		d.albumMediaID = meta.Album.Mid
+	}
+
+	return nil
+}
+
 func (d *Decoder) GetCoverImage(ctx context.Context) ([]byte, error) {
 	if d.cover != nil {
 		return d.cover, nil
 	}
 
-	// todo: get meta if possible
+	if d.embeddedCover {
+		img, err := ffmpeg.ExtractAlbumArt(ctx, d.probeBuf)
+		if err != nil {
+			return nil, fmt.Errorf("qmc[GetCoverImage] extract album art: %w", err)
+		}
+
+		d.cover, err = io.ReadAll(img)
+		if err != nil {
+			return nil, fmt.Errorf("qmc[GetCoverImage] read embed cover: %w", err)
+		}
+
+		return d.cover, nil
+	}
+
 	c := client.NewQQMusicClient() // todo: use global client
 	var err error
 
@@ -62,4 +128,5 @@ func (d *Decoder) GetCoverImage(ctx context.Context) ([]byte, error) {
 	}
 
 	return d.cover, nil
+
 }
diff --git a/internal/ffmpeg/ffprobe.go b/internal/ffmpeg/ffprobe.go
index 53a3d00..f98ef9d 100644
--- a/internal/ffmpeg/ffprobe.go
+++ b/internal/ffmpeg/ffprobe.go
@@ -45,6 +45,10 @@ func (r *Result) GetArtists() []string {
 	return artists
 }
 
+func (r *Result) HasMetadata() bool {
+	return r.GetTitle() != "" || r.GetAlbum() != "" || len(r.GetArtists()) > 0
+}
+
 type Format struct {
 	Filename       string            `json:"filename"`
 	NbStreams      int               `json:"nb_streams"`