better error logging

server/internal/process.go

@@ -2,8 +2,11 @@ package internal
 
 import (
 	"bufio"
+	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"regexp"
 	"slices"
@@ -35,13 +38,6 @@ const (
 	StatusErrored
 )
 
-type ProgressTemplate struct {
-	Percentage string  `json:"percentage"`
-	Speed      float32 `json:"speed"`
-	Size       string  `json:"size"`
-	Eta        float32 `json:"eta"`
-}
-
 // Process descriptor
 type Process struct {
 	Id       string
@@ -54,12 +50,6 @@ type Process struct {
 	Logger   *slog.Logger
 }
 
-type DownloadOutput struct {
-	Path          string
-	Filename      string
-	SavedFilePath string `json:"savedFilePath"`
-}
-
 // Starts spawns/forks a new yt-dlp process and parse its stdout.
 // The process is spawned to outputting a custom progress text that
 // Resembles a JSON Object in order to Unmarshal it later.
@@ -123,7 +113,6 @@ func (p *Process) Start() {
 		)
 		panic(err)
 	}
-	scan := bufio.NewScanner(r)
 
 	err = cmd.Start()
 	if err != nil {
@@ -145,6 +134,8 @@ func (p *Process) Start() {
 	// spawn a goroutine that does the dirty job of parsing the stdout
 	// filling the channel with as many stdout line as yt-dlp produces (producer)
 	go func() {
+		scan := bufio.NewScanner(r)
+
 		defer func() {
 			r.Close()
 			p.Complete()
@@ -161,21 +152,24 @@ func (p *Process) Start() {
 	// Slows down the unmarshal operation to every 500ms
 	go func() {
 		rx.Sample(time.Millisecond*500, sourceChan, doneChan, func(event []byte) {
-			stdout := ProgressTemplate{}
-			err := json.Unmarshal(event, &stdout)
-			if err == nil {
-				p.Progress = DownloadProgress{
-					Status:     StatusDownloading,
-					Percentage: stdout.Percentage,
-					Speed:      stdout.Speed,
-					ETA:        stdout.Eta,
-				}
-				p.Logger.Info("progress",
-					slog.String("id", p.getShortId()),
-					slog.String("url", p.Url),
-					slog.String("percentege", stdout.Percentage),
-				)
+			var progress ProgressTemplate
+
+			if err := json.Unmarshal(event, &progress); err != nil {
+				return
 			}
+
+			p.Progress = DownloadProgress{
+				Status:     StatusDownloading,
+				Percentage: progress.Percentage,
+				Speed:      progress.Speed,
+				ETA:        progress.Eta,
+			}
+
+			p.Logger.Info("progress",
+				slog.String("id", p.getShortId()),
+				slog.String("url", p.Url),
+				slog.String("percentege", progress.Percentage),
+			)
 		})
 	}()
 
@@ -223,9 +217,13 @@ func (p *Process) Kill() error {
 // Returns the available format for this URL
 func (p *Process) GetFormatsSync() (DownloadFormats, error) {
 	cmd := exec.Command(config.Instance().DownloaderPath, p.Url, "-J")
-	stdout, err := cmd.Output()
 
+	stdout, err := cmd.Output()
 	if err != nil {
+		p.Logger.Error(
+			"failed to retrieve metadata",
+			slog.String("err", err.Error()),
+		)
 		return DownloadFormats{}, err
 	}
 
@@ -306,7 +304,17 @@ func (p *Process) SetMetadata() error {
 
 	stdout, err := cmd.StdoutPipe()
 	if err != nil {
-		p.Logger.Error("failed retrieving info",
+		p.Logger.Error("failed to connect to stdout",
+			slog.String("id", p.getShortId()),
+			slog.String("url", p.Url),
+			slog.String("err", err.Error()),
+		)
+		return err
+	}
+
+	stderr, err := cmd.StderrPipe()
+	if err != nil {
+		p.Logger.Error("failed to connect to stderr",
 			slog.String("id", p.getShortId()),
 			slog.String("url", p.Url),
 			slog.String("err", err.Error()),
@@ -319,27 +327,33 @@ func (p *Process) SetMetadata() error {
 		CreatedAt: time.Now(),
 	}
 
-	err = cmd.Start()
-	if err != nil {
+	if err := cmd.Start(); err != nil {
 		return err
 	}
 
+	var bufferedStderr bytes.Buffer
+
+	go func() {
+		io.Copy(&bufferedStderr, stderr)
+	}()
+
 	p.Logger.Info("retrieving metadata",
 		slog.String("id", p.getShortId()),
 		slog.String("url", p.Url),
 	)
 
-	err = json.NewDecoder(stdout).Decode(&info)
-	if err != nil {
+	if err := json.NewDecoder(stdout).Decode(&info); err != nil {
 		return err
 	}
 
 	p.Info = info
 	p.Progress.Status = StatusPending
 
-	err = cmd.Wait()
+	if err := cmd.Wait(); err != nil {
+		return errors.New(bufferedStderr.String())
+	}
 
-	return err
+	return nil
 }
 
 func (p *Process) getShortId() string {