From 84cba437249e3c109435c9b93a4026c6098cb491 Mon Sep 17 00:00:00 2001
From: James Mills <prologic@shortcircuit.net.au>
Date: Sat, 21 Mar 2020 10:46:03 +1000
Subject: [PATCH] Add support for on-demand thumbnail generation via
 github.com/mutschler/mt

---
 media/utils.go | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
 media/video.go | 14 +++++++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 media/utils.go

diff --git a/media/utils.go b/media/utils.go
new file mode 100644
index 0000000..b67f276
--- /dev/null
+++ b/media/utils.go
@@ -0,0 +1,56 @@
+package media
+
+import (
+	"bytes"
+	"fmt"
+	"os/exec"
+	"time"
+)
+
+func cmdExists(cmd string) bool {
+	_, err := exec.LookPath(cmd)
+	return err == nil
+}
+
+func runCmd(timeout int, command string, args ...string) error {
+	// instantiate new command
+	cmd := exec.Command(command, args...)
+
+	// get pipe to standard output
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return fmt.Errorf("cmd.StdoutPipe() error: %w", err)
+	}
+
+	// start process via command
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("cmd.Start() error: %w", err)
+	}
+
+	// setup a buffer to capture standard output
+	var buf bytes.Buffer
+
+	// create a channel to capture any errors from wait
+	done := make(chan error)
+	go func() {
+		if _, err := buf.ReadFrom(stdout); err != nil {
+			panic("buf.Read(stdout) error: " + err.Error())
+		}
+		done <- cmd.Wait()
+	}()
+
+	// block on select, and switch based on actions received
+	select {
+	case <-time.After(time.Duration(timeout) * time.Second):
+		if err := cmd.Process.Kill(); err != nil {
+			return fmt.Errorf("failed to kill: %w", err)
+		}
+		return fmt.Errorf("timeout reached, process killed")
+	case err := <-done:
+		if err != nil {
+			close(done)
+			return fmt.Errorf("process done, with error: %w", err)
+		}
+		return nil
+	}
+}
diff --git a/media/video.go b/media/video.go
index 9340e86..9c10b1e 100644
--- a/media/video.go
+++ b/media/video.go
@@ -1,8 +1,11 @@
 package media
 
 import (
+	"fmt"
+	"io/ioutil"
 	"os"
 	"path"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -72,6 +75,17 @@ func ParseVideo(p *Path, name string) (*Video, error) {
 	if pic != nil {
 		v.Thumb = pic.Data
 		v.ThumbType = pic.MIMEType
+	} else if cmdExists("mt") {
+		if err := runCmd(3, "mt", "-s", "-n", "1", pth); err != nil {
+			return nil, err
+		}
+		data, err := ioutil.ReadFile(fmt.Sprintf("%s.jpg", strings.TrimSuffix(pth, filepath.Ext(pth))))
+		if err != nil {
+			return nil, err
+		}
+		v.Thumb = data
+		v.ThumbType = "image/jpeg"
 	}
+
 	return v, nil
 }