Convert .tgs with go libraries (and cgo) (telegram) (#1569)

This commit adds support for go/cgo tgs conversion when building with the -tags `cgo`
The default binaries are still "pure" go and uses the old way of converting.

* Move lottie_convert.py conversion code to its own file

* Add optional libtgsconverter

* Update vendor

* Apply suggestions from code review

* Update bridge/helper/libtgsconverter.go

Co-authored-by: Wim <wim@42.be>

1 files changed, 0 insertions, 66 deletions

diff --git a/bridge/helper/helper.go b/bridge/helper/helper.go
index 1bdd8a40..581a2c43 100644
--- a/bridge/helper/helper.go
+++ b/bridge/helper/helper.go
@@ -5,10 +5,7 @@ import (
 	"fmt"
 	"image/png"
 	"io"
-	"io/ioutil"
 	"net/http"
-	"os"
-	"os/exec"
 	"regexp"
 	"strings"
 	"time"
@@ -239,66 +236,3 @@ func ConvertWebPToPNG(data *[]byte) error {
 	*data = w.Bytes()
 	return nil
 }
-
-// CanConvertTgsToX Checks whether the external command necessary for ConvertTgsToX works.
-func CanConvertTgsToX() error {
-	// We depend on the fact that `lottie_convert.py --help` has exit status 0.
-	// Hyrum's Law predicted this, and Murphy's Law predicts that this will break eventually.
-	// However, there is no alternative like `lottie_convert.py --is-properly-installed`
-	cmd := exec.Command("lottie_convert.py", "--help")
-	return cmd.Run()
-}
-
-// ConvertTgsToWebP convert input data (which should be tgs format) to WebP format
-// This relies on an external command, which is ugly, but works.
-func ConvertTgsToX(data *[]byte, outputFormat string, logger *logrus.Entry) error {
-	// lottie can't handle input from a pipe, so write to a temporary file:
-	tmpInFile, err := ioutil.TempFile(os.TempDir(), "matterbridge-lottie-input-*.tgs")
-	if err != nil {
-		return err
-	}
-	tmpInFileName := tmpInFile.Name()
-	defer func() {
-		if removeErr := os.Remove(tmpInFileName); removeErr != nil {
-			logger.Errorf("Could not delete temporary (input) file %s: %v", tmpInFileName, removeErr)
-		}
-	}()
-	// lottie can handle writing to a pipe, but there is no way to do that platform-independently.
-	// "/dev/stdout" won't work on Windows, and "-" upsets Cairo for some reason. So we need another file:
-	tmpOutFile, err := ioutil.TempFile(os.TempDir(), "matterbridge-lottie-output-*.data")
-	if err != nil {
-		return err
-	}
-	tmpOutFileName := tmpOutFile.Name()
-	defer func() {
-		if removeErr := os.Remove(tmpOutFileName); removeErr != nil {
-			logger.Errorf("Could not delete temporary (output) file %s: %v", tmpOutFileName, removeErr)
-		}
-	}()
-
-	if _, writeErr := tmpInFile.Write(*data); writeErr != nil {
-		return writeErr
-	}
-	// Must close before calling lottie to avoid data races:
-	if closeErr := tmpInFile.Close(); closeErr != nil {
-		return closeErr
-	}
-
-	// Call lottie to transform:
-	cmd := exec.Command("lottie_convert.py", "--input-format", "lottie", "--output-format", outputFormat, tmpInFileName, tmpOutFileName)
-	cmd.Stdout = nil
-	cmd.Stderr = nil
-	// NB: lottie writes progress into to stderr in all cases.
-	_, stderr := cmd.Output()
-	if stderr != nil {
-		// 'stderr' already contains some parts of Stderr, because it was set to 'nil'.
-		return stderr
-	}
-	dataContents, err := ioutil.ReadFile(tmpOutFileName)
-	if err != nil {
-		return err
-	}
-
-	*data = dataContents
-	return nil
-}