feat(api): add debug route

pkg/modules/pdfcpu/pdfcpu.go

@@ -5,7 +5,10 @@ import (
 	"errors"
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
+	"strings"
+	"syscall"
 
 	"go.uber.org/zap"
 
@@ -52,6 +55,32 @@ func (engine *PdfCpu) Validate() error {
 	return nil
 }
 
+// Debug returns additional debug data.
+func (engine *PdfCpu) Debug() map[string]interface{} {
+	debug := make(map[string]interface{})
+
+	cmd := exec.Command(engine.binPath, "version") //nolint:gosec
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+
+	output, err := cmd.Output()
+	if err != nil {
+		debug["version"] = err.Error()
+		return debug
+	}
+
+	debug["version"] = "Unable to determine pdfcpu version"
+
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		if strings.HasPrefix(line, "pdfcpu:") {
+			debug["version"] = strings.TrimSpace(strings.TrimPrefix(line, "pdfcpu:"))
+			break
+		}
+	}
+
+	return debug
+}
+
 // Merge combines multiple PDFs into a single PDF.
 func (engine *PdfCpu) Merge(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
 	var args []string
@@ -132,5 +161,6 @@ var (
 	_ gotenberg.Module      = (*PdfCpu)(nil)
 	_ gotenberg.Provisioner = (*PdfCpu)(nil)
 	_ gotenberg.Validator   = (*PdfCpu)(nil)
+	_ gotenberg.Debuggable  = (*PdfCpu)(nil)
 	_ gotenberg.PdfEngine   = (*PdfCpu)(nil)
 )

pkg/modules/pdfcpu/pdfcpu_test.go

@@ -71,6 +71,59 @@ func TestPdfCpu_Validate(t *testing.T) {
 	}
 }
 
+func TestPdfCpu_Debug(t *testing.T) {
+	for _, tc := range []struct {
+		scenario    string
+		engine      *PdfCpu
+		expect      map[string]interface{}
+		doNotExpect map[string]interface{}
+	}{
+		{
+			scenario: "cannot determine version (command error)",
+			engine: &PdfCpu{
+				binPath: "foo",
+			},
+			expect: map[string]interface{}{
+				"version": `exec: "foo": executable file not found in $PATH`,
+			},
+		},
+		{
+			scenario: "cannot determine version (no pdfcpu)",
+			engine: &PdfCpu{
+				binPath: "echo",
+			},
+			expect: map[string]interface{}{
+				"version": "Unable to determine pdfcpu version",
+			},
+		},
+		{
+			scenario: "success",
+			engine: &PdfCpu{
+				binPath: "pdfcpu",
+			},
+			doNotExpect: map[string]interface{}{
+				"version": "Unable to determine pdfcpu version",
+			},
+		},
+	} {
+		t.Run(tc.scenario, func(t *testing.T) {
+			d := tc.engine.Debug()
+
+			if tc.expect != nil {
+				if !reflect.DeepEqual(d, tc.expect) {
+					t.Errorf("expected '%v' but got '%v'", tc.expect, d)
+				}
+			}
+
+			if tc.doNotExpect != nil {
+				if reflect.DeepEqual(d, tc.doNotExpect) {
+					t.Errorf("did not expect '%v'", d)
+				}
+			}
+		})
+	}
+}
+
 func TestPdfCpu_Merge(t *testing.T) {
 	for _, tc := range []struct {
 		scenario    string