Update wasm

cmd/wasm/main.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"syscall/js"
 
+	"github.com/go-pdf/fpdf"
 	"github.com/thegrumpylion/jsref"
 
 	"covergen/pkg/covergen"
@@ -70,6 +71,18 @@ func settingsFromValue(arg js.Value) (*covergen.CoverSettings, error) {
 	}, nil
 }
 
+func pdfToJs(pdf *fpdf.Fpdf) (js.Value, error) {
+	var buf bytes.Buffer
+	if err := pdf.Output(&buf); err != nil {
+		return js.Null(), fmt.Errorf("failed to write pdf: %w", err)
+	}
+
+	s := buf.Bytes()
+	ta := js.Global().Get("Uint8Array").New(len(s))
+	js.CopyBytesToJS(ta, s)
+	return ta, nil
+}
+
 func generateCover(this js.Value, args []js.Value) interface{} {
 	defer func() {
 		if r := recover(); r != nil {
@@ -96,18 +109,61 @@ func generateCover(this js.Value, args []js.Value) interface{} {
 		return jsmap{"error": err.Error()}
 	}
 
-	var buf bytes.Buffer
-	if err = pdf.Output(&buf); err != nil {
+	jsBytes, err := pdfToJs(pdf)
+	if err != nil {
+		return jsmap{"error": err.Error()}
+	}
+	return jsBytes
+}
+
+func generateSplitCover(this js.Value, args []js.Value) interface{} {
+	defer func() {
+		if r := recover(); r != nil {
+			fmt.Println("recovered", r)
+		}
+	}()
+
+	if len(args) != 1 {
+		return jsmap{"error": "missing argument"}
+	}
+
+	arg := args[0]
+	if arg.Type() != js.TypeObject {
+		return jsmap{"error": "expected object"}
+	}
+
+	settings, err := settingsFromValue(arg)
+	if err != nil {
 		return jsmap{"error": err.Error()}
 	}
 
-	s := buf.Bytes()
-	ta := js.Global().Get("Uint8Array").New(len(s))
-	js.CopyBytesToJS(ta, s)
-	return ta
+	front, err := covergen.GenerateFrontCover(*settings)
+	if err != nil {
+		return jsmap{"error": fmt.Sprintf("failed to render front: %s", err.Error())}
+	}
+
+	back, err := covergen.GenerateBackCover(*settings)
+	if err != nil {
+		return jsmap{"error": fmt.Sprintf("failed to render back: %s", err.Error())}
+	}
+
+	frontJSBytes, err := pdfToJs(front)
+	if err != nil {
+		return jsmap{"error": fmt.Sprintf("failed to render front: %s", err.Error())}
+	}
+	backJSBytes, err := pdfToJs(back)
+	if err != nil {
+		return jsmap{"error": fmt.Sprintf("failed to render back: %s", err.Error())}
+	}
+
+	return jsmap{
+		"front": frontJSBytes,
+		"back":  backJSBytes,
+	}
 }
 
 func main() {
-	js.Global().Set("covergen", js.FuncOf(generateCover))
+	js.Global().Set("generateCover", js.FuncOf(generateCover))
+	js.Global().Set("generateSplitCover", js.FuncOf(generateSplitCover))
 	<-make(chan bool)
 }