feat: add theme support

Author: Watt3r

README.md

@@ -32,6 +32,8 @@ D2-Live is a dynamic tool for creating live, embeddable diagrams using the D2 la
 
 ![Diagram Example](https://d2.atlas.lucas.tools/?script=LNExDsIwEETR3qf4nSt8ABeUSNCGCzhkRSxIHGUXiHN6ZET9NKORZotcx2ReuRfDCr1go9CLGktekwln_xZaFBWZ3cbhSHU10hWy8Smv59BoCiG42nSPXNLtQbf8FnttnZOgllZTt0dOaRDybIX_ge4bAAD__w%3D%3D)
 
+You can use any of the [D2-Themes](https://d2lang.com/tour/themes) to customize the look of your diagram, just add `&theme=<theme_id>` to the URL.
+
 ## Contributing to D2-Live
 We welcome contributions! Please refer to our [Contribution Guidelines](https://github.com/Watt3r/d2-live/CONTRIBUTING.md) for details on how to submit changes, coding standards, and testing procedures.
 

go.mod

@@ -5,7 +5,6 @@ go 1.20
 require (
 	github.com/DataDog/datadog-go/v5 v5.3.0
 	github.com/husobee/vestigo v1.1.1
-	github.com/smartystreets/assertions v1.13.1
 	github.com/stretchr/testify v1.8.1
 	oss.terrastruct.com/d2 v0.4.1
 )
@@ -31,7 +30,6 @@ require (
 	github.com/mazznoer/csscolorparser v0.1.3 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.4.3 // indirect
-	github.com/stretchr/objx v0.5.0 // indirect
 	github.com/yuin/goldmark v1.5.3 // indirect
 	go.opencensus.io v0.24.0 // indirect
 	golang.org/x/crypto v0.0.0-20210921155107-089bfa567519 // indirect

go.sum

@@ -109,8 +109,6 @@ github.com/rogpeppe/go-internal v1.6.1 h1:/FiVV8dS/e+YqF2JvO3yXRFbBLTIuSDkuC7aBO
 github.com/rogpeppe/go-internal v1.6.1/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/ruudk/golang-pdf417 v0.0.0-20181029194003-1af4ab5afa58/go.mod h1:6lfFZQK844Gfx8o5WFuvpxWRwnSoipWe/p622j1v06w=
 github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
-github.com/smartystreets/assertions v1.13.1 h1:Ef7KhSmjZcK6AVf9YbJdvPYG9avaF0ZxudX+ThRdWfU=
-github.com/smartystreets/assertions v1.13.1/go.mod h1:cXr/IwVfSo/RbCSPhoAPv73p3hlSdrBH/b3SdnW/LMY=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0 h1:1zr/of2m5FGMsad5YfcqgdqdWrIhu+EBEJRhR1U7z/c=

internal/handlers/get_svg.go

@@ -4,12 +4,14 @@ import (
 	"context"
 	"errors"
 	"net/http"
+	"strconv"
 
 	"github.com/husobee/vestigo"
 	"github.com/watt3r/d2-live/internal/urlenc"
 	"oss.terrastruct.com/d2/d2layouts/d2dagrelayout"
 	"oss.terrastruct.com/d2/d2lib"
 	"oss.terrastruct.com/d2/d2renderers/d2svg"
+	"oss.terrastruct.com/d2/d2themes/d2themescatalog"
 	"oss.terrastruct.com/d2/lib/textmeasure"
 )
 
@@ -30,10 +32,25 @@ func (c *Controller) GetD2SVGHandler(rw http.ResponseWriter, req *http.Request)
 		return
 	}
 
+	// Get theme if provided
+	themeStr := req.URL.Query().Get("theme")
+	var theme int64
+	var err error
+	if themeStr != "" {
+		theme, err = strconv.ParseInt(themeStr, 10, 64)
+		if err != nil {
+			http.Error(rw, "Invalid theme parameter", http.StatusBadRequest)
+			return
+		}
+	} else {
+		// Use a default theme if none is provided
+		theme = d2themescatalog.NeutralDefault.ID
+	}
+
 	// Emit complexity metric
 	c.Metrics.Histogram("d2-live.complexity", float64(len(urlencoded)), []string{}, 1)
 
-	svg, err := c.handleGetD2SVG(ctx, urlencoded)
+	svg, err := c.handleGetD2SVG(ctx, urlencoded, theme)
 
 	if err != nil {
 		http.Error(rw, err.Error(), http.StatusBadRequest)
@@ -44,7 +61,7 @@ func (c *Controller) GetD2SVGHandler(rw http.ResponseWriter, req *http.Request)
 	rw.Write(svg)
 }
 
-func (c *Controller) handleGetD2SVG(ctx context.Context, encoded string) ([]byte, error) {
+func (c *Controller) handleGetD2SVG(ctx context.Context, encoded string, theme int64) ([]byte, error) {
 	decoded, err := urlenc.Decode(encoded)
 	if err != nil {
 		return nil, errors.New("Invalid Base64 data.")
@@ -59,7 +76,8 @@ func (c *Controller) handleGetD2SVG(ctx context.Context, encoded string) ([]byte
 
 	// Render to SVG
 	out, err := d2svg.Render(diagram, &d2svg.RenderOpts{
-		Pad: d2svg.DEFAULT_PADDING,
+		Pad:     d2svg.DEFAULT_PADDING,
+		ThemeID: theme,
 	})
 	if err != nil {
 		return nil, errors.New("Invalid D2 data.")

internal/handlers/get_svg_test.go

@@ -16,6 +16,7 @@ func TestController_GetD2SVGHandler(t *testing.T) {
 	type state struct {
 		pathEncoded  string
 		queryEncoded string
+		queryTheme   string
 	}
 	type want struct {
 		code int
@@ -28,8 +29,11 @@ func TestController_GetD2SVGHandler(t *testing.T) {
 	}{
 		{"happy path with path param", state{pathEncoded: "qlDQtVOo5AIEAAD__w=="}, want{200, "<?xml version=\"1.0\" encoding=\"utf-8\"?>"}},
 		{"happy path with query param", state{queryEncoded: "qlDQtVOo5AIEAAD__w=="}, want{200, "<?xml version=\"1.0\" encoding=\"utf-8\"?>"}},
+		{"happy path with valid theme", state{queryEncoded: "qlDQtVOo5AIEAAD__w==", queryTheme: "100"}, want{200, "<?xml version=\"1.0\" encoding=\"utf-8\"?>"}},
 		{"fail bad request with path param", state{pathEncoded: "qlDQtVOo5AIEAAD__w==&"}, want{400, "Invalid Base64 data."}},
 		{"fail bad request with query param", state{queryEncoded: "qlDQtVOo5AIEAAD__w==&"}, want{400, "Invalid Base64 data."}},
+		{"fail bad request with no param", state{}, want{400, "encodedD2 or script parameter not provided"}},
+		{"fail bad request with invalid theme", state{queryEncoded: "qlDQtVOo5AIEAAD__w==", queryTheme: "invalid"}, want{400, "Invalid theme parameter"}},
 	}
 
 	for _, tc := range testCases {
@@ -44,6 +48,9 @@ func TestController_GetD2SVGHandler(t *testing.T) {
 			if tc.state.queryEncoded != "" {
 				q.Set("script", tc.state.queryEncoded)
 			}
+			if tc.state.queryTheme != "" {
+				q.Set("theme", tc.state.queryTheme)
+			}
 			req.URL.RawQuery = q.Encode()
 
 			resp := httptest.NewRecorder()