Split embedded and standalone chart surfaces

viewer/handler.go

@@ -1,7 +1,10 @@
 package viewer
 
 import (
+	"errors"
+	"fmt"
 	"io"
+	"mime"
 	"net/http"
 	"strings"
 
@@ -9,10 +12,21 @@ import (
 )
 
 type HandlerOptions struct {
-	Title string
+	Title      string
+	Standalone bool
 }
 
 func NewHandler(opts HandlerOptions) http.Handler {
+	opts.Standalone = false
+	return newHandler(opts)
+}
+
+func NewStandaloneHandler(opts HandlerOptions) http.Handler {
+	opts.Standalone = true
+	return newHandler(opts)
+}
+
+func newHandler(opts HandlerOptions) http.Handler {
 	title := strings.TrimSpace(opts.Title)
 	if title == "" {
 		title = "Reanimator Chart"
@@ -25,7 +39,15 @@ func NewHandler(opts HandlerOptions) http.Handler {
 		_, _ = w.Write([]byte("ok"))
 	})
 	mux.HandleFunc("GET /", func(w http.ResponseWriter, r *http.Request) {
-		html, err := RenderHTML(nil, title)
+		var (
+			html []byte
+			err  error
+		)
+		if opts.Standalone {
+			html, err = web.RenderUpload(pageData{Title: title})
+		} else {
+			html, err = RenderHTML(nil, title)
+		}
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
@@ -34,31 +56,28 @@ func NewHandler(opts HandlerOptions) http.Handler {
 		_, _ = w.Write(html)
 	})
 	mux.HandleFunc("POST /render", func(w http.ResponseWriter, r *http.Request) {
-		var payload string
-		if strings.Contains(r.Header.Get("Content-Type"), "application/json") {
-			body, err := io.ReadAll(r.Body)
-			if err != nil {
-				http.Error(w, err.Error(), http.StatusBadRequest)
-				return
-			}
-			payload = string(body)
-		} else {
-			if err := r.ParseForm(); err != nil {
-				http.Error(w, err.Error(), http.StatusBadRequest)
-				return
-			}
-			payload = r.FormValue("snapshot")
+		payload, err := readSnapshotPayload(r)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
 		}
 
 		page, err := buildPageData([]byte(payload), title)
 		if err != nil {
-			page = pageData{
-				Title:     title,
-				Error:     err.Error(),
-				InputJSON: prettyJSON(payload),
+			if opts.Standalone {
+				html, renderErr := web.RenderUpload(pageData{
+					Title: title,
+					Error: err.Error(),
+				})
+				if renderErr != nil {
+					http.Error(w, renderErr.Error(), http.StatusInternalServerError)
+					return
+				}
+				w.Header().Set("Content-Type", "text/html; charset=utf-8")
+				_, _ = w.Write(html)
+				return
 			}
-		} else {
-			page.InputJSON = prettyJSON(payload)
+			page = pageData{Title: title, Error: err.Error()}
 		}
 
 		html, renderErr := web.Render(page)
@@ -71,3 +90,51 @@ func NewHandler(opts HandlerOptions) http.Handler {
 	})
 	return mux
 }
+
+func readSnapshotPayload(r *http.Request) (string, error) {
+	mediaType, _, err := mime.ParseMediaType(r.Header.Get("Content-Type"))
+	if err != nil {
+		return "", fmt.Errorf("parse content type: %w", err)
+	}
+
+	switch mediaType {
+	case "application/json":
+		body, err := io.ReadAll(r.Body)
+		if err != nil {
+			return "", fmt.Errorf("read request body: %w", err)
+		}
+		return string(body), nil
+	case "multipart/form-data":
+		if err := r.ParseMultipartForm(32 << 20); err != nil {
+			return "", fmt.Errorf("parse multipart form: %w", err)
+		}
+
+		payload, err := readSnapshotFile(r, "snapshot_file")
+		if err == nil && strings.TrimSpace(payload) != "" {
+			return payload, nil
+		}
+		if err != nil && !errors.Is(err, http.ErrMissingFile) {
+			return "", err
+		}
+		return r.FormValue("snapshot"), nil
+	default:
+		if err := r.ParseForm(); err != nil {
+			return "", fmt.Errorf("parse form: %w", err)
+		}
+		return r.FormValue("snapshot"), nil
+	}
+}
+
+func readSnapshotFile(r *http.Request, field string) (string, error) {
+	file, _, err := r.FormFile(field)
+	if err != nil {
+		return "", fmt.Errorf("read uploaded file: %w", err)
+	}
+	defer file.Close()
+
+	body, err := io.ReadAll(file)
+	if err != nil {
+		return "", fmt.Errorf("read uploaded file contents: %w", err)
+	}
+	return string(body), nil
+}