Use Accept header for returning JSON instead of plain text

main.go

@@ -177,12 +177,19 @@ func main() {
 			return
 		}
 
-		for _, d := range departures.Departures {
-			fmt.Fprintf(w, "%2s %-11s %6s\n",
-				d.Symbol,
-				d.Direction[:min(11, len(d.Direction))],
-				d.Leaving,
-			)
+		// Does not handle multiple media types
+		if r.Header.Get("Accept") == "application/json" {
+			w.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(w).Encode(departures)
+		} else {
+			// plain text
+			for _, d := range departures.Departures {
+				fmt.Fprintf(w, "%2s %-11s %6s\n",
+					d.Symbol,
+					d.Direction[:min(11, len(d.Direction))],
+					d.Leaving,
+				)
+			}
 		}
 	})
 	log.Fatal(http.ListenAndServe(":8000", nil))