feat: proxy requests to service adapter upstreams instead of echoing

internal/serviceadapter/router.go

@@ -2,7 +2,11 @@ package serviceadapter
 
 import (
 	"fmt"
+	"net"
 	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"time"
 
 	"forgejo.riotpiao.com/rock/homelab-frontend/internal/problem"
 )
@@ -104,12 +108,36 @@ func (d *Dispatcher) Dispatch(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	// TODO: Call upstream with method.UpstreamPath, apply retry logic, etc.
-	// For now, just echo that dispatch would happen
-	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(http.StatusOK)
-	fmt.Fprintf(w, `{"service":"%s","resource":"%s","method":"%s","upstream":"%s"}`,
-		serviceName, resourceName, r.Method, adapter.Spec.Upstream.URL)
+	// Build upstream URL
+	upstreamURL, err := url.Parse(adapter.Spec.Upstream.URL)
+	if err != nil {
+		d.writeError(w, problem.NewProblem(http.StatusInternalServerError, "about:blank#server-error",
+			"Internal Server Error", fmt.Sprintf("invalid upstream URL: %v", err)))
+		return
+	}
+
+	// Create reverse proxy with director that rewrites the path
+	proxy := httputil.NewSingleHostReverseProxy(upstreamURL)
+	proxy.Director = func(req *http.Request) {
+		req.URL.Scheme = upstreamURL.Scheme
+		req.URL.Host = upstreamURL.Host
+		req.URL.Path = method.UpstreamPath
+		req.RequestURI = ""
+		req.Host = upstreamURL.Host
+	}
+
+	// Set timeout
+	timeout := adapter.Spec.Upstream.TimeoutSeconds
+	if timeout <= 0 {
+		timeout = 30
+	}
+	proxy.Transport = &http.Transport{
+		DialContext:         (&net.Dialer{Timeout: time.Duration(timeout) * time.Second}).DialContext,
+		TLSHandshakeTimeout: time.Duration(timeout) * time.Second,
+	}
+
+	// Forward the request
+	proxy.ServeHTTP(w, r)
 }
 
 // hasCapability checks if the request has the required capability.