Support localhost hosts

Author: williammartin

internal/ghmcp/server.go

@@ -249,6 +249,41 @@ type apiHost struct {
 	rawURL      *url.URL
 }
 
+// newLocalhostHost creates a new apiHost for localhost, which is used for development purposes.
+func newLocalhostHost(hostname string) (apiHost, error) {
+	u, err := url.Parse(hostname)
+	if err != nil {
+		return apiHost{}, fmt.Errorf("failed to parse localhost URL: %w", err)
+	}
+
+	restURL, err := url.Parse(fmt.Sprintf("%s://api.%s/", u.Scheme, u.Hostname()))
+	if err != nil {
+		return apiHost{}, fmt.Errorf("failed to parse localhost REST URL: %w", err)
+	}
+
+	gqlURL, err := url.Parse(fmt.Sprintf("%s://api.%s/graphql", u.Scheme, u.Hostname()))
+	if err != nil {
+		return apiHost{}, fmt.Errorf("failed to parse localhost GraphQL URL: %w", err)
+	}
+
+	uploadURL, err := url.Parse(fmt.Sprintf("%s://uploads.%s", u.Scheme, u.Hostname()))
+	if err != nil {
+		return apiHost{}, fmt.Errorf("failed to parse localhost Upload URL: %w", err)
+	}
+
+	rawURL, err := url.Parse(fmt.Sprintf("%s://raw.%s/", u.Scheme, u.Hostname()))
+	if err != nil {
+		return apiHost{}, fmt.Errorf("failed to parse localhost Raw URL: %w", err)
+	}
+
+	return apiHost{
+		baseRESTURL: restURL,
+		graphqlURL:  gqlURL,
+		uploadURL:   uploadURL,
+		rawURL:      rawURL,
+	}, nil
+}
+
 func newDotcomHost() (apiHost, error) {
 	baseRestURL, err := url.Parse("https://api.github.com/")
 	if err != nil {
@@ -365,6 +400,10 @@ func parseAPIHost(s string) (apiHost, error) {
 		return apiHost{}, fmt.Errorf("host must have a scheme (http or https): %s", s)
 	}
 
+	if strings.HasSuffix(u.Hostname(), "localhost") {
+		return newLocalhostHost(s)
+	}
+
 	if strings.HasSuffix(u.Hostname(), "github.com") {
 		return newDotcomHost()
 	}