dev

internal/httprule/rule.go

@@ -0,0 +1,94 @@
+package httprule
+
+import (
+	"fmt"
+	"net/http"
+
+	"google.golang.org/genproto/googleapis/api/annotations"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
+)
+
+func Get(m protoreflect.MethodDescriptor) (*annotations.HttpRule, bool) {
+	descriptor, ok := proto.GetExtension(m.Options(), annotations.E_Http).(*annotations.HttpRule)
+	if !ok || descriptor == nil {
+		return nil, false
+	}
+	return descriptor, true
+}
+
+type Rule struct {
+	// The HTTP method to use.
+	Method string
+	// The template describing the URL to use.
+	Template        Template
+	Body            string
+	AdditionalRules []Rule
+}
+
+func ParseRule(httpRule *annotations.HttpRule) (Rule, error) {
+	method, err := httpRuleMethod(httpRule)
+	if err != nil {
+		return Rule{}, err
+	}
+	url, err := httpRuleURL(httpRule)
+	if err != nil {
+		return Rule{}, err
+	}
+	template, err := ParseTemplate(url)
+	if err != nil {
+		return Rule{}, err
+	}
+	additional := make([]Rule, len(httpRule.GetAdditionalBindings()))
+	for i, r := range httpRule.GetAdditionalBindings() {
+		a, err := ParseRule(r)
+		if err != nil {
+			return Rule{}, fmt.Errorf("parse additional binding %d: %w", i, err)
+		}
+		additional[i] = a
+	}
+	return Rule{
+		Method:          method,
+		Template:        template,
+		Body:            httpRule.GetBody(),
+		AdditionalRules: additional,
+	}, nil
+}
+
+func httpRuleURL(rule *annotations.HttpRule) (string, error) {
+	switch v := rule.GetPattern().(type) {
+	case *annotations.HttpRule_Get:
+		return v.Get, nil
+	case *annotations.HttpRule_Post:
+		return v.Post, nil
+	case *annotations.HttpRule_Delete:
+		return v.Delete, nil
+	case *annotations.HttpRule_Patch:
+		return v.Patch, nil
+	case *annotations.HttpRule_Put:
+		return v.Put, nil
+	case *annotations.HttpRule_Custom:
+		return v.Custom.GetPath(), nil
+	default:
+		return "", fmt.Errorf("http rule does not have an URL defined")
+	}
+}
+
+func httpRuleMethod(rule *annotations.HttpRule) (string, error) {
+	switch v := rule.GetPattern().(type) {
+	case *annotations.HttpRule_Get:
+		return http.MethodGet, nil
+	case *annotations.HttpRule_Post:
+		return http.MethodPost, nil
+	case *annotations.HttpRule_Delete:
+		return http.MethodDelete, nil
+	case *annotations.HttpRule_Patch:
+		return http.MethodPatch, nil
+	case *annotations.HttpRule_Put:
+		return http.MethodPut, nil
+	case *annotations.HttpRule_Custom:
+		return v.Custom.GetKind(), nil
+	default:
+		return "", fmt.Errorf("http rule does not have an URL defined")
+	}
+}