feat(rewriter): add redirect(), get_cookie(), add_cookie() methods to rule engine (#36)

internal/rule/http/response.go

@@ -3,6 +3,7 @@ package http
 import (
 	"context"
 	"fmt"
+	"net/http"
 	"strconv"
 	"strings"
 	"time"
@@ -41,7 +42,7 @@ func addResponseHeaderFunc() expr.Option {
 				value = fmt.Sprintf("%v", rawValue)
 			}
 
-			r, ok := ctxResponse(ctx)
+			r, ok := CtxResponse(ctx)
 			if !ok {
 				return nil, errors.New("could not find http response in context")
 			}
@@ -82,7 +83,7 @@ func setResponseHeaderFunc() expr.Option {
 				value = fmt.Sprintf("%v", rawValue)
 			}
 
-			r, ok := ctxResponse(ctx)
+			r, ok := CtxResponse(ctx)
 			if !ok {
 				return nil, errors.New("could not find http response in context")
 			}
@@ -109,7 +110,7 @@ func delResponseHeadersFunc() expr.Option {
 				return nil, errors.WithStack(err)
 			}
 
-			r, ok := ctxResponse(ctx)
+			r, ok := CtxResponse(ctx)
 			if !ok {
 				return nil, errors.New("could not find http response in context")
 			}
@@ -130,3 +131,84 @@ func delResponseHeadersFunc() expr.Option {
 		new(func(context.Context, string) bool),
 	)
 }
+
+func addResponseCookieFunc() expr.Option {
+	return expr.Function(
+		"add_cookie",
+		func(params ...any) (any, error) {
+			ctx, err := rule.Assert[context.Context](params[0])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			values, err := rule.Assert[map[string]any](params[1])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			cookie, err := cookieFrom(values)
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			r, ok := CtxResponse(ctx)
+			if !ok {
+				return nil, errors.New("could not find http request in context")
+			}
+
+			r.Header.Add("Set-Cookie", cookie.String())
+
+			return true, nil
+		},
+		new(func(context.Context, map[string]any) bool),
+	)
+}
+
+func getResponseCookieFunc() expr.Option {
+	return expr.Function(
+		"get_cookie",
+		func(params ...any) (any, error) {
+			ctx, err := rule.Assert[context.Context](params[0])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			name, err := rule.Assert[string](params[1])
+			if err != nil {
+				return nil, errors.WithStack(err)
+			}
+
+			res, ok := CtxResponse(ctx)
+			if !ok {
+				return nil, errors.New("could not find http response in context")
+			}
+
+			var cookie *http.Cookie
+			for _, c := range res.Cookies() {
+				if c.Name != name {
+					continue
+				}
+
+				cookie = c
+				break
+			}
+
+			if cookie == nil {
+				return nil, nil
+			}
+
+			return CookieVar{
+				Name:     cookie.Name,
+				Value:    cookie.Value,
+				Path:     cookie.Path,
+				Domain:   cookie.Domain,
+				Expires:  cookie.Expires,
+				MaxAge:   cookie.MaxAge,
+				Secure:   cookie.Secure,
+				HttpOnly: cookie.HttpOnly,
+				SameSite: cookie.SameSite,
+			}, nil
+		},
+		new(func(context.Context, string) CookieVar),
+	)
+}