From 9726827706004a610a53a70ee649512b63945abf Mon Sep 17 00:00:00 2001
From: sam <sam@sleepycat.moe>
Date: Wed, 27 Dec 2023 01:44:41 +0100
Subject: [PATCH] improve parse errors, they now return type errors, no field
 name though because that's broken for some reason

---
 backend/routes/v2/admin/user_action.go | 20 ++--------
 backend/server/error_v2.go             | 52 ++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 17 deletions(-)

diff --git a/backend/routes/v2/admin/user_action.go b/backend/routes/v2/admin/user_action.go
index ee079c9..90e4569 100644
--- a/backend/routes/v2/admin/user_action.go
+++ b/backend/routes/v2/admin/user_action.go
@@ -1,11 +1,8 @@
 package admin
 
 import (
-	"encoding/json"
 	"net/http"
-	"reflect"
 
-	"codeberg.org/pronounscc/pronouns.cc/backend/log"
 	"codeberg.org/pronounscc/pronouns.cc/backend/server"
 	"github.com/aarondl/opt/omit"
 	"github.com/go-chi/render"
@@ -68,22 +65,11 @@ func (s *Server) UserAction(w http.ResponseWriter, r *http.Request) (err error)
 	ctx := r.Context()
 	claims, _ := server.ClaimsFromContext(ctx)
 
-	var req UserActionRequest
-	err = json.NewDecoder(r.Body).Decode(&req)
+	req, err := server.Decode[UserActionRequest](r)
 	if err != nil {
-		// TODO: figure out why this isn't working
-		log.Debug(reflect.TypeOf(err).String())
-		log.Debugf("%#v", err)
-		log.Debugf("%T", err)
-		if pe, ok := err.(*json.UnmarshalTypeError); ok {
-			log.Debugf("value = %q, field = %q\n", pe.Value, pe.Field)
-		} else {
-			log.Debugf("type assertion for %T to *json.UnmarshalTypeError failed", err)
-		}
-
-		return server.NewV2Error(server.ErrBadRequest, "")
+		return err
 	}
-
+	// validate input
 	if errs := req.Validate(); len(errs) != 0 {
 		return server.NewV2Error(server.ErrBadRequest, "", errs...)
 	}
diff --git a/backend/server/error_v2.go b/backend/server/error_v2.go
index ac6474d..e413c54 100644
--- a/backend/server/error_v2.go
+++ b/backend/server/error_v2.go
@@ -1,8 +1,12 @@
 package server
 
 import (
+	"encoding/json"
 	"fmt"
+	"io"
+	"net/http"
 
+	json2 "github.com/aarondl/json"
 	"github.com/getsentry/sentry-go"
 )
 
@@ -58,6 +62,9 @@ type ModelParseError struct {
 	ExpectedValues []any `json:"expected_values,omitempty"`
 	ActualValue    any   `json:"actual_value,omitempty"`
 
+	ExpectedType string `json:"expected_type,omitempty"`
+	ActualType   string `json:"actual_type,omitempty"`
+
 	Key string `json:"-"`
 }
 
@@ -82,3 +89,48 @@ func NewModelParseErrorWithValues(key, message string, expectedValues []any, act
 		ActualValue:    actualValue,
 	}
 }
+
+func ParseJSONError(err error) *ModelParseError {
+	switch pe := err.(type) {
+	case *json.UnmarshalTypeError:
+		key := pe.Field
+		if key == "" {
+			key = "parse"
+		}
+
+		return &ModelParseError{
+			Key:          key,
+			ExpectedType: pe.Type.String(),
+			ActualType:   pe.Value,
+		}
+	case *json2.UnmarshalTypeError:
+		key := pe.Field
+		if key == "" {
+			key = "parse"
+		}
+
+		return &ModelParseError{
+			Key:          key,
+			ExpectedType: pe.Type.String(),
+			ActualType:   pe.Value,
+		}
+	}
+
+	return nil
+}
+
+func Decode[T any](r *http.Request) (T, error) {
+	var t T
+
+	b, _ := io.ReadAll(r.Body)
+	err := json.Unmarshal(b, &t)
+	// err := render.Decode(r, &t)
+	if err != nil {
+		pe := ParseJSONError(err)
+		if pe != nil {
+			return t, NewV2Error(ErrBadRequest, "", *pe)
+		}
+		return t, NewV2Error(ErrBadRequest, "")
+	}
+	return t, nil
+}