From 54414dab9352a608c8ced947a2395e471efd069c Mon Sep 17 00:00:00 2001
From: Fabian Quist <frog_from_the_lake@gmx.de>
Date: Wed, 14 Feb 2024 21:16:30 +0100
Subject: [PATCH] feat(errors, validator): improve error handling, added
 validator

---
 gapi/error.go          | 81 ++++++++++++++++++++++++++++++++++++++++++
 go.mod                 |  2 +-
 validator/validator.go | 33 +++++++++++++++++
 3 files changed, 115 insertions(+), 1 deletion(-)
 create mode 100644 gapi/error.go
 create mode 100644 validator/validator.go

diff --git a/gapi/error.go b/gapi/error.go
new file mode 100644
index 0000000..37d601d
--- /dev/null
+++ b/gapi/error.go
@@ -0,0 +1,81 @@
+package gapi
+
+import (
+	"errors"
+	"strings"
+
+	"github.com/jackc/pgx/v5/pgconn"
+	"google.golang.org/genproto/googleapis/rpc/errdetails"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func fieldViolation(field string, err error) *errdetails.BadRequest_FieldViolation {
+	return &errdetails.BadRequest_FieldViolation{
+		Field:       field,
+		Description: err.Error(),
+	}
+}
+
+func invalidArgumentError(violations []*errdetails.BadRequest_FieldViolation) error {
+	badRequest := &errdetails.BadRequest{FieldViolations: violations}
+	statusInvalid := status.New(codes.InvalidArgument, "invalid parameters")
+
+	statusDetails, err := statusInvalid.WithDetails(badRequest)
+	if err != nil {
+		return statusInvalid.Err()
+	}
+
+	return statusDetails.Err()
+}
+
+type MultiError []error
+
+func (me MultiError) Error() string {
+	var sb strings.Builder
+	for _, err := range me {
+		sb.WriteString(err.Error())
+		sb.WriteString("\n")
+	}
+	return sb.String()
+}
+
+func handleDatabaseError(err error) error {
+	var pgErr *pgconn.PgError
+	var errs MultiError
+
+	if errors.As(err, &pgErr) {
+		switch pgErr.Code {
+		case "23505": // unique_violation
+			errs = append(errs, status.Errorf(codes.AlreadyExists, "unique violation occurred: %v", err))
+		case "23503": // foreign_key_violation
+			errs = append(errs, status.Errorf(codes.FailedPrecondition, "foreign key violation occurred: %v", err))
+		case "23502": // not_null_violation
+			errs = append(errs, status.Errorf(codes.InvalidArgument, "not null violation occurred: %v", err))
+		case "23514": // check_violation
+			errs = append(errs, status.Errorf(codes.OutOfRange, "check violation occurred: %v", err))
+		case "2200L": // invalid_text_representation
+			errs = append(errs, status.Errorf(codes.InvalidArgument, "invalid text representation: %v", err))
+		case "22P02": // invalid_text_representation
+			errs = append(errs, status.Errorf(codes.InvalidArgument, "invalid text representation: %v", err))
+		case "23P01": // exclusion_violation
+			errs = append(errs, status.Errorf(codes.AlreadyExists, "exclusion violation occurred: %v", err))
+		case "25006": // read_only_sql_transaction
+			errs = append(errs, status.Errorf(codes.PermissionDenied, "read-only SQL transaction: %v", err))
+		case "22023": // no_data
+			errs = append(errs, status.Errorf(codes.NotFound, "no data: %v", err))
+		case "54000": // too_many_connections
+			errs = append(errs, status.Errorf(codes.ResourceExhausted, "too many connections: %v", err))
+		default:
+			errs = append(errs, status.Errorf(codes.Unknown, "unknown database error: %v", err))
+		}
+	} else {
+		errs = append(errs, status.Errorf(codes.Internal, "internal error: %v", err))
+	}
+
+	if len(errs) > 0 {
+		return errs
+	}
+
+	return nil
+}
diff --git a/go.mod b/go.mod
index 1116c47..dc2c0ca 100644
--- a/go.mod
+++ b/go.mod
@@ -15,6 +15,7 @@ require (
 	golang.org/x/crypto v0.18.0
 	golang.org/x/net v0.20.0
 	google.golang.org/genproto/googleapis/api v0.0.0-20240205150955-31a09d347014
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240125205218-1f4bbc51befe
 	google.golang.org/grpc v1.61.0
 	google.golang.org/protobuf v1.32.0
 )
@@ -65,7 +66,6 @@ require (
 	golang.org/x/sys v0.16.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	google.golang.org/genproto v0.0.0-20240125205218-1f4bbc51befe // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20240125205218-1f4bbc51befe // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/validator/validator.go b/validator/validator.go
new file mode 100644
index 0000000..a921481
--- /dev/null
+++ b/validator/validator.go
@@ -0,0 +1,33 @@
+package validator
+
+import (
+	"fmt"
+	"time"
+)
+
+// Function to validate a string value based on the minimum and maximum length
+func ValidateString(value string, minLen int, maxLen int) error {
+	n := len(value)
+	if n < minLen || n > maxLen {
+		return fmt.Errorf("must contain %d-%d characters", minLen, maxLen)
+	}
+	return nil
+}
+
+// Function to validate UserId
+func ValidateUserId(userId int64) error {
+	// Assuming the UserId should be a positive integer
+	if userId <= 0 {
+		return fmt.Errorf("UserId must be a positive integer")
+	}
+	return nil
+}
+
+// ValidateDuration checks if the given string can be parsed as a duration
+func ValidateDuration(durationStr string) error {
+	_, err := time.ParseDuration(durationStr)
+	if err != nil {
+		return fmt.Errorf("invalid duration format: %w", err)
+	}
+	return nil
+}