chore: initial commit

internal/pkg/errors/codes.go

@@ -0,0 +1,62 @@
+// Copyright (C) 2024 Declan Teevan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package errors
+
+import (
+	"google.golang.org/grpc/codes"
+)
+
+type ErrorCode int32
+
+const (
+	ErrCodeUnknown ErrorCode = iota
+
+	ErrCodeService
+	ErrCodeExtService
+
+	ErrCodeNotFound
+	ErrCodeAlreadyExists
+
+	ErrCodeForbidden
+	ErrCodeUnauthorised
+
+	ErrCodeInvalidArgument
+)
+
+// Maps the custom service error codes
+// to their gRPC status code equivalents.
+func (c ErrorCode) GRPCCode() codes.Code {
+	codeMap := map[ErrorCode]codes.Code{
+		ErrCodeUnknown: codes.Unknown,
+
+		ErrCodeService:    codes.Internal,
+		ErrCodeExtService: codes.Unavailable,
+
+		ErrCodeNotFound:      codes.NotFound,
+		ErrCodeAlreadyExists: codes.AlreadyExists,
+
+		ErrCodeForbidden:    codes.PermissionDenied,
+		ErrCodeUnauthorised: codes.PermissionDenied,
+
+		ErrCodeInvalidArgument: codes.InvalidArgument,
+	}
+
+	grpcCode, mapped := codeMap[c]
+	if mapped {
+		return grpcCode
+	}
+	return codes.Unknown
+}

internal/pkg/errors/errors.go

@@ -0,0 +1,71 @@
+// Copyright (C) 2024 Declan Teevan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package errors
+
+import (
+	"fmt"
+
+	"google.golang.org/grpc/status"
+)
+
+type ServiceError struct {
+	code    ErrorCode
+	msg     string
+	wrapped error
+}
+
+func NewServiceError(code ErrorCode, msg string) error {
+	return &ServiceError{
+		code: code,
+		msg:  msg,
+	}
+}
+
+func NewServiceErrorf(code ErrorCode, msg string, args ...interface{}) error {
+	return NewServiceError(code, fmt.Sprintf(msg, args...))
+}
+
+func WrapServiceError(code ErrorCode, msg string, wrapped error) error {
+	return &ServiceError{
+		code:    code,
+		msg:     msg,
+		wrapped: wrapped,
+	}
+}
+
+func (e ServiceError) Error() string {
+	if e.wrapped != nil {
+		return fmt.Sprintf("%s: %s", e.msg, e.wrapped.Error())
+	}
+
+	return e.msg
+}
+
+func (e ServiceError) Code() ErrorCode {
+	return e.code
+}
+
+// Set the gRPC status to only expose the top error message.
+//
+// This is to prevent any full error contexts (from wrapped errors) being exposed to users by the gateway.
+// e.g. "{"code":2,"message":"something went wrong scanning order: failed to connect to `host=postgres user=postgres database=postgres`: hostname resolving error (lookup postgres on 127.0.0.11:53: server misbehaving)","details":[]}"
+func (e ServiceError) GRPCStatus() *status.Status {
+	return status.New(e.Code().GRPCCode(), e.msg)
+}
+
+func (e ServiceError) Unwrap() error {
+	return e.wrapped
+}