data layer

data-layer/api/internal/apperr/apperr.go

@@ -0,0 +1,75 @@
+// Package apperr defines AppError, the single error type returned by every
+// service/repo function. Handlers translate AppError into HTTP responses.
+package apperr
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+)
+
+type AppError struct {
+	Code       int    // HTTP status to return
+	Message    string // user-facing message (safe to expose)
+	Field      string // optional: which field caused the error
+	RetryAfter int    // seconds, for 429
+	Err        error  // original error for logging (never exposed)
+}
+
+func (e *AppError) Error() string {
+	if e.Err != nil {
+		return fmt.Sprintf("%s: %v", e.Message, e.Err)
+	}
+	return e.Message
+}
+
+func (e *AppError) Unwrap() error { return e.Err }
+
+// As reports whether err is or wraps an *AppError.
+func As(err error) (*AppError, bool) {
+	var ae *AppError
+	if errors.As(err, &ae) {
+		return ae, true
+	}
+	return nil, false
+}
+
+// ---------------------------------------------------------------------------
+// Constructors
+// ---------------------------------------------------------------------------
+
+func BadRequest(msg, field string, err error) *AppError {
+	return &AppError{Code: http.StatusBadRequest, Message: msg, Field: field, Err: err}
+}
+
+func Unauthorized(msg string) *AppError {
+	return &AppError{Code: http.StatusUnauthorized, Message: msg}
+}
+
+func Forbidden(msg string) *AppError {
+	return &AppError{Code: http.StatusForbidden, Message: msg}
+}
+
+func NotFound(msg string) *AppError {
+	return &AppError{Code: http.StatusNotFound, Message: msg}
+}
+
+func Conflict(msg string, err error) *AppError {
+	return &AppError{Code: http.StatusConflict, Message: msg, Err: err}
+}
+
+func UnprocessableEntity(msg string) *AppError {
+	return &AppError{Code: http.StatusUnprocessableEntity, Message: msg}
+}
+
+func TooManyRequests(retryAfterSeconds int) *AppError {
+	return &AppError{
+		Code:       http.StatusTooManyRequests,
+		Message:    "rate limit exceeded",
+		RetryAfter: retryAfterSeconds,
+	}
+}
+
+func Internal(err error) *AppError {
+	return &AppError{Code: http.StatusInternalServerError, Message: "internal server error", Err: err}
+}