photoplaces/backend/internal/handlers/errors.go

// Package handlers
package handlers

import (
	"encoding/json"
	"log/slog"
	"net/http"
)

const maxRequestBodySize = 1 << 20 // 1 MB

// AppEnv is set at startup to control error detail exposure
var AppEnv string

// writeJSON writes a JSON response
func writeJSON(w http.ResponseWriter, status int, v interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(v)
}

// writeError writes an error response.
// In production, internal server errors return a generic message.
// In development, the actual error message is returned.
func writeError(w http.ResponseWriter, status int, msg string, err error) {
	if err != nil {
		slog.Error("handler error", "status", status, "error", err)
	}

	if status == http.StatusInternalServerError && AppEnv == "production" {
		msg = "internal server error"
	}

	writeJSON(w, status, map[string]string{"error": msg})
}

// writeValidationError writes a validation error response (422).
// In production, hides internal field names and rules from the client.
func writeValidationError(w http.ResponseWriter, err error) {
	details := err.Error()
	if AppEnv == "production" {
		slog.Error("validation error", "error", details)
		details = "validation failed"
	}
	writeJSON(w, http.StatusUnprocessableEntity, map[string]interface{}{
		"error":   "validation failed",
		"details": details,
	})
}