lookbook/internal/handlers/handler.go

package handlers

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

// Handler is a function that handles HTTP requests and can return an error.
// It receives a RequestContext with injected dependencies (DB, Logger).
type Handler func(rc *RequestContext, w http.ResponseWriter, r *http.Request) error

// WithErrorHandling wraps a Handler to automatically handle errors.
func WithErrorHandling(rc *RequestContext, h Handler) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		wrapper := &responseWrapper{
			ResponseWriter: w,
			written:        false,
		}

		err := h(rc, wrapper, r)
		if err != nil {
			rc.Logger.Error("handler error",
				slog.String("method", r.Method),
				slog.String("path", r.URL.Path),
				slog.Any("error", err),
			)

			if !wrapper.written {
				http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			}
		}
	}
}

// responseWrapper tracks if response was written
type responseWrapper struct {
	http.ResponseWriter
	written bool
}

func (w *responseWrapper) Write(b []byte) (int, error) {
	w.written = true
	return w.ResponseWriter.Write(b)
}

func (w *responseWrapper) WriteHeader(statusCode int) {
	w.written = true
	w.ResponseWriter.WriteHeader(statusCode)
}