package middleware

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

type responseWriter struct {
	http.ResponseWriter
	status int
	size   int
}

func (rw *responseWriter) WriteHeader(status int) {
	rw.status = status
	rw.ResponseWriter.WriteHeader(status)
}

func (rw *responseWriter) Write(b []byte) (int, error) {
	n, err := rw.ResponseWriter.Write(b)
	rw.size += n
	return n, err
}

// Logging emits a single structured log line per request once the handler
// returns. The status code defaults to 200 if the handler never explicitly
// calls WriteHeader.
func Logging(logger *slog.Logger) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			start := time.Now()
			rw := &responseWriter{ResponseWriter: w, status: http.StatusOK}
			next.ServeHTTP(rw, r)

			logger.Info("http request",
				"method", r.Method,
				"path", r.URL.Path,
				"status", rw.status,
				"size", rw.size,
				"duration", time.Since(start),
				"request_id", GetRequestID(r.Context()),
			)
		})
	}
}