package middleware

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

// Logging returns a middleware that logs each request's method, URL, status
// code, duration, and error (if any) using the provided structured logger.
// Successful responses are logged at Info level; errors at Error level.
func Logging(logger *slog.Logger) Middleware {
	return func(next http.RoundTripper) http.RoundTripper {
		return RoundTripperFunc(func(req *http.Request) (*http.Response, error) {
			start := time.Now()

			resp, err := next.RoundTrip(req)

			duration := time.Since(start)
			attrs := []slog.Attr{
				slog.String("method", req.Method),
				slog.String("url", req.URL.String()),
				slog.Duration("duration", duration),
			}

			if err != nil {
				attrs = append(attrs, slog.String("error", err.Error()))
				logger.LogAttrs(req.Context(), slog.LevelError, "request failed", attrs...)
				return resp, err
			}

			attrs = append(attrs, slog.Int("status", resp.StatusCode))
			logger.LogAttrs(req.Context(), slog.LevelInfo, "request completed", attrs...)

			return resp, nil
		})
	}
}