package server

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

// RecoveryOption configures the Recovery middleware.
type RecoveryOption func(*recoveryOptions)

type recoveryOptions struct {
	logger *slog.Logger
}

// WithRecoveryLogger sets the logger for the Recovery middleware.
// If not set, panics are recovered silently (500 is still returned).
func WithRecoveryLogger(l *slog.Logger) RecoveryOption {
	return func(o *recoveryOptions) { o.logger = l }
}

// Recovery returns a middleware that recovers from panics in downstream
// handlers. A recovered panic results in a 500 Internal Server Error
// response and is logged (if a logger is configured) with the stack trace.
func Recovery(opts ...RecoveryOption) Middleware {
	o := &recoveryOptions{}
	for _, opt := range opts {
		opt(o)
	}

	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			defer func() {
				if v := recover(); v != nil {
					if o.logger != nil {
						o.logger.LogAttrs(r.Context(), slog.LevelError, "panic recovered",
							slog.Any("panic", v),
							slog.String("stack", string(debug.Stack())),
							slog.String("method", r.Method),
							slog.String("path", r.URL.Path),
							slog.String("request_id", RequestIDFromContext(r.Context())),
						)
					}
					http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
				}
			}()
			next.ServeHTTP(w, r)
		})
	}
}