package main

import (
	"fmt"
	"net/http"
)

// recoverPanic provides middleware for recovering from panics in the same goroutine that
// executred the recoverPanic middleware.
//
// This means that panics from goroutines created in handler operations will still need
// to be handled separately.Failure to do so will cause the application to exit and bring
// down the server.
func (app *application) recoverPanic(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Create a deferred function (which will always be run in the event of a panic
		// as Go unwinds the stack).
		defer func() {
			if err := recover(); err != nil {
				// If there was a panic, set a "Connection: close" header on the
				// response. This acts as a trigger to make Go's HTTP server
				// automatically close the current connection after a response has been
				// sent.
				w.Header().Set("Connection", "close")
				app.serverErrorResponse(w, r, fmt.Errorf("%s", http.ErrAbortHandler))
			}
		}()
		next.ServeHTTP(w, r)
	})
}