package webserver

import (
	"context"
	"errors"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"
)

const defaultTimeout = 90 * time.Second
const defaultShutdownTimeout = 10 * time.Second

type cleanupFunc func() error

// ExecuteServerParams are the parameters expected in the ExecuteServer function.
type ExecuteServerParams struct {
	Cleanup         cleanupFunc
	ShutdownTimeout *time.Duration
}

// ExecuteServer will launche a http.Server and handle the "exit" signals and gracefully stop the server
// and call the cleanup function.
func ExecuteServer(ctx context.Context, srv *http.Server, params *ExecuteServerParams) {

	if srv == nil {
		log.Panicf("missing http.server params")
		return
	}

	if srv.ReadTimeout == 0 {
		srv.ReadTimeout = defaultTimeout
	}

	if srv.WriteTimeout == 0 {
		srv.WriteTimeout = defaultTimeout
	}

	log.Printf("launching webserver on %s", srv.Addr)

	go func() {
		if err := srv.ListenAndServe(); !errors.Is(err, http.ErrServerClosed) {
			log.Panicf("HTTP server error: %v", err)
			return
		}
		log.Printf("Stopped serving new connections.")
	}()

	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
	<-sigChan

	shutdownCtx, shutdownRelease := context.WithTimeout(ctx, defaultShutdownTimeout)
	defer shutdownRelease()

	if err := srv.Shutdown(shutdownCtx); err != nil {
		log.Panicf("HTTP shutdown error: %v", err)
		return
	}

	if params != nil && params.Cleanup != nil {
		if err := params.Cleanup(); err != nil {
			log.Panicf("Impossible to cleanup correctly after shutdown. error : %v", err)
			return
		}
	}

	log.Print("Graceful shutdown complete.")
}