package utils

import (
	"context"
	"errors"
	"net/http"
	"time"
)

// ServeHTTP drains requests before its caller closes databases and files.
func ServeHTTP(ctx context.Context, address string, handler http.Handler) error {
	server := &http.Server{Addr: address, Handler: handler, ReadHeaderTimeout: 10 * time.Second, IdleTimeout: 60 * time.Second}
	finished := make(chan struct{})
	defer close(finished)
	shutdownDone := make(chan struct{})
	go func() {
		defer close(shutdownDone)
		select {
		case <-ctx.Done():
			timeout, cancel := context.WithTimeout(context.Background(), 10*time.Second)
			defer cancel()
			if err := server.Shutdown(timeout); err != nil {
				_ = server.Close()
			}
		case <-finished:
		}
	}()
	err := server.ListenAndServe()
	if errors.Is(err, http.ErrServerClosed) {
		<-shutdownDone
		return nil
	}
	return err
}