package server

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

	"github.com/dhao2001/mygo/internal/config"
)

// Address returns the HTTP listen address for a server config.
func Address(cfg config.ServerConfig) string {
	return fmt.Sprintf("%s:%d", cfg.Host, cfg.Port)
}

// RunWithGracefulShutdown starts an HTTP server and shuts it down when ctx is canceled.
func RunWithGracefulShutdown(ctx context.Context, addr string, handler http.Handler) error {
	if handler == nil {
		return errors.New("handler: must not be nil")
	}

	httpServer := &http.Server{
		Addr:              addr,
		Handler:           handler,
		ReadHeaderTimeout: 5 * time.Second,
	}

	errCh := make(chan error, 1)
	go func() {
		errCh <- httpServer.ListenAndServe()
	}()

	select {
	case <-ctx.Done():
		shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		if err := httpServer.Shutdown(shutdownCtx); err != nil {
			return fmt.Errorf("shutdown server: %w", err)
		}
		return nil
	case err := <-errCh:
		if errors.Is(err, http.ErrServerClosed) {
			return nil
		}
		return fmt.Errorf("listen and serve: %w", err)
	}
}