package server

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

	"go.uber.org/fx"
)

const (
	readTimeout    = 10 * time.Second
	maxHeaderBytes = 1 << 20 // 1 MiB

	// requestTimeout (routes.go) is the single per-request
	// processing budget, enforced by chi's middleware.Timeout.
	// writeTimeout must exceed that budget so a handler can write
	// its 503 when the chi timeout fires; if it were shorter the
	// server would abort the write first and the chi budget would
	// be unreachable dead configuration.
	writeTimeout = requestTimeout + 5*time.Second
)

// newHTTPServer constructs the http.Server. It performs no I/O
// and does not start listening.
func (s *Server) newHTTPServer() *http.Server {
	listenAddr := fmt.Sprintf(":%d", s.params.Config.Port)

	return &http.Server{
		Addr:           listenAddr,
		Handler:        s,
		MaxHeaderBytes: maxHeaderBytes,
		ReadTimeout:    readTimeout,
		WriteTimeout:   writeTimeout,
	}
}

// listenAndServe runs the listener until the server is shut
// down. A genuine listen failure (not the expected
// ErrServerClosed from a clean shutdown) requests process
// shutdown through fx with a non-zero exit code, so the failure
// is visible to any supervisor.
func (s *Server) listenAndServe() {
	s.log.Info("http begin listen",
		"listenaddr", s.httpServer.Addr,
		"version", s.params.Globals.Version,
		"buildarch", s.params.Globals.Buildarch,
	)

	err := s.httpServer.ListenAndServe()
	if err == nil || errors.Is(err, http.ErrServerClosed) {
		return
	}

	s.log.Error("listen error", "error", err)

	shutdownErr := s.shutdowner.Shutdown(fx.ExitCode(1))
	if shutdownErr != nil {
		s.log.Error("request shutdown failed", "error", shutdownErr)
	}
}