package server

import (
	"log/slog"
	"net/http"
	"time"
)

// HTTP server hardening limits. These are the connection-level bounds;
// the per-request deadline is middleware.Timeout, driven by
// REQUEST_TIMEOUT.
const (
	// readHeaderTimeout is the slowloris bound: request headers must
	// arrive within it, and it starts on connection accept.
	readHeaderTimeout = 5 * time.Second

	// readTimeout covers headers plus body. Bodies are capped by
	// MAX_REQUEST_BODY, which transfers well inside this even on a
	// slow mobile link.
	readTimeout = 30 * time.Second

	// writeTimeout must exceed the per-request timeout: it starts when
	// the headers are read, so it spans handler execution, and a
	// smaller value would cut the connection instead of letting the
	// request context deadline end the request with a status. The
	// margin is added to whatever REQUEST_TIMEOUT is configured to.
	writeTimeoutMargin = 15 * time.Second

	// idleTimeout bounds how long an idle keep-alive connection is
	// held; browsers reconnect transparently.
	idleTimeout = 120 * time.Second

	maxHeaderBytes = 1 << 20
)

// newHTTPServer builds the http.Server.
//
// ErrorLog is set on purpose: net/http internals (TLS handshake
// errors, request parse errors, panics net/http itself recovers) write
// through it, and unset they would emit plain text on stderr via the
// default log package — a few lines of unstructured output in the
// middle of a JSON log stream, which is exactly the kind of thing a log
// pipeline drops on the floor.
func (s *Server) newHTTPServer(listenAddr string) *http.Server {
	return &http.Server{
		Addr:              listenAddr,
		ReadHeaderTimeout: readHeaderTimeout,
		ReadTimeout:       readTimeout,
		WriteTimeout:      s.params.Config.RequestTimeout + writeTimeoutMargin,
		IdleTimeout:       idleTimeout,
		MaxHeaderBytes:    maxHeaderBytes,
		Handler:           s,
		ErrorLog:          slog.NewLogLogger(s.log.Handler(), slog.LevelError),
	}
}