package runtime

import (
	"fmt"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	"net"
	"net/http"
	"sorbet/internal/util"
	"sorbet/pkg/env"
	"sorbet/pkg/rsp"
	"time"
)

var (
	// maxHeaderBytes is used by the http server to limit the size of request headers.
	// This may need to be increased if accepting cookies from the public.
	maxHeaderBytes = 1 << 20
	// readTimeout is used by the http server to set a maximum duration before
	// timing out read of the request. The default timeout is 10 seconds.
	readTimeout = 10 * time.Second
	// writeTimeout is used by the http server to set a maximum duration before
	// timing out write of the response. The default timeout is 10 seconds.
	writeTimeout = 10 * time.Second
	// idleTimeout is used by the http server to set a maximum duration for
	// keep-alive connections.
	idleTimeout = 120 * time.Second
)

func newEchoFramework() (*echo.Echo, error) {
	e := echo.New()
	e.HideBanner = true
	e.HidePort = true
	e.HTTPErrorHandler = rsp.HTTPErrorHandler
	e.Debug = !env.IsEnv("prod")
	e.Logger = util.NewEchoLogger()
	e.Use(middleware.Recover())
	e.Use(middleware.CORS())
	e.Use(middleware.Logger())
	for _, servlet := range servlets {
		group := e.Group("")
		for _, routable := range servlet.Routes() {
			routable.InitRoutes(group)
		}
	}
	routes := e.Routes()
	e.GET("/_routes", func(c echo.Context) error {
		return c.JSON(http.StatusOK, routes)
	})
	return e, nil
}

func createServer() (*http.Server, net.Listener, error) {
	e, err := newEchoFramework()
	if err != nil {
		return nil, nil, err
	}

	l, err := createTCPListener()
	if err != nil {
		return nil, nil, err
	}

	s := &http.Server{
		Handler:        e,
		MaxHeaderBytes: env.Int("SERVER_MAX_HEADER_BYTES", maxHeaderBytes),
		ReadTimeout:    env.Duration("SERVER_READ_TIMEOUT", readTimeout),
		WriteTimeout:   env.Duration("SERVER_WRITE_TIMEOUT", writeTimeout),
		IdleTimeout:    env.Duration("SERVER_IDLE_TIMEOUT", idleTimeout),
	}

	return s, l, nil
}

func createTCPListener() (net.Listener, error) {
	l, err := net.Listen(
		env.String("SERVER_NETWORK", "tcp"),
		fmt.Sprintf("%s:%d",
			env.String("SERVER_ADDRESS", "0.0.0.0"),
			env.Int("SERVER_PORT", 1324),
		),
	)
	if err == nil {
		l = net.Listener(TCPKeepAliveListener{
			TCPListener: l.(*net.TCPListener),
		})
	}
	return l, err
}

// TCPKeepAliveListener sets TCP keep-alive timeouts on accepted
// connections. It's used by ListenAndServe and ListenAndServeTLS so
// dead TCP connections (e.g. closing laptop mid-download) eventually
// go away.
//
// This is here because it is not exposed in the stdlib and
// we'd prefer to have a hold of the http.Server's net.Listener so we can close it
// on shutdown.
//
// Taken from here: https://golang.org/src/net/http/server.go?s=63121:63175#L2120
type TCPKeepAliveListener struct {
	*net.TCPListener
}

// Accept accepts the next incoming call and returns the new
// connection. KeepAlivePeriod is set properly.
func (ln TCPKeepAliveListener) Accept() (c net.Conn, err error) {
	tc, err := ln.AcceptTCP()
	if err != nil {
		return
	}
	err = tc.SetKeepAlive(true)
	if err != nil {
		return
	}
	err = tc.SetKeepAlivePeriod(3 * time.Minute)
	if err != nil {
		return
	}
	return tc, nil
}