package http

import (
	"context"
	"github.com/spiral/roadrunner"
	"github.com/spiral/roadrunner/service"
	"github.com/spiral/roadrunner/service/rpc"
	"net/http"
	"sync"
	"sync/atomic"
)

// ID contains default svc name.
const ID = "http"

// must return true if request/response pair is handled within the middleware.
type middleware func(w http.ResponseWriter, r *http.Request) bool

// Service manages rr, http servers.
type Service struct {
	cfg  *Config
	lsns []func(event int, ctx interface{})
	mdws []middleware

	mu         sync.Mutex
	rr         *roadrunner.Server
	inStopping int32
	srv        *Handler
	http       *http.Server
}

// AddMiddleware adds new net/http middleware.
func (s *Service) AddMiddleware(m middleware) {
	s.mdws = append(s.mdws, m)
}

// AddListener attaches server event watcher.
func (s *Service) AddListener(l func(event int, ctx interface{})) {
	s.lsns = append(s.lsns, l)
}

// Init must return configure svc and return true if svc hasStatus enabled. Must return error in case of
// misconfiguration. Services must not be used without proper configuration pushed first.
func (s *Service) Init(cfg service.Config, c service.Container) (bool, error) {
	config := &Config{}

	if err := cfg.Unmarshal(config); err != nil {
		return false, err
	}

	if !config.Enable {
		return false, nil
	}

	if err := config.Valid(); err != nil {
		return false, err
	}

	s.cfg = config

	// registering http RPC interface
	if r, ok := c.Get(rpc.ID); ok >= service.StatusConfigured {
		if h, ok := r.(*rpc.Service); ok {
			h.Register(ID, &rpcServer{s})
		}
	}

	return true, nil
}

// Serve serves the svc.
func (s *Service) Serve() error {
	s.mu.Lock()
	rr := roadrunner.NewServer(s.cfg.Workers)

	s.rr = rr
	s.srv = &Handler{cfg: s.cfg, rr: s.rr}
	s.http = &http.Server{Addr: s.cfg.Address}

	s.rr.Listen(s.listener)
	s.srv.Listen(s.listener)

	if len(s.mdws) == 0 {
		s.http.Handler = s.srv
	} else {
		s.http.Handler = s
	}
	s.mu.Unlock()

	if err := rr.Start(); err != nil {
		return err
	}
	defer s.rr.Stop()

	return s.http.ListenAndServe()
}

// Stop stops the svc.
func (s *Service) Stop() {
	atomic.AddInt32(&s.inStopping, 1)
	defer atomic.AddInt32(&s.inStopping, -1)

	s.mu.Lock()
	defer s.mu.Unlock()
	if s.http == nil || s.stopping() {
		return
	}

	s.http.Shutdown(context.Background())
}

// middleware handles connection using set of mdws and rr PSR-7 server.
func (s *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	for _, m := range s.mdws {
		if m(w, r) {
			return
		}
	}

	s.srv.ServeHTTP(w, r)
}

func (s *Service) stopping() bool {
	return atomic.LoadInt32(&s.inStopping) != 0
}

func (s *Service) listener(event int, ctx interface{}) {
	for _, l := range s.lsns {
		l(event, ctx)
	}

	if event == roadrunner.EventServerFailure && !s.stopping() {
		// attempting rr server restart
		if err := s.rr.Start(); err != nil {
			s.Stop()
		}
	}
}