package micro

import (
	"os"
	"os/signal"
	"runtime"
	"strings"
	"sync"
	"syscall"

	"github.com/micro/go-micro/v2/auth"
	"github.com/micro/go-micro/v2/client"
	"github.com/micro/go-micro/v2/config/cmd"
	"github.com/micro/go-micro/v2/debug/service/handler"
	"github.com/micro/go-micro/v2/debug/stats"
	"github.com/micro/go-micro/v2/debug/trace"
	"github.com/micro/go-micro/v2/logger"
	"github.com/micro/go-micro/v2/plugin"
	"github.com/micro/go-micro/v2/server"
	"github.com/micro/go-micro/v2/store"
	"github.com/micro/go-micro/v2/util/wrapper"
)

type service struct {
	opts Options

	once sync.Once
}

func newService(opts ...Option) Service {
	service := new(service)
	options := newOptions(opts...)

	// service name
	serviceName := options.Server.Options().Name

	// authFn returns the auth, we pass as a function since auth
	// has not yet been set at this point.
	authFn := func() auth.Auth { return options.Server.Options().Auth }

	// wrap client to inject From-Service header on any calls
	options.Client = wrapper.FromService(serviceName, options.Client, authFn)
	options.Client = wrapper.TraceCall(serviceName, trace.DefaultTracer, options.Client)

	// wrap the server to provide handler stats
	options.Server.Init(
		server.WrapHandler(wrapper.HandlerStats(stats.DefaultStats)),
		server.WrapHandler(wrapper.TraceHandler(trace.DefaultTracer)),
		server.WrapHandler(wrapper.AuthHandler(authFn)),
	)

	// set opts
	service.opts = options

	return service
}

func (s *service) Name() string {
	return s.opts.Server.Options().Name
}

// Init initialises options. Additionally it calls cmd.Init
// which parses command line flags. cmd.Init is only called
// on first Init.
func (s *service) Init(opts ...Option) {
	// process options
	for _, o := range opts {
		o(&s.opts)
	}

	s.once.Do(func() {
		// setup the plugins
		for _, p := range strings.Split(os.Getenv("MICRO_PLUGIN"), ",") {
			if len(p) == 0 {
				continue
			}

			// load the plugin
			c, err := plugin.Load(p)
			if err != nil {
				logger.Fatal(err)
			}

			// initialise the plugin
			if err := plugin.Init(c); err != nil {
				logger.Fatal(err)
			}
		}

		// set cmd name
		if len(s.opts.Cmd.App().Name) == 0 {
			s.opts.Cmd.App().Name = s.Server().Options().Name
		}

		// Initialise the command flags, overriding new service
		if err := s.opts.Cmd.Init(
			cmd.Auth(&s.opts.Auth),
			cmd.Broker(&s.opts.Broker),
			cmd.Registry(&s.opts.Registry),
			cmd.Transport(&s.opts.Transport),
			cmd.Client(&s.opts.Client),
			cmd.Config(&s.opts.Config),
			cmd.Server(&s.opts.Server),
			cmd.Profile(&s.opts.Profile),
		); err != nil {
			logger.Fatal(err)
		}

		// If the store has no namespace set, fallback to the
		// services name
		if len(store.DefaultStore.Options().Namespace) == 0 {
			name := s.opts.Cmd.App().Name
			store.DefaultStore.Init(store.Namespace(name))
		}

		// TODO: replace Cmd.Init with config.Load
		// Right now we're just going to load a token
		// May need to re-read value on change
		// TODO: should be scoped to micro/auth/token
		// if tk, _ := config.Get("token"); len(tk) > 0 {
		// 	s.opts.Auth.Init(auth.ServiceToken(tk))
		// }
	})
}

func (s *service) Options() Options {
	return s.opts
}

func (s *service) Client() client.Client {
	return s.opts.Client
}

func (s *service) Server() server.Server {
	return s.opts.Server
}

func (s *service) String() string {
	return "micro"
}

func (s *service) Start() error {
	for _, fn := range s.opts.BeforeStart {
		if err := fn(); err != nil {
			return err
		}
	}

	if err := s.opts.Server.Start(); err != nil {
		return err
	}

	for _, fn := range s.opts.AfterStart {
		if err := fn(); err != nil {
			return err
		}
	}

	return nil
}

func (s *service) Stop() error {
	var gerr error

	for _, fn := range s.opts.BeforeStop {
		if err := fn(); err != nil {
			gerr = err
		}
	}

	if err := s.opts.Server.Stop(); err != nil {
		return err
	}

	for _, fn := range s.opts.AfterStop {
		if err := fn(); err != nil {
			gerr = err
		}
	}

	return gerr
}

func (s *service) Run() error {
	// register the debug handler
	s.opts.Server.Handle(
		s.opts.Server.NewHandler(
			handler.NewHandler(),
			server.InternalHandler(true),
		),
	)

	// start the profiler
	if s.opts.Profile != nil {
		// to view mutex contention
		runtime.SetMutexProfileFraction(5)
		// to view blocking profile
		runtime.SetBlockProfileRate(1)

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

	if logger.V(logger.InfoLevel, logger.DefaultLogger) {
		logger.Infof("Starting [service] %s", s.Name())
	}

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

	ch := make(chan os.Signal, 1)
	if s.opts.Signal {
		signal.Notify(ch, syscall.SIGTERM, syscall.SIGINT, syscall.SIGQUIT)
	}

	select {
	// wait on kill signal
	case <-ch:
	// wait on context cancel
	case <-s.opts.Context.Done():
	}

	return s.Stop()
}