package micro

import (
	"fmt"
	"os"
	"os/signal"
	rtime "runtime"
	"strings"
	"sync"

	"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"
	registrySrv "github.com/micro/go-micro/v2/registry/service"
	"github.com/micro/go-micro/v2/runtime"
	"github.com/micro/go-micro/v2/server"
	"github.com/micro/go-micro/v2/store"
	signalutil "github.com/micro/go-micro/v2/util/signal"
	"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)
	options.Client = wrapper.TraceCall(serviceName, trace.DefaultTracer, options.Client)
	options.Client = wrapper.AuthClient(serviceName, options.Server.Options().Id, authFn, 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 the client in the service implementations
	options.Auth.Init(auth.WithClient(options.Client))
	options.Registry.Init(registrySrv.WithClient(options.Client))
	options.Runtime.Init(runtime.WithClient(options.Client))
	options.Store.Init(store.WithClient(options.Client))

	// 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.Runtime(&s.opts.Runtime),
			cmd.Transport(&s.opts.Transport),
			cmd.Client(&s.opts.Client),
			cmd.Config(&s.opts.Config),
			cmd.Server(&s.opts.Server),
			cmd.Store(&s.opts.Store),
			cmd.Profile(&s.opts.Profile),
		); err != nil {
			logger.Fatal(err)
		}

		// Explicitly set the table name to the service name
		name := s.opts.Cmd.App().Name
		s.opts.Store.Init(store.Table(name))

		// Reset the clients for the micro services, this is done
		// previously in newService for micro (since init is never called)
		// however it needs to be done again here since for normal go-micro
		// services the implementation may have changed by CLI flags.
		s.opts.Auth.Init(auth.WithClient(s.Client()))
		s.opts.Registry.Init(registrySrv.WithClient(s.Client()))
		s.opts.Runtime.Init(runtime.WithClient(s.Client()))
		s.opts.Store.Init(store.WithClient(s.Client()))
	})
}

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 {
	// generate an auth account
	if err := s.generateAccount(); err != nil {
		return err
	}

	// 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
		rtime.SetMutexProfileFraction(5)
		// to view blocking profile
		rtime.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, signalutil.Shutdown()...)
	}

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

	return s.Stop()
}

func (s *service) generateAccount() error {
	// generate a new auth account for the service
	name := fmt.Sprintf("%v-%v", s.Name(), s.Server().Options().Id)
	opts := []auth.GenerateOption{
		auth.WithType("service"),
		auth.WithRoles("service"),
		auth.WithNamespace(s.Options().Auth.Options().Namespace),
	}
	acc, err := s.Options().Auth.Generate(name, opts...)
	if err != nil {
		return err
	}

	// generate a token
	token, err := s.Options().Auth.Token(auth.WithCredentials(acc.ID, acc.Secret))
	if err != nil {
		return err
	}

	s.Options().Auth.Init(auth.ClientToken(token), auth.Credentials(acc.ID, acc.Secret))
	logger.Infof("Auth [%v] Authenticated as %v", s.Options().Auth, name)
	return nil
}