package registry

import (
	"crypto/tls"
	"crypto/x509"
	"fmt"
	"io/ioutil"
	"net"
	"net/http"
	"os"
	"time"

	log "github.com/Sirupsen/logrus"
	"github.com/Sirupsen/logrus/formatters/logstash"
	"github.com/bugsnag/bugsnag-go"
	"github.com/docker/distribution/configuration"
	ctxu "github.com/docker/distribution/context"
	"github.com/docker/distribution/health"
	"github.com/docker/distribution/registry/handlers"
	"github.com/docker/distribution/registry/listener"
	"github.com/docker/distribution/uuid"
	"github.com/docker/distribution/version"
	gorhandlers "github.com/gorilla/handlers"
	"github.com/yvasiyarov/gorelic"
	"golang.org/x/net/context"
)

// A Registry represents a complete instance of the registry.
type Registry struct {
	config  *configuration.Configuration
	app     *handlers.App
	server  *http.Server
	ln      net.Listener
	debugLn net.Listener
}

// NewRegistry creates a new registry from a context and configuration struct.
func NewRegistry(ctx context.Context, config *configuration.Configuration) (*Registry, error) {
	// Note this
	ctx = ctxu.WithValue(ctx, "version", version.Version)

	var err error
	ctx, err = configureLogging(ctx, config)
	if err != nil {
		return nil, fmt.Errorf("error configuring logger: %v", err)
	}

	// inject a logger into the uuid library. warns us if there is a problem
	// with uuid generation under low entropy.
	uuid.Loggerf = ctxu.GetLogger(ctx).Warnf

	app := handlers.NewApp(ctx, config)
	// TODO(aaronl): The global scope of the health checks means NewRegistry
	// can only be called once per process.
	app.RegisterHealthChecks()
	handler := configureReporting(app)
	handler = alive("/", handler)
	handler = health.Handler(handler)
	handler = panicHandler(handler)
	handler = gorhandlers.CombinedLoggingHandler(os.Stdout, handler)

	server := &http.Server{
		Handler: handler,
	}

	ln, err := listener.NewListener(config.HTTP.Net, config.HTTP.Addr)
	if err != nil {
		return nil, err
	}

	var debugLn net.Listener
	if config.HTTP.Debug.Addr != "" {
		debugLn, err = listener.NewListener("tcp", config.HTTP.Debug.Addr)
		if err != nil {
			return nil, fmt.Errorf("error listening on debug interface: %v", err)
		}
		log.Infof("debug server listening %v", config.HTTP.Debug.Addr)
	}

	if config.HTTP.TLS.Certificate != "" {
		tlsConf := &tls.Config{
			ClientAuth:               tls.NoClientCert,
			NextProtos:               []string{"http/1.1"},
			Certificates:             make([]tls.Certificate, 1),
			MinVersion:               tls.VersionTLS10,
			PreferServerCipherSuites: true,
			CipherSuites: []uint16{
				tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
				tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
				tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
				tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
				tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
				tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
				tls.TLS_RSA_WITH_AES_128_CBC_SHA,
				tls.TLS_RSA_WITH_AES_256_CBC_SHA,
			},
		}

		tlsConf.Certificates[0], err = tls.LoadX509KeyPair(config.HTTP.TLS.Certificate, config.HTTP.TLS.Key)
		if err != nil {
			return nil, err
		}

		if len(config.HTTP.TLS.ClientCAs) != 0 {
			pool := x509.NewCertPool()

			for _, ca := range config.HTTP.TLS.ClientCAs {
				caPem, err := ioutil.ReadFile(ca)
				if err != nil {
					return nil, err
				}

				if ok := pool.AppendCertsFromPEM(caPem); !ok {
					return nil, fmt.Errorf("Could not add CA to pool")
				}
			}

			for _, subj := range pool.Subjects() {
				ctxu.GetLogger(app).Debugf("CA Subject: %s", string(subj))
			}

			tlsConf.ClientAuth = tls.RequireAndVerifyClientCert
			tlsConf.ClientCAs = pool
		}

		ln = tls.NewListener(ln, tlsConf)
		ctxu.GetLogger(app).Infof("listening on %v, tls", ln.Addr())
	} else {
		ctxu.GetLogger(app).Infof("listening on %v", ln.Addr())
	}

	return &Registry{
		app:     app,
		config:  config,
		server:  server,
		ln:      ln,
		debugLn: debugLn,
	}, nil
}

// Serve runs the registry's HTTP server(s).
func (registry *Registry) Serve() error {
	defer registry.ln.Close()

	errChan := make(chan error)

	if registry.debugLn != nil {
		defer registry.debugLn.Close()
		go func() {
			errChan <- http.Serve(registry.debugLn, nil)
		}()
	}

	go func() {
		errChan <- registry.server.Serve(registry.ln)
	}()

	return <-errChan
}

func configureReporting(app *handlers.App) http.Handler {
	var handler http.Handler = app

	if app.Config.Reporting.Bugsnag.APIKey != "" {
		bugsnagConfig := bugsnag.Configuration{
			APIKey: app.Config.Reporting.Bugsnag.APIKey,
			// TODO(brianbland): provide the registry version here
			// AppVersion: "2.0",
		}
		if app.Config.Reporting.Bugsnag.ReleaseStage != "" {
			bugsnagConfig.ReleaseStage = app.Config.Reporting.Bugsnag.ReleaseStage
		}
		if app.Config.Reporting.Bugsnag.Endpoint != "" {
			bugsnagConfig.Endpoint = app.Config.Reporting.Bugsnag.Endpoint
		}
		bugsnag.Configure(bugsnagConfig)

		handler = bugsnag.Handler(handler)
	}

	if app.Config.Reporting.NewRelic.LicenseKey != "" {
		agent := gorelic.NewAgent()
		agent.NewrelicLicense = app.Config.Reporting.NewRelic.LicenseKey
		if app.Config.Reporting.NewRelic.Name != "" {
			agent.NewrelicName = app.Config.Reporting.NewRelic.Name
		}
		agent.CollectHTTPStat = true
		agent.Verbose = app.Config.Reporting.NewRelic.Verbose
		agent.Run()

		handler = agent.WrapHTTPHandler(handler)
	}

	return handler
}

// configureLogging prepares the context with a logger using the
// configuration.
func configureLogging(ctx ctxu.Context, config *configuration.Configuration) (context.Context, error) {
	if config.Log.Level == "" && config.Log.Formatter == "" {
		// If no config for logging is set, fallback to deprecated "Loglevel".
		log.SetLevel(logLevel(config.Loglevel))
		ctx = ctxu.WithLogger(ctx, ctxu.GetLogger(ctx, "version"))
		return ctx, nil
	}

	log.SetLevel(logLevel(config.Log.Level))

	formatter := config.Log.Formatter
	if formatter == "" {
		formatter = "text" // default formatter
	}

	switch formatter {
	case "json":
		log.SetFormatter(&log.JSONFormatter{
			TimestampFormat: time.RFC3339Nano,
		})
	case "text":
		log.SetFormatter(&log.TextFormatter{
			TimestampFormat: time.RFC3339Nano,
		})
	case "logstash":
		log.SetFormatter(&logstash.LogstashFormatter{
			TimestampFormat: time.RFC3339Nano,
		})
	default:
		// just let the library use default on empty string.
		if config.Log.Formatter != "" {
			return ctx, fmt.Errorf("unsupported logging formatter: %q", config.Log.Formatter)
		}
	}

	if config.Log.Formatter != "" {
		log.Debugf("using %q logging formatter", config.Log.Formatter)
	}

	// log the application version with messages
	ctx = ctxu.WithLogger(ctx, ctxu.GetLogger(ctx, "version"))

	if len(config.Log.Fields) > 0 {
		// build up the static fields, if present.
		var fields []interface{}
		for k := range config.Log.Fields {
			fields = append(fields, k)
		}

		ctx = ctxu.WithValues(ctx, config.Log.Fields)
		ctx = ctxu.WithLogger(ctx, ctxu.GetLogger(ctx, fields...))
	}

	return ctx, nil
}

func logLevel(level configuration.Loglevel) log.Level {
	l, err := log.ParseLevel(string(level))
	if err != nil {
		l = log.InfoLevel
		log.Warnf("error parsing level %q: %v, using %q	", level, err, l)
	}

	return l
}

// panicHandler add a HTTP handler to web app. The handler recover the happening
// panic. logrus.Panic transmits panic message to pre-config log hooks, which is
// defined in config.yml.
func panicHandler(handler http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			if err := recover(); err != nil {
				log.Panic(fmt.Sprintf("%v", err))
			}
		}()
		handler.ServeHTTP(w, r)
	})
}

// alive simply wraps the handler with a route that always returns an http 200
// response when the path is matched. If the path is not matched, the request
// is passed to the provided handler. There is no guarantee of anything but
// that the server is up. Wrap with other handlers (such as health.Handler)
// for greater affect.
func alive(path string, handler http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path == path {
			w.Header().Set("Cache-Control", "no-cache")
			w.WriteHeader(http.StatusOK)
			return
		}

		handler.ServeHTTP(w, r)
	})
}