package main

import (
	"context"
	"flag"
	"fmt"
	"net"
	"net/http"
	"net/http/pprof"
	"os"
	"os/signal"
	"strings"
	"syscall"

	"github.com/apache/thrift/lib/go/thrift"
	lightstep "github.com/lightstep/lightstep-tracer-go"
	stdopentracing "github.com/opentracing/opentracing-go"
	zipkin "github.com/openzipkin/zipkin-go-opentracing"
	stdprometheus "github.com/prometheus/client_golang/prometheus"
	"google.golang.org/grpc"
	"sourcegraph.com/sourcegraph/appdash"
	appdashot "sourcegraph.com/sourcegraph/appdash/opentracing"

	"github.com/go-kit/kit/endpoint"
	"github.com/go-kit/kit/examples/addsvc"
	"github.com/go-kit/kit/examples/addsvc/pb"
	thriftadd "github.com/go-kit/kit/examples/addsvc/thrift/gen-go/addsvc"
	"github.com/go-kit/kit/log"
	"github.com/go-kit/kit/metrics"
	"github.com/go-kit/kit/metrics/prometheus"
	"github.com/go-kit/kit/tracing/opentracing"
)

func main() {
	var (
		debugAddr        = flag.String("debug.addr", ":8080", "Debug and metrics listen address")
		httpAddr         = flag.String("http.addr", ":8081", "HTTP listen address")
		grpcAddr         = flag.String("grpc.addr", ":8082", "gRPC (HTTP) listen address")
		thriftAddr       = flag.String("thrift.addr", ":8083", "Thrift listen address")
		thriftProtocol   = flag.String("thrift.protocol", "binary", "binary, compact, json, simplejson")
		thriftBufferSize = flag.Int("thrift.buffer.size", 0, "0 for unbuffered")
		thriftFramed     = flag.Bool("thrift.framed", false, "true to enable framing")
		zipkinAddr       = flag.String("zipkin.addr", "", "Enable Zipkin tracing via a Zipkin HTTP Collector endpoint")
		zipkinKafkaAddr  = flag.String("zipkin.kafka.addr", "", "Enable Zipkin tracing via a Kafka server host:port")
		appdashAddr      = flag.String("appdash.addr", "", "Enable Appdash tracing via an Appdash server host:port")
		lightstepToken   = flag.String("lightstep.token", "", "Enable LightStep tracing via a LightStep access token")
	)
	flag.Parse()

	// Logging domain.
	var logger log.Logger
	{
		logger = log.NewLogfmtLogger(os.Stdout)
		logger = log.NewContext(logger).With("ts", log.DefaultTimestampUTC)
		logger = log.NewContext(logger).With("caller", log.DefaultCaller)
	}
	logger.Log("msg", "hello")
	defer logger.Log("msg", "goodbye")

	// Metrics domain.
	var ints, chars metrics.Counter
	{
		// Business level metrics.
		ints = prometheus.NewCounterFrom(stdprometheus.CounterOpts{
			Namespace: "addsvc",
			Name:      "integers_summed",
			Help:      "Total count of integers summed via the Sum method.",
		}, []string{})
		chars = prometheus.NewCounterFrom(stdprometheus.CounterOpts{
			Namespace: "addsvc",
			Name:      "characters_concatenated",
			Help:      "Total count of characters concatenated via the Concat method.",
		}, []string{})
	}
	var duration metrics.Histogram
	{
		// Transport level metrics.
		duration = prometheus.NewSummaryFrom(stdprometheus.SummaryOpts{
			Namespace: "addsvc",
			Name:      "request_duration_ns",
			Help:      "Request duration in nanoseconds.",
		}, []string{"method", "success"})
	}

	// Tracing domain.
	var tracer stdopentracing.Tracer
	{
		if *zipkinAddr != "" {
			logger := log.NewContext(logger).With("tracer", "ZipkinHTTP")
			logger.Log("addr", *zipkinAddr)

			// endpoint typically looks like: http://zipkinhost:9411/api/v1/spans
			collector, err := zipkin.NewHTTPCollector(*zipkinAddr)
			if err != nil {
				logger.Log("err", err)
				os.Exit(1)
			}
			defer collector.Close()

			tracer, err = zipkin.NewTracer(
				zipkin.NewRecorder(collector, false, "localhost:80", "addsvc"),
			)
			if err != nil {
				logger.Log("err", err)
				os.Exit(1)
			}
		} else if *zipkinKafkaAddr != "" {
			logger := log.NewContext(logger).With("tracer", "ZipkinKafka")
			logger.Log("addr", *zipkinKafkaAddr)

			collector, err := zipkin.NewKafkaCollector(
				strings.Split(*zipkinKafkaAddr, ","),
				zipkin.KafkaLogger(log.NewNopLogger()),
			)
			if err != nil {
				logger.Log("err", err)
				os.Exit(1)
			}
			defer collector.Close()

			tracer, err = zipkin.NewTracer(
				zipkin.NewRecorder(collector, false, "localhost:80", "addsvc"),
			)
			if err != nil {
				logger.Log("err", err)
				os.Exit(1)
			}
		} else if *appdashAddr != "" {
			logger := log.NewContext(logger).With("tracer", "Appdash")
			logger.Log("addr", *appdashAddr)
			tracer = appdashot.NewTracer(appdash.NewRemoteCollector(*appdashAddr))
		} else if *lightstepToken != "" {
			logger := log.NewContext(logger).With("tracer", "LightStep")
			logger.Log() // probably don't want to print out the token :)
			tracer = lightstep.NewTracer(lightstep.Options{
				AccessToken: *lightstepToken,
			})
			defer lightstep.FlushLightStepTracer(tracer)
		} else {
			logger := log.NewContext(logger).With("tracer", "none")
			logger.Log()
			tracer = stdopentracing.GlobalTracer() // no-op
		}
	}

	// Business domain.
	var service addsvc.Service
	{
		service = addsvc.NewBasicService()
		service = addsvc.ServiceLoggingMiddleware(logger)(service)
		service = addsvc.ServiceInstrumentingMiddleware(ints, chars)(service)
	}

	// Endpoint domain.
	var sumEndpoint endpoint.Endpoint
	{
		sumDuration := duration.With("method", "Sum")
		sumLogger := log.NewContext(logger).With("method", "Sum")

		sumEndpoint = addsvc.MakeSumEndpoint(service)
		sumEndpoint = opentracing.TraceServer(tracer, "Sum")(sumEndpoint)
		sumEndpoint = addsvc.EndpointInstrumentingMiddleware(sumDuration)(sumEndpoint)
		sumEndpoint = addsvc.EndpointLoggingMiddleware(sumLogger)(sumEndpoint)
	}
	var concatEndpoint endpoint.Endpoint
	{
		concatDuration := duration.With("method", "Concat")
		concatLogger := log.NewContext(logger).With("method", "Concat")

		concatEndpoint = addsvc.MakeConcatEndpoint(service)
		concatEndpoint = opentracing.TraceServer(tracer, "Concat")(concatEndpoint)
		concatEndpoint = addsvc.EndpointInstrumentingMiddleware(concatDuration)(concatEndpoint)
		concatEndpoint = addsvc.EndpointLoggingMiddleware(concatLogger)(concatEndpoint)
	}
	endpoints := addsvc.Endpoints{
		SumEndpoint:    sumEndpoint,
		ConcatEndpoint: concatEndpoint,
	}

	// Mechanical domain.
	errc := make(chan error)
	ctx := context.Background()

	// Interrupt handler.
	go func() {
		c := make(chan os.Signal, 1)
		signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
		errc <- fmt.Errorf("%s", <-c)
	}()

	// Debug listener.
	go func() {
		logger := log.NewContext(logger).With("transport", "debug")

		m := http.NewServeMux()
		m.Handle("/debug/pprof/", http.HandlerFunc(pprof.Index))
		m.Handle("/debug/pprof/cmdline", http.HandlerFunc(pprof.Cmdline))
		m.Handle("/debug/pprof/profile", http.HandlerFunc(pprof.Profile))
		m.Handle("/debug/pprof/symbol", http.HandlerFunc(pprof.Symbol))
		m.Handle("/debug/pprof/trace", http.HandlerFunc(pprof.Trace))
		m.Handle("/metrics", stdprometheus.Handler())

		logger.Log("addr", *debugAddr)
		errc <- http.ListenAndServe(*debugAddr, m)
	}()

	// HTTP transport.
	go func() {
		logger := log.NewContext(logger).With("transport", "HTTP")
		h := addsvc.MakeHTTPHandler(endpoints, tracer, logger)
		logger.Log("addr", *httpAddr)
		errc <- http.ListenAndServe(*httpAddr, h)
	}()

	// gRPC transport.
	go func() {
		logger := log.NewContext(logger).With("transport", "gRPC")

		ln, err := net.Listen("tcp", *grpcAddr)
		if err != nil {
			errc <- err
			return
		}

		srv := addsvc.MakeGRPCServer(endpoints, tracer, logger)
		s := grpc.NewServer()
		pb.RegisterAddServer(s, srv)

		logger.Log("addr", *grpcAddr)
		errc <- s.Serve(ln)
	}()

	// Thrift transport.
	go func() {
		logger := log.NewContext(logger).With("transport", "Thrift")

		var protocolFactory thrift.TProtocolFactory
		switch *thriftProtocol {
		case "binary":
			protocolFactory = thrift.NewTBinaryProtocolFactoryDefault()
		case "compact":
			protocolFactory = thrift.NewTCompactProtocolFactory()
		case "json":
			protocolFactory = thrift.NewTJSONProtocolFactory()
		case "simplejson":
			protocolFactory = thrift.NewTSimpleJSONProtocolFactory()
		default:
			errc <- fmt.Errorf("invalid Thrift protocol %q", *thriftProtocol)
			return
		}

		var transportFactory thrift.TTransportFactory
		if *thriftBufferSize > 0 {
			transportFactory = thrift.NewTBufferedTransportFactory(*thriftBufferSize)
		} else {
			transportFactory = thrift.NewTTransportFactory()
		}
		if *thriftFramed {
			transportFactory = thrift.NewTFramedTransportFactory(transportFactory)
		}

		transport, err := thrift.NewTServerSocket(*thriftAddr)
		if err != nil {
			errc <- err
			return
		}

		logger.Log("addr", *thriftAddr)
		errc <- thrift.NewTSimpleServer4(
			thriftadd.NewAddServiceProcessor(addsvc.MakeThriftHandler(ctx, endpoints)),
			transport,
			transportFactory,
			protocolFactory,
		).Serve()
	}()

	// Run!
	logger.Log("exit", <-errc)
}