package stackdriver // import "contrib.go.opencensus.io/exporter/stackdriver"

import (
	"context"
	"errors"
	"fmt"
	"log"
	"os"
	"path"
	"strings"
	"time"

	metadataapi "cloud.google.com/go/compute/metadata"
	traceapi "cloud.google.com/go/trace/apiv2"
	"contrib.go.opencensus.io/exporter/stackdriver/monitoredresource"
	opencensus "go.opencensus.io"
	"go.opencensus.io/resource"
	"go.opencensus.io/resource/resourcekeys"
	"go.opencensus.io/stats/view"
	"go.opencensus.io/trace"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/option"
	monitoredrespb "google.golang.org/genproto/googleapis/api/monitoredres"

	commonpb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/common/v1"
	metricspb "github.com/census-instrumentation/opencensus-proto/gen-go/metrics/v1"
	resourcepb "github.com/census-instrumentation/opencensus-proto/gen-go/resource/v1"
	"go.opencensus.io/metric/metricdata"
)

	ProjectID string

	Location string

	OnError func(err error)

	MonitoringClientOptions []option.ClientOption

	TraceClientOptions []option.ClientOption

	BundleDelayThreshold time.Duration

	BundleCountThreshold int

	TraceSpansBufferMaxBytes int

	Resource *monitoredrespb.MonitoredResource

	MonitoredResource monitoredresource.Interface

	ResourceDetector resource.Detector

	MapResource func(*resource.Resource) *monitoredrespb.MonitoredResource

	MetricPrefix string

	GetMetricDisplayName func(view *view.View) string

	GetMetricType func(view *view.View) string

	GetMetricPrefix func(name string) string

	DefaultTraceAttributes map[string]interface{}

	DefaultMonitoringLabels *Labels

	Context context.Context

	SkipCMD bool

	Timeout time.Duration

	ReportingInterval time.Duration

	NumberOfWorkers int

	ResourceByDescriptor func(*metricdata.Descriptor, map[string]string) (map[string]string, monitoredresource.Interface)

	UserAgent string
}

const defaultTimeout = 5 * time.Second

var defaultDomain = path.Join("custom.googleapis.com", "opencensus")

var defaultUserAgent = fmt.Sprintf("opencensus-go %s; stackdriver-exporter %s", opencensus.Version(), version)

type Exporter struct {
	traceExporter *traceExporter
	statsExporter *statsExporter
}

func NewExporter(o Options) (*Exporter, error) {
	if o.ProjectID == "" {
		ctx := o.Context
		if ctx == nil {
			ctx = context.Background()
		}
		creds, err := google.FindDefaultCredentials(ctx, traceapi.DefaultAuthScopes()...)
		if err != nil {
			return nil, fmt.Errorf("stackdriver: %v", err)
		}
		if creds.ProjectID == "" {
			return nil, errors.New("stackdriver: no project found with application default credentials")
		}
		o.ProjectID = creds.ProjectID
	}
	if o.Location == "" {
		if metadataapi.OnGCE() {
			zone, err := metadataapi.Zone()

				err = fmt.Errorf("setting Stackdriver default location failed: %s", err)
				if o.OnError != nil {
					o.OnError(err)
				} else {
					log.Print(err)
				}
			} else {
				o.Location = zone
			}
		}
	}

	if o.MonitoredResource != nil {
		o.Resource = convertMonitoredResourceToPB(o.MonitoredResource)
	}
	if o.MapResource == nil {
		o.MapResource = DefaultMapResource
	}

		if o.Resource != nil {
			return nil, errors.New("stackdriver: ResourceDetector must not be used in combination with deprecated resource fields")
		}
		res, err := o.ResourceDetector(o.Context)
		if err != nil {
			return nil, fmt.Errorf("stackdriver: detect resource: %s", err)

		if res.Labels == nil {
			res.Labels = make(map[string]string)
		}
		res.Labels[stackdriverProjectID] = o.ProjectID
		res.Labels[resourcekeys.CloudKeyZone] = o.Location
		res.Labels[stackdriverGenericTaskNamespace] = "default"
		res.Labels[stackdriverGenericTaskJob] = path.Base(os.Args[0])
		res.Labels[stackdriverGenericTaskID] = getTaskValue()
		log.Printf("OpenCensus detected resource: %v", res)

		o.Resource = o.MapResource(res)
		log.Printf("OpenCensus using monitored resource: %v", o.Resource)
	}
	if o.MetricPrefix != "" && !strings.HasSuffix(o.MetricPrefix, "/") {
		o.MetricPrefix = o.MetricPrefix + "/"
	}
	if o.UserAgent == "" {
		o.UserAgent = defaultUserAgent
	}

	se, err := newStatsExporter(o)
	if err != nil {
		return nil, err
	}
	te, err := newTraceExporter(o)
	if err != nil {
		return nil, err
	}
	return &Exporter{
		statsExporter: se,
		traceExporter: te,
	}, nil
}

func (e *Exporter) ExportView(vd *view.Data) {
	e.statsExporter.ExportView(vd)
}

func (e *Exporter) ExportMetricsProto(ctx context.Context, node *commonpb.Node, rsc *resourcepb.Resource, metrics []*metricspb.Metric) error {
	_, err := e.statsExporter.PushMetricsProto(ctx, node, rsc, metrics)
	return err
}

func (e *Exporter) PushMetricsProto(ctx context.Context, node *commonpb.Node, rsc *resourcepb.Resource, metrics []*metricspb.Metric) (int, error) {
	return e.statsExporter.PushMetricsProto(ctx, node, rsc, metrics)
}

func (e *Exporter) ExportMetrics(ctx context.Context, metrics []*metricdata.Metric) error {
	return e.statsExporter.ExportMetrics(ctx, metrics)
}

func (e *Exporter) StartMetricsExporter() error {
	return e.statsExporter.startMetricsReader()
}

func (e *Exporter) StopMetricsExporter() {
	e.statsExporter.stopMetricsReader()
}

func (e *Exporter) ExportSpan(sd *trace.SpanData) {
	if len(e.traceExporter.o.DefaultTraceAttributes) > 0 {
		sd = e.sdWithDefaultTraceAttributes(sd)
	}
	e.traceExporter.ExportSpan(sd)
}

func (e *Exporter) PushTraceSpans(ctx context.Context, node *commonpb.Node, rsc *resourcepb.Resource, spans []*trace.SpanData) (int, error) {
	return e.traceExporter.pushTraceSpans(ctx, node, rsc, spans)
}

func (e *Exporter) sdWithDefaultTraceAttributes(sd *trace.SpanData) *trace.SpanData {
	newSD := *sd
	newSD.Attributes = make(map[string]interface{})
	for k, v := range e.traceExporter.o.DefaultTraceAttributes {
		newSD.Attributes[k] = v
	}
	for k, v := range sd.Attributes {
		newSD.Attributes[k] = v
	}
	return &newSD
}

func (e *Exporter) Flush() {
	e.statsExporter.Flush()
	e.traceExporter.Flush()
}

func (o Options) handleError(err error) {
	if o.OnError != nil {
		o.OnError(err)
		return
	}
	log.Printf("Failed to export to Stackdriver: %v", err)
}

func newContextWithTimeout(ctx context.Context, timeout time.Duration) (context.Context, func()) {
	if ctx == nil {
		ctx = context.Background()
	}
	if timeout <= 0 {
		timeout = defaultTimeout
	}
	return context.WithTimeout(ctx, timeout)
}

func convertMonitoredResourceToPB(mr monitoredresource.Interface) *monitoredrespb.MonitoredResource {
	mrpb := new(monitoredrespb.MonitoredResource)
	var labels map[string]string
	mrpb.Type, labels = mr.MonitoredResource()
	mrpb.Labels = make(map[string]string)
	for k, v := range labels {
		mrpb.Labels[k] = v
	}
	return mrpb