// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package wire

import (
	"encoding/json"
	"fmt"
)

type ExportMetricsServiceRequest struct {
	Node     *Node     `json:"node,omitempty"`
	Metrics  []*Metric `json:"metrics,omitempty"`
	Resource *Resource `json:"resource,omitempty"`
}

type Metric struct {
	MetricDescriptor *MetricDescriptor `json:"metric_descriptor,omitempty"`
	Timeseries       []*TimeSeries     `json:"timeseries,omitempty"`
	Resource         *Resource         `json:"resource,omitempty"`
}

type MetricDescriptor struct {
	Name        string                `json:"name,omitempty"`
	Description string                `json:"description,omitempty"`
	Unit        string                `json:"unit,omitempty"`
	Type        MetricDescriptor_Type `json:"type,omitempty"`
	LabelKeys   []*LabelKey           `json:"label_keys,omitempty"`
}

type MetricDescriptor_Type int32

const (
	MetricDescriptor_UNSPECIFIED             MetricDescriptor_Type = 0
	MetricDescriptor_GAUGE_INT64             MetricDescriptor_Type = 1
	MetricDescriptor_GAUGE_DOUBLE            MetricDescriptor_Type = 2
	MetricDescriptor_GAUGE_DISTRIBUTION      MetricDescriptor_Type = 3
	MetricDescriptor_CUMULATIVE_INT64        MetricDescriptor_Type = 4
	MetricDescriptor_CUMULATIVE_DOUBLE       MetricDescriptor_Type = 5
	MetricDescriptor_CUMULATIVE_DISTRIBUTION MetricDescriptor_Type = 6
	MetricDescriptor_SUMMARY                 MetricDescriptor_Type = 7
)

type LabelKey struct {
	Key         string `json:"key,omitempty"`
	Description string `json:"description,omitempty"`
}

type TimeSeries struct {
	StartTimestamp *Timestamp    `json:"start_timestamp,omitempty"`
	LabelValues    []*LabelValue `json:"label_values,omitempty"`
	Points         []*Point      `json:"points,omitempty"`
}

type LabelValue struct {
	Value    string `json:"value,omitempty"`
	HasValue bool   `json:"has_value,omitempty"`
}

type Point struct {
	Timestamp *Timestamp `json:"timestamp,omitempty"`
	Value     PointValue `json:"value,omitempty"`
}

type PointInt64Value struct {
	Int64Value int64 `json:"int64Value,omitempty"`
}

// MarshalJSON creates JSON formatted the same way as jsonpb so that the
// OpenCensus service can correctly determine the underlying value type.
// This custom MarshalJSON exists because,
// by default *Point is JSON marshalled as:
//     {"value": {"int64Value": 1}}
// but it should be marshalled as:
//     {"int64Value": 1}
func (p *Point) MarshalJSON() ([]byte, error) {
	if p == nil {
		return []byte("null"), nil
	}

	switch d := p.Value.(type) {
	case PointInt64Value:
		return json.Marshal(&struct {
			Timestamp *Timestamp `json:"timestamp,omitempty"`
			Value     int64      `json:"int64Value,omitempty"`
		}{
			Timestamp: p.Timestamp,
			Value:     d.Int64Value,
		})
	case PointDoubleValue:
		return json.Marshal(&struct {
			Timestamp *Timestamp `json:"timestamp,omitempty"`
			Value     float64    `json:"doubleValue,omitempty"`
		}{
			Timestamp: p.Timestamp,
			Value:     d.DoubleValue,
		})
	case PointDistributionValue:
		return json.Marshal(&struct {
			Timestamp *Timestamp         `json:"timestamp,omitempty"`
			Value     *DistributionValue `json:"distributionValue,omitempty"`
		}{
			Timestamp: p.Timestamp,
			Value:     d.DistributionValue,
		})
	default:
		return nil, fmt.Errorf("unknown point type %T", p.Value)
	}
}

type PointDoubleValue struct {
	DoubleValue float64 `json:"doubleValue,omitempty"`
}

type PointDistributionValue struct {
	DistributionValue *DistributionValue `json:"distributionValue,omitempty"`
}

type PointSummaryValue struct {
	SummaryValue *SummaryValue `json:"summaryValue,omitempty"`
}

type PointValue interface {
	tagPointValue()
}

func (PointInt64Value) tagPointValue()        {}
func (PointDoubleValue) tagPointValue()       {}
func (PointDistributionValue) tagPointValue() {}
func (PointSummaryValue) tagPointValue()      {}

type DistributionValue struct {
	Count                 int64         `json:"count,omitempty"`
	Sum                   float64       `json:"sum,omitempty"`
	SumOfSquaredDeviation float64       `json:"sum_of_squared_deviation,omitempty"`
	BucketOptions         BucketOptions `json:"bucket_options,omitempty"`
	Buckets               []*Bucket     `json:"buckets,omitempty"`
}

type BucketOptionsExplicit struct {
	Bounds []float64 `json:"bounds,omitempty"`
}

type BucketOptions interface {
	tagBucketOptions()
}

func (*BucketOptionsExplicit) tagBucketOptions() {}

var _ BucketOptions = (*BucketOptionsExplicit)(nil)
var _ json.Marshaler = (*BucketOptionsExplicit)(nil)

// Declared for the purpose of custom JSON marshalling without cycles.
type bucketOptionsExplicitAlias BucketOptionsExplicit

// MarshalJSON creates JSON formatted the same way as jsonpb so that the
// OpenCensus service can correctly determine the underlying value type.
// This custom MarshalJSON exists because,
// by default BucketOptionsExplicit is JSON marshalled as:
//     {"bounds":[1,2,3]}
// but it should be marshalled as:
//     {"explicit":{"bounds":[1,2,3]}}
func (be *BucketOptionsExplicit) MarshalJSON() ([]byte, error) {
	return json.Marshal(&struct {
		Explicit *bucketOptionsExplicitAlias `json:"explicit,omitempty"`
	}{
		Explicit: (*bucketOptionsExplicitAlias)(be),
	})
}

type Bucket struct {
	Count    int64     `json:"count,omitempty"`
	Exemplar *Exemplar `json:"exemplar,omitempty"`
}

type Exemplar struct {
	Value       float64           `json:"value,omitempty"`
	Timestamp   *Timestamp        `json:"timestamp,omitempty"`
	Attachments map[string]string `json:"attachments,omitempty"`
}

type SummaryValue struct {
	Count    *Int64Value  `json:"count,omitempty"`
	Sum      *DoubleValue `json:"sum,omitempty"`
	Snapshot *Snapshot    `json:"snapshot,omitempty"`
}

type Snapshot struct {
	Count            *Int64Value                  `json:"count,omitempty"`
	Sum              *DoubleValue                 `json:"sum,omitempty"`
	PercentileValues []*SnapshotValueAtPercentile `json:"percentile_values,omitempty"`
}

type SnapshotValueAtPercentile struct {
	Percentile float64 `json:"percentile,omitempty"`
	Value      float64 `json:"value,omitempty"`
}