package metric

import (
	"github.com/prometheus/client_golang/prometheus"
	"sync"
)

const missVal = "MissLabel"

// CounterVecDecorator Add safe decorator
type CounterVecDecorator struct {
	*prometheus.CounterVec
	secureLabels []string
	once         *sync.Once
}

func NewCounterVec(opts prometheus.CounterOpts, labelNames []string) *CounterVecDecorator {
	v := &CounterVecDecorator{prometheus.NewCounterVec(opts, labelNames), labelNames, &sync.Once{}}

	return v
}

// With is secure wrap for with of prometheus.CounterVec
// there is no panic, and always calculate to metrics , if miss values, will calculate to MissLabel
// It's secure
func (v *CounterVecDecorator) With(labels prometheus.Labels) prometheus.Counter {
	// To avoid initialization sequence, so must delay register to with func
	v.once.Do(func() {
		Register(v)
	})

	safeLabels := labelAlignment(v.secureLabels, labels)

	//
	c, err := v.GetMetricWith(safeLabels)

	if err != nil {
		// should never happen , but should still add handler to record alert
		// TODO singleton alert Gauge and return an alert counter

	}
	return c
}

// GaugeVecDecorator Add safe decorator
type GaugeVecDecorator struct {
	*prometheus.GaugeVec
	secureLabels []string
	once         *sync.Once
}

func NewGaugeVec(opts prometheus.GaugeOpts, labelNames []string) *GaugeVecDecorator {
	v := &GaugeVecDecorator{prometheus.NewGaugeVec(opts, labelNames), labelNames, &sync.Once{}}

	return v
}

// With is secure wrap for with of prometheus.GaugeVec
// there is no panic, and always calculate to metrics , if miss values, will calculate to MissLabel
// It's secure
func (v *GaugeVecDecorator) With(labels prometheus.Labels) prometheus.Gauge {
	// To avoid initialization sequence, so must delay register to with func
	v.once.Do(func() {
		Register(v)
	})

	safeLabels := labelAlignment(v.secureLabels, labels)
	//
	c, err := v.GetMetricWith(safeLabels)

	if err != nil {
		// should never happen , but should still add handler to record alert
		// TODO singleton alert Gauge and return
	}
	return c
}

// HistogramVecDecorator Add safe
type HistogramVecDecorator struct {
	*prometheus.HistogramVec
	secureLabels []string
	once         *sync.Once
}

func NewHistogramVec(opts prometheus.HistogramOpts, labelNames []string) *HistogramVecDecorator {
	v := &HistogramVecDecorator{prometheus.NewHistogramVec(opts, labelNames), labelNames, &sync.Once{}}

	return v
}

// With is secure wrap for with of prometheus.HistogramVec
// there is no panic, and always calculate to metrics , if miss values, will calculate to MissLabel
// It's secure
func (v *HistogramVecDecorator) With(labels prometheus.Labels) prometheus.Observer {
	// To avoid initialization sequence, so must delay register to with func
	v.once.Do(func() {
		Register(v)
	})

	safeLabels := labelAlignment(v.secureLabels, labels)
	//
	c, err := v.GetMetricWith(safeLabels)

	if err != nil {
		// should never happen , but should still add handler to record alert
		// TODO singleton alert Histogram and return
	}
	return c
}

// SummaryVecDecorator Add safe
type SummaryVecDecorator struct {
	*prometheus.SummaryVec
	secureLabels []string
	once         *sync.Once
}

func NewSummaryVec(opts prometheus.SummaryOpts, labelNames []string) *SummaryVecDecorator {
	v := &SummaryVecDecorator{prometheus.NewSummaryVec(opts, labelNames), labelNames, &sync.Once{}}
	//if len(autoReg) == 0 || autoReg[0] == true {
	//	Register(v)
	//}
	return v
}

// With is secure wrap for with of prometheus.SummaryVec
// there is no panic, and always calculate to metrics , if miss values, will calculate to MissLabel
// It's secure
func (v *SummaryVecDecorator) With(labels prometheus.Labels) prometheus.Observer {
	// To avoid initialization sequence, so must delay register to with func
	v.once.Do(func() {
		Register(v)
	})

	safeLabels := labelAlignment(v.secureLabels, labels)
	//
	c, err := v.GetMetricWith(safeLabels)

	if err != nil {
		// should never happen , but should still add handler to record alert
		// TODO singleton alert Gauge and return
	}
	//prometheus.NewCounter(v.SummaryVec.)
	return c
}

// 标签对齐
func labelAlignment(labelNames []string, labels prometheus.Labels) prometheus.Labels {

	newLabels := make(prometheus.Labels, len(labelNames))

	for _, val := range labelNames {
		if v, ok := labels[val]; ok {
			newLabels[val] = v
		} else {
			newLabels[val] = missVal
		}
	}
	return newLabels
}