package metric

import (
	"maps"
	"math"
	"sync/atomic"

	"github.com/prometheus/client_golang/prometheus"
	"repositories.action2quare.com/ayo/gocommon/logger"
)

const (
	METRIC_HEAD_INLINE = byte(14)
	METRIC_TAIL_INLINE = byte(15)
)

type MetricType int

const (
	MetricCounter   = MetricType(1)
	MetricGuage     = MetricType(2)
	metric_key_size = 8
)

func convertValueType(in MetricType) prometheus.ValueType {
	switch in {
	case MetricCounter:
		return prometheus.CounterValue

	case MetricGuage:
		return prometheus.GaugeValue
	}

	return prometheus.UntypedValue
}

type prometheusMetricDesc struct {
	*prometheus.Desc
	valueType prometheus.ValueType
	valptr    *uint64
	key       string
}

type PrometheusCollector struct {
	namespace string
	metrics   map[string]*prometheusMetricDesc
	registry  *prometheus.Registry
}

func (pc *PrometheusCollector) Describe(ch chan<- *prometheus.Desc) {
	for _, v := range pc.metrics {
		logger.Println("collector describe :", v.Desc.String())
		ch <- v.Desc
	}
}

func (pc *PrometheusCollector) Collect(ch chan<- prometheus.Metric) {
	for _, v := range pc.metrics {
		value := atomic.LoadUint64(v.valptr)
		cm, err := prometheus.NewConstMetric(v.Desc, v.valueType, math.Float64frombits(value))
		if err == nil {
			ch <- cm
		}
	}
}

func (pc *PrometheusCollector) RegisterMetric(md *MetricDescription) *PrometheusCollector {
	nm := &prometheusMetricDesc{
		Desc:      prometheus.NewDesc(prometheus.BuildFQName("ou", "", md.Name), md.Help, nil, md.ConstLabels),
		valueType: convertValueType(md.Type),
		valptr:    new(uint64),
		key:       md.Key,
	}

	next := NewPrometheusCollector(pc.namespace, pc.registry)
	maps.Copy(next.metrics, pc.metrics)
	next.metrics[nm.key] = nm

	pc.registry.Unregister(pc)
	pc.registry.Register(next)

	return next
}

func (pc *PrometheusCollector) UpdateMetric(key string, val float64) {
	if m := pc.metrics[key]; m != nil {
		atomic.StoreUint64(m.valptr, math.Float64bits(val))
	}
}

func (pc *PrometheusCollector) UnregisterMetric(key string) *PrometheusCollector {
	next := NewPrometheusCollector(pc.namespace, pc.registry)
	maps.Copy(next.metrics, pc.metrics)
	delete(next.metrics, key)

	pc.registry.Unregister(pc)
	pc.registry.Register(next)

	return next
}

func NewPrometheusCollector(namespace string, registry *prometheus.Registry) *PrometheusCollector {
	return &PrometheusCollector{
		namespace: namespace,
		metrics:   make(map[string]*prometheusMetricDesc),
		registry:  registry,
	}
}