package telemetry

import (
	"fmt"
	"net/http"
	"sync/atomic"
)

type Metrics struct {
	requests     atomic.Uint64
	failed       atomic.Uint64
	inFlight     atomic.Int64
	attempts     atomic.Uint64
	droppedUsage atomic.Uint64
}

func (m *Metrics) RequestStarted() {
	m.requests.Add(1)
	m.inFlight.Add(1)
}

func (m *Metrics) RequestFinished(success bool) {
	m.inFlight.Add(-1)
	if !success {
		m.failed.Add(1)
	}
}

func (m *Metrics) UpstreamAttempt() {
	m.attempts.Add(1)
}

func (m *Metrics) UsageDropped() {
	m.droppedUsage.Add(1)
}

func (m *Metrics) ServeHTTP(w http.ResponseWriter, _ *http.Request) {
	w.Header().Set("Content-Type", "text/plain; version=0.0.4")
	fmt.Fprintf(w, "# TYPE aigw_requests_total counter\naigw_requests_total %d\n", m.requests.Load())
	fmt.Fprintf(w, "# TYPE aigw_requests_failed_total counter\naigw_requests_failed_total %d\n", m.failed.Load())
	fmt.Fprintf(w, "# TYPE aigw_requests_in_flight gauge\naigw_requests_in_flight %d\n", m.inFlight.Load())
	fmt.Fprintf(w, "# TYPE aigw_upstream_attempts_total counter\naigw_upstream_attempts_total %d\n", m.attempts.Load())
	fmt.Fprintf(w, "# TYPE aigw_usage_events_dropped_total counter\naigw_usage_events_dropped_total %d\n", m.droppedUsage.Load())
}