package metrics

import (
	"testing"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/testutil"
	"github.com/stretchr/testify/assert"
)

func newTestRegistry() *prometheus.Registry {
	return prometheus.NewRegistry()
}

func TestRequestsTotalCounter(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.RequestsTotal.WithLabelValues("1", "gpt-4", "200", "true", "chat").Inc()
	m.RequestsTotal.WithLabelValues("1", "gpt-4", "200", "true", "chat").Inc()
	m.RequestsTotal.WithLabelValues("2", "claude-3", "429", "false", "chat").Inc()

	assert.Equal(t, float64(2), testutil.ToFloat64(m.RequestsTotal.WithLabelValues("1", "gpt-4", "200", "true", "chat")))
	assert.Equal(t, float64(1), testutil.ToFloat64(m.RequestsTotal.WithLabelValues("2", "claude-3", "429", "false", "chat")))
}

func TestRequestErrorsTotalCounter(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.RequestErrorsTotal.WithLabelValues("1", "gpt-4", "upstream", "429").Inc()
	m.RequestErrorsTotal.WithLabelValues("1", "gpt-4", "upstream", "429").Inc()
	m.RequestErrorsTotal.WithLabelValues("2", "claude-3", "timeout", "context_deadline_exceeded").Inc()

	assert.Equal(t, float64(2), testutil.ToFloat64(m.RequestErrorsTotal.WithLabelValues("1", "gpt-4", "upstream", "429")))
	assert.Equal(t, float64(1), testutil.ToFloat64(m.RequestErrorsTotal.WithLabelValues("2", "claude-3", "timeout", "context_deadline_exceeded")))
}

func TestRequestRetriesTotalCounter(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.RequestRetriesTotal.WithLabelValues("1", "gpt-4").Inc()
	m.RequestRetriesTotal.WithLabelValues("1", "gpt-4").Inc()

	assert.Equal(t, float64(2), testutil.ToFloat64(m.RequestRetriesTotal.WithLabelValues("1", "gpt-4")))
}

func TestTokensTotalCounter(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.TokensTotal.WithLabelValues("1", "gpt-4", "prompt").Add(100)
	m.TokensTotal.WithLabelValues("1", "gpt-4", "completion").Add(50)
	m.TokensTotal.WithLabelValues("1", "gpt-4", "cache").Add(20)

	assert.Equal(t, float64(100), testutil.ToFloat64(m.TokensTotal.WithLabelValues("1", "gpt-4", "prompt")))
	assert.Equal(t, float64(50), testutil.ToFloat64(m.TokensTotal.WithLabelValues("1", "gpt-4", "completion")))
	assert.Equal(t, float64(20), testutil.ToFloat64(m.TokensTotal.WithLabelValues("1", "gpt-4", "cache")))
}

func TestQuotaConsumedTotalCounter(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.QuotaConsumedTotal.WithLabelValues("1", "gpt-4", "wallet").Add(5000)

	assert.Equal(t, float64(5000), testutil.ToFloat64(m.QuotaConsumedTotal.WithLabelValues("1", "gpt-4", "wallet")))
}

func TestRequestDurationHistogram(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.RequestDuration.WithLabelValues("1", "gpt-4", "true", "chat").Observe(1.5)
	m.RequestDuration.WithLabelValues("1", "gpt-4", "true", "chat").Observe(2.5)

	// 验证 histogram metric family 被注册且有数据
	assert.Equal(t, 1, testutil.CollectAndCount(m.RequestDuration))
}

func TestUpstreamDurationHistogram(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.UpstreamDuration.WithLabelValues("1", "gpt-4").Observe(0.5)

	assert.Equal(t, 1, testutil.CollectAndCount(m.UpstreamDuration))
}

func TestFirstTokenDurationHistogram(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.FirstTokenDuration.WithLabelValues("1", "gpt-4").Observe(0.1)

	assert.Equal(t, 1, testutil.CollectAndCount(m.FirstTokenDuration))
}

func TestActiveRequestsGauge(t *testing.T) {
	reg := newTestRegistry()
	m := NewMetrics(reg)

	m.ActiveRequests.WithLabelValues("gpt-4").Inc()
	m.ActiveRequests.WithLabelValues("gpt-4").Inc()
	m.ActiveRequests.WithLabelValues("claude-3").Inc()

	assert.Equal(t, float64(2), testutil.ToFloat64(m.ActiveRequests.WithLabelValues("gpt-4")))
	assert.Equal(t, float64(1), testutil.ToFloat64(m.ActiveRequests.WithLabelValues("claude-3")))

	m.ActiveRequests.WithLabelValues("gpt-4").Dec()
	assert.Equal(t, float64(1), testutil.ToFloat64(m.ActiveRequests.WithLabelValues("gpt-4")))
}

func TestMetricsDisabledIsNoOp(t *testing.T) {
	// 当 METRICS_ENABLED=false 时，使用独立 registry（Discard）
	reg := prometheus.NewPedanticRegistry()
	m := NewMetrics(reg)
	// 这些调用不应该 panic
	m.RequestsTotal.WithLabelValues("1", "gpt-4", "200", "true", "chat").Inc()
	m.ActiveRequests.WithLabelValues("gpt-4").Inc()
	m.RequestDuration.WithLabelValues("1", "gpt-4", "true", "chat").Observe(1.0)
}