// Package observability provides logging and metrics infrastructure
package observability

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

// Metrics defines the metrics collection interface
type Metrics interface {
	// RecordSwapEvent records a swap event being processed
	RecordSwapEvent(protocol string, success bool)

	// RecordParseLatency records parsing latency in seconds
	RecordParseLatency(protocol string, latencySeconds float64)

	// RecordArbitrageOpportunity records an arbitrage opportunity
	RecordArbitrageOpportunity(profit float64)

	// RecordExecution records a trade execution
	RecordExecution(success bool, netProfit float64)

	// IncrementPoolCacheSize increments the pool cache size
	IncrementPoolCacheSize()

	// DecrementPoolCacheSize decrements the pool cache size
	DecrementPoolCacheSize()
}

// prometheusMetrics implements Metrics using Prometheus
type prometheusMetrics struct {
	swapEventsTotal       *prometheus.CounterVec
	parseLatency          *prometheus.HistogramVec
	arbitrageOpportunities *prometheus.CounterVec
	arbitrageProfit       *prometheus.HistogramVec
	executionsTotal       *prometheus.CounterVec
	executionProfit       *prometheus.HistogramVec
	poolCacheSize         prometheus.Gauge
}

// NewMetrics creates a new Prometheus metrics collector
func NewMetrics(namespace string) Metrics {
	return &prometheusMetrics{
		swapEventsTotal: promauto.NewCounterVec(
			prometheus.CounterOpts{
				Namespace: namespace,
				Name:      "swap_events_total",
				Help:      "Total number of swap events processed",
			},
			[]string{"protocol", "status"},
		),
		parseLatency: promauto.NewHistogramVec(
			prometheus.HistogramOpts{
				Namespace: namespace,
				Name:      "parse_latency_seconds",
				Help:      "Latency of parsing swap events in seconds",
				Buckets:   []float64{0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1.0},
			},
			[]string{"protocol"},
		),
		arbitrageOpportunities: promauto.NewCounterVec(
			prometheus.CounterOpts{
				Namespace: namespace,
				Name:      "arbitrage_opportunities_total",
				Help:      "Total number of arbitrage opportunities detected",
			},
			[]string{"status"},
		),
		arbitrageProfit: promauto.NewHistogramVec(
			prometheus.HistogramOpts{
				Namespace: namespace,
				Name:      "arbitrage_profit_eth",
				Help:      "Arbitrage profit in ETH",
				Buckets:   []float64{0.01, 0.05, 0.1, 0.5, 1.0, 5.0, 10.0},
			},
			[]string{"status"},
		),
		executionsTotal: promauto.NewCounterVec(
			prometheus.CounterOpts{
				Namespace: namespace,
				Name:      "executions_total",
				Help:      "Total number of trade executions",
			},
			[]string{"status"},
		),
		executionProfit: promauto.NewHistogramVec(
			prometheus.HistogramOpts{
				Namespace: namespace,
				Name:      "execution_profit_eth",
				Help:      "Execution profit in ETH (after gas)",
				Buckets:   []float64{-1.0, -0.1, -0.01, 0, 0.01, 0.1, 1.0, 10.0},
			},
			[]string{"status"},
		),
		poolCacheSize: promauto.NewGauge(
			prometheus.GaugeOpts{
				Namespace: namespace,
				Name:      "pool_cache_size",
				Help:      "Current number of pools in cache",
			},
		),
	}
}

func (m *prometheusMetrics) RecordSwapEvent(protocol string, success bool) {
	status := "success"
	if !success {
		status = "failure"
	}
	m.swapEventsTotal.WithLabelValues(protocol, status).Inc()
}

func (m *prometheusMetrics) RecordParseLatency(protocol string, latencySeconds float64) {
	m.parseLatency.WithLabelValues(protocol).Observe(latencySeconds)
}

func (m *prometheusMetrics) RecordArbitrageOpportunity(profit float64) {
	m.arbitrageOpportunities.WithLabelValues("detected").Inc()
	m.arbitrageProfit.WithLabelValues("detected").Observe(profit)
}

func (m *prometheusMetrics) RecordExecution(success bool, netProfit float64) {
	status := "success"
	if !success {
		status = "failure"
	}
	m.executionsTotal.WithLabelValues(status).Inc()
	m.executionProfit.WithLabelValues(status).Observe(netProfit)
}

func (m *prometheusMetrics) IncrementPoolCacheSize() {
	m.poolCacheSize.Inc()
}

func (m *prometheusMetrics) DecrementPoolCacheSize() {
	m.poolCacheSize.Dec()
}