package queue

import (
	"sync/atomic"
	"time"
)

type Metrics struct {
	received             atomic.Int64
	processed            atomic.Int64
	retried              atomic.Int64
	failed               atomic.Int64
	deadLettered         atomic.Int64
	duplicates           atomic.Int64
	malformed            atomic.Int64
	ackFailures          atomic.Int64
	retryFailures        atomic.Int64
	deadLetterFailures   atomic.Int64
	lastQueueDepth       atomic.Int64
	totalProcessingNanos atomic.Int64
	lastProcessingNanos  atomic.Int64
}

type MetricsSnapshot struct {
	Received                 int64         `json:"received"`
	Processed                int64         `json:"processed"`
	Retried                  int64         `json:"retried"`
	Failed                   int64         `json:"failed"`
	DeadLettered             int64         `json:"dead_lettered"`
	Duplicates               int64         `json:"duplicates"`
	Malformed                int64         `json:"malformed"`
	AckFailures              int64         `json:"ack_failures"`
	RetryFailures            int64         `json:"retry_failures"`
	DeadLetterFailures       int64         `json:"dead_letter_failures"`
	ApproximateQueueDepth    int64         `json:"approximate_queue_depth"`
	LastProcessingLatency    time.Duration `json:"last_processing_latency"`
	AverageProcessingLatency time.Duration `json:"average_processing_latency"`
}

func NewMetrics() *Metrics {
	return &Metrics{}
}

func (m *Metrics) RecordReceive(n int) {
	m.received.Add(int64(n))
}

func (m *Metrics) RecordProcessed(duration time.Duration) {
	m.processed.Add(1)
	m.lastProcessingNanos.Store(duration.Nanoseconds())
	m.totalProcessingNanos.Add(duration.Nanoseconds())
}

func (m *Metrics) RecordRetry() {
	m.retried.Add(1)
}

func (m *Metrics) RecordFailure() {
	m.failed.Add(1)
}

func (m *Metrics) RecordDeadLetter() {
	m.deadLettered.Add(1)
}

func (m *Metrics) RecordDuplicate() {
	m.duplicates.Add(1)
}

func (m *Metrics) RecordMalformed() {
	m.malformed.Add(1)
}

func (m *Metrics) RecordAckFailure() {
	m.ackFailures.Add(1)
}

func (m *Metrics) RecordRetryFailure() {
	m.retryFailures.Add(1)
}

func (m *Metrics) RecordDeadLetterFailure() {
	m.deadLetterFailures.Add(1)
}

func (m *Metrics) SetQueueDepth(depth int64) {
	m.lastQueueDepth.Store(depth)
}

func (m *Metrics) Snapshot() MetricsSnapshot {
	processed := m.processed.Load()
	total := m.totalProcessingNanos.Load()
	avg := time.Duration(0)
	if processed > 0 {
		avg = time.Duration(total / processed)
	}
	return MetricsSnapshot{
		Received:                 m.received.Load(),
		Processed:                processed,
		Retried:                  m.retried.Load(),
		Failed:                   m.failed.Load(),
		DeadLettered:             m.deadLettered.Load(),
		Duplicates:               m.duplicates.Load(),
		Malformed:                m.malformed.Load(),
		AckFailures:              m.ackFailures.Load(),
		RetryFailures:            m.retryFailures.Load(),
		DeadLetterFailures:       m.deadLetterFailures.Load(),
		ApproximateQueueDepth:    m.lastQueueDepth.Load(),
		LastProcessingLatency:    time.Duration(m.lastProcessingNanos.Load()),
		AverageProcessingLatency: avg,
	}
}