package queue

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

var (
	// QueueDepth tracks the number of tasks in the queue.
	QueueDepth = promauto.NewGauge(prometheus.GaugeOpts{
		Name: "fetch_ml_queue_depth",
		Help: "Number of tasks in the queue",
	})

	// TasksQueued tracks the total number of tasks queued.
	TasksQueued = promauto.NewCounter(prometheus.CounterOpts{
		Name: "fetch_ml_tasks_queued_total",
		Help: "Total number of tasks queued",
	})

	// TaskDuration tracks task execution duration in seconds.
	TaskDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
		Name:    "fetch_ml_task_duration_seconds",
		Help:    "Task execution duration in seconds",
		Buckets: []float64{1, 5, 10, 30, 60, 120, 300, 600, 1800, 3600}, // 1s to 1h
	}, []string{"job_name", "status"})

	// TasksCompleted tracks the total number of completed tasks.
	TasksCompleted = promauto.NewCounterVec(prometheus.CounterOpts{
		Name: "fetch_ml_tasks_completed_total",
		Help: "Total number of completed tasks",
	}, []string{"job_name", "status"})

	// TaskFailures tracks failed tasks by error category.
	TaskFailures = promauto.NewCounterVec(prometheus.CounterOpts{
		Name: "fetch_ml_task_failures_total",
		Help: "Total number of failed tasks by error category",
	}, []string{"job_name", "error_category"})

	// TaskRetries tracks the total number of task retries.
	TaskRetries = promauto.NewCounterVec(prometheus.CounterOpts{
		Name: "fetch_ml_task_retries_total",
		Help: "Total number of task retries",
	}, []string{"job_name", "error_category"})

	// LeaseExpirations tracks expired leases that were reclaimed.
	LeaseExpirations = promauto.NewCounter(prometheus.CounterOpts{
		Name: "fetch_ml_lease_expirations_total",
		Help: "Total number of expired leases reclaimed",
	})

	// LeaseRenewals tracks successful lease renewals.
	LeaseRenewals = promauto.NewCounterVec(prometheus.CounterOpts{
		Name: "fetch_ml_lease_renewals_total",
		Help: "Total number of successful lease renewals",
	}, []string{"worker_id"})

	// DLQSize tracks the number of tasks in dead letter queue.
	DLQSize = promauto.NewGauge(prometheus.GaugeOpts{
		Name: "fetch_ml_dlq_size",
		Help: "Number of tasks in dead letter queue",
	})

	// DLQAdditions tracks tasks moved to dead letter queue.
	DLQAdditions = promauto.NewCounterVec(prometheus.CounterOpts{
		Name: "fetch_ml_dlq_additions_total",
		Help: "Total number of tasks moved to DLQ",
	}, []string{"reason"})

	// ActiveTasks tracks currently executing tasks.
	ActiveTasks = promauto.NewGaugeVec(prometheus.GaugeOpts{
		Name: "fetch_ml_active_tasks",
		Help: "Number of currently executing tasks",
	}, []string{"worker_id"})

	// WorkerHeartbeats tracks worker heartbeat events.
	WorkerHeartbeats = promauto.NewCounterVec(prometheus.CounterOpts{
		Name: "fetch_ml_worker_heartbeats_total",
		Help: "Total number of worker heartbeats",
	}, []string{"worker_id"})
)

// RecordTaskStart records when a task starts
func RecordTaskStart(_, workerID string) {
	ActiveTasks.WithLabelValues(workerID).Inc()
}

// RecordTaskEnd records when a task completes
func RecordTaskEnd(jobName, workerID, status string, durationSeconds float64) {
	ActiveTasks.WithLabelValues(workerID).Dec()
	TaskDuration.WithLabelValues(jobName, status).Observe(durationSeconds)
	TasksCompleted.WithLabelValues(jobName, status).Inc()
}

// RecordTaskFailure records a task failure with error category
func RecordTaskFailure(jobName string, errorCategory ErrorCategory) {
	TaskFailures.WithLabelValues(jobName, string(errorCategory)).Inc()
}

// RecordTaskRetry records a task retry
func RecordTaskRetry(jobName string, errorCategory ErrorCategory) {
	TaskRetries.WithLabelValues(jobName, string(errorCategory)).Inc()
}

// RecordLeaseExpiration records a lease expiration
func RecordLeaseExpiration() {
	LeaseExpirations.Inc()
}

// RecordLeaseRenewal records a successful lease renewal
func RecordLeaseRenewal(workerID string) {
	LeaseRenewals.WithLabelValues(workerID).Inc()
}

// RecordDLQAddition records a task being moved to DLQ
func RecordDLQAddition(reason string) {
	DLQAdditions.WithLabelValues(reason).Inc()
	DLQSize.Inc()
}

// UpdateQueueDepth updates the current queue depth gauge
func UpdateQueueDepth(depth int64) {
	QueueDepth.Set(float64(depth))
}