package observability

import (
	"net/http"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

// Metrics holds Prometheus metrics for the wrapper
type Metrics struct {
	requestsTotal    prometheus.Counter
	errorsTotal      prometheus.Counter
	decryptFails     prometheus.Counter
	encryptFails     prometheus.Counter
	policyDenials    prometheus.Counter
	requestDuration  prometheus.Histogram
}

// InitMetrics initializes Prometheus metrics
func InitMetrics() *Metrics {
	return &Metrics{
		requestsTotal: promauto.NewCounter(prometheus.CounterOpts{
			Name: "seqthink_requests_total",
			Help: "Total number of requests received",
		}),
		errorsTotal: promauto.NewCounter(prometheus.CounterOpts{
			Name: "seqthink_errors_total",
			Help: "Total number of errors",
		}),
		decryptFails: promauto.NewCounter(prometheus.CounterOpts{
			Name: "seqthink_decrypt_failures_total",
			Help: "Total number of decryption failures",
		}),
		encryptFails: promauto.NewCounter(prometheus.CounterOpts{
			Name: "seqthink_encrypt_failures_total",
			Help: "Total number of encryption failures",
		}),
		policyDenials: promauto.NewCounter(prometheus.CounterOpts{
			Name: "seqthink_policy_denials_total",
			Help: "Total number of policy denials",
		}),
		requestDuration: promauto.NewHistogram(prometheus.HistogramOpts{
			Name:    "seqthink_request_duration_seconds",
			Help:    "Request duration in seconds",
			Buckets: prometheus.DefBuckets,
		}),
	}
}

// IncrementRequests increments the request counter
func (m *Metrics) IncrementRequests() {
	m.requestsTotal.Inc()
}

// IncrementErrors increments the error counter
func (m *Metrics) IncrementErrors() {
	m.errorsTotal.Inc()
}

// IncrementDecryptFails increments the decrypt failure counter
func (m *Metrics) IncrementDecryptFails() {
	m.decryptFails.Inc()
}

// IncrementEncryptFails increments the encrypt failure counter
func (m *Metrics) IncrementEncryptFails() {
	m.encryptFails.Inc()
}

// IncrementPolicyDenials increments the policy denial counter
func (m *Metrics) IncrementPolicyDenials() {
	m.policyDenials.Inc()
}

// ObserveRequestDuration records request duration
func (m *Metrics) ObserveRequestDuration(seconds float64) {
	m.requestDuration.Observe(seconds)
}

// Handler returns the Prometheus metrics HTTP handler
func (m *Metrics) Handler() http.Handler {
	return promhttp.Handler()
}