package metrics

import (
	"context"
	"io"
	"net"
	"net/http"
	"strings"
	"testing"
	"time"
)

func TestListenAndServeShutdown(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	errCh := make(chan error, 1)
	go func() {
		errCh <- ListenAndServe(ctx, "127.0.0.1:0", "/metrics")
	}()

	time.Sleep(50 * time.Millisecond)
	cancel()

	select {
	case err := <-errCh:
		if err != nil {
			t.Fatalf("ListenAndServe returned error: %v", err)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("ListenAndServe did not return after context cancel")
	}
}

func TestMetricsEndpoint(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	addr := ln.Addr().String()
	_ = ln.Close()

	// Increment counters so they appear in output.
	ConnectionsTotal.WithLabelValues("127.0.0.1:4430", "l4").Inc()
	FirewallBlockedTotal.WithLabelValues("ip").Inc()
	ConnectionsActive.WithLabelValues("127.0.0.1:4430").Set(1)

	go func() { _ = ListenAndServe(ctx, addr, "/metrics") }()
	time.Sleep(100 * time.Millisecond)

	resp, err := http.Get("http://" + addr + "/metrics")
	if err != nil {
		t.Fatalf("GET /metrics: %v", err)
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode != 200 {
		t.Fatalf("status = %d, want 200", resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		t.Fatalf("reading body: %v", err)
	}

	text := string(body)
	for _, want := range []string{
		"mcproxy_connections_total",
		"mcproxy_firewall_blocked_total",
		"mcproxy_connections_active",
	} {
		if !strings.Contains(text, want) {
			t.Errorf("response missing %s", want)
		}
	}
}

func TestMetricsDefaultPath(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	addr := ln.Addr().String()
	_ = ln.Close()

	go func() { _ = ListenAndServe(ctx, addr, "") }()
	time.Sleep(100 * time.Millisecond)

	resp, err := http.Get("http://" + addr + "/metrics")
	if err != nil {
		t.Fatalf("GET /metrics: %v", err)
	}
	defer func() { _ = resp.Body.Close() }()

	if resp.StatusCode != 200 {
		t.Fatalf("status = %d, want 200", resp.StatusCode)
	}
}

func TestMetricsSanity(t *testing.T) {
	// Verify all metric vars can be used without panicking.
	ConnectionsTotal.WithLabelValues("test:443", "l4").Inc()
	ConnectionsActive.WithLabelValues("test:443").Set(5)
	FirewallBlockedTotal.WithLabelValues("ip").Inc()
	FirewallBlockedTotal.WithLabelValues("cidr").Inc()
	FirewallBlockedTotal.WithLabelValues("country").Inc()
	FirewallBlockedTotal.WithLabelValues("rate_limit").Inc()
	BackendDialDuration.WithLabelValues("127.0.0.1:8080").Observe(0.005)
	TransferredBytesTotal.WithLabelValues("client_to_backend", "example.com").Add(1024)
	TransferredBytesTotal.WithLabelValues("backend_to_client", "example.com").Add(2048)
	L7ResponsesTotal.WithLabelValues("example.com", "200").Inc()
	L7ResponsesTotal.WithLabelValues("example.com", "502").Inc()
	L7PolicyBlocksTotal.WithLabelValues("example.com", "block_user_agent").Inc()
	L7PolicyBlocksTotal.WithLabelValues("example.com", "require_header").Inc()
}