package calendartest

import (
	"context"
	"errors"
	"fmt"
	"net"
	"os"
	"runtime"
	"strings"
	"testing"
	"time"

	"amadan.net/oficina/calendar/internal/calendar/keymailtest"
)

// TestMain keeps Keymail classification inside the process: every POST
// /signin now classifies its address, and without this each one would
// ask the real network whether example.com runs Keymail. Every DNS
// query is answered NXDOMAIN; no fixture is registered here, so every
// address is plain email.
func TestMain(m *testing.M) {
	restore, err := keymailtest.Install()
	if err != nil {
		fmt.Fprintln(os.Stderr, "keymailtest.Install:", err)
		os.Exit(1)
	}
	code := m.Run()
	// No test may leave a sign-in mail worker running: every app a test
	// builds is closed in its cleanup.
	if code == 0 {
		deadline := time.Now().Add(5 * time.Second)
		for mailWorkers() > 0 && time.Now().Before(deadline) {
			time.Sleep(10 * time.Millisecond)
		}
		if n := mailWorkers(); n > 0 {
			fmt.Fprintf(os.Stderr, "FAIL: %d sign-in mail queue goroutines still running after the tests\n", n)
			code = 1
		}
	}
	restore()
	os.Exit(code)
}

// mailWorkers counts goroutines running a sign-in mail queue's worker
// or log pump (internal/calendar/signin_mail.go).
func mailWorkers() int {
	buf := make([]byte, 1<<22)
	stacks := string(buf[:runtime.Stack(buf, true)])
	return strings.Count(stacks, "(*mailQueue).run(") + strings.Count(stacks, "(*mailQueue).pump(")
}

// TestKeymailDiscoveryStaysInProcess: every unforced POST /signin
// classifies its address (rastrillo/auth's Keymail discovery), so this
// package's tests must not ask the real network whether example.com runs
// Keymail. With keymailtest installed every query is answered NXDOMAIN
// in-process, so even example.com, which public DNS resolves, must not.
func TestKeymailDiscoveryStaysInProcess(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()
	addrs, err := net.DefaultResolver.LookupHost(ctx, "example.com")
	var dnsErr *net.DNSError
	if !errors.As(err, &dnsErr) || !dnsErr.IsNotFound {
		t.Fatalf("LookupHost(example.com) = %v, %v; want NXDOMAIN from keymailtest's in-process resolver", addrs, err)
	}
}