package notify

import (
	"bufio"
	"context"
	"encoding/base64"
	"net"
	"strconv"
	"strings"
	"testing"
	"time"

	"dana/internal/domain"
)

// fakeSMTP — минимальный SMTP-сервер без TLS и авторизации: принимает одно письмо.
func fakeSMTP(t *testing.T) (host string, port int, got <-chan string) {
	t.Helper()
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { ln.Close() })

	ch := make(chan string, 1)
	go func() {
		conn, err := ln.Accept()
		if err != nil {
			return
		}
		defer conn.Close()
		r := bufio.NewReader(conn)
		w := func(s string) { conn.Write([]byte(s + "\r\n")) }

		w("220 fake")
		var transcript strings.Builder
		inData := false
		for {
			line, err := r.ReadString('\n')
			if err != nil {
				return
			}
			if inData {
				if line == ".\r\n" {
					inData = false
					w("250 queued")
					continue
				}
				transcript.WriteString(line)
				continue
			}
			cmd := strings.ToUpper(strings.TrimSpace(line))
			switch {
			case strings.HasPrefix(cmd, "EHLO"), strings.HasPrefix(cmd, "HELO"):
				w("250 fake")
			case strings.HasPrefix(cmd, "MAIL FROM"), strings.HasPrefix(cmd, "RCPT TO"):
				transcript.WriteString(strings.TrimSpace(line) + "\n")
				w("250 ok")
			case cmd == "DATA":
				inData = true
				w("354 go")
			case cmd == "QUIT":
				w("221 bye")
				ch <- transcript.String()
				return
			default:
				w("250 ok")
			}
		}
	}()

	addr := ln.Addr().(*net.TCPAddr)
	return "127.0.0.1", addr.Port, ch
}

func TestEmailLeadCreated(t *testing.T) {
	host, port, got := fakeSMTP(t)
	e := &Email{Host: host, Port: port, From: "DANA сайт <site@example.ru>", To: []string{"admin@example.ru"}, SiteURL: "https://danamedical.ru"}

	lead := domain.LeadNotice{
		ID:        42,
		FormTitle: "Запись на приём",
		Name:      "Иван\r\nBcc: evil@example.com",
		Phone:     "+7 (928) 000-00-99",
		Service:   "Консультация педиатра",
		Extra:     map[string]any{"date": "2026-09-20", "time": "Утро, 08:00–12:00"},
		Message:   "Тестовая заявка",
		PageURL:   "/services/detskaya-klinika/priem-pediatra/",
		CreatedAt: time.Date(2026, 9, 15, 9, 30, 0, 0, time.UTC),
	}

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if err := e.LeadCreated(ctx, lead); err != nil {
		t.Fatalf("LeadCreated: %v", err)
	}

	var transcript string
	select {
	case transcript = <-got:
	case <-time.After(5 * time.Second):
		t.Fatal("fake SMTP did not receive message")
	}

	if !strings.Contains(transcript, "MAIL FROM:<site@example.ru>") || !strings.Contains(transcript, "RCPT TO:<admin@example.ru>") {
		t.Fatalf("envelope not as expected:\n%s", transcript)
	}
	// перевод строки в имени не должен стать заголовком письма
	if strings.Contains(transcript, "\r\nBcc:") {
		t.Fatalf("header injection:\n%s", transcript)
	}

	body := decodeBody(t, transcript)
	for _, want := range []string{
		"Новая заявка № 42",
		"Время: 15.09.2026 12:30",
		"Форма: Запись на приём",
		"Имя: Иван Bcc: evil@example.com",
		"Телефон: +7 (928) 000-00-99",
		"Услуга: Консультация педиатра",
		"Желаемая дата: 2026-09-20",
		"Удобное время: Утро, 08:00–12:00",
		"Тестовая заявка",
		"Все заявки: https://danamedical.ru/admin/",
	} {
		if !strings.Contains(body, want) {
			t.Errorf("body has no %q:\n%s", want, body)
		}
	}
}

func TestFormRecipientsOverrideDefault(t *testing.T) {
	host, port, got := fakeSMTP(t)
	e := &Email{Host: host, Port: port, From: "site@example.ru", To: []string{"default@example.ru"}}
	lead := domain.LeadNotice{ID: 1, Recipients: []string{"doctors@example.ru", "не адрес"}}

	if err := e.LeadCreated(context.Background(), lead); err != nil {
		t.Fatal(err)
	}
	transcript := <-got
	if !strings.Contains(transcript, "RCPT TO:<doctors@example.ru>") || strings.Contains(transcript, "default@example.ru") {
		t.Fatalf("recipients of the form must replace defaults:\n%s", transcript)
	}
}

func TestNoRecipients(t *testing.T) {
	e := &Email{Host: "127.0.0.1", Port: 1, From: "site@example.ru"}
	if err := e.LeadCreated(context.Background(), domain.LeadNotice{ID: 1}); err != errNoRecipients {
		t.Fatalf("want errNoRecipients, got %v", err)
	}
}

func decodeBody(t *testing.T, transcript string) string {
	t.Helper()
	parts := strings.SplitN(transcript, "\r\n\r\n", 2)
	if len(parts) != 2 {
		t.Fatalf("no body separator:\n%s", transcript)
	}
	raw, err := base64.StdEncoding.DecodeString(strings.ReplaceAll(parts[1], "\r\n", ""))
	if err != nil {
		t.Fatalf("decode body: %v", err)
	}
	return string(raw)
}

var _ = strconv.Itoa