package screens

import (
	"context"
	"fmt"
	"regexp"
	"strings"

	"example.com/m/adapter/backend"
	"example.com/m/bot"
	"github.com/NicoNex/echotron/v3"
	"github.com/rs/zerolog/log"
)

type PurchaseChannelInput struct {
	Username    string
	PlannedCost *float64
	Comment     *string
}

type SelectChannelsForPurchase struct {
	WorkspaceID      string
	ProjectID        string
	ProjectTitle     string
	CreativeID       string
	CreativeTitle    string
	Channels         []PurchaseChannelInput
	CurrentPage      int
	InvalidUsernames []string
	BackState        bot.State
}

var channelUsernameRe = regexp.MustCompile(`^[A-Za-z][A-Za-z0-9_]{4,31}$`)

func (s *SelectChannelsForPurchase) Enter(b *bot.Bot, mode bot.RenderMode) {
	s.renderChannelSelection(b, mode)
}

func (s *SelectChannelsForPurchase) renderChannelSelection(b *bot.Bot, mode bot.RenderMode) {
	text := "<i>… › Создание › Каналы</i>\n\n"
	text += "<b>Создание закупа</b>\n\n"
	text += "<b>Шаг 2/2:</b> Добавление каналов\n\n"

	var buttons [][]echotron.InlineKeyboardButton

	if len(s.Channels) == 0 {
		text += `Добавьте каналы для размещения рекламы

Отправьте username канала (без @)
Например: <code>channel_name</code>

После добавления всех каналов нажмите <b>Далее</b>`
	} else {
		text += fmt.Sprintf("Добавлено каналов: <b>%d</b>\n\n", len(s.Channels))

		for i, ch := range s.Channels {
			channelText := fmt.Sprintf("  %d. @%s", i+1, ch.Username)
			if ch.PlannedCost != nil {
				channelText += fmt.Sprintf(" — %.0f₽", *ch.PlannedCost)
			}
			text += channelText + "\n"
		}
		text += "\n"

		const channelsPerPage = 6
		start := s.CurrentPage * channelsPerPage
		if start >= len(s.Channels) {
			s.CurrentPage = 0
			start = 0
		}
		end := start + channelsPerPage
		if end > len(s.Channels) {
			end = len(s.Channels)
		}

		var slots []echotron.InlineKeyboardButton
		for i := start; i < end; i++ {
			ch := s.Channels[i]
			buttonText := fmt.Sprintf("@%s", ch.Username)
			if ch.PlannedCost != nil {
				buttonText = fmt.Sprintf("@%s — %.0f₽", ch.Username, *ch.PlannedCost)
			}
			slots = append(slots, bot.Button(buttonText, fmt.Sprintf("remove_channel:%d", i)))
		}

		if len(s.Channels) > channelsPerPage {
			for len(slots) < channelsPerPage {
				slots = append(slots, bot.Button(" ", "empty"))
			}
		}

		for i := 0; i < len(slots); i += 2 {
			row := []echotron.InlineKeyboardButton{slots[i]}
			if i+1 < len(slots) {
				row = append(row, slots[i+1])
			} else {
				row = append(row, bot.Button(" ", "empty"))
			}
			buttons = append(buttons, row)
		}

		pages := (len(s.Channels) + channelsPerPage - 1) / channelsPerPage
		if pages > 1 {
			var navRow []echotron.InlineKeyboardButton
			if s.CurrentPage > 0 {
				navRow = append(navRow, bot.Button("←", "prev_page"))
			} else {
				navRow = append(navRow, bot.Button("·", "empty"))
			}
			navRow = append(navRow, bot.Button(fmt.Sprintf("• %d/%d •", s.CurrentPage+1, pages), "page_info"))
			if s.CurrentPage+1 < pages {
				navRow = append(navRow, bot.Button("→", "next_page"))
			} else {
				navRow = append(navRow, bot.Button("·", "empty"))
			}
			buttons = append(buttons, navRow)
		}

		text += "\nДобавьте еще каналы или создайте закуп"

		// Кнопка создания закупа (доступна только если есть каналы)
	}

	if len(s.InvalidUsernames) > 0 {
		text += fmt.Sprintf("\n\n⚠️ Пропущены: %s", strings.Join(s.InvalidUsernames, ", "))
		s.InvalidUsernames = nil
	}

	// Кнопки навигации
	if len(s.Channels) > 0 {
		buttons = append(buttons, bot.Row(
			bot.Button("← Назад", "back"),
			bot.Button("→ Далее", "next"),
		))
	} else {
		buttons = append(buttons, bot.Row(
			bot.Button("← Назад", "back"),
		))
	}

	keyboard := bot.Keyboard(buttons...)
	b.Render(text, keyboard, mode)
}

func (s *SelectChannelsForPurchase) ensureJWT(b *bot.Bot) (string, error) {
	if b.Session.JWT != "" {
		return b.Session.JWT, nil
	}

	jwt, err := b.Backend.GetJWTByTelegramID(context.Background(), b.ChatID)
	if err != nil {
		return "", err
	}

	b.Session.JWT = jwt
	return jwt, nil
}

func (s *SelectChannelsForPurchase) HandleCallback(b *bot.Bot, u *echotron.Update) {
	if u.CallbackQuery == nil || u.CallbackQuery.Data == "" {
		return
	}

	data := u.CallbackQuery.Data

	switch data {
	case "back":
		// Возвращаемся к выбору креатива
		b.SetState(&AddPurchase{
			WorkspaceID:   s.WorkspaceID,
			ProjectID:     s.ProjectID,
			ProjectTitle:  s.ProjectTitle,
			CreativeID:    s.CreativeID,
			CreativeTitle: s.CreativeTitle,
			ActivePicker:  "",
			BackState:     s.BackState,
		}, bot.EditMessage)

	case "next":
		if len(s.Channels) == 0 {
			b.Edit("❌ Добавьте хотя бы один канал", bot.Keyboard(
				bot.Row(bot.Button("← Назад", "back_to_select")),
			))
			return
		}

		b.SetState(&PurchaseOptionalDetails{
			WorkspaceID:   s.WorkspaceID,
			ProjectID:     s.ProjectID,
			ProjectTitle:  s.ProjectTitle,
			CreativeID:    s.CreativeID,
			CreativeTitle: s.CreativeTitle,
			Channels:      s.Channels,
			BackState:     s.BackState,
		}, bot.EditMessage)

	case "back_to_select":
		s.Enter(b, bot.EditMessage)

	case "prev_page":
		if s.CurrentPage > 0 {
			s.CurrentPage--
		}
		s.Enter(b, bot.EditMessage)

	case "next_page":
		s.CurrentPage++
		s.Enter(b, bot.EditMessage)

	default:
		if len(data) > 15 && data[:15] == "remove_channel:" {
			var index int
			if _, err := fmt.Sscanf(data[15:], "%d", &index); err == nil {
				if index >= 0 && index < len(s.Channels) {
					s.Channels = append(s.Channels[:index], s.Channels[index+1:]...)
					if s.CurrentPage > 0 {
						channelsPerPage := 6
						pages := (len(s.Channels) + channelsPerPage - 1) / channelsPerPage
						if s.CurrentPage >= pages {
							s.CurrentPage = pages - 1
						}
					}
					s.Enter(b, bot.EditMessage)
					return
				}
			}
		}
		s.Enter(b, bot.NewMessage)
	}
}

func (s *SelectChannelsForPurchase) createPurchase(b *bot.Bot, jwt string) {
	// Преобразуем каналы в формат API
	var apiChannels []backend.CreatePurchaseChannelInput
	for _, ch := range s.Channels {
		apiChannels = append(apiChannels, backend.CreatePurchaseChannelInput{
			Username:    ch.Username,
			PlannedCost: ch.PlannedCost,
			Comment:     ch.Comment,
		})
	}

	input := backend.CreatePurchaseInput{
		CreativeID: s.CreativeID,
		Channels:   apiChannels,
	}

	purchase, err := b.Backend.CreatePurchase(
		context.Background(),
		jwt,
		s.WorkspaceID,
		s.ProjectID,
		input,
	)

	if err != nil {
		log.Error().Err(err).Msg("Failed to create purchase")
		b.Edit("❌ Не удалось создать закуп\n\nВозможные причины:\n• Один из каналов не найден\n• Ошибка сервера", bot.Keyboard(
			bot.Row(bot.Button("← Назад", "back_to_select")),
		))
		return
	}

	// Показываем успешное создание
	successText := fmt.Sprintf(`<i>… › Создание › Готово</i>

<b>Закуп создан</b>

  ▪ <b>ID:</b> %s
  ▪ <b>Креатив:</b> %s
  ▪ <b>Каналов:</b> %d

Закуп создан и готов к работе`, purchase.ID, purchase.CreativeID, len(purchase.Channels))

	b.Edit(successText, bot.Keyboard(
		bot.Row(bot.Button("● Готово", "done")),
	))
}

func (s *SelectChannelsForPurchase) HandleMessage(b *bot.Bot, u *echotron.Update) {
	if u.Message == nil || u.Message.Text == "" {
		return
	}

	raw := strings.TrimSpace(u.Message.Text)
	if raw == "" {
		return
	}

	tokens := strings.FieldsFunc(raw, func(r rune) bool {
		return r == ' ' || r == '\n' || r == '\t' || r == ',' || r == ';'
	})

	added := 0
	var invalid []string
	for _, token := range tokens {
		username := strings.TrimSpace(token)
		username = strings.TrimPrefix(username, "@")
		username = strings.Trim(username, "@")
		username = strings.Trim(username, ",;")

		if username == "" {
			continue
		}
		if !channelUsernameRe.MatchString(username) {
			invalid = append(invalid, username)
			continue
		}

		exists := false
		for _, ch := range s.Channels {
			if ch.Username == username {
				exists = true
				break
			}
		}
		if exists {
			continue
		}

		s.Channels = append(s.Channels, PurchaseChannelInput{
			Username: username,
		})
		added++
	}

	if added == 0 {
		if len(invalid) == 0 {
			return
		}
	}

	s.InvalidUsernames = invalid

	// Обновляем экран
	s.Enter(b, bot.NewMessage)
}

func (s *SelectChannelsForPurchase) Handle(b *bot.Bot, u *echotron.Update) {
	// Обрабатываем callback после успешного создания
	if u.CallbackQuery != nil && u.CallbackQuery.Data == "done" {
		// Возвращаемся к списку закупов
		if s.BackState != nil {
			b.SetState(s.BackState, bot.EditMessage)
		}
	}
}