package webhook

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"

	"github.com/gin-gonic/gin"

	"github.com/gochat/gochat/internal/channel"
	channelprovider "github.com/gochat/gochat/internal/channel/provider"
	telegramchannel "github.com/gochat/gochat/internal/channel/telegram"
	"github.com/gochat/gochat/internal/model"
	channelmodel "github.com/gochat/gochat/internal/model/channel"
	"github.com/gochat/gochat/internal/worker"
	applogger "github.com/gochat/gochat/pkg/logger"
	"gorm.io/gorm"
)

// TelegramWebhookHandler processes incoming Telegram webhook HTTP requests via Gin.
// Reference: Chatwoot routes Telegram webhooks at:
//   post '/webhooks/telegram/:bot_token' => 'telegram_bots#process_message'
//
// The handler:
// 1. Receives raw Update JSON from Telegram's webhook POST
// 2. Validates the update structure
// 3. Routes to appropriate processing (message, edited_message, callback_query)
// 4. Returns 200 OK to Telegram (required to prevent retries)
//
// Telegram webhook requirements:
//   - Must respond within 10 seconds
//   - Must return 200 OK even on processing errors (async processing recommended)
//   - Updates are sent as JSON POST to the webhook URL

// TelegramWebhookHandler processes Telegram webhook requests via Gin.
type TelegramWebhookHandler struct {
	provider   *channelprovider.TelegramProvider
	telWebhook *telegramchannel.WebhookHandler
	db         *gorm.DB
	persister  *IncomingPersister
}

// NewTelegramWebhookHandler creates a Telegram webhook handler for Gin integration.
func NewTelegramWebhookHandler(
	provider *channelprovider.TelegramProvider,
	telWebhook *telegramchannel.WebhookHandler,
	db *gorm.DB,
	dispatcher ...*channel.Dispatcher,
) *TelegramWebhookHandler {
	return &TelegramWebhookHandler{
		provider:   provider,
		telWebhook: telWebhook,
		db:         db,
		persister:  NewIncomingPersister(db, dispatcher...),
	}
}

func (h *TelegramWebhookHandler) WithWorkerPool(wp *worker.WorkerPool) *TelegramWebhookHandler {
	if h != nil && h.persister != nil {
		h.persister.SetWorkerPool(wp)
	}
	return h
}

func (h *TelegramWebhookHandler) WithSearchIndexer(indexer IncomingSearchIndexer) *TelegramWebhookHandler {
	if h != nil && h.persister != nil {
		h.persister.SetSearchIndexer(indexer)
	}
	return h
}

// HandleTelegramWebhook processes an incoming Telegram webhook Gin request.
// URL pattern: /webhooks/telegram/:bot_token
// Method: POST
// Content-Type: application/json
//
// Reference: Chatwoot: Telegram webhook receives Update payloads
// at /webhooks/telegram/{bot_token}
//
// Flow:
// 1. Parse bot_token from URL path → lookup Inbox + ChannelTelegram
// 2. Read Update JSON from request body
// 3. Dispatch to appropriate processing pipeline
// 4. Return 200 OK immediately (Telegram requires fast response)
func (h *TelegramWebhookHandler) HandleTelegramWebhook(c *gin.Context) {
	botToken := c.Param("bot_token")
	if botToken == "" {
		applogger.L().Warn("Telegram webhook: missing bot_token in path")
		// Still return 200 to prevent Telegram retries
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}

	// Read request body
	body, err := io.ReadAll(c.Request.Body)
	if err != nil {
		applogger.L().Errorf("Telegram webhook: failed to read body: %v", err)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}
	defer c.Request.Body.Close()

	applogger.L().Info("Telegram webhook received")

	// Parse the update to extract update_id for logging
	var update telegramchannel.TelegramUpdate
	if err := json.Unmarshal(body, &update); err != nil {
		applogger.L().Errorf("Telegram webhook: failed to parse update: %v", err)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}

	// Look up Inbox for this bot_token
	// In production: query GORM for Inbox with channel_type=telegram matching the bot_token
	inbox, err := h.lookupInbox(botToken)
	if err != nil {
		applogger.L().Errorf("Telegram webhook: inbox lookup failed: %v", err)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}

	// Parse raw payload for provider processing
	var payload map[string]interface{}
	if err := json.Unmarshal(body, &payload); err != nil {
		applogger.L().Errorf("Telegram webhook: failed to parse payload: %v", err)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}

	// Process the incoming message via the provider pipeline
	// Reference: Chatwoot processes updates via IncomingMessageService
	incomingMsg, err := h.provider.ProcessIncomingMessage(c.Request.Context(), inbox, payload)
	if err != nil {
		applogger.L().Errorf("Telegram webhook: message processing failed (update_id=%d): %v", update.UpdateID, err)
	} else if incomingMsg != nil {
		if _, persistErr := h.persister.PersistIncoming(c.Request.Context(), inbox, incomingMsg); persistErr != nil {
			applogger.L().Errorf("Telegram webhook: persist message failed (update_id=%d source_id=%s): %v", update.UpdateID, incomingMsg.SourceID, persistErr)
		} else {
			applogger.L().Infof("Telegram webhook: message persisted (inbox_id=%d, source_id=%s)",
				incomingMsg.InboxID, incomingMsg.SourceID)
		}
	}

	// Always return 200 OK to Telegram — it retries if not 200
	c.JSON(http.StatusOK, gin.H{"status": "ok"})
}

// lookupInbox finds the Inbox associated with a Telegram bot token.
// In production: queries GORM for Inbox with channel_type=telegram matching the bot_token.
// Reference: Chatwoot: Inbox.find_by(channel: telegram, bot_token: token)
func (h *TelegramWebhookHandler) lookupInbox(botToken string) (*model.Inbox, error) {
	if h.db == nil {
		return nil, fmt.Errorf("telegram webhook database is not configured")
	}

	var channel channelmodel.ChannelTelegram
	if err := h.db.Where("bot_token = ?", botToken).First(&channel).Error; err != nil {
		return nil, fmt.Errorf("telegram channel not found for bot_token: %w", err)
	}

	var inbox model.Inbox
	if err := h.db.Where("id = ? AND channel_type = ?", channel.InboxID, "telegram").First(&inbox).Error; err != nil {
		return nil, fmt.Errorf("telegram inbox not found for channel inbox_id=%d: %w", channel.InboxID, err)
	}
	return &inbox, nil
}

// maskBotToken masks a bot token for safe logging (show first 8 chars only).
func maskBotToken(token string) string {
	if len(token) > 8 {
		return token[:8] + "..."
	}
	return token
}