package line

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

	"github.com/gochat/gochat/internal/model"
	applogger "github.com/gochat/gochat/pkg/logger"
)

// WebhookHandler handles LINE webhook HTTP requests.
type WebhookHandler struct {
	pipeline *IncomingProcessor
	service  *LineService
}

// NewWebhookHandler creates a LINE webhook handler.
func NewWebhookHandler(pipeline *IncomingProcessor, service *LineService) *WebhookHandler {
	return &WebhookHandler{
		pipeline: pipeline,
		service:  service,
	}
}

// HandleWebhook processes an incoming LINE webhook HTTP request.
func (h *WebhookHandler) HandleWebhook(w http.ResponseWriter, r *http.Request, inbox *model.Inbox) {
	// Read request body for signature verification
	body, err := io.ReadAll(r.Body)
	if err != nil {
		applogger.L().Errorf("LINE HandleWebhook: failed to read body: %v", err)
		http.Error(w, "Failed to read request body", http.StatusBadRequest)
		return
	}
	defer r.Body.Close()

	// Verify webhook signature
	config := parseInboxConfig(inbox.ChannelConfig)
	channelSecret := configStr(config, "channel_secret", "")
	signature := r.Header.Get("X-Line-Signature")

	if channelSecret != "" && signature != "" {
		if !h.service.VerifySignature(channelSecret, string(body), signature) {
			applogger.L().Warnf("LINE HandleWebhook: invalid signature for inbox=%d", inbox.ID)
			http.Error(w, "Invalid signature", http.StatusUnauthorized)
			return
		}
	}

	// Parse webhook event
	var webhookEvent WebhookEvent
	if err := json.Unmarshal(body, &webhookEvent); err != nil {
		applogger.L().Errorf("LINE HandleWebhook: failed to parse JSON: %v", err)
		http.Error(w, "Invalid JSON", http.StatusBadRequest)
		return
	}

	// Process each event
	for _, event := range webhookEvent.Events {
		ctx := r.Context()
		incomingMsg, err := h.pipeline.ProcessEvent(ctx, inbox, event)
		if err != nil {
			applogger.L().Errorf("LINE HandleWebhook: process event failed: %v", err)
			continue
		}
		if incomingMsg == nil {
			continue // unhandled event type
		}

		// Log processed event
		applogger.L().Debugf("LINE HandleWebhook: processed event type=%s sender=%s",
			event.Type, incomingMsg.SenderID)
	}

	w.WriteHeader(http.StatusOK)
}

// HandleWebhookVerification responds to LINE webhook URL verification requests.
func (h *WebhookHandler) HandleWebhookVerification(w http.ResponseWriter, r *http.Request) {
	// LINE webhook verification is handled during the initial setup
	// The verification endpoint returns a 200 OK to confirm the webhook URL
	w.WriteHeader(http.StatusOK)
}