package webhook

// FakeWebhookHandler processes incoming FakeMessagePlatform webhook HTTP
// requests via Gin.
//
// URL pattern: /webhooks/fake/:identifier
//   - GET:  webhook verification (echo challenge)
//   - POST: incoming message/event processing
//
// Unlike Telegram/LINE which have a dedicated channel model table, the fake
// channel stores all config (identifier, webhook_url, token) directly in the
// Inbox.ChannelConfig JSON column. lookupInbox therefore queries by
// channel_type='fake' and filters the identifier in Go (plan §7.2 错误 2).

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

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"

	"github.com/gochat/gochat/internal/channel"
	channelprovider "github.com/gochat/gochat/internal/channel/provider"
	"github.com/gochat/gochat/internal/model"
	"github.com/gochat/gochat/internal/worker"
	applogger "github.com/gochat/gochat/pkg/logger"
)

// FakeWebhookHandler processes FakeMessagePlatform webhook requests via Gin.
type FakeWebhookHandler struct {
	provider  *channelprovider.FakeProvider
	db        *gorm.DB
	persister *IncomingPersister
}

// NewFakeWebhookHandler creates a Fake webhook handler for Gin integration.
func NewFakeWebhookHandler(
	provider *channelprovider.FakeProvider,
	db *gorm.DB,
	dispatcher ...*channel.Dispatcher,
) *FakeWebhookHandler {
	return &FakeWebhookHandler{
		provider:  provider,
		db:        db,
		persister: NewIncomingPersister(db, dispatcher...),
	}
}

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

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

// HandleFakeWebhookVerification echoes a challenge token for webhook URL
// verification. FakeMessagePlatform sends GET /webhooks/fake/:identifier with
// a "hub.challenge" query param (mirroring the Facebook/WhatsApp pattern).
func (h *FakeWebhookHandler) HandleFakeWebhookVerification(c *gin.Context) {
	challenge := c.Query("hub.challenge")
	if challenge == "" {
		challenge = c.Query("challenge")
	}
	if challenge == "" {
		c.JSON(http.StatusOK, gin.H{"status": "verified"})
		return
	}
	c.String(http.StatusOK, challenge)
}

// HandleFakeWebhook processes an incoming FakeMessagePlatform webhook POST.
func (h *FakeWebhookHandler) HandleFakeWebhook(c *gin.Context) {
	identifier := c.Param("identifier")
	if identifier == "" {
		applogger.L().Warn("Fake webhook: missing identifier in path")
		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("Fake webhook: failed to read body: %v", err)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}
	defer c.Request.Body.Close()

	applogger.L().Infof("Fake webhook received for identifier=%s", identifier)

	// Look up Inbox by channel_type='fake' and config identifier
	inbox, err := h.lookupInbox(identifier)
	if err != nil {
		applogger.L().Errorf("Fake webhook: inbox lookup failed for identifier=%s: %v", identifier, err)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}

	// Validate webhook request (X-Fake-Token header)
	headers := make(map[string]string)
	for k, v := range c.Request.Header {
		if len(v) > 0 {
			headers[k] = v[0]
		}
	}
	wr := &channel.WebhookRequest{
		ChannelType: channel.ChannelFake,
		Identifier:  identifier,
		Headers:     headers,
		Body:        body,
		Method:      c.Request.Method,
	}
	if err := h.provider.ValidateWebhookRequest(c.Request.Context(), inbox, wr); err != nil {
		applogger.L().Warnf("Fake webhook: validation failed for inbox=%d: %v", inbox.ID, err)
		c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
		return
	}

	// Process the incoming message via the provider
	incomingMsg, err := h.provider.ProcessIncoming(c.Request.Context(), inbox, body)
	if err != nil {
		applogger.L().Errorf("Fake webhook: message processing failed for inbox=%d: %v", inbox.ID, err)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}
	if incomingMsg == nil {
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}

	// Persist the incoming message
	if _, persistErr := h.persister.PersistIncoming(c.Request.Context(), inbox, incomingMsg); persistErr != nil {
		applogger.L().Errorf("Fake webhook: persist message failed for inbox=%d source_id=%s: %v",
			inbox.ID, incomingMsg.SourceID, persistErr)
		c.JSON(http.StatusOK, gin.H{"status": "ignored"})
		return
	}

	applogger.L().Infof("Fake webhook: message persisted (inbox_id=%d, source_id=%s, sender=%s)",
		inbox.ID, incomingMsg.SourceID, incomingMsg.SenderID)

	c.JSON(http.StatusOK, gin.H{"status": "ok"})
}

// lookupInbox finds the Inbox for a fake channel by config identifier.
// On PostgreSQL, uses jsonb containment for a DB-side indexed lookup.
// On SQLite (test mode), falls back to loading all fake inboxes and
// filtering in Go — acceptable for low-volume test traffic.
func (h *FakeWebhookHandler) lookupInbox(identifier string) (*model.Inbox, error) {
	if h.db == nil {
		return nil, fmt.Errorf("fake webhook database is not configured")
	}

	// PostgreSQL: use jsonb @> for a server-side, indexable query.
	if h.db.Dialector.Name() == "postgres" {
		var inbox model.Inbox
		// channel_config is TEXT, so cast to jsonb before using the @> operator.
		// channel_config::jsonb @> '{"identifier":"<id>"}'
		query := fmt.Sprintf(`channel_type = 'fake' AND channel_config::jsonb @> '{"identifier":"%s"}'`, identifier)
		if err := h.db.Where(query).First(&inbox).Error; err != nil {
			return nil, fmt.Errorf("fake inbox not found for identifier=%s: %w", identifier, err)
		}
		return &inbox, nil
	}

	// SQLite fallback: load all fake inboxes and filter in Go.
	var inboxes []model.Inbox
	if err := h.db.Where("channel_type = ?", "fake").Find(&inboxes).Error; err != nil {
		return nil, fmt.Errorf("failed to query fake inboxes: %w", err)
	}

	for i := range inboxes {
		cfg := parseFakeInboxConfig(&inboxes[i])
		if id, _ := cfg["identifier"].(string); id == identifier {
			return &inboxes[i], nil
		}
	}
	return nil, fmt.Errorf("fake inbox not found for identifier=%s", identifier)
}

// parseFakeInboxConfig decodes the Inbox.ChannelConfig JSON into a map.
func parseFakeInboxConfig(inbox *model.Inbox) map[string]interface{} {
	if inbox == nil || inbox.ChannelConfig == "" {
		return map[string]interface{}{}
	}
	var cfg map[string]interface{}
	if err := json.Unmarshal([]byte(inbox.ChannelConfig), &cfg); err != nil {
		applogger.L().Warnf("Fake: failed to parse ChannelConfig for inbox %d: %v", inbox.ID, err)
		return map[string]interface{}{}
	}
	return cfg
}