package service

import (
	"context"
	"fmt"

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

// ChannelFacebookService implements business logic for Facebook channel operations.
// Reference: Chatwoot app/controllers/api/v1/accounts/channels/facebook_controller.rb
//
// Facebook Messenger channels use the Facebook Graph API to send/receive messages
// via a connected Facebook Page. The Page access token grants pages_messaging
// permission for Messenger interactions.
type ChannelFacebookService struct {
	repo *repository.ChannelFacebookRepo
}

// NewChannelFacebookService creates a new ChannelFacebook service.
func NewChannelFacebookService(repo *repository.ChannelFacebookRepo) *ChannelFacebookService {
	return &ChannelFacebookService{repo: repo}
}

// GetByID retrieves a Facebook channel by ID.
func (s *ChannelFacebookService) GetByID(ctx context.Context, id uint) (*channelmodel.ChannelFacebook, error) {
	return s.repo.FindByID(ctx, id)
}

// GetByInboxID retrieves a Facebook channel by inbox ID.
func (s *ChannelFacebookService) GetByInboxID(ctx context.Context, inboxID uint) (*channelmodel.ChannelFacebook, error) {
	return s.repo.FindByInboxID(ctx, inboxID)
}

// GetByAccountAndInboxID retrieves a Facebook channel scoped to an account and inbox.
func (s *ChannelFacebookService) GetByAccountAndInboxID(ctx context.Context, accountID, inboxID uint) (*channelmodel.ChannelFacebook, error) {
	return s.repo.FindByAccountAndInboxID(ctx, accountID, inboxID)
}

// FindByPageID retrieves a Facebook channel by Facebook Page ID.
// Used by the webhook handler to route incoming Facebook messages.
func (s *ChannelFacebookService) FindByPageID(ctx context.Context, pageID string) (*channelmodel.ChannelFacebook, error) {
	return s.repo.FindByPageID(ctx, pageID)
}

// UpdateFacebookChannelRequest is the DTO for updating Facebook channel config.
type UpdateFacebookChannelRequest struct {
	PageName                 *string `json:"page_name,omitempty"`
	ReauthorizationRequired  *bool   `json:"reauthorization_required,omitempty"`
}

// Update modifies an existing Facebook channel's configurable fields.
func (s *ChannelFacebookService) Update(ctx context.Context, accountID, inboxID uint, req UpdateFacebookChannelRequest) (*channelmodel.ChannelFacebook, error) {
	ch, err := s.repo.FindByAccountAndInboxID(ctx, accountID, inboxID)
	if err != nil {
		return nil, fmt.Errorf("facebook channel not found: %w", err)
	}

	if req.PageName != nil {
		ch.PageName = *req.PageName
	}
	if req.ReauthorizationRequired != nil {
		ch.ReauthorizationRequired = *req.ReauthorizationRequired
	}

	if err := s.repo.Update(ctx, ch); err != nil {
		applogger.L().Errorf("Failed to update facebook channel: %v", err)
		return nil, err
	}
	return ch, nil
}

// MarkReauthorizationRequired flags a Facebook channel as needing token refresh.
// Called when the Facebook webhook delivers a token expiration event.
func (s *ChannelFacebookService) MarkReauthorizationRequired(ctx context.Context, inboxID uint) error {
	ch, err := s.repo.FindByInboxID(ctx, inboxID)
	if err != nil {
		return fmt.Errorf("facebook channel not found: %w", err)
	}

	ch.ReauthorizationRequired = true
	if err := s.repo.Update(ctx, ch); err != nil {
		applogger.L().Errorf("Failed to mark facebook channel for reauthorization: %v", err)
		return err
	}

	applogger.L().Infof("Facebook channel marked for reauthorization (inbox_id=%d)", inboxID)
	return nil
}

// ListByAccount retrieves all Facebook channels for an account.
func (s *ChannelFacebookService) ListByAccount(ctx context.Context, accountID uint) ([]channelmodel.ChannelFacebook, error) {
	return s.repo.ListByAccount(ctx, accountID)
}

// Delete soft-deletes a Facebook channel record.
// Note: This should be called BEFORE deleting the Inbox (same pattern as Chatwoot's after_destroy).
func (s *ChannelFacebookService) Delete(ctx context.Context, id uint) error {
	if err := s.repo.Delete(ctx, id); err != nil {
		applogger.L().Errorf("Failed to delete facebook channel: %v", err)
		return err
	}
	applogger.L().Infof("Facebook channel deleted (id=%d)", id)
	return nil
}