package canned

import (
	"context"
	"strings"

	"gorm.io/gorm"
)

// DBProvider provides database access — implemented by app.App to break the import cycle.
type DBProvider interface {
	DB() *gorm.DB
}

// CannedResponseService provides CRUD and search for canned responses.
// Reference: Chatwoot CannedResponse — CRUD + order_by_search scope
// (ranks by short_code match then content match).
type CannedResponseService struct {
	db DBProvider
}

// NewCannedResponseService creates a new CannedResponseService.
func NewCannedResponseService(db DBProvider) *CannedResponseService {
	return &CannedResponseService{db: db}
}

// Create creates a new canned response.
func (s *CannedResponseService) Create(ctx context.Context, response *CannedResponse) error {
	return s.db.DB().WithContext(ctx).Create(response).Error
}

// GetByID retrieves a canned response by ID.
func (s *CannedResponseService) GetByID(ctx context.Context, id uint) (*CannedResponse, error) {
	var resp CannedResponse
	if err := s.db.DB().WithContext(ctx).First(&resp, id).Error; err != nil {
		return nil, err
	}
	return &resp, nil
}

// GetByAccountAndID retrieves a canned response scoped through its account.
func (s *CannedResponseService) GetByAccountAndID(ctx context.Context, accountID, id uint) (*CannedResponse, error) {
	var resp CannedResponse
	if err := s.db.DB().WithContext(ctx).
		Where("account_id = ? AND id = ?", accountID, id).
		First(&resp).Error; err != nil {
		return nil, err
	}
	return &resp, nil
}

// Update updates a canned response.
func (s *CannedResponseService) Update(ctx context.Context, id uint, updates map[string]interface{}) error {
	return s.db.DB().WithContext(ctx).Model(&CannedResponse{}).Where("id = ?", id).Updates(updates).Error
}

// UpdateByAccountAndID updates a canned response scoped through its account.
func (s *CannedResponseService) UpdateByAccountAndID(ctx context.Context, accountID, id uint, updates map[string]interface{}) error {
	resp, err := s.GetByAccountAndID(ctx, accountID, id)
	if err != nil {
		return err
	}
	return s.db.DB().WithContext(ctx).Model(resp).Updates(updates).Error
}

// Delete soft-deletes a canned response.
func (s *CannedResponseService) Delete(ctx context.Context, id uint) error {
	return s.db.DB().WithContext(ctx).Delete(&CannedResponse{}, id).Error
}

// DeleteByAccountAndID deletes a canned response scoped through its account.
func (s *CannedResponseService) DeleteByAccountAndID(ctx context.Context, accountID, id uint) error {
	resp, err := s.GetByAccountAndID(ctx, accountID, id)
	if err != nil {
		return err
	}
	return s.db.DB().WithContext(ctx).Unscoped().Delete(resp).Error
}

// ListByAccount returns all canned responses for an account.
func (s *CannedResponseService) ListByAccount(ctx context.Context, accountID uint) ([]CannedResponse, error) {
	var responses []CannedResponse
	err := s.db.DB().WithContext(ctx).
		Where("account_id = ?", accountID).
		Order("short_code ASC").
		Find(&responses).Error
	return responses, err
}

// Search performs a ranked search over canned responses.
// Reference: Chatwoot order_by_search scope — ranks by short_code match then content match.
// Results are ordered so that short_code matches appear first, then content matches.
func (s *CannedResponseService) Search(ctx context.Context, accountID uint, query string) ([]CannedResponse, error) {
	if query == "" {
		return s.ListByAccount(ctx, accountID)
	}

	var responses []CannedResponse
	// Use a CASE-based ordering: short_code matches rank higher than content matches.
	// This mirrors Chatwoot's order_by_search scope.
	// The search is case-insensitive.
	lowerQuery := strings.ToLower(query)
	prefixPattern := lowerQuery + "%"
	likePattern := "%" + lowerQuery + "%"
	err := s.db.DB().WithContext(ctx).
		Select("canned_responses.*, CASE WHEN LOWER(short_code) LIKE ? THEN 1.0 WHEN LOWER(short_code) LIKE ? THEN 0.5 WHEN LOWER(content) LIKE ? THEN 0.2 ELSE 0 END AS search_rank", prefixPattern, likePattern, likePattern).
		Where("account_id = ? AND (LOWER(short_code) LIKE ? OR LOWER(content) LIKE ?)", accountID, likePattern, likePattern).
		Order("search_rank DESC").
		Order("short_code ASC").
		Find(&responses).Error
	return responses, err
}

// GetByShortCode retrieves a canned response by its short code within an account.
func (s *CannedResponseService) GetByShortCode(ctx context.Context, accountID uint, shortCode string) (*CannedResponse, error) {
	var resp CannedResponse
	if err := s.db.DB().WithContext(ctx).
		Where("account_id = ? AND short_code = ?", accountID, shortCode).
		First(&resp).Error; err != nil {
		return nil, err
	}
	return &resp, nil
}