// Package repository provides data access layer for the application
package repository

import (
	"errors"

	"accounting-app/internal/models"

	"gorm.io/gorm"
)

// Template repository errors
var (
	ErrTemplateNotFound = errors.New("template not found")
)

// TemplateRepository handles database operations for transaction templates
// Feature: api-interface-optimization
// Validates: Requirements 15.1, 15.2
type TemplateRepository struct {
	db *gorm.DB
}

// NewTemplateRepository creates a new TemplateRepository instance
func NewTemplateRepository(db *gorm.DB) *TemplateRepository {
	return &TemplateRepository{db: db}
}

// Create creates a new transaction template
func (r *TemplateRepository) Create(template *models.TransactionTemplate) error {
	return r.db.Create(template).Error
}

// GetByID retrieves a template by ID
func (r *TemplateRepository) GetByID(userID uint, id uint) (*models.TransactionTemplate, error) {
	var template models.TransactionTemplate
	if err := r.db.Where("user_id = ?", userID).Preload("Category").Preload("Account").First(&template, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTemplateNotFound
		}
		return nil, err
	}
	return &template, nil
}

// GetAll retrieves all templates for a user
func (r *TemplateRepository) GetAll(userID uint) ([]models.TransactionTemplate, error) {
	var templates []models.TransactionTemplate
	query := r.db.Where("user_id = ?", userID).Preload("Category").Preload("Account").Order("sort_order ASC, created_at DESC")

	if err := query.Find(&templates).Error; err != nil {
		return nil, err
	}
	return templates, nil
}

// Update updates a template
func (r *TemplateRepository) Update(template *models.TransactionTemplate) error {
	return r.db.Save(template).Error
}

// Delete deletes a template
func (r *TemplateRepository) Delete(userID uint, id uint) error {
	result := r.db.Where("user_id = ?", userID).Delete(&models.TransactionTemplate{}, id)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return ErrTemplateNotFound
	}
	return nil
}

// UpdateSortOrder updates the sort order of templates
func (r *TemplateRepository) UpdateSortOrder(userID uint, ids []uint) error {
	return r.db.Transaction(func(tx *gorm.DB) error {
		for i, id := range ids {
			if err := tx.Model(&models.TransactionTemplate{}).Where("id = ? AND user_id = ?", id, userID).Update("sort_order", i).Error; err != nil {
				return err
			}
		}
		return nil
	})
}