package models

import (
	"time"

	"gorm.io/gorm"
)

// DefaultCategory represents a category template for new user initialization
// These templates are copied to users' categories table when they first access categories
type DefaultCategory struct {
	ID        uint         `gorm:"primarykey" json:"id"`
	Name      string       `gorm:"size:50;not null" json:"name"`
	Icon      string       `gorm:"size:100" json:"icon"`         // Iconify format: mdi:icon-name
	Color     string       `gorm:"size:20" json:"color"`         // HEX color code (e.g., #FF6B35)
	Type      CategoryType `gorm:"size:20;not null" json:"type"` // income or expense
	ParentID  *uint        `gorm:"index" json:"parent_id,omitempty"`
	SortOrder int          `gorm:"default:0" json:"sort_order"`
	IsActive  bool         `gorm:"default:true" json:"is_active"`
	CreatedAt time.Time    `json:"created_at"`
	UpdatedAt time.Time    `json:"updated_at"`

	// Relationships
	Parent   *DefaultCategory  `gorm:"foreignKey:ParentID" json:"parent,omitempty"`
	Children []DefaultCategory `gorm:"foreignKey:ParentID" json:"children,omitempty"`
}

// TableName specifies the table name for DefaultCategory
func (DefaultCategory) TableName() string {
	return "default_categories"
}

// GetAllDefaultCategories retrieves all active default categories from the database
func GetAllDefaultCategories(db *gorm.DB) ([]DefaultCategory, error) {
	var categories []DefaultCategory
	err := db.Where("is_active = ?", true).Order("sort_order ASC").Find(&categories).Error
	return categories, err
}

// GetDefaultCategoriesWithChildren retrieves all active root categories with their children
func GetDefaultCategoriesWithChildren(db *gorm.DB) ([]DefaultCategory, error) {
	var categories []DefaultCategory
	err := db.Where("is_active = ? AND parent_id IS NULL", true).
		Preload("Children", "is_active = ?", true).
		Order("sort_order ASC").
		Find(&categories).Error
	return categories, err
}

// CopyToUserCategories copies default categories to a user's categories
// Returns a map of old DefaultCategory ID to new Category ID for parent-child mapping
func CopyDefaultCategoriesToUser(db *gorm.DB, userID uint) error {
	// Get all default categories
	var defaults []DefaultCategory
	if err := db.Where("is_active = ?", true).Order("sort_order ASC").Find(&defaults).Error; err != nil {
		return err
	}

	if len(defaults) == 0 {
		return nil // No default categories to copy
	}

	// Map to track old ID -> new ID for parent references
	idMap := make(map[uint]uint)

	// First pass: create all root categories (no parent)
	for _, dc := range defaults {
		if dc.ParentID == nil {
			cat := Category{
				UserID:    userID,
				Name:      dc.Name,
				Icon:      dc.Icon,
				Color:     dc.Color,
				Type:      dc.Type,
				ParentID:  nil,
				SortOrder: dc.SortOrder,
			}
			if err := db.Create(&cat).Error; err != nil {
				return err
			}
			idMap[dc.ID] = cat.ID
		}
	}

	// Second pass: create all child categories
	for _, dc := range defaults {
		if dc.ParentID != nil {
			newParentID := idMap[*dc.ParentID]
			cat := Category{
				UserID:    userID,
				Name:      dc.Name,
				Icon:      dc.Icon,
				Color:     dc.Color,
				Type:      dc.Type,
				ParentID:  &newParentID,
				SortOrder: dc.SortOrder,
			}
			if err := db.Create(&cat).Error; err != nil {
				return err
			}
			idMap[dc.ID] = cat.ID
		}
	}

	return nil
}