import (
  "github.com/jinzhu/gorm"
  "github.com/qor/sorting"
)

func main() {
  db, err := gorm.Open("sqlite3", "demo_db")
  sorting.RegisterCallbacks(db)
}

// Ascending mode
type Category struct {
  gorm.Model
  sorting.Sorting // this will register a `position` column to model Category, used to save record's order
}

db.Find(&categories)
// SELECT * FROM categories ORDER BY position;

// Descending mode
type Product struct {
  gorm.Model
  sorting.SortingDESC // this will register a `position` column to model Product, used to save record's order
}

db.Find(&products)
// SELECT * FROM products ORDER BY position DESC;

// Move Up
sorting.MoveUp(&db, &product, 1)
// If a record is in positon 5, it will be brought to 4

// Move Down
sorting.MoveDown(&db, &product, 1)
// If a record is in positon 5, it will be brought to 6

// Move To
sorting.MoveTo(&db, &product, 1)
// If a record is in positon 5, it will be brought to 1

sorter := sorting.SortableCollection{
  PrimaryKeys: []string{"5", "3", "1", "2"}
}

products := []Product{
  {Model: gorm.Model{ID: 1}, Code: "1"},
  {Model: gorm.Model{ID: 2}, Code: "2"},
  {Model: gorm.Model{ID: 3}, Code: "3"},
  {Model: gorm.Model{ID: 3}, Code: "4"},
  {Model: gorm.Model{ID: 3}, Code: "5"},
}

sorter.Sort(products)

products // => []Product{
         //      {Model: gorm.Model{ID: 3}, Code: "5"},
         //      {Model: gorm.Model{ID: 3}, Code: "3"},
         //      {Model: gorm.Model{ID: 1}, Code: "1"},
         //      {Model: gorm.Model{ID: 2}, Code: "2"},
         //      {Model: gorm.Model{ID: 3}, Code: "4"},
         //    }

// For model relations
type Product struct {
  gorm.Model
  l10n.Locale
  Collections           []Collection
  CollectionsSorter     sorting.SortableCollection
  ColorVariations       []ColorVariation `l10n:"sync"`
  ColorVariationsSorter sorting.SortableCollection
}

// For virtual arguments
type selectedProductsArgument struct {
  Products       []string
  ProductsSorter sorting.SortableCollection
}

selectedProductsResource := Admin.NewResource(&selectedProductsArgument{})
selectedProductsResource.Meta(&admin.Meta{Name: "Products", Type: "select_many", Collection: func(value interface{}, context *qor.Context) [][]string {
  var collectionValues [][]string
  var products []*models.Product
  db.DB.Find(&products)
  for _, product := range products {
    collectionValues = append(collectionValues, []string{fmt.Sprint(product.ID), product.Name})
  }
  return collectionValues
}})

Widgets.RegisterWidget(&widget.Widget{
  Name:      "Products",
  Templates: []string{"products"},
  Setting:   selectedProductsResource,
}