package mgocrud

import (
	"fmt"
	"reflect"
	"strings"

	mgo "gopkg.in/mgo.v2"
)

// EnsureIndex ensured mongodb index reflecting model struct index tag
func EnsureIndex(db *mgo.Database, m ModelInterface) error {
	colName := GetCollectionName(m)
	col := db.C(colName)

	mType := reflect.TypeOf(m)

	textFields := []string{}

	var _indexWalk func(t reflect.Type, fieldbase string) error
	_indexWalk = func(t reflect.Type, fieldbase string) error {

		for i := 0; i < 2; i++ {
			if t.Kind() == reflect.Ptr || t.Kind() == reflect.Slice {
				t = t.Elem()
			}
		}

		if t.Kind() == reflect.Struct {

			for i := 0; i < t.NumField(); i++ {
				field := t.Field(i)
				indexTag := field.Tag.Get("index")

				bsonField := strings.Split(field.Tag.Get("bson"), ",")[0]
				if bsonField == "" {
					bsonField = strings.ToLower(field.Name)
				}

				if bsonField != "-" {
					if indexTag != "" {
						index := mgo.Index{
							Background: false,
							Sparse:     false,
							Unique:     false,
						}
						for _, indexEl := range strings.Split(indexTag, ",") {
							switch {
							case indexEl == "single":
								index.Key = []string{fieldbase + bsonField}
							case indexEl == "unique":
								index.Unique = true
							case indexEl == "sparse":
								index.Sparse = true
							case indexEl == "background":
								index.Background = true
							case indexEl == "text":
								textFields = append(textFields, "$text:"+fieldbase+bsonField)
							default:
								return fmt.Errorf("invalid index tag on collection %s.%s for field %s%s in model %+v", db.Name, colName, fieldbase, bsonField, t)
							}

						}
						if len(index.Key) > 0 {
							// fmt.Println(bsonField, index)
							fmt.Printf("ensure index on collection %s.%s for field %s%s\n", db.Name, colName, fieldbase, bsonField)
							err := col.EnsureIndex(index)
							if err != nil {
								return err
							}
						}
					}

					fBase := bsonField + "."
					if field.Anonymous {
						fBase = ""
					}
					err := _indexWalk(field.Type, fBase)
					if err != nil {
						return err
					}
				}
			}
		}

		return nil
	}

	err := _indexWalk(mType, "")
	if err != nil {
		return err
	}

	if len(textFields) > 0 {
		// fmt.Println("$text", textFields)
		fmt.Printf("ensure text index on collection %s.%s for fields %v\n", db.Name, GetCollectionName(m), textFields)
		err := col.EnsureIndex(mgo.Index{
			Name:            "textindex",
			Key:             textFields,
			DefaultLanguage: "german",
			Background:      false,
		})
		if err != nil {
			return err
		}
	}

	return nil
}