package utils

import (
	"reflect"

	"github.com/karlkfi/inject"
)

var Graph inject.Graph

var (
	definitions map[reflect.Type]interface{}
)

func DefineSingleton(ptr interface{}, constructor interface{}) interface{} {
	typ := reflect.TypeOf(ptr)
	provider := inject.NewAutoProvider(constructor)

	if _, found := definitions[typ]; found {
		ptr = definitions[typ]
	} else {
		definitions[typ] = ptr
	}
	Graph.Define(ptr, provider)
	return ptr
}

func ResolveDependencies(ptrs ...interface{}) {
	for _, p := range ptrs {
		inject.ExtractAssignable(Graph, p)
	}
}

func init() {
	definitions = make(map[reflect.Type]interface{})
	Graph = inject.NewGraph()
}