package main

import (
	"testing"

	"github.com/mongodb/mongo-go-driver/bson"
	"github.com/mongodb/mongo-go-driver/bson/objectid"
)

type ThingOmitID struct {
	ID    objectid.ObjectID `bson:"_id,omitempty"`
	Field string            `bson:"field"`
}

type ThingOmitIDPtr struct {
	ID    *objectid.ObjectID `bson:"_id,omitempty"`
	Field string             `bson:"field"`
}

type ThingOmitStringField struct {
	ID    objectid.ObjectID `bson:"_id"`
	Field string            `bson:"field,omitempty"`
}

func TestOmitEmptyID_NilObjectID(t *testing.T) {
	thing := &ThingOmitID{
		ID:    objectid.NilObjectID,
		Field: "content",
	}
	validateNumKeys(t, 1, thing)
}

func TestOmitEmptyID_Omit(t *testing.T) {
	thing := &ThingOmitID{
		Field: "content",
	}
	validateNumKeys(t, 1, thing)
}

func TestOmitEmptyIDPtr_Nil(t *testing.T) {
	thing := &ThingOmitIDPtr{
		ID:    nil,
		Field: "content",
	}
	validateNumKeys(t, 1, thing)
}

func TestOmitEmptyIDPtr_NilObjectID(t *testing.T) {
	thing := &ThingOmitIDPtr{
		ID:    &objectid.NilObjectID,
		Field: "content",
	}
	validateNumKeys(t, 2, thing)
}

func TestOmitEmptyStringField_Empty(t *testing.T) {
	thing := &ThingOmitStringField{
		ID:    objectid.NilObjectID,
		Field: "",
	}
	validateNumKeys(t, 1, thing)
}

func TestOmitEmptyStringField_Omit(t *testing.T) {
	thing := &ThingOmitStringField{
		ID: objectid.NilObjectID,
	}
	validateNumKeys(t, 1, thing)
}

func validateNumKeys(t *testing.T, numKeys int, obj interface{}) {
	encodedObj, err := bson.NewDocumentEncoder().EncodeDocument(obj)
	if err != nil {
		t.Error(err.Error())
	}

	keys, err := encodedObj.Keys(false)
	if err != nil {
		t.Error(err.Error())
	}
	if numKeys != len(keys) {
		for _, key := range keys {
			t.Log(key.Prefix, key.Name)
		}
		t.Errorf("Expected number of keys: %d, actual: %d", numKeys, len(keys))
	}
}