helper_test.go

/*
 * Copyright (c) 2022-2023 Tochemey
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package ego

import (
	"context"

	"github.com/pkg/errors"
	testpb "github.com/tochemey/ego/test/data/pb/v1"
)

// AccountEntityBehavior implement EntityBehavior
type AccountEntityBehavior struct {
	id string
}

// make sure that testAccountBehavior is a true persistence behavior
var _ EntityBehavior[*testpb.Account] = &AccountEntityBehavior{}

// NewAccountEntityBehavior creates an instance of AccountEntityBehavior
func NewAccountEntityBehavior(id string) *AccountEntityBehavior {
	return &AccountEntityBehavior{id: id}
}
func (t *AccountEntityBehavior) ID() string {
	return t.id
}

func (t *AccountEntityBehavior) InitialState() *testpb.Account {
	return new(testpb.Account)
}

func (t *AccountEntityBehavior) HandleCommand(_ context.Context, command Command, _ *testpb.Account) (event Event, err error) {
	switch cmd := command.(type) {
	case *testpb.CreateAccount:
		// TODO in production grid app validate the command using the prior state
		return &testpb.AccountCreated{
			AccountId:      t.id,
			AccountBalance: cmd.GetAccountBalance(),
		}, nil

	case *testpb.CreditAccount:
		if cmd.GetAccountId() == t.id {
			return &testpb.AccountCredited{
				AccountId:      cmd.GetAccountId(),
				AccountBalance: cmd.GetBalance(),
			}, nil
		}

		return nil, errors.New("command sent to the wrong entity")

	case *testpb.TestNoEvent:
		return nil, nil

	default:
		return nil, errors.New("unhandled command")
	}
}

func (t *AccountEntityBehavior) HandleEvent(_ context.Context, event Event, priorState *testpb.Account) (state *testpb.Account, err error) {
	switch evt := event.(type) {
	case *testpb.AccountCreated:
		return &testpb.Account{
			AccountId:      evt.GetAccountId(),
			AccountBalance: evt.GetAccountBalance(),
		}, nil

	case *testpb.AccountCredited:
		bal := priorState.GetAccountBalance() + evt.GetAccountBalance()
		return &testpb.Account{
			AccountId:      evt.GetAccountId(),
			AccountBalance: bal,
		}, nil

	default:
		return nil, errors.New("unhandled event")
	}
}