// VulcanizeDB
// Copyright © 2019 Vulcanize

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package storage_test

import (
	"bytes"
	"encoding/json"
	"errors"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/ethereum/go-ethereum/statediff"
	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"

	"github.com/vulcanize/vulcanizedb/libraries/shared/storage"
	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
	"github.com/vulcanize/vulcanizedb/libraries/shared/test_data"
	"github.com/vulcanize/vulcanizedb/pkg/geth/client"
)

type mockClient struct {
	MappedStateDiffAt map[uint64][]byte
}

// SetReturnDiffAt method to set what statediffs the mock client returns
func (mc *mockClient) SetReturnDiffAt(height uint64, diffPayload statediff.Payload) error {
	if mc.MappedStateDiffAt == nil {
		mc.MappedStateDiffAt = make(map[uint64][]byte)
	}
	by, err := json.Marshal(diffPayload)
	if err != nil {
		return err
	}
	mc.MappedStateDiffAt[height] = by
	return nil
}

// BatchCall mockClient method to simulate batch call to geth
func (mc *mockClient) BatchCall(batch []client.BatchElem) error {
	if mc.MappedStateDiffAt == nil {
		return errors.New("mockclient needs to be initialized with statediff payloads and errors")
	}
	for _, batchElem := range batch {
		if len(batchElem.Args) != 1 {
			return errors.New("expected batch elem to contain single argument")
		}
		blockHeight, ok := batchElem.Args[0].(uint64)
		if !ok {
			return errors.New("expected batch elem argument to be a uint64")
		}
		err := json.Unmarshal(mc.MappedStateDiffAt[blockHeight], batchElem.Result)
		if err != nil {
			return err
		}
	}
	return nil
}

var _ = Describe("BackFiller", func() {
	Describe("BackFill", func() {
		var (
			mc         *mockClient
			backFiller storage.IBackFiller
		)
		BeforeEach(func() {
			mc = new(mockClient)
			setDiffAtErr1 := mc.SetReturnDiffAt(test_data.BlockNumber.Uint64(), test_data.MockStatediffPayload)
			Expect(setDiffAtErr1).ToNot(HaveOccurred())
			setDiffAtErr2 := mc.SetReturnDiffAt(test_data.BlockNumber2.Uint64(), test_data.MockStatediffPayload2)
			Expect(setDiffAtErr2).ToNot(HaveOccurred())
			backFiller = storage.NewStorageBackFiller(mc)
		})
		It("Batch calls statediff_stateDiffAt", func() {
			backFillArgs := storage.BackFillerArgs{
				WantedStorage: map[common.Hash][]common.Hash{
					test_data.ContractLeafKey:        {common.BytesToHash(test_data.StorageKey)},
					test_data.AnotherContractLeafKey: {common.BytesToHash(test_data.StorageKey)},
				},
				StartingBlock: test_data.BlockNumber.Uint64(),
				EndingBlock:   test_data.BlockNumber2.Uint64(),
			}
			backFillStorage, backFillErr := backFiller.BackFill(backFillArgs)
			Expect(backFillErr).ToNot(HaveOccurred())
			Expect(len(backFillStorage)).To(Equal(2))
			Expect(len(backFillStorage[test_data.ContractLeafKey])).To(Equal(1))
			Expect(len(backFillStorage[test_data.AnotherContractLeafKey])).To(Equal(3))
			Expect(backFillStorage[test_data.ContractLeafKey][0]).To(Equal(test_data.CreatedExpectedStorageDiff))
			// Can only rlp encode the slice of diffs as part of a struct
			// Rlp encoding allows us to compare content of the slices when the order in the slice may vary
			expectedDiffStruct := struct {
				diffs []utils.StorageDiff
			}{
				[]utils.StorageDiff{
					test_data.UpdatedExpectedStorageDiff,
					test_data.UpdatedExpectedStorageDiff2,
					test_data.DeletedExpectedStorageDiff,
				},
			}
			expectedDiffBytes, rlpErr1 := rlp.EncodeToBytes(expectedDiffStruct)
			Expect(rlpErr1).ToNot(HaveOccurred())
			receivedDiffStruct := struct {
				diffs []utils.StorageDiff
			}{
				backFillStorage[test_data.AnotherContractLeafKey],
			}
			receivedDiffBytes, rlpErr2 := rlp.EncodeToBytes(receivedDiffStruct)
			Expect(rlpErr2).ToNot(HaveOccurred())
			Expect(bytes.Equal(expectedDiffBytes, receivedDiffBytes)).To(BeTrue())
		})

		It("Only returns storage for provided addresses (address hashes)", func() {
			backFillArgs := storage.BackFillerArgs{
				WantedStorage: map[common.Hash][]common.Hash{
					test_data.ContractLeafKey: {common.BytesToHash(test_data.StorageKey)},
				},
				StartingBlock: test_data.BlockNumber.Uint64(),
				EndingBlock:   test_data.BlockNumber2.Uint64(),
			}
			backFillStorage, backFillErr := backFiller.BackFill(backFillArgs)
			Expect(backFillErr).ToNot(HaveOccurred())
			Expect(len(backFillStorage)).To(Equal(1))
			Expect(len(backFillStorage[test_data.ContractLeafKey])).To(Equal(1))
			Expect(len(backFillStorage[test_data.AnotherContractLeafKey])).To(Equal(0))
			Expect(backFillStorage[test_data.ContractLeafKey][0]).To(Equal(test_data.CreatedExpectedStorageDiff))
		})

		It("Only returns storage for provided storage keys", func() {
			backFillArgs := storage.BackFillerArgs{
				WantedStorage: map[common.Hash][]common.Hash{
					test_data.ContractLeafKey: nil,
				},
				StartingBlock: test_data.BlockNumber.Uint64(),
				EndingBlock:   test_data.BlockNumber2.Uint64(),
			}
			backFillStorage, backFillErr := backFiller.BackFill(backFillArgs)
			Expect(backFillErr).ToNot(HaveOccurred())
			Expect(len(backFillStorage)).To(Equal(0))
		})
	})
})