package core

import (
	"testing"
	"time"

	"github.com/nspcc-dev/neo-go/pkg/config"
	"github.com/nspcc-dev/neo-go/pkg/core/block"
	"github.com/nspcc-dev/neo-go/pkg/core/mpt"
	"github.com/nspcc-dev/neo-go/pkg/core/storage"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/util/slice"
	"github.com/stretchr/testify/require"
)

func TestStateSyncModule_Init(t *testing.T) {
	var (
		stateSyncInterval        = 2
		maxTraceable      uint32 = 3
	)
	spoutCfg := func(c *config.Config) {
		c.ProtocolConfiguration.StateRootInHeader = true
		c.ProtocolConfiguration.P2PStateExchangeExtensions = true
		c.ProtocolConfiguration.StateSyncInterval = stateSyncInterval
		c.ProtocolConfiguration.MaxTraceableBlocks = maxTraceable
	}
	bcSpout := newTestChainWithCustomCfg(t, spoutCfg)
	for i := 0; i <= 2*stateSyncInterval+int(maxTraceable)+1; i++ {
		require.NoError(t, bcSpout.AddBlock(bcSpout.newBlock()))
	}

	boltCfg := func(c *config.Config) {
		spoutCfg(c)
		c.ProtocolConfiguration.KeepOnlyLatestState = true
		c.ProtocolConfiguration.RemoveUntraceableBlocks = true
	}
	t.Run("error: module disabled by config", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, func(c *config.Config) {
			boltCfg(c)
			c.ProtocolConfiguration.RemoveUntraceableBlocks = false
		})
		module := bcBolt.GetStateSyncModule()
		require.Error(t, module.Init(bcSpout.BlockHeight())) // module inactive (non-archival node)
	})

	t.Run("inactive: spout chain is too low to start state sync process", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, boltCfg)
		module := bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(uint32(2*stateSyncInterval-1)))
		require.False(t, module.IsActive())
	})

	t.Run("inactive: bolt chain height is close enough to spout chain height", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, boltCfg)
		for i := 1; i < int(bcSpout.BlockHeight())-stateSyncInterval; i++ {
			b, err := bcSpout.GetBlock(bcSpout.GetHeaderHash(i))
			require.NoError(t, err)
			require.NoError(t, bcBolt.AddBlock(b))
		}
		module := bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.False(t, module.IsActive())
	})

	t.Run("error: bolt chain is too low to start state sync process", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, boltCfg)
		require.NoError(t, bcBolt.AddBlock(bcBolt.newBlock()))

		module := bcBolt.GetStateSyncModule()
		require.Error(t, module.Init(uint32(3*stateSyncInterval)))
	})

	t.Run("initialized: no previous state sync point", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, boltCfg)

		module := bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.True(t, module.NeedHeaders())
		require.False(t, module.NeedMPTNodes())
	})

	t.Run("error: outdated state sync point in the storage", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, boltCfg)
		module := bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))

		module = bcBolt.GetStateSyncModule()
		require.Error(t, module.Init(bcSpout.BlockHeight()+2*uint32(stateSyncInterval)))
	})

	t.Run("initialized: valid previous state sync point in the storage", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, boltCfg)
		module := bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))

		module = bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.True(t, module.NeedHeaders())
		require.False(t, module.NeedMPTNodes())
	})

	t.Run("initialization from headers/blocks/mpt synced stages", func(t *testing.T) {
		bcBolt := newTestChainWithCustomCfg(t, boltCfg)
		module := bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))

		// firstly, fetch all headers to create proper DB state (where headers are in sync)
		stateSyncPoint := (int(bcSpout.BlockHeight()) / stateSyncInterval) * stateSyncInterval
		var expectedHeader *block.Header
		for i := 1; i <= int(bcSpout.HeaderHeight()); i++ {
			header, err := bcSpout.GetHeader(bcSpout.GetHeaderHash(i))
			require.NoError(t, err)
			require.NoError(t, module.AddHeaders(header))
			if i == stateSyncPoint+1 {
				expectedHeader = header
			}
		}
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.False(t, module.NeedHeaders())
		require.True(t, module.NeedMPTNodes())

		// then create new statesync module with the same DB and check that state is proper
		// (headers are in sync)
		module = bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.False(t, module.NeedHeaders())
		require.True(t, module.NeedMPTNodes())
		unknownNodes := module.GetUnknownMPTNodesBatch(2)
		require.Equal(t, 1, len(unknownNodes))
		require.Equal(t, expectedHeader.PrevStateRoot, unknownNodes[0])

		// add several blocks to create DB state where blocks are not in sync yet, but it's not a genesis.
		for i := stateSyncPoint - int(maxTraceable) + 1; i <= stateSyncPoint-stateSyncInterval-1; i++ {
			block, err := bcSpout.GetBlock(bcSpout.GetHeaderHash(i))
			require.NoError(t, err)
			require.NoError(t, module.AddBlock(block))
		}
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.False(t, module.NeedHeaders())
		require.True(t, module.NeedMPTNodes())
		require.Equal(t, uint32(stateSyncPoint-stateSyncInterval-1), module.BlockHeight())

		// then create new statesync module with the same DB and check that state is proper
		// (blocks are not in sync yet)
		module = bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.False(t, module.NeedHeaders())
		require.True(t, module.NeedMPTNodes())
		unknownNodes = module.GetUnknownMPTNodesBatch(2)
		require.Equal(t, 1, len(unknownNodes))
		require.Equal(t, expectedHeader.PrevStateRoot, unknownNodes[0])
		require.Equal(t, uint32(stateSyncPoint-stateSyncInterval-1), module.BlockHeight())

		// add rest of blocks to create DB state where blocks are in sync
		for i := stateSyncPoint - stateSyncInterval; i <= stateSyncPoint; i++ {
			block, err := bcSpout.GetBlock(bcSpout.GetHeaderHash(i))
			require.NoError(t, err)
			require.NoError(t, module.AddBlock(block))
		}
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.False(t, module.NeedHeaders())
		require.True(t, module.NeedMPTNodes())
		lastBlock, err := bcBolt.GetBlock(expectedHeader.PrevHash)
		require.NoError(t, err)
		require.Equal(t, uint32(stateSyncPoint), lastBlock.Index)
		require.Equal(t, uint32(stateSyncPoint), module.BlockHeight())

		// then create new statesync module with the same DB and check that state is proper
		// (headers and blocks are in sync)
		module = bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.False(t, module.NeedHeaders())
		require.True(t, module.NeedMPTNodes())
		unknownNodes = module.GetUnknownMPTNodesBatch(2)
		require.Equal(t, 1, len(unknownNodes))
		require.Equal(t, expectedHeader.PrevStateRoot, unknownNodes[0])
		require.Equal(t, uint32(stateSyncPoint), module.BlockHeight())

		// add a few MPT nodes to create DB state where some of MPT nodes are missing
		count := 5
		for {
			unknownHashes := module.GetUnknownMPTNodesBatch(1) // restore nodes one-by-one
			if len(unknownHashes) == 0 {
				break
			}
			err := bcSpout.GetStateSyncModule().Traverse(unknownHashes[0], func(node mpt.Node, nodeBytes []byte) bool {
				require.NoError(t, module.AddMPTNodes([][]byte{nodeBytes}))
				return true // add nodes one-by-one
			})
			require.NoError(t, err)
			count--
			if count < 0 {
				break
			}
		}

		// then create new statesync module with the same DB and check that state is proper
		// (headers and blocks are in sync, mpt is not yet synced)
		module = bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.True(t, module.IsActive())
		require.True(t, module.IsInitialized())
		require.False(t, module.NeedHeaders())
		require.True(t, module.NeedMPTNodes())
		unknownNodes = module.GetUnknownMPTNodesBatch(100)
		require.True(t, len(unknownNodes) > 0)
		require.NotContains(t, unknownNodes, expectedHeader.PrevStateRoot)
		require.Equal(t, uint32(stateSyncPoint), module.BlockHeight())

		// add the rest of MPT nodes and jump to state
		alreadyRequested := make(map[util.Uint256]struct{})
		for {
			unknownHashes := module.GetUnknownMPTNodesBatch(1) // restore nodes one-by-one
			if len(unknownHashes) == 0 {
				break
			}
			if _, ok := alreadyRequested[unknownHashes[0]]; ok {
				t.Fatal("bug: node was requested twice")
			}
			alreadyRequested[unknownHashes[0]] = struct{}{}
			var callbackCalled bool
			err := bcSpout.GetStateSyncModule().Traverse(unknownHashes[0], func(node mpt.Node, nodeBytes []byte) bool {
				require.NoError(t, module.AddMPTNodes([][]byte{slice.Copy(nodeBytes)}))
				callbackCalled = true
				return true // add nodes one-by-one
			})
			require.NoError(t, err)
			require.True(t, callbackCalled)
		}

		// check that module is inactive and statejump is completed
		require.False(t, module.IsActive())
		require.False(t, module.NeedHeaders())
		require.False(t, module.NeedMPTNodes())
		unknownNodes = module.GetUnknownMPTNodesBatch(1)
		require.True(t, len(unknownNodes) == 0)
		require.Equal(t, uint32(stateSyncPoint), module.BlockHeight())
		require.Equal(t, uint32(stateSyncPoint), bcBolt.BlockHeight())

		// create new module from completed state: the module should recognise that state sync is completed
		module = bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.False(t, module.IsActive())
		require.False(t, module.NeedHeaders())
		require.False(t, module.NeedMPTNodes())
		unknownNodes = module.GetUnknownMPTNodesBatch(1)
		require.True(t, len(unknownNodes) == 0)
		require.Equal(t, uint32(stateSyncPoint), module.BlockHeight())
		require.Equal(t, uint32(stateSyncPoint), bcBolt.BlockHeight())

		// add one more block to the restored chain and start new module: the module should recognise state sync is completed
		// and regular blocks processing was started
		require.NoError(t, bcBolt.AddBlock(bcBolt.newBlock()))
		module = bcBolt.GetStateSyncModule()
		require.NoError(t, module.Init(bcSpout.BlockHeight()))
		require.False(t, module.IsActive())
		require.False(t, module.NeedHeaders())
		require.False(t, module.NeedMPTNodes())
		unknownNodes = module.GetUnknownMPTNodesBatch(1)
		require.True(t, len(unknownNodes) == 0)
		require.Equal(t, uint32(stateSyncPoint)+1, module.BlockHeight())
		require.Equal(t, uint32(stateSyncPoint)+1, bcBolt.BlockHeight())
	})
}

func TestStateSyncModule_RestoreBasicChain(t *testing.T) {
	var (
		stateSyncInterval        = 4
		maxTraceable      uint32 = 6
		stateSyncPoint           = 20
	)
	spoutCfg := func(c *config.Config) {
		c.ProtocolConfiguration.StateRootInHeader = true
		c.ProtocolConfiguration.P2PStateExchangeExtensions = true
		c.ProtocolConfiguration.StateSyncInterval = stateSyncInterval
		c.ProtocolConfiguration.MaxTraceableBlocks = maxTraceable
	}
	bcSpout := newTestChainWithCustomCfg(t, spoutCfg)
	initBasicChain(t, bcSpout)

	// make spout chain higher that latest state sync point (add several blocks up to stateSyncPoint+2)
	require.NoError(t, bcSpout.AddBlock(bcSpout.newBlock()))
	require.Equal(t, stateSyncPoint+2, int(bcSpout.BlockHeight()))

	boltCfg := func(c *config.Config) {
		spoutCfg(c)
		c.ProtocolConfiguration.KeepOnlyLatestState = true
		c.ProtocolConfiguration.RemoveUntraceableBlocks = true
	}
	bcBoltStore := memoryStore{storage.NewMemoryStore()}
	bcBolt := initTestChain(t, bcBoltStore, boltCfg)
	go bcBolt.Run()
	module := bcBolt.GetStateSyncModule()

	t.Run("error: add headers before initialisation", func(t *testing.T) {
		h, err := bcSpout.GetHeader(bcSpout.GetHeaderHash(1))
		require.NoError(t, err)
		require.Error(t, module.AddHeaders(h))
	})
	t.Run("no error: add blocks before initialisation", func(t *testing.T) {
		b, err := bcSpout.GetBlock(bcSpout.GetHeaderHash(1))
		require.NoError(t, err)
		require.NoError(t, module.AddBlock(b))
	})
	t.Run("error: add MPT nodes without initialisation", func(t *testing.T) {
		require.Error(t, module.AddMPTNodes([][]byte{}))
	})

	require.NoError(t, module.Init(bcSpout.BlockHeight()))
	require.True(t, module.IsActive())
	require.True(t, module.IsInitialized())
	require.True(t, module.NeedHeaders())
	require.False(t, module.NeedMPTNodes())

	// add headers to module
	headers := make([]*block.Header, 0, bcSpout.HeaderHeight())
	for i := uint32(1); i <= bcSpout.HeaderHeight(); i++ {
		h, err := bcSpout.GetHeader(bcSpout.GetHeaderHash(int(i)))
		require.NoError(t, err)
		headers = append(headers, h)
	}
	require.NoError(t, module.AddHeaders(headers...))
	require.True(t, module.IsActive())
	require.True(t, module.IsInitialized())
	require.False(t, module.NeedHeaders())
	require.True(t, module.NeedMPTNodes())
	require.Equal(t, bcSpout.HeaderHeight(), bcBolt.HeaderHeight())

	// add blocks
	t.Run("error: unexpected block index", func(t *testing.T) {
		b, err := bcSpout.GetBlock(bcSpout.GetHeaderHash(stateSyncPoint - int(maxTraceable)))
		require.NoError(t, err)
		require.Error(t, module.AddBlock(b))
	})
	t.Run("error: missing state root in block header", func(t *testing.T) {
		b := &block.Block{
			Header: block.Header{
				Index:            uint32(stateSyncPoint) - maxTraceable + 1,
				StateRootEnabled: false,
			},
		}
		require.Error(t, module.AddBlock(b))
	})
	t.Run("error: invalid block merkle root", func(t *testing.T) {
		b := &block.Block{
			Header: block.Header{
				Index:            uint32(stateSyncPoint) - maxTraceable + 1,
				StateRootEnabled: true,
				MerkleRoot:       util.Uint256{1, 2, 3},
			},
		}
		require.Error(t, module.AddBlock(b))
	})

	for i := stateSyncPoint - int(maxTraceable) + 1; i <= stateSyncPoint; i++ {
		b, err := bcSpout.GetBlock(bcSpout.GetHeaderHash(i))
		require.NoError(t, err)
		require.NoError(t, module.AddBlock(b))
	}
	require.True(t, module.IsActive())
	require.True(t, module.IsInitialized())
	require.False(t, module.NeedHeaders())
	require.True(t, module.NeedMPTNodes())
	require.Equal(t, uint32(stateSyncPoint), module.BlockHeight())

	// add MPT nodes in batches
	h, err := bcSpout.GetHeader(bcSpout.GetHeaderHash(stateSyncPoint + 1))
	require.NoError(t, err)
	unknownHashes := module.GetUnknownMPTNodesBatch(100)
	require.Equal(t, 1, len(unknownHashes))
	require.Equal(t, h.PrevStateRoot, unknownHashes[0])
	nodesMap := make(map[util.Uint256][]byte)
	err = bcSpout.GetStateSyncModule().Traverse(h.PrevStateRoot, func(n mpt.Node, nodeBytes []byte) bool {
		nodesMap[n.Hash()] = nodeBytes
		return false
	})
	require.NoError(t, err)
	for {
		need := module.GetUnknownMPTNodesBatch(10)
		if len(need) == 0 {
			break
		}
		add := make([][]byte, len(need))
		for i, h := range need {
			nodeBytes, ok := nodesMap[h]
			if !ok {
				t.Fatal("unknown or restored node requested")
			}
			add[i] = nodeBytes
			delete(nodesMap, h)
		}
		require.NoError(t, module.AddMPTNodes(add))
	}
	require.False(t, module.IsActive())
	require.False(t, module.NeedHeaders())
	require.False(t, module.NeedMPTNodes())
	unknownNodes := module.GetUnknownMPTNodesBatch(1)
	require.True(t, len(unknownNodes) == 0)
	require.Equal(t, uint32(stateSyncPoint), module.BlockHeight())
	require.Equal(t, uint32(stateSyncPoint), bcBolt.BlockHeight())

	// add missing blocks to bcBolt: should be ok, because state is synced
	for i := stateSyncPoint + 1; i <= int(bcSpout.BlockHeight()); i++ {
		b, err := bcSpout.GetBlock(bcSpout.GetHeaderHash(i))
		require.NoError(t, err)
		require.NoError(t, bcBolt.AddBlock(b))
	}
	require.Equal(t, bcSpout.BlockHeight(), bcBolt.BlockHeight())

	// compare storage states
	fetchStorage := func(bc *Blockchain) []storage.KeyValue {
		var kv []storage.KeyValue
		bc.dao.Store.Seek(storage.SeekRange{Prefix: bc.dao.Version.StoragePrefix.Bytes()}, func(k, v []byte) bool {
			key := slice.Copy(k)
			value := slice.Copy(v)
			if key[0] == byte(storage.STTempStorage) {
				key[0] = byte(storage.STStorage)
			}
			kv = append(kv, storage.KeyValue{
				Key:   key,
				Value: value,
			})
			return true
		})
		return kv
	}
	expected := fetchStorage(bcSpout)
	actual := fetchStorage(bcBolt)
	require.ElementsMatch(t, expected, actual)

	// no temp items should be left
	require.Eventually(t, func() bool {
		var haveItems bool
		bcBolt.dao.Store.Seek(storage.SeekRange{Prefix: storage.STStorage.Bytes()}, func(_, _ []byte) bool {
			haveItems = true
			return false
		})
		return !haveItems
	}, time.Second*5, time.Millisecond*100)
	bcBolt.Close()

	// Check restoring with new prefix.
	bcBolt = initTestChain(t, bcBoltStore, boltCfg)
	go bcBolt.Run()
	defer bcBolt.Close()
	require.Equal(t, storage.STTempStorage, bcBolt.dao.Version.StoragePrefix)
	require.Equal(t, storage.STTempStorage, bcBolt.persistent.Version.StoragePrefix)
}