package splitstore

import (
	"context"
	"errors"
	"fmt"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/filecoin-project/go-state-types/abi"
	"github.com/filecoin-project/lotus/blockstore"
	"github.com/filecoin-project/lotus/chain/types"
	"github.com/filecoin-project/lotus/chain/types/mock"

	blocks "github.com/ipfs/go-block-format"
	cid "github.com/ipfs/go-cid"
	datastore "github.com/ipfs/go-datastore"
	dssync "github.com/ipfs/go-datastore/sync"
	logging "github.com/ipfs/go-log/v2"
)

func init() {
	CompactionThreshold = 5
	CompactionBoundary = 2
	logging.SetLogLevel("splitstore", "DEBUG")
}

func testSplitStore(t *testing.T, cfg *Config) {
	chain := &mockChain{t: t}

	// the myriads of stores
	ds := dssync.MutexWrap(datastore.NewMapDatastore())
	hot := newMockStore()
	cold := newMockStore()

	// this is necessary to avoid the garbage mock puts in the blocks
	garbage := blocks.NewBlock([]byte{1, 2, 3})
	err := cold.Put(garbage)
	if err != nil {
		t.Fatal(err)
	}

	// genesis
	genBlock := mock.MkBlock(nil, 0, 0)
	genBlock.Messages = garbage.Cid()
	genBlock.ParentMessageReceipts = garbage.Cid()
	genBlock.ParentStateRoot = garbage.Cid()
	genBlock.Timestamp = uint64(time.Now().Unix())

	genTs := mock.TipSet(genBlock)
	chain.push(genTs)

	// put the genesis block to cold store
	blk, err := genBlock.ToStorageBlock()
	if err != nil {
		t.Fatal(err)
	}

	err = cold.Put(blk)
	if err != nil {
		t.Fatal(err)
	}

	// open the splitstore
	ss, err := Open("", ds, hot, cold, cfg)
	if err != nil {
		t.Fatal(err)
	}
	defer ss.Close() //nolint

	err = ss.Start(chain)
	if err != nil {
		t.Fatal(err)
	}

	// make some tipsets, but not enough to cause compaction
	mkBlock := func(curTs *types.TipSet, i int) *types.TipSet {
		blk := mock.MkBlock(curTs, uint64(i), uint64(i))

		blk.Messages = garbage.Cid()
		blk.ParentMessageReceipts = garbage.Cid()
		blk.ParentStateRoot = garbage.Cid()
		blk.Timestamp = uint64(time.Now().Unix())

		sblk, err := blk.ToStorageBlock()
		if err != nil {
			t.Fatal(err)
		}
		err = ss.Put(sblk)
		if err != nil {
			t.Fatal(err)
		}
		ts := mock.TipSet(blk)
		chain.push(ts)

		return ts
	}

	waitForCompaction := func() {
		for atomic.LoadInt32(&ss.compacting) == 1 {
			time.Sleep(100 * time.Millisecond)
		}
	}

	curTs := genTs
	for i := 1; i < 5; i++ {
		curTs = mkBlock(curTs, i)
		waitForCompaction()
	}

	// count objects in the cold and hot stores
	countBlocks := func(bs blockstore.Blockstore) int {
		count := 0
		bs.(blockstore.BlockstoreIterator).ForEachKey(func(_ cid.Cid) error {
			count++
			return nil
		})
		return count
	}

	coldCnt := countBlocks(cold)
	hotCnt := countBlocks(hot)

	if coldCnt != 2 {
		t.Errorf("expected %d blocks, but got %d", 2, coldCnt)
	}

	if hotCnt != 6 {
		t.Errorf("expected %d blocks, but got %d", 6, hotCnt)
	}

	// trigger a compaction
	for i := 5; i < 10; i++ {
		curTs = mkBlock(curTs, i)
		waitForCompaction()
	}

	coldCnt = countBlocks(cold)
	hotCnt = countBlocks(hot)

	if coldCnt != 2 {
		t.Errorf("expected %d cold blocks, but got %d", 2, coldCnt)
	}

	if hotCnt != 11 {
		t.Errorf("expected %d hot blocks, but got %d", 11, hotCnt)
	}

	// Make sure we can revert without panicking.
	chain.revert(2)
}

func TestSplitStoreCompaction(t *testing.T) {
	testSplitStore(t, &Config{MarkSetType: "mapts"})
}

type mockChain struct {
	t testing.TB

	sync.Mutex
	genesis  *types.BlockHeader
	tipsets  []*types.TipSet
	listener func(revert []*types.TipSet, apply []*types.TipSet) error
}

func (c *mockChain) push(ts *types.TipSet) {
	c.Lock()
	c.tipsets = append(c.tipsets, ts)
	if c.genesis == nil {
		c.genesis = ts.Blocks()[0]
	}
	c.Unlock()

	if c.listener != nil {
		err := c.listener(nil, []*types.TipSet{ts})
		if err != nil {
			c.t.Errorf("mockchain: error dispatching listener: %s", err)
		}
	}
}

func (c *mockChain) revert(count int) {
	c.Lock()
	revert := make([]*types.TipSet, count)
	if count > len(c.tipsets) {
		c.Unlock()
		c.t.Fatalf("not enough tipsets to revert")
	}
	copy(revert, c.tipsets[len(c.tipsets)-count:])
	c.tipsets = c.tipsets[:len(c.tipsets)-count]
	c.Unlock()

	if c.listener != nil {
		err := c.listener(revert, nil)
		if err != nil {
			c.t.Errorf("mockchain: error dispatching listener: %s", err)
		}
	}
}

func (c *mockChain) GetGenesis() (*types.BlockHeader, error) {
	return c.genesis, nil
}

func (c *mockChain) GetTipsetByHeight(_ context.Context, epoch abi.ChainEpoch, _ *types.TipSet, _ bool) (*types.TipSet, error) {
	c.Lock()
	defer c.Unlock()

	iEpoch := int(epoch)
	if iEpoch > len(c.tipsets) {
		return nil, fmt.Errorf("bad epoch %d", epoch)
	}

	return c.tipsets[iEpoch], nil
}

func (c *mockChain) GetHeaviestTipSet() *types.TipSet {
	c.Lock()
	defer c.Unlock()

	return c.tipsets[len(c.tipsets)-1]
}

func (c *mockChain) SubscribeHeadChanges(change func(revert []*types.TipSet, apply []*types.TipSet) error) {
	c.listener = change
}

type mockStore struct {
	mx  sync.Mutex
	set map[cid.Cid]blocks.Block
}

func newMockStore() *mockStore {
	return &mockStore{set: make(map[cid.Cid]blocks.Block)}
}

func (b *mockStore) Has(cid cid.Cid) (bool, error) {
	b.mx.Lock()
	defer b.mx.Unlock()
	_, ok := b.set[cid]
	return ok, nil
}

func (b *mockStore) HashOnRead(hor bool) {}

func (b *mockStore) Get(cid cid.Cid) (blocks.Block, error) {
	b.mx.Lock()
	defer b.mx.Unlock()

	blk, ok := b.set[cid]
	if !ok {
		return nil, blockstore.ErrNotFound
	}
	return blk, nil
}

func (b *mockStore) GetSize(cid cid.Cid) (int, error) {
	blk, err := b.Get(cid)
	if err != nil {
		return 0, err
	}

	return len(blk.RawData()), nil
}

func (b *mockStore) View(cid cid.Cid, f func([]byte) error) error {
	blk, err := b.Get(cid)
	if err != nil {
		return err
	}
	return f(blk.RawData())
}

func (b *mockStore) Put(blk blocks.Block) error {
	b.mx.Lock()
	defer b.mx.Unlock()

	b.set[blk.Cid()] = blk
	return nil
}

func (b *mockStore) PutMany(blks []blocks.Block) error {
	b.mx.Lock()
	defer b.mx.Unlock()

	for _, blk := range blks {
		b.set[blk.Cid()] = blk
	}
	return nil
}

func (b *mockStore) DeleteBlock(cid cid.Cid) error {
	b.mx.Lock()
	defer b.mx.Unlock()

	delete(b.set, cid)
	return nil
}

func (b *mockStore) DeleteMany(cids []cid.Cid) error {
	b.mx.Lock()
	defer b.mx.Unlock()

	for _, c := range cids {
		delete(b.set, c)
	}
	return nil
}

func (b *mockStore) AllKeysChan(ctx context.Context) (<-chan cid.Cid, error) {
	return nil, errors.New("not implemented")
}

func (b *mockStore) ForEachKey(f func(cid.Cid) error) error {
	b.mx.Lock()
	defer b.mx.Unlock()

	for c := range b.set {
		err := f(c)
		if err != nil {
			return err
		}
	}
	return nil
}

func (b *mockStore) Close() error {
	return nil
}