package splitstore

import (
	"context"
	"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"

	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
	CompactionCold = 1
	CompactionBoundary = 2
	logging.SetLogLevel("splitstore", "DEBUG")
}

func testSplitStore(t *testing.T, cfg *Config) {
	chain := &mockChain{t: t}
	// genesis
	genBlock := mock.MkBlock(nil, 0, 0)
	genTs := mock.TipSet(genBlock)
	chain.push(genTs)

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

	// 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))
		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
	}

	mkGarbageBlock := func(curTs *types.TipSet, i int) {
		blk := mock.MkBlock(curTs, uint64(i), uint64(i))
		sblk, err := blk.ToStorageBlock()
		if err != nil {
			t.Fatal(err)
		}
		err = ss.Put(sblk)
		if err != nil {
			t.Fatal(err)
		}
	}

	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()
	}

	mkGarbageBlock(genTs, 1)

	// count objects in the cold and hot stores
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	countBlocks := func(bs blockstore.Blockstore) int {
		count := 0
		ch, err := bs.AllKeysChan(ctx)
		if err != nil {
			t.Fatal(err)
		}
		for range ch {
			count++
		}
		return count
	}

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

	if coldCnt != 1 {
		t.Errorf("expected %d blocks, but got %d", 1, coldCnt)
	}

	if hotCnt != 5 {
		t.Errorf("expected %d blocks, but got %d", 5, hotCnt)
	}

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

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

	if !cfg.EnableFullCompaction {
		if coldCnt != 5 {
			t.Errorf("expected %d cold blocks, but got %d", 5, coldCnt)
		}

		if hotCnt != 5 {
			t.Errorf("expected %d hot blocks, but got %d", 5, hotCnt)
		}
	}

	if cfg.EnableFullCompaction && !cfg.EnableGC {
		if coldCnt != 3 {
			t.Errorf("expected %d cold blocks, but got %d", 3, coldCnt)
		}

		if hotCnt != 7 {
			t.Errorf("expected %d hot blocks, but got %d", 7, hotCnt)
		}
	}

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

		if hotCnt != 7 {
			t.Errorf("expected %d hot blocks, but got %d", 7, hotCnt)
		}
	}

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

func TestSplitStoreSimpleCompaction(t *testing.T) {
	testSplitStore(t, &Config{TrackingStoreType: "mem"})
}

func TestSplitStoreFullCompactionWithoutGC(t *testing.T) {
	testSplitStore(t, &Config{
		TrackingStoreType:    "mem",
		EnableFullCompaction: true,
	})
}

func TestSplitStoreFullCompactionWithGC(t *testing.T) {
	testSplitStore(t, &Config{
		TrackingStoreType:    "mem",
		EnableFullCompaction: true,
		EnableGC:             true,
	})
}

type mockChain struct {
	t testing.TB

	sync.Mutex
	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)
	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) 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-1], 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
}

func (c *mockChain) WalkSnapshot(_ context.Context, ts *types.TipSet, epochs abi.ChainEpoch, _ bool, _ bool, f func(cid.Cid) error) error {
	c.Lock()
	defer c.Unlock()

	start := int(ts.Height()) - 1
	end := start - int(epochs)
	if end < 0 {
		end = -1
	}
	for i := start; i > end; i-- {
		ts := c.tipsets[i]
		for _, cid := range ts.Cids() {
			err := f(cid)
			if err != nil {
				return err
			}
		}
	}

	return nil
}