Implement BlockChainInfo RPC method (cosmos#282)

CHANGELOG-PENDING.md

@@ -26,6 +26,7 @@ Month, DD, YYYY
 - [rpc] [Implement Tx Method #272](https://github.com/celestiaorg/optimint/pull/272) [@mauriceLC92](https://github.com/mauriceLC92)
 - [rpc] [Implement Commit and BlockSearch method #258](https://github.com/celestiaorg/optimint/pull/258) [@raneet10](https://github.com/Raneet10/)
 - [rpc] [Remove extra variable #280](https://github.com/celestiaorg/optimint/pull/280) [@raneet10](https://github.com/Raneet10/)
+- [rpc] [Implement BlockChainInfo RPC method #282](https://github.com/celestiaorg/optimint/pull/282) [@raneet10](https://github.com/Raneet10/)
 
 ### BUG FIXES
 

conv/abci/block.go

@@ -98,6 +98,22 @@ func ToABCIBlock(block *types.Block) (*tmtypes.Block, error) {
 	return &abciBlock, nil
 }
 
+// ToABCIBlockMeta converts Optimint block into BlockMeta format defined by ABCI
+func ToABCIBlockMeta(block *types.Block) (*tmtypes.BlockMeta, error) {
+	tmblock, err := ToABCIBlock(block)
+	if err != nil {
+		return nil, err
+	}
+	blockId := tmtypes.BlockID{Hash: tmblock.Hash()}
+
+	return &tmtypes.BlockMeta{
+		BlockID:   blockId,
+		BlockSize: tmblock.Size(),
+		Header:    tmblock.Header,
+		NumTxs:    len(tmblock.Txs),
+	}, nil
+}
+
 // ToABCICommit converts Optimint commit into commit format defined by ABCI.
 // This function only converts fields that are available in Optimint commit.
 // Other fields (especially ValidatorAddress and Timestamp of Signature) has to be filled by caller.

rpc/client/client.go

@@ -267,8 +267,40 @@ func (c *Client) GenesisChunked(context context.Context, id uint) (*ctypes.Resul
 }
 
 func (c *Client) BlockchainInfo(ctx context.Context, minHeight, maxHeight int64) (*ctypes.ResultBlockchainInfo, error) {
-	// needs block store
-	panic("BlockchainInfo - not implemented!")
+	const limit int64 = 20
+
+	// Currently blocks are not pruned and are synced linearly so the base height is 0
+	minHeight, maxHeight, err := filterMinMax(
+		0,
+		int64(c.node.Store.Height()),
+		minHeight,
+		maxHeight,
+		limit)
+	if err != nil {
+		return nil, err
+	}
+	c.Logger.Debug("BlockchainInfo", "maxHeight", maxHeight, "minHeight", minHeight)
+
+	blocks := make([]*types.BlockMeta, 0, maxHeight-minHeight+1)
+	for height := maxHeight; height >= minHeight; height-- {
+		block, err := c.node.Store.LoadBlock(uint64(height))
+		if err != nil {
+			return nil, err
+		}
+		if block != nil {
+			tmblockmeta, err := abciconv.ToABCIBlockMeta(block)
+			if err != nil {
+				return nil, err
+			}
+			blocks = append(blocks, tmblockmeta)
+		}
+	}
+
+	return &ctypes.ResultBlockchainInfo{
+		LastHeight: int64(c.node.Store.Height()),
+		BlockMetas: blocks,
+	}, nil
+
 }
 
 func (c *Client) NetInfo(ctx context.Context) (*ctypes.ResultNetInfo, error) {
@@ -749,3 +781,34 @@ func validateSkipCount(page, perPage int) int {
 
 	return skipCount
 }
+
+func filterMinMax(base, height, min, max, limit int64) (int64, int64, error) {
+	// filter negatives
+	if min < 0 || max < 0 {
+		return min, max, errors.New("height must be greater than zero")
+	}
+
+	// adjust for default values
+	if min == 0 {
+		min = 1
+	}
+	if max == 0 {
+		max = height
+	}
+
+	// limit max to the height
+	max = tmmath.MinInt64(height, max)
+
+	// limit min to the base
+	min = tmmath.MaxInt64(base, min)
+
+	// limit min to within `limit` of max
+	// so the total number of blocks returned will be `limit`
+	min = tmmath.MaxInt64(min, max-limit+1)
+
+	if min > max {
+		return min, max, fmt.Errorf("%w: min height %d can't be greater than max height %d",
+			errors.New("invalid request"), min, max)
+	}
+	return min, max, nil
+}

rpc/client/client_test.go

@@ -22,6 +22,7 @@ import (
 	tmtypes "github.com/tendermint/tendermint/types"
 
 	"github.com/celestiaorg/optimint/config"
+	abciconv "github.com/celestiaorg/optimint/conv/abci"
 	"github.com/celestiaorg/optimint/mocks"
 	"github.com/celestiaorg/optimint/node"
 	"github.com/celestiaorg/optimint/state"
@@ -498,6 +499,79 @@ func TestConsensusState(t *testing.T) {
 	assert.ErrorIs(err, ErrConsensusStateNotAvailable)
 }
 
+func TestBlockchainInfo(t *testing.T) {
+	require := require.New(t)
+	assert := assert.New(t)
+	mockApp, rpc := getRPC(t)
+	mockApp.On("BeginBlock", mock.Anything).Return(abci.ResponseBeginBlock{})
+	mockApp.On("Commit", mock.Anything).Return(abci.ResponseCommit{})
+
+	heights := []int64{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+	for _, h := range heights {
+		block := getRandomBlock(uint64(h), 5)
+		err := rpc.node.Store.SaveBlock(block, &types.Commit{
+			Height:     uint64(h),
+			HeaderHash: block.Header.Hash(),
+		})
+		require.NoError(err)
+	}
+
+	tests := []struct {
+		desc string
+		min  int64
+		max  int64
+		exp  []*tmtypes.BlockMeta
+		err  bool
+	}{
+		{
+			desc: "min = 1 and max = 5",
+			min:  1,
+			max:  5,
+			exp:  []*tmtypes.BlockMeta{getBlockMeta(rpc, 1), getBlockMeta(rpc, 5)},
+			err:  false,
+		}, {
+			desc: "min height is 0",
+			min:  0,
+			max:  10,
+			exp:  []*tmtypes.BlockMeta{getBlockMeta(rpc, 1), getBlockMeta(rpc, 10)},
+			err:  false,
+		}, {
+			desc: "max height is out of range",
+			min:  0,
+			max:  15,
+			exp:  []*tmtypes.BlockMeta{getBlockMeta(rpc, 1), getBlockMeta(rpc, 10)},
+			err:  false,
+		}, {
+			desc: "negative min height",
+			min:  -1,
+			max:  11,
+			exp:  nil,
+			err:  true,
+		}, {
+			desc: "negative max height",
+			min:  1,
+			max:  -1,
+			exp:  nil,
+			err:  true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			result, err := rpc.BlockchainInfo(context.Background(), test.min, test.max)
+			if test.err {
+				require.Error(err)
+			} else {
+				require.NoError(err)
+				assert.Equal(result.LastHeight, heights[9])
+				assert.Contains(result.BlockMetas, test.exp[0])
+				assert.Contains(result.BlockMetas, test.exp[1])
+			}
+
+		})
+	}
+}
+
 // copy-pasted from store/store_test.go
 func getRandomBlock(height uint64, nTxs int) *types.Block {
 	block := &types.Block{
@@ -546,6 +620,19 @@ func getRandomBytes(n int) []byte {
 	return data
 }
 
+func getBlockMeta(rpc *Client, n int64) *tmtypes.BlockMeta {
+	b, err := rpc.node.Store.LoadBlock(uint64(n))
+	if err != nil {
+		return nil
+	}
+	bmeta, err := abciconv.ToABCIBlockMeta(b)
+	if err != nil {
+		return nil
+	}
+
+	return bmeta
+}
+
 func getRPC(t *testing.T) (*mocks.Application, *Client) {
 	t.Helper()
 	require := require.New(t)