package light_test

import (
	"context"
	"errors"
	"testing"
	"time"

	dbm "github.com/tendermint/tm-db"

	"github.com/tendermint/tendermint/libs/log"
	"github.com/tendermint/tendermint/light"
	"github.com/tendermint/tendermint/light/provider"
	dbs "github.com/tendermint/tendermint/light/store/db"
	"github.com/tendermint/tendermint/types"
)

// NOTE: block is produced every minute. Make sure the verification time
// provided in the function call is correct for the size of the blockchain. The
// benchmarking may take some time hence it can be more useful to set the time
// or the amount of iterations use the flag -benchtime t -> i.e. -benchtime 5m
// or -benchtime 100x.
//
// Remember that none of these benchmarks account for network latency.
var ()

type providerBenchmarkImpl struct {
	currentHeight int64
	blocks        map[int64]*types.LightBlock
}

func newProviderBenchmarkImpl(headers map[int64]*types.SignedHeader,
	vals map[int64]*types.ValidatorSet) provider.Provider {
	impl := providerBenchmarkImpl{
		blocks: make(map[int64]*types.LightBlock, len(headers)),
	}
	for height, header := range headers {
		if height > impl.currentHeight {
			impl.currentHeight = height
		}
		impl.blocks[height] = &types.LightBlock{
			SignedHeader: header,
			ValidatorSet: vals[height],
		}
	}
	return &impl
}

func (impl *providerBenchmarkImpl) LightBlock(ctx context.Context, height int64) (*types.LightBlock, error) {
	if height == 0 {
		return impl.blocks[impl.currentHeight], nil
	}
	lb, ok := impl.blocks[height]
	if !ok {
		return nil, provider.ErrLightBlockNotFound
	}
	return lb, nil
}

func (impl *providerBenchmarkImpl) ReportEvidence(_ context.Context, _ types.Evidence) error {
	return errors.New("not implemented")
}

func BenchmarkSequence(b *testing.B) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	headers, vals, _ := genLightBlocksWithKeys(b, chainID, 1000, 100, 1, bTime)
	benchmarkFullNode := newProviderBenchmarkImpl(headers, vals)
	genesisBlock, _ := benchmarkFullNode.LightBlock(ctx, 1)

	logger := log.NewTestingLogger(b)

	c, err := light.NewClient(
		ctx,
		chainID,
		light.TrustOptions{
			Period: 24 * time.Hour,
			Height: 1,
			Hash:   genesisBlock.Hash(),
		},
		benchmarkFullNode,
		[]provider.Provider{benchmarkFullNode},
		dbs.New(dbm.NewMemDB()),
		light.Logger(logger),
		light.SequentialVerification(),
	)
	if err != nil {
		b.Fatal(err)
	}
	b.ResetTimer()

	for n := 0; n < b.N; n++ {
		_, err = c.VerifyLightBlockAtHeight(ctx, 1000, bTime.Add(1000*time.Minute))
		if err != nil {
			b.Fatal(err)
		}
	}
}

func BenchmarkBisection(b *testing.B) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	headers, vals, _ := genLightBlocksWithKeys(b, chainID, 1000, 100, 1, bTime)
	benchmarkFullNode := newProviderBenchmarkImpl(headers, vals)
	genesisBlock, _ := benchmarkFullNode.LightBlock(ctx, 1)

	logger := log.NewTestingLogger(b)

	c, err := light.NewClient(
		context.Background(),
		chainID,
		light.TrustOptions{
			Period: 24 * time.Hour,
			Height: 1,
			Hash:   genesisBlock.Hash(),
		},
		benchmarkFullNode,
		[]provider.Provider{benchmarkFullNode},
		dbs.New(dbm.NewMemDB()),
		light.Logger(logger),
	)
	if err != nil {
		b.Fatal(err)
	}
	b.ResetTimer()

	for n := 0; n < b.N; n++ {
		_, err = c.VerifyLightBlockAtHeight(ctx, 1000, bTime.Add(1000*time.Minute))
		if err != nil {
			b.Fatal(err)
		}
	}
}

func BenchmarkBackwards(b *testing.B) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	headers, vals, _ := genLightBlocksWithKeys(b, chainID, 1000, 100, 1, bTime)
	benchmarkFullNode := newProviderBenchmarkImpl(headers, vals)
	trustedBlock, _ := benchmarkFullNode.LightBlock(ctx, 0)

	logger := log.NewTestingLogger(b)

	c, err := light.NewClient(
		ctx,
		chainID,
		light.TrustOptions{
			Period: 24 * time.Hour,
			Height: trustedBlock.Height,
			Hash:   trustedBlock.Hash(),
		},
		benchmarkFullNode,
		[]provider.Provider{benchmarkFullNode},
		dbs.New(dbm.NewMemDB()),
		light.Logger(logger),
	)
	if err != nil {
		b.Fatal(err)
	}
	b.ResetTimer()

	for n := 0; n < b.N; n++ {
		_, err = c.VerifyLightBlockAtHeight(ctx, 1, bTime)
		if err != nil {
			b.Fatal(err)
		}
	}
}