package stateutil

import (
	"strconv"
	"sync"
	"testing"

	fuzz "github.com/google/gofuzz"
	ethereum_beacon_p2p_v1 "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
	"github.com/prysmaticlabs/prysm/shared/mputil"
	"github.com/prysmaticlabs/prysm/shared/params"
)

func init() {
	params.UseMinimalConfig()
}

func TestStateRootCacheFuzz_10(t *testing.T) {
	fuzzStateRootCache(t, 0, 10)
}

func TestStateRootCacheFuzz_100(t *testing.T) {
	fuzzStateRootCache(t, 1, 100)
}

func TestStateRootCacheFuzz_1000(t *testing.T) {
	fuzzStateRootCache(t, 2, 1000)
}

func fuzzStateRootCache(t *testing.T, seed int64, iterations uint64) {
	fuzzer := fuzz.NewWithSeed(seed)

	hasher := &stateRootHasher{}
	hasherWithCache := cachedHasher

	mismatch := 0
	mismatchedIndices := make([]uint64, 0)

	// Use scatter to run tests in parallel.
	if _, err := mputil.Scatter(int(iterations), func(start int, length int, _ *sync.RWMutex) (i interface{}, err error) {
		state := &ethereum_beacon_p2p_v1.BeaconState{}
		for i := start; i < start+length; i++ {
			func() {
				defer func() {
					if r := recover(); r != nil {
						// Ignore fuzzing panics for out of range values
					}
				}()
				fuzzer.Fuzz(state)
			}()
			var a, b [32]byte
			func() {
				defer func() {
					if r := recover(); r != nil {
						t.Errorf("Non-cached HTR panicked on iteration %d", i)
						panic(r)
					}
				}()
				var err error
				a, err = hasher.hashTreeRootState(state)
				if err != nil {
					t.Fatal(err)
				}
			}()

			func() {
				defer func() {
					if r := recover(); r != nil {
						t.Errorf("Cached HTR panicked on iteration %d", i)
						panic(r)
					}
				}()
				var err error
				b, err = hasherWithCache.hashTreeRootState(state)
				if err != nil {
					t.Fatal(err)
				}
			}()

			if a != b {
				mismatch++
				mismatchedIndices = append(mismatchedIndices, uint64(i))
			}
		}
		return nil, nil
	}); err != nil {
		t.Error(err)
	}

	if mismatch > 0 {
		t.Errorf("Mismatched indices: %v", mismatchedIndices)
		t.Fatalf("%d of %d random states had different roots", mismatch, iterations)
	}
}

func TestHashTreeRootState_ElementsChanged_RecomputeBranch(t *testing.T) {
	hasher := &stateRootHasher{}
	hasherWithCache := cachedHasher
	state := &ethereum_beacon_p2p_v1.BeaconState{}
	initialRoots := make([][]byte, 5)
	for i := 0; i < len(initialRoots); i++ {
		var someRt [32]byte
		copy(someRt[:], "hello")
		initialRoots[i] = someRt[:]
	}
	state.RandaoMixes = initialRoots
	if _, err := hasherWithCache.hashTreeRootState(state); err != nil {
		t.Fatal(err)
	}

	badRoots := make([][]byte, 5)
	for i := 0; i < len(badRoots); i++ {
		var someRt [32]byte
		copy(someRt[:], strconv.Itoa(i))
		badRoots[i] = someRt[:]
	}

	state.RandaoMixes = badRoots
	r1, err := hasher.hashTreeRootState(state)
	if err != nil {
		t.Fatal(err)
	}
	r2, err := hasherWithCache.hashTreeRootState(state)
	if err != nil {
		t.Fatal(err)
	}
	if r1 != r2 {
		t.Errorf("Wanted %#x (nocache), received %#x (withcache)", r1, r2)
	}
}