package multisig

import (
	"math/rand"
	"testing"

	"github.com/stretchr/testify/require"

	"github.com/tendermint/tendermint/crypto"
	"github.com/tendermint/tendermint/crypto/ed25519"
	"github.com/tendermint/tendermint/crypto/secp256k1"
	"github.com/tendermint/tendermint/crypto/sr25519"
)

// This tests multisig functionality, but it expects the first k signatures to be valid
// TODO: Adapt it to give more flexibility about first k signatures being valid
func TestThresholdMultisigValidCases(t *testing.T) {
	pkSet1, sigSet1 := generatePubKeysAndSignatures(5, []byte{1, 2, 3, 4})
	cases := []struct {
		msg            []byte
		k              int
		pubkeys        []crypto.PubKey
		signingIndices []int
		// signatures should be the same size as signingIndices.
		signatures           [][]byte
		passAfterKSignatures []bool
	}{
		{
			msg:                  []byte{1, 2, 3, 4},
			k:                    2,
			pubkeys:              pkSet1,
			signingIndices:       []int{0, 3, 1},
			signatures:           sigSet1,
			passAfterKSignatures: []bool{false},
		},
	}
	for tcIndex, tc := range cases {
		multisigKey := NewPubKeyMultisigThreshold(tc.k, tc.pubkeys)
		multisignature := NewMultisig(len(tc.pubkeys))

		for i := 0; i < tc.k-1; i++ {
			signingIndex := tc.signingIndices[i]
			require.NoError(
				t,
				multisignature.AddSignatureFromPubKey(tc.signatures[signingIndex], tc.pubkeys[signingIndex], tc.pubkeys),
			)
			require.False(
				t,
				multisigKey.VerifyBytes(tc.msg, multisignature.Marshal()),
				"multisig passed when i < k, tc %d, i %d", tcIndex, i,
			)
			require.NoError(
				t,
				multisignature.AddSignatureFromPubKey(tc.signatures[signingIndex], tc.pubkeys[signingIndex], tc.pubkeys),
			)
			require.Equal(
				t,
				i+1,
				len(multisignature.Sigs),
				"adding a signature for the same pubkey twice increased signature count by 2, tc %d", tcIndex,
			)
		}

		require.False(
			t,
			multisigKey.VerifyBytes(tc.msg, multisignature.Marshal()),
			"multisig passed with k - 1 sigs, tc %d", tcIndex,
		)
		require.NoError(
			t,
			multisignature.AddSignatureFromPubKey(
				tc.signatures[tc.signingIndices[tc.k]],
				tc.pubkeys[tc.signingIndices[tc.k]],
				tc.pubkeys,
			),
		)
		require.True(
			t,
			multisigKey.VerifyBytes(tc.msg, multisignature.Marshal()),
			"multisig failed after k good signatures, tc %d", tcIndex,
		)

		for i := tc.k + 1; i < len(tc.signingIndices); i++ {
			signingIndex := tc.signingIndices[i]

			require.NoError(
				t,
				multisignature.AddSignatureFromPubKey(tc.signatures[signingIndex], tc.pubkeys[signingIndex], tc.pubkeys),
			)
			require.Equal(
				t,
				tc.passAfterKSignatures[i-tc.k-1],
				multisigKey.VerifyBytes(tc.msg, multisignature.Marshal()),
				"multisig didn't verify as expected after k sigs, tc %d, i %d", tcIndex, i,
			)
			require.NoError(
				t,
				multisignature.AddSignatureFromPubKey(tc.signatures[signingIndex], tc.pubkeys[signingIndex], tc.pubkeys),
			)
			require.Equal(
				t,
				i+1,
				len(multisignature.Sigs),
				"adding a signature for the same pubkey twice increased signature count by 2, tc %d", tcIndex,
			)
		}
	}
}

// TODO: Fully replace this test with table driven tests
func TestThresholdMultisigDuplicateSignatures(t *testing.T) {
	msg := []byte{1, 2, 3, 4, 5}
	pubkeys, sigs := generatePubKeysAndSignatures(5, msg)
	multisigKey := NewPubKeyMultisigThreshold(2, pubkeys)
	multisignature := NewMultisig(5)
	require.False(t, multisigKey.VerifyBytes(msg, multisignature.Marshal()))
	multisignature.AddSignatureFromPubKey(sigs[0], pubkeys[0], pubkeys)
	// Add second signature manually
	multisignature.Sigs = append(multisignature.Sigs, sigs[0])
	require.False(t, multisigKey.VerifyBytes(msg, multisignature.Marshal()))
}

// TODO: Fully replace this test with table driven tests
func TestMultiSigPubKeyEquality(t *testing.T) {
	msg := []byte{1, 2, 3, 4}
	pubkeys, _ := generatePubKeysAndSignatures(5, msg)
	multisigKey := NewPubKeyMultisigThreshold(2, pubkeys)
	var unmarshalledMultisig PubKey
	cdc.MustUnmarshalBinaryBare(multisigKey.Bytes(), &unmarshalledMultisig)
	require.True(t, multisigKey.Equals(unmarshalledMultisig))

	// Ensure that reordering pubkeys is treated as a different pubkey
	pubkeysCpy := make([]crypto.PubKey, 5)
	copy(pubkeysCpy, pubkeys)
	pubkeysCpy[4] = pubkeys[3]
	pubkeysCpy[3] = pubkeys[4]
	multisigKey2 := NewPubKeyMultisigThreshold(2, pubkeysCpy)
	require.False(t, multisigKey.Equals(multisigKey2))
}

func TestAddress(t *testing.T) {
	msg := []byte{1, 2, 3, 4}
	pubkeys, _ := generatePubKeysAndSignatures(5, msg)
	multisigKey := NewPubKeyMultisigThreshold(2, pubkeys)
	require.Len(t, multisigKey.Address().Bytes(), 20)
}

func TestPubKeyMultisigThresholdAminoToIface(t *testing.T) {
	msg := []byte{1, 2, 3, 4}
	pubkeys, _ := generatePubKeysAndSignatures(5, msg)
	multisigKey := NewPubKeyMultisigThreshold(2, pubkeys)

	ab, err := cdc.MarshalBinaryLengthPrefixed(multisigKey)
	require.NoError(t, err)
	// like other crypto.Pubkey implementations (e.g. ed25519.PubKey),
	// PubKey should be deserializable into a crypto.PubKey:
	var pubKey crypto.PubKey
	err = cdc.UnmarshalBinaryLengthPrefixed(ab, &pubKey)
	require.NoError(t, err)

	require.Equal(t, multisigKey, pubKey)
}

func generatePubKeysAndSignatures(n int, msg []byte) (pubkeys []crypto.PubKey, signatures [][]byte) {
	pubkeys = make([]crypto.PubKey, n)
	signatures = make([][]byte, n)
	for i := 0; i < n; i++ {
		var privkey crypto.PrivKey
		switch rand.Int63() % 3 {
		case 0:
			privkey = ed25519.GenPrivKey()
		case 1:
			privkey = secp256k1.GenPrivKey()
		case 2:
			privkey = sr25519.GenPrivKey()
		}
		pubkeys[i] = privkey.PubKey()
		signatures[i], _ = privkey.Sign(msg)
	}
	return
}