package testutil

import (
	"encoding/binary"
	"encoding/hex"
	"fmt"
	"strings"
	"testing"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/stretchr/testify/require"

	"github.com/ethereum-optimism/optimism/cannon/mipsevm"
	preimage "github.com/ethereum-optimism/optimism/op-preimage"
)

type TestOracle struct {
	hint        func(v []byte)
	getPreimage func(k [32]byte) []byte
}

var _ mipsevm.PreimageOracle = (*TestOracle)(nil)

func (t *TestOracle) Hint(v []byte) {
	t.hint(v)
}

func (t *TestOracle) GetPreimage(k [32]byte) []byte {
	return t.getPreimage(k)
}

func StaticOracle(t *testing.T, preimageData []byte) *TestOracle {
	return &TestOracle{
		hint: func(v []byte) {},
		getPreimage: func(k [32]byte) []byte {
			if k != preimage.Keccak256Key(crypto.Keccak256Hash(preimageData)).PreimageKey() {
				t.Fatalf("invalid preimage request for %x", k)
			}
			return preimageData
		},
	}
}

func StaticPrecompileOracle(t *testing.T, precompile common.Address, input []byte, result []byte) *TestOracle {
	return &TestOracle{
		hint: func(v []byte) {},
		getPreimage: func(k [32]byte) []byte {
			keyData := append(precompile.Bytes(), input...)
			switch k[0] {
			case byte(preimage.Keccak256KeyType):
				if k != preimage.Keccak256Key(crypto.Keccak256Hash(keyData)).PreimageKey() {
					t.Fatalf("invalid preimage request for %x", k)
				}
				return keyData
			case byte(preimage.PrecompileKeyType):
				if k != preimage.PrecompileKey(crypto.Keccak256Hash(keyData)).PreimageKey() {
					t.Fatalf("invalid preimage request for %x", k)
				}
				return result
			}
			panic("unreachable")
		},
	}
}

func ClaimTestOracle(t *testing.T) (po mipsevm.PreimageOracle, stdOut string, stdErr string) {
	s := uint64(1000)
	a := uint64(3)
	b := uint64(4)

	encodeU64 := func(x uint64) []byte {
		return binary.BigEndian.AppendUint64(nil, x)
	}

	var diff []byte
	diff = append(diff, crypto.Keccak256(encodeU64(a))...)
	diff = append(diff, crypto.Keccak256(encodeU64(b))...)

	preHash := crypto.Keccak256Hash(encodeU64(s))
	diffHash := crypto.Keccak256Hash(diff)

	images := make(map[[32]byte][]byte)
	images[preimage.LocalIndexKey(0).PreimageKey()] = preHash[:]
	images[preimage.LocalIndexKey(1).PreimageKey()] = diffHash[:]
	images[preimage.LocalIndexKey(2).PreimageKey()] = encodeU64(s*a + b)

	oracle := &TestOracle{
		hint: func(v []byte) {
			parts := strings.Split(string(v), " ")
			require.Len(t, parts, 2)
			p, err := hex.DecodeString(parts[1])
			require.NoError(t, err)
			require.Len(t, p, 32)
			h := common.Hash(*(*[32]byte)(p))
			switch parts[0] {
			case "fetch-state":
				require.Equal(t, h, preHash, "expecting request for pre-state pre-image")
				images[preimage.Keccak256Key(preHash).PreimageKey()] = encodeU64(s)
			case "fetch-diff":
				require.Equal(t, h, diffHash, "expecting request for diff pre-images")
				images[preimage.Keccak256Key(diffHash).PreimageKey()] = diff
				images[preimage.Keccak256Key(crypto.Keccak256Hash(encodeU64(a))).PreimageKey()] = encodeU64(a)
				images[preimage.Keccak256Key(crypto.Keccak256Hash(encodeU64(b))).PreimageKey()] = encodeU64(b)
			default:
				t.Fatalf("unexpected hint: %q", parts[0])
			}
		},
		getPreimage: func(k [32]byte) []byte {
			p, ok := images[k]
			if !ok {
				t.Fatalf("missing pre-image %s", k)
			}
			return p
		},
	}

	return oracle, fmt.Sprintf("computing %d * %d + %d\nclaim %d is good!\n", s, a, b, s*a+b), "started!"
}

func AllocOracle(t *testing.T, numAllocs int) *TestOracle {
	return &TestOracle{
		hint: func(v []byte) {},
		getPreimage: func(k [32]byte) []byte {
			if k != preimage.LocalIndexKey(0).PreimageKey() {
				t.Fatalf("invalid preimage request for %x", k)
			}
			return binary.LittleEndian.AppendUint64(nil, uint64(numAllocs))
		},
	}
}

func SelectOracleFixture(t *testing.T, programName string) mipsevm.PreimageOracle {
	if strings.HasPrefix(programName, "oracle_kzg") {
		precompile := common.BytesToAddress([]byte{0xa})
		input := common.FromHex("01e798154708fe7789429634053cbf9f99b619f9f084048927333fce637f549b564c0a11a0f704f4fc3e8acfe0f8245f0ad1347b378fbf96e206da11a5d3630624d25032e67a7e6a4910df5834b8fe70e6bcfeeac0352434196bdf4b2485d5a18f59a8d2a1a625a17f3fea0fe5eb8c896db3764f3185481bc22f91b4aaffcca25f26936857bc3a7c2539ea8ec3a952b7873033e038326e87ed3e1276fd140253fa08e9fc25fb2d9a98527fc22a2c9612fbeafdad446cbc7bcdbdcd780af2c16a")
		blobPrecompileReturnValue := common.FromHex("000000000000000000000000000000000000000000000000000000000000100073eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000001")
		return StaticPrecompileOracle(t, precompile, input, append([]byte{0x1}, blobPrecompileReturnValue...))
	} else if strings.HasPrefix(programName, "oracle") {
		return StaticOracle(t, []byte("hello world"))
	} else {
		return nil
	}
}
