// Copyright 2014 The go-ethereum Authors
// (original work)
// Copyright 2024 The Erigon Authors
// (modifications)
// This file is part of Erigon.
//
// Erigon is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Erigon is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with Erigon. If not, see <http://www.gnu.org/licenses/>.

package rlp

import (
	"bytes"
	"crypto/rand"
	"errors"
	"fmt"
	"io"
	"runtime"
	"sync"
	"testing"

	"github.com/holiman/uint256"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"github.com/erigontech/erigon/common"
	"github.com/erigontech/erigon/common/hexutil"
)

type testEncoder struct {
	err error
}

func (e *testEncoder) EncodeRLP(w io.Writer) error {
	if e == nil {
		panic("EncodeRLP called on nil value")
	}
	if e.err != nil {
		return e.err
	}
	if _, err := w.Write([]byte{0, 1, 0, 1, 0, 1, 0, 1, 0, 1}); err != nil {
		return err
	}
	return nil
}

type testEncoderValueMethod struct{}

func (e testEncoderValueMethod) EncodeRLP(w io.Writer) error {
	_, err := w.Write([]byte{0xFA, 0xFE, 0xF0})
	return err
}

type byteEncoder byte

func (e byteEncoder) EncodeRLP(w io.Writer) error {
	_, err := w.Write([]byte{EmptyListCode})
	return err
}

type undecodableEncoder func()

func (f undecodableEncoder) EncodeRLP(w io.Writer) error {
	_, err := w.Write([]byte{0xF5, 0xF5, 0xF5})
	return err
}

type encodableReader struct {
	A, B uint
}

func (e *encodableReader) Read(b []byte) (int, error) {
	panic("called")
}

type namedByteType byte

var (
	_ = Encoder(&testEncoder{})
	_ = Encoder(byteEncoder(0))

	reader io.Reader = &encodableReader{1, 2}
)

type encTest struct {
	val           any
	output, error string
}

var encTests = []encTest{
	// booleans
	{val: true, output: "01"},
	{val: false, output: "80"},

	// integers
	{val: uint32(0), output: "80"},
	{val: uint32(127), output: "7F"},
	{val: uint32(128), output: "8180"},
	{val: uint32(256), output: "820100"},
	{val: uint32(1024), output: "820400"},
	{val: uint32(0xFFFFFF), output: "83FFFFFF"},
	{val: uint32(0xFFFFFFFF), output: "84FFFFFFFF"},
	{val: uint64(0xFFFFFFFF), output: "84FFFFFFFF"},
	{val: uint64(0xFFFFFFFFFF), output: "85FFFFFFFFFF"},
	{val: uint64(0xFFFFFFFFFFFF), output: "86FFFFFFFFFFFF"},
	{val: uint64(0xFFFFFFFFFFFFFF), output: "87FFFFFFFFFFFFFF"},
	{val: uint64(0xFFFFFFFFFFFFFFFF), output: "88FFFFFFFFFFFFFFFF"},

	// uint256 integers (should match uint for small values)
	{val: uint256.NewInt(0), output: "80"},
	{val: uint256.NewInt(1), output: "01"},
	{val: uint256.NewInt(127), output: "7F"},
	{val: uint256.NewInt(128), output: "8180"},
	{val: uint256.NewInt(256), output: "820100"},
	{val: uint256.NewInt(1024), output: "820400"},
	{val: uint256.NewInt(0xFFFFFF), output: "83FFFFFF"},
	{val: uint256.NewInt(0xFFFFFFFF), output: "84FFFFFFFF"},
	{val: uint256.NewInt(0xFFFFFFFFFF), output: "85FFFFFFFFFF"},
	{val: uint256.NewInt(0xFFFFFFFFFFFF), output: "86FFFFFFFFFFFF"},
	{val: uint256.NewInt(0xFFFFFFFFFFFFFF), output: "87FFFFFFFFFFFFFF"},
	{
		val:    uint256.NewInt(0).SetBytes(unhex("102030405060708090A0B0C0D0E0F2")),
		output: "8F102030405060708090A0B0C0D0E0F2",
	},
	{
		val:    uint256.NewInt(0).SetBytes(unhex("0100020003000400050006000700080009000A000B000C000D000E01")),
		output: "9C0100020003000400050006000700080009000A000B000C000D000E01",
	},

	// named byte type arrays
	{val: [0]namedByteType{}, output: "80"},
	{val: [1]namedByteType{0}, output: "00"},
	{val: [1]namedByteType{1}, output: "01"},
	{val: [1]namedByteType{0x7F}, output: "7F"},
	{val: [1]namedByteType{0x80}, output: "8180"},
	{val: [1]namedByteType{0xFF}, output: "81FF"},
	{val: [3]namedByteType{1, 2, 3}, output: "83010203"},
	{val: [57]namedByteType{1, 2, 3}, output: "B839010203000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"},

	// byte slices
	{val: []byte{}, output: "80"},
	{val: []byte{0}, output: "00"},
	{val: []byte{0x7E}, output: "7E"},
	{val: []byte{0x7F}, output: "7F"},
	{val: []byte{0x80}, output: "8180"},
	{val: []byte{1, 2, 3}, output: "83010203"},

	// named byte type slices
	{val: []namedByteType{}, output: "80"},
	{val: []namedByteType{0}, output: "00"},
	{val: []namedByteType{0x7E}, output: "7E"},
	{val: []namedByteType{0x7F}, output: "7F"},
	{val: []namedByteType{0x80}, output: "8180"},
	{val: []namedByteType{1, 2, 3}, output: "83010203"},

	// strings
	{val: "", output: "80"},
	{val: "\x7E", output: "7E"},
	{val: "\x7F", output: "7F"},
	{val: "\x80", output: "8180"},
	{val: "dog", output: "83646F67"},
	{
		val:    "Lorem ipsum dolor sit amet, consectetur adipisicing eli",
		output: "B74C6F72656D20697073756D20646F6C6F722073697420616D65742C20636F6E7365637465747572206164697069736963696E6720656C69",
	},
	{
		val:    "Lorem ipsum dolor sit amet, consectetur adipisicing elit",
		output: "B8384C6F72656D20697073756D20646F6C6F722073697420616D65742C20636F6E7365637465747572206164697069736963696E6720656C6974",
	},
	{
		val:    "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur mauris magna, suscipit sed vehicula non, iaculis faucibus tortor. Proin suscipit ultricies malesuada. Duis tortor elit, dictum quis tristique eu, ultrices at risus. Morbi a est imperdiet mi ullamcorper aliquet suscipit nec lorem. Aenean quis leo mollis, vulputate elit varius, consequat enim. Nulla ultrices turpis justo, et posuere urna consectetur nec. Proin non convallis metus. Donec tempor ipsum in mauris congue sollicitudin. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Suspendisse convallis sem vel massa faucibus, eget lacinia lacus tempor. Nulla quis ultricies purus. Proin auctor rhoncus nibh condimentum mollis. Aliquam consequat enim at metus luctus, a eleifend purus egestas. Curabitur at nibh metus. Nam bibendum, neque at auctor tristique, lorem libero aliquet arcu, non interdum tellus lectus sit amet eros. Cras rhoncus, metus ac ornare cursus, dolor justo ultrices metus, at ullamcorper volutpat",
		output: "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",
	},

	// slices
	{val: []uint{}, output: "C0"},
	{val: []uint{1, 2, 3}, output: "C3010203"},
	{
		// [ [], [[]], [ [], [[]] ] ]
		val:    []any{[]any{}, [][]any{{}}, []any{[]any{}, [][]any{{}}}},
		output: "C7C0C1C0C3C0C1C0",
	},
	{
		val:    []string{"aaa", "bbb", "ccc", "ddd", "eee", "fff", "ggg", "hhh", "iii", "jjj", "kkk", "lll", "mmm", "nnn", "ooo"},
		output: "F83C836161618362626283636363836464648365656583666666836767678368686883696969836A6A6A836B6B6B836C6C6C836D6D6D836E6E6E836F6F6F",
	},
	{
		val:    []any{uint(1), uint(0xFFFFFF), []any{[]uint{4, 5, 5}}, "abc"},
		output: "CE0183FFFFFFC4C304050583616263",
	},
	{
		val: [][]string{
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
			{"asdf", "qwer", "zxcv"},
		},
		output: "F90200CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376CF84617364668471776572847A786376",
	},

	// RawValue
	{val: RawValue(unhex("01")), output: "01"},
	{val: RawValue(unhex("82FFFF")), output: "82FFFF"},
	{val: []RawValue{unhex("01"), unhex("02")}, output: "C20102"},

	// structs
	{val: simplestruct{}, output: "C28080"},
	{val: simplestruct{A: 3, B: "foo"}, output: "C50383666F6F"},
	{val: &recstruct{5, nil}, output: "C205C0"},
	{val: &recstruct{5, &recstruct{4, &recstruct{3, nil}}}, output: "C605C404C203C0"},
	{val: &intField{X: -3}, error: "rlp: type int -ve values are not RLP-serializable"},
	{val: &intField{X: 3}, output: "C103"},

	// struct tag "-"
	{val: &ignoredField{A: 1, B: 2, C: 3}, output: "C20103"},

	// struct tag "tail"
	{val: &tailRaw{A: 1, Tail: []RawValue{unhex("02"), unhex("03")}}, output: "C3010203"},
	{val: &tailRaw{A: 1, Tail: []RawValue{unhex("02")}}, output: "C20102"},
	{val: &tailRaw{A: 1, Tail: []RawValue{}}, output: "C101"},
	{val: &tailRaw{A: 1, Tail: nil}, output: "C101"},

	// struct tag "optional"
	{val: &optionalFields{}, output: "C180"},
	{val: &optionalFields{A: 1}, output: "C101"},
	{val: &optionalFields{A: 1, B: 2}, output: "C20102"},
	{val: &optionalFields{A: 1, B: 2, C: 3}, output: "C3010203"},
	{val: &optionalFields{A: 1, B: 0, C: 3}, output: "C3018003"},
	{val: &optionalAndTailField{A: 1}, output: "C101"},
	{val: &optionalAndTailField{A: 1, B: 2}, output: "C20102"},
	{val: &optionalAndTailField{A: 1, Tail: []uint{5, 6}}, output: "C401800506"},
	{val: &optionalAndTailField{A: 1, Tail: []uint{5, 6}}, output: "C401800506"},
	{val: &optionalPtrField{A: 1}, output: "C101"},
	{val: &optionalPtrFieldNil{A: 1}, output: "C101"},

	// nil
	{val: (*uint)(nil), output: "80"},
	{val: (*string)(nil), output: "80"},
	{val: (*[]byte)(nil), output: "80"},
	{val: (*[10]byte)(nil), output: "80"},
	{val: (*uint256.Int)(nil), output: "80"},
	{val: (*[]string)(nil), output: "C0"},
	{val: (*[10]string)(nil), output: "C0"},
	{val: (*[]any)(nil), output: "C0"},
	{val: (*[]struct{ uint })(nil), output: "C0"},
	{val: (*any)(nil), output: "C0"},

	// nil struct fields
	{
		val: struct {
			X *[]byte
		}{},
		output: "C180",
	},
	{
		val: struct {
			X *[2]byte
		}{},
		output: "C180",
	},
	{
		val: struct {
			X *uint64
		}{},
		output: "C180",
	},
	{
		val: struct {
			X *uint64 `rlp:"nilList"`
		}{},
		output: "C1C0",
	},
	{
		val: struct {
			X *[]uint64
		}{},
		output: "C1C0",
	},
	{
		val: struct {
			X *[]uint64 `rlp:"nilString"`
		}{},
		output: "C180",
	},

	// interfaces
	{val: []io.Reader{reader}, output: "C3C20102"}, // the contained value is a struct

	// Encoder
	{val: (*testEncoder)(nil), output: "C0"},
	{val: &testEncoder{}, output: "00010001000100010001"},
	{val: &testEncoder{errors.New("test error")}, error: "test error"},
	{val: struct{ E testEncoderValueMethod }{}, output: "C3FAFEF0"},
	{val: struct{ E *testEncoderValueMethod }{}, output: "C1C0"},

	// Verify that the Encoder interface works for unsupported types like func().
	{val: undecodableEncoder(func() {}), output: "F5F5F5"},

	// Verify that pointer method testEncoder.EncodeRLP is called for
	// addressable non-pointer values.
	{val: &struct{ TE testEncoder }{testEncoder{}}, output: "CA00010001000100010001"},
	{val: &struct{ TE testEncoder }{testEncoder{errors.New("test error")}}, error: "test error"},

	// Verify the error for non-addressable non-pointer Encoder.
	{val: testEncoder{}, error: "rlp: unaddressable value of type rlp.testEncoder, EncodeRLP is pointer method"},

	// Verify Encoder takes precedence over []byte.
	{val: []byteEncoder{0, 1, 2, 3, 4}, output: "C5C0C0C0C0C0"},
}

func runEncTests(t *testing.T, f func(val any) ([]byte, error)) {
	for i, test := range encTests {
		output, err := f(test.val)
		if err != nil && test.error == "" {
			t.Errorf("test %d: unexpected error: %v\nvalue %#v\ntype %T",
				i, err, test.val, test.val)
			continue
		}
		if test.error != "" && fmt.Sprint(err) != test.error {
			t.Errorf("test %d: error mismatch\ngot   %v\nwant  %v\nvalue %#v\ntype  %T",
				i, err, test.error, test.val, test.val)
			continue
		}
		if err == nil && !bytes.Equal(output, unhex(test.output)) {
			t.Errorf("test %d: output mismatch:\ngot   %X\nwant  %s\nvalue %#v\ntype  %T",
				i, output, test.output, test.val, test.val)
		}
	}
}

func TestEncode(t *testing.T) {
	runEncTests(t, func(val any) ([]byte, error) {
		b := new(bytes.Buffer)
		err := Encode(b, val)
		return b.Bytes(), err
	})
}

func TestEncodeToBytes(t *testing.T) {
	runEncTests(t, EncodeToBytes)
}

func TestEncodeToReader(t *testing.T) {
	runEncTests(t, func(val any) ([]byte, error) {
		_, r, err := EncodeToReader(val)
		if err != nil {
			return nil, err
		}
		return io.ReadAll(r)
	})
}

func TestEncodeToReaderPiecewise(t *testing.T) {
	runEncTests(t, func(val any) ([]byte, error) {
		size, r, err := EncodeToReader(val)
		if err != nil {
			return nil, err
		}

		// read output piecewise
		output := make([]byte, size)
		for start, end := 0, 0; start < size; start = end {
			if remaining := size - start; remaining < 3 {
				end += remaining
			} else {
				end = start + 3
			}
			n, err := r.Read(output[start:end])
			end = start + n
			if errors.Is(err, io.EOF) {
				break
			} else if err != nil {
				return nil, err
			}
		}
		return output, nil
	})
}

// This is a regression test verifying that encReader
// returns its encBuffer to the pool only once.
func TestEncodeToReaderReturnToPool(t *testing.T) {
	buf := make([]byte, 50)
	wg := new(sync.WaitGroup)
	for range 5 {
		wg.Go(func() {
			for range 1000 {
				_, r, _ := EncodeToReader("foo")
				io.ReadAll(r)
				r.Read(buf)
				r.Read(buf)
				r.Read(buf)
				r.Read(buf)
			}
		})
	}
	wg.Wait()
}

var sink any

func BenchmarkPutint(b *testing.B) {
	buf := make([]byte, 8)
	for b.Loop() {
		putint(buf, 0x12345678)
		sink = buf
	}
}

func BenchmarkEncodeUint256Ints(b *testing.B) {
	ints := make([]*uint256.Int, 200)
	for i := range ints {
		ints[i] = new(uint256.Int).Lsh(uint256.NewInt(1), uint(i))
	}
	out := bytes.NewBuffer(make([]byte, 0, 4096))

	b.ReportAllocs()

	for b.Loop() {
		out.Reset()
		if err := Encode(out, ints); err != nil {
			b.Fatal(err)
		}
	}
}

func TestStringLen56(t *testing.T) {
	str := hexutil.MustDecodeHex("7907ca011864321def1e92a3021868f397516ce37c959f25f8dddd3161d7b8301152b35f135c814fae9f487206471b6b0d713cd51a2d3598")
	require.Len(t, str, 56)

	strLen := StringLen(str)
	assert.Equal(t, 56+2, strLen)

	encoded := make([]byte, strLen)
	EncodeStringToBuf(str, encoded)

	dataPos, dataLen, err := ParseString(encoded, 0)
	require.NoError(t, err)
	assert.Equal(t, 2, dataPos)
	assert.Equal(t, 56, dataLen)
}

// Any buffer of 32 bytes or more should be fine for EncodeUint256.
// See https://github.com/erigontech/erigon/pull/13574
func TestEncodeUint256Buffer(t *testing.T) {
	i := *uint256.NewInt(128)
	output := "8180"

	var writer1 bytes.Buffer
	var buf32 [32]byte
	require.NoError(t, EncodeUint256(i, &writer1, buf32[:]))
	assert.Equal(t, output, common.Bytes2Hex(writer1.Bytes()))

	var writer2 bytes.Buffer
	var buf33 [33]byte
	require.NoError(t, EncodeUint256(i, &writer2, buf33[:]))
	assert.Equal(t, output, common.Bytes2Hex(writer2.Bytes()))

	var writer3 bytes.Buffer
	var buf31 [31]byte
	require.Panics(t, func() { EncodeUint256(i, &writer3, buf31[:]) })
}

func TestEncodeUint256Random(t *testing.T) {
	for size := 1; size <= 32; size++ {
		t.Run(fmt.Sprintf("size=%d", size), func(t *testing.T) {
			randomBytes := make([]byte, size)
			_, err := rand.Read(randomBytes)
			require.NoError(t, err)

			i := *new(uint256.Int).SetBytes(randomBytes)
			var writer bytes.Buffer
			var buf [32]byte
			require.NoError(t, EncodeUint256(i, &writer, buf[:]))
			encoded := bytes.NewReader(writer.Bytes())

			s := NewStream(encoded, 0)
			decoded, err := s.Uint256Bytes()
			require.NoError(t, err)
			assert.Equal(t, i, *uint256.NewInt(0).SetBytes(decoded))
		})
	}
}

func BenchmarkEncodeConcurrentInterface(b *testing.B) {
	type struct1 struct {
		A string
		B *uint256.Int
		C [20]byte
	}
	value := []any{
		uint(999),
		&struct1{A: "hello", B: uint256.NewInt(0xFFFFFFFF)},
		[10]byte{1, 2, 3, 4, 5, 6},
		[]string{"yeah", "yeah", "yeah"},
	}

	var wg sync.WaitGroup
	for cpu := 0; cpu < runtime.NumCPU(); cpu++ {
		wg.Go(func() {
			var buffer bytes.Buffer
			for i := 0; i < b.N; i++ {
				buffer.Reset()
				err := Encode(&buffer, value)
				if err != nil {
					panic(err)
				}
			}
		})
	}
	wg.Wait()
}
