// Copyright 2024 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library 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.
//
// The go-ethereum library 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 the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package vm

import (
	"encoding/hex"
	"reflect"
	"testing"

	"github.com/ethereum/go-ethereum/common"
)

func MakeTestContainer(
	types []*functionMetadata,
	codeSections [][]byte,
	subContainers []*Container,
	data []byte,
	dataSize int) Container {

	testBytes := make([]byte, 0, 16*1024)

	codeSectionOffsets := make([]int, 0, len(codeSections))
	idx := 0
	for _, code := range codeSections {
		codeSectionOffsets = append(codeSectionOffsets, idx)
		idx += len(code)
		testBytes = append(testBytes, code...)
	}
	codeSectionEnd := idx

	var subContainerOffsets []int
	subContainerEnd := 0
	if len(subContainers) > 0 {
		subContainerOffsets = make([]int, len(subContainers))
		for _, subContainer := range subContainers {
			containerBytes := subContainer.MarshalBinary()
			subContainerOffsets = append(subContainerOffsets, idx)
			idx += len(containerBytes)
			testBytes = append(testBytes, containerBytes...)
		}
		subContainerEnd = idx
	}

	testBytes = append(testBytes, data...)

	return Container{
		types:               types,
		codeSectionOffsets:  codeSectionOffsets,
		codeSectionEnd:      codeSectionEnd,
		subContainers:       subContainers,
		subContainerOffsets: subContainerOffsets,
		subContainerEnd:     subContainerEnd,
		dataOffest:          subContainerEnd,
		dataSize:            dataSize,
		rawContainer:        testBytes,
	}
}

func TestEOFMarshaling(t *testing.T) {
	for i, test := range []struct {
		want Container
		err  error
	}{
		{
			want: Container{
				types:              []*functionMetadata{{inputs: 0, outputs: 0x80, maxStackHeight: 1}},
				codeSectionOffsets: []int{19}, // 604200
				codeSectionEnd:     22,
				dataOffest:         22,
				dataSize:           3,
				rawContainer:       common.Hex2Bytes("ef000101000402000100030400030000800001604200010203"),
			},
		},
		{
			want: Container{
				types: []*functionMetadata{
					{inputs: 0, outputs: 0x80, maxStackHeight: 1},
					{inputs: 2, outputs: 3, maxStackHeight: 4},
					{inputs: 1, outputs: 1, maxStackHeight: 1},
				},
				codeSectionOffsets: []int{31, 34, 39}, // 604200, 6042604200, 00
				codeSectionEnd:     40,
				dataOffest:         40,
				rawContainer:       common.Hex2Bytes("ef000101000c02000300030005000104000000008000010203000401010001604200604260420000"),
			},
		},
	} {
		var (
			b   = test.want.MarshalBinary()
			got Container
		)
		t.Logf("b: %#x", b)
		if err := got.UnmarshalBinary(b, true); err != nil && err != test.err {
			t.Fatalf("test %d: got error \"%v\", want \"%v\"", i, err, test.err)
		}
		if !reflect.DeepEqual(got, test.want) {
			t.Fatalf("test %d: got %+v, want %+v", i, got, test.want)
		}
	}
}

func TestEOFSubcontainer(t *testing.T) {
	var subcontainer = new(Container)
	if err := subcontainer.UnmarshalBinary(common.Hex2Bytes("ef000101000402000100010400000000800000fe"), true); err != nil {
		t.Fatal(err)
	}
	container := MakeTestContainer(
		[]*functionMetadata{{inputs: 0, outputs: 0x80, maxStackHeight: 1}},
		[][]byte{common.Hex2Bytes("604200")},
		[]*Container{subcontainer},
		[]byte{0x01, 0x02, 0x03},
		3,
	)
	var (
		b   = container.MarshalBinary()
		got Container
	)
	if err := got.UnmarshalBinary(b, true); err != nil {
		t.Fatal(err)
	}
	if res := got.MarshalBinary(); !reflect.DeepEqual(res, b) {
		t.Fatalf("invalid marshalling, want %v got %v", b, res)
	}
}

func TestMarshaling(t *testing.T) {
	tests := []string{
		"EF000101000402000100040400000000800000E0000000",
		"ef0001010004020001000d04000000008000025fe100055f5fe000035f600100",
	}
	for i, test := range tests {
		s, err := hex.DecodeString(test)
		if err != nil {
			t.Fatalf("test %d: error decoding: %v", i, err)
		}
		var got Container
		if err := got.UnmarshalBinary(s, true); err != nil {
			t.Fatalf("test %d: got error %v", i, err)
		}
	}
}