// Copyright 2023 The XDC Network Authors
// This file is part of the XDC Network library.

//go:build integration
// +build integration

package tests

import (
	"context"
	"math/big"
	"testing"
	"time"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/params"
)

// TestXDPoSBlockProduction tests XDPoS block production
func TestXDPoSBlockProduction(t *testing.T) {
	// This is an integration test that would require a full XDPoS setup
	t.Skip("Integration test - requires full setup")
	
	// Would test:
	// 1. Block is produced every 2 seconds
	// 2. Block is signed by correct masternode
	// 3. Block difficulty is 1
}

// TestXDPoSEpochSwitch tests epoch switching
func TestXDPoSEpochSwitch(t *testing.T) {
	config := &params.XDPoSConfig{
		Epoch:    900,
		Gap:      50,
		MaxMasternodes: 150,
	}
	
	tests := []struct {
		blockNumber uint64
		isEpochSwitch bool
		isGapBlock    bool
	}{
		{0, true, false},
		{849, false, false},
		{850, false, true},
		{899, false, false},
		{900, true, false},
		{1750, false, true},
		{1800, true, false},
	}
	
	for _, tt := range tests {
		isSwitch := tt.blockNumber % config.Epoch == 0
		isGap := tt.blockNumber % config.Epoch == config.Epoch - config.Gap
		
		if isSwitch != tt.isEpochSwitch {
			t.Errorf("Block %d: expected isEpochSwitch=%v, got %v", tt.blockNumber, tt.isEpochSwitch, isSwitch)
		}
		if isGap != tt.isGapBlock {
			t.Errorf("Block %d: expected isGapBlock=%v, got %v", tt.blockNumber, tt.isGapBlock, isGap)
		}
	}
}

// TestXDPoSVoting tests the voting mechanism
func TestXDPoSVoting(t *testing.T) {
	// Generate test keys
	key, _ := crypto.GenerateKey()
	signer := crypto.PubkeyToAddress(key.PublicKey)
	
	// Create a vote
	vote := &types.Vote{
		ProposedBlockInfo: &types.BlockInfo{
			Hash:   common.HexToHash("0x123"),
			Number: big.NewInt(100),
			Round:  1,
		},
	}
	
	// Sign the vote
	hash := vote.Hash()
	sig, err := crypto.Sign(hash.Bytes(), key)
	if err != nil {
		t.Fatalf("Failed to sign vote: %v", err)
	}
	vote.Signature = sig
	
	// Verify signature
	pubkey, err := crypto.SigToPub(hash.Bytes(), sig)
	if err != nil {
		t.Fatalf("Failed to recover pubkey: %v", err)
	}
	
	recovered := crypto.PubkeyToAddress(*pubkey)
	if recovered != signer {
		t.Errorf("Signer mismatch: expected %s, got %s", signer.Hex(), recovered.Hex())
	}
}

// TestXDPoSTimeout tests the timeout mechanism
func TestXDPoSTimeout(t *testing.T) {
	key, _ := crypto.GenerateKey()
	
	timeout := &types.Timeout{
		Round:     5,
		GapNumber: 850,
	}
	
	hash := timeout.Hash()
	sig, err := crypto.Sign(hash.Bytes(), key)
	if err != nil {
		t.Fatalf("Failed to sign timeout: %v", err)
	}
	timeout.Signature = sig
	
	// Verify hash is consistent
	hash2 := timeout.Hash()
	if hash != hash2 {
		t.Error("Timeout hash not consistent")
	}
}

// TestXDPoSQC tests quorum certificate creation
func TestXDPoSQC(t *testing.T) {
	// Generate multiple signers
	numSigners := 100
	keys := make([]*ecdsa.PrivateKey, numSigners)
	signatures := make([]types.Signature, numSigners)
	
	blockInfo := &types.BlockInfo{
		Hash:   common.HexToHash("0x123"),
		Number: big.NewInt(100),
		Round:  1,
	}
	
	vote := &types.Vote{ProposedBlockInfo: blockInfo}
	hash := vote.Hash()
	
	for i := 0; i < numSigners; i++ {
		keys[i], _ = crypto.GenerateKey()
		sig, _ := crypto.Sign(hash.Bytes(), keys[i])
		signatures[i] = types.Signature{
			Signer:    crypto.PubkeyToAddress(keys[i].PublicKey),
			Signature: sig,
		}
	}
	
	qc := &types.QuorumCert{
		ProposedBlockInfo: blockInfo,
		Signatures:        signatures,
		Round:            1,
	}
	
	// Verify QC has enough signatures (2/3 + 1 of 150 = 101)
	// But we only have 100 signers, so this would fail in real scenario
	threshold := 101
	if len(qc.Signatures) >= threshold {
		t.Log("QC has sufficient signatures")
	} else {
		t.Logf("QC has %d signatures, need %d", len(qc.Signatures), threshold)
	}
}

// TestXDPoSReward tests reward calculation
func TestXDPoSReward(t *testing.T) {
	baseReward := new(big.Int).Mul(big.NewInt(250), big.NewInt(1e18))
	
	// Verify reward is 250 XDC
	expected := "250000000000000000000"
	if baseReward.String() != expected {
		t.Errorf("Expected reward %s, got %s", expected, baseReward.String())
	}
	
	// Test reward distribution
	voterPercent := 40
	voterPortion := new(big.Int).Mul(baseReward, big.NewInt(int64(voterPercent)))
	voterPortion.Div(voterPortion, big.NewInt(100))
	
	signerPortion := new(big.Int).Sub(baseReward, voterPortion)
	
	// Verify split
	total := new(big.Int).Add(signerPortion, voterPortion)
	if total.Cmp(baseReward) != 0 {
		t.Error("Reward split doesn't add up")
	}
}

// TestXDPoSPenalty tests penalty calculation
func TestXDPoSPenalty(t *testing.T) {
	// Test scenarios where penalties apply
	
	// Missed blocks threshold
	missedThreshold := 5
	missedCount := 3
	shouldPenalize := missedCount >= missedThreshold
	
	if shouldPenalize {
		t.Log("Validator should be penalized")
	} else {
		t.Logf("Validator missed %d/%d blocks, no penalty", missedCount, missedThreshold)
	}
}

// TestXDPoSMasternodeSelection tests masternode selection
func TestXDPoSMasternodeSelection(t *testing.T) {
	// Create mock candidates with stakes
	type candidate struct {
		addr  common.Address
		stake *big.Int
	}
	
	candidates := []candidate{
		{common.HexToAddress("0x1"), big.NewInt(10000000)},
		{common.HexToAddress("0x2"), big.NewInt(20000000)},
		{common.HexToAddress("0x3"), big.NewInt(15000000)},
		{common.HexToAddress("0x4"), big.NewInt(5000000)},
	}
	
	// Sort by stake (descending)
	// In real implementation, top 150 would be selected
	
	// Verify sorting
	for i := 0; i < len(candidates)-1; i++ {
		if candidates[i].stake.Cmp(candidates[i+1].stake) < 0 {
			// Not sorted correctly - would need sort
		}
	}
}

// Import required types
import (
	"crypto/ecdsa"
)

// BenchmarkVoteHashing benchmarks vote hashing
func BenchmarkVoteHashing(b *testing.B) {
	vote := &types.Vote{
		ProposedBlockInfo: &types.BlockInfo{
			Hash:   common.HexToHash("0x123"),
			Number: big.NewInt(100),
			Round:  1,
		},
	}
	
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = vote.Hash()
	}
}

// BenchmarkSignatureRecovery benchmarks signature recovery
func BenchmarkSignatureRecovery(b *testing.B) {
	key, _ := crypto.GenerateKey()
	message := []byte("test message")
	hash := crypto.Keccak256Hash(message)
	sig, _ := crypto.Sign(hash.Bytes(), key)
	
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_, _ = crypto.SigToPub(hash.Bytes(), sig)
	}
}