package tracers

import (
	"encoding/hex"
	"fmt"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/ethereum/go-ethereum/params"
	"github.com/stretchr/testify/require"
	"regexp"
	"strconv"
	"strings"
	"testing"
)

func TestFirehose_BlockPrintsToFirehoseInOrder(t *testing.T) {
	f := NewFirehose(&FirehoseConfig{
		ApplyBackwardCompatibility: ptr(false),
		private: &privateFirehoseConfig{
			FlushToTestBuffer: true,
		},
	})

	f.OnBlockchainInit(params.AllEthashProtocolChanges)

	blockNumbers := []uint64{123, 124, 125}
	blockHashes := make([]string, 3)

	for i, blockNum := range blockNumbers {
		f.OnBlockStart(blockEvent(blockNum))
		blockHashes[i] = hex.EncodeToString(f.block.Hash) // Store the hash before it gets reset

		f.onTxStart(txEvent(), hex2Hash(fmt.Sprintf("ABCD%d", i)), from, to)
		f.OnCallEnter(0, byte(vm.CALL), from, to, nil, 0, nil)
		f.OnBalanceChange(from, b(100), b(50), 0)
		f.OnCallExit(0, nil, 0, nil, false)
		f.OnTxEnd(txReceiptEvent(0), nil)

		f.OnBlockEnd(nil)
	}

	output := f.InternalTestingBuffer().String()

	require.Contains(t, output, "FIRE BLOCK", "expected FIRE BLOCK output not found")

	for i, blockNum := range blockNumbers {
		require.Contains(t, output, fmt.Sprintf("%d", blockNum),
			"expected block number %d not found in output", blockNum)
		require.Contains(t, output, blockHashes[i],
			"expected block hash for block %d not found in output", blockNum)
	}

	blockNumIndex123 := strings.Index(output, "123")
	blockNumIndex124 := strings.Index(output, "124")
	blockNumIndex125 := strings.Index(output, "125")

	require.True(t, blockNumIndex123 < blockNumIndex124,
		"Block 123 should appear before block 124 in output")
	require.True(t, blockNumIndex124 < blockNumIndex125,
		"Block 124 should appear before block 125 in output")
}

func TestFirehose_BlocksPrintToFirehoseInOrder(t *testing.T) {

	const blockCount = 100
	const baseBlockNum = 1000

	f := NewFirehose(&FirehoseConfig{
		ApplyBackwardCompatibility: ptr(false),
		private: &privateFirehoseConfig{
			FlushToTestBuffer: true,
		},
	})

	f.OnBlockchainInit(params.AllEthashProtocolChanges)

	blockHashes := make(map[uint64]string, blockCount)

	for i := 0; i < blockCount; i++ {
		blockNum := uint64(baseBlockNum + i)

		f.OnBlockStart(blockEvent(blockNum))
		blockHashes[blockNum] = hex.EncodeToString(f.block.Hash) // Store hash before block reset

		f.onTxStart(txEvent(), hex2Hash(fmt.Sprintf("TX%d", i)), from, to)
		f.OnCallEnter(0, byte(vm.CALL), from, to, nil, 0, nil)
		f.OnBalanceChange(from, b(100), b(50), 0)
		f.OnCallExit(0, nil, 0, nil, false)
		f.OnTxEnd(txReceiptEvent(0), nil)

		f.OnBlockEnd(nil)
	}

	f.Shutdown()

	output := f.InternalTestingBuffer().String()
	extractedBlocks := extractBlocksFromOutput(t, output)

	// Verify block count
	require.Equal(t, blockCount, len(extractedBlocks),
		"Expected %d blocks in output, found %d", blockCount, len(extractedBlocks))

	// Verify blocks in order
	verifyBlockSequence(t, extractedBlocks, baseBlockNum)

	// Verify block hashes
	for _, block := range extractedBlocks {
		expectedHash, exists := blockHashes[block.number]
		require.True(t, exists, "Block %d not found in tracked blocks", block.number)
		require.Equal(t, expectedHash, block.hash,
			"Hash mismatch for block %d", block.number)
	}
}

type extractedBlock struct {
	number uint64
	hash   string
}

func extractBlocksFromOutput(t *testing.T, output string) []extractedBlock {
	t.Helper()

	// Regex to extract the block number and hash from the FIRE BLOCK line
	blockInfoRegex := regexp.MustCompile(`FIRE BLOCK (\d+) ([0-9a-fA-F]+)`)

	lines := strings.Split(output, "\n")
	var blocks []extractedBlock

	for _, line := range lines {
		if strings.HasPrefix(line, "FIRE BLOCK") {
			matches := blockInfoRegex.FindStringSubmatch(line)
			if len(matches) == 3 {
				blockNumStr := matches[1]
				blockHash := matches[2]

				blockNum, err := strconv.ParseUint(blockNumStr, 10, 64)
				require.NoError(t, err, "failed to parse block number: %s", blockNumStr)

				blocks = append(blocks, extractedBlock{
					number: blockNum,
					hash:   blockHash,
				})
			}
		}
	}

	return blocks
}

func verifyBlockSequence(t *testing.T, blocks []extractedBlock, baseBlockNum uint64) {
	t.Helper()

	// First block should be the base block number
	require.Equal(t, baseBlockNum, blocks[0].number,
		"First block should be %d, got %d", baseBlockNum, blocks[0].number)

	// Last block should be base + count - 1
	expectedLast := baseBlockNum + uint64(len(blocks)) - 1
	require.Equal(t, expectedLast, blocks[len(blocks)-1].number,
		"Last block should be %d, got %d", expectedLast, blocks[len(blocks)-1].number)

	// Verify sequence
	for i := 0; i < len(blocks)-1; i++ {
		current := blocks[i].number
		next := blocks[i+1].number
		require.Equal(t, current+1, next,
			"Blocks out of order at position %d: %d followed by %d", i, current, next)
	}
}