refactor

verifyer/bitcoin.go

@@ -0,0 +1,15 @@
+package verifyer
+
+import (
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/rpcclient"
+	"github.com/btcsuite/btcd/wire"
+)
+
+type Bitcoin interface {
+	GetBlockHash(height int64) (*chainhash.Hash, error)
+	GetBlockHeader(hash *chainhash.Hash) (*wire.BlockHeader, error)
+}
+
+var _ Bitcoin = (*esplora)(nil)
+var _ Bitcoin = (*rpcclient.Client)(nil)

verifyer/bitcoind.go

@@ -0,0 +1,7 @@
+package verifyer
+
+import "github.com/btcsuite/btcd/rpcclient"
+
+func NewBitcoindInterface(config rpcclient.ConnConfig) (Bitcoin, error) {
+	return rpcclient.New(&config, nil)
+}

verifyer/esplora.go

@@ -0,0 +1,85 @@
+package verifyer
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"slices"
+
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/wire"
+)
+
+// esplora is a client for the Esplora API, which provides access to Bitcoin
+// blockchain data.
+type esplora struct {
+	httpClient *http.Client
+	baseURL    string
+}
+
+func NewEsploraClient(url string, timeout time.Duration) Bitcoin {
+	url = strings.TrimSuffix(url, "/")
+
+	h := &http.Client{
+		Timeout: timeout,
+	}
+
+	return esplora{h, url}
+}
+
+func (e esplora) GetBlockHash(height int64) (*chainhash.Hash, error) {
+	resp, err := e.httpClient.Get(e.baseURL + "/block-height/" + strconv.FormatInt(height, 10))
+	if err != nil {
+		return nil, fmt.Errorf("failed to get block hash: %w", err)
+	}
+	defer resp.Body.Close()
+
+	hexb, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read block hash: %w", err)
+	}
+
+	hash, err := hex.DecodeString(string(hexb))
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode block hash: %w", err)
+	}
+	if len(hash) != chainhash.HashSize {
+		return nil, fmt.Errorf("got block hash (%x) of invalid size (expected %d)", hash, chainhash.HashSize)
+	}
+
+	slices.Reverse(hash)
+	var chash chainhash.Hash
+	copy(chash[:], hash)
+	return &chash, nil
+}
+
+func (e esplora) GetBlockHeader(hash *chainhash.Hash) (*wire.BlockHeader, error) {
+	resp, err := e.httpClient.Get(fmt.Sprintf("%s/block/%s/header", e.baseURL, hash.String()))
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	hexb, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	headerHash, err := hex.DecodeString(string(hexb))
+	if err != nil {
+		return nil, err
+	}
+
+	header := &wire.BlockHeader{}
+	if err := header.BtcDecode(bytes.NewBuffer(headerHash), 0, 0); err != nil {
+		return nil, err
+	}
+
+	return header, nil
+}