simplify codebase.

esplora.go

@@ -0,0 +1,63 @@
+package opentimestamps
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/wire"
+)
+
+func NewEsploraClient(url string) Bitcoin {
+	if strings.HasSuffix(url, "/") {
+		url = url[0 : len(url)-1]
+	}
+	return esplora{url}
+}
+
+type esplora struct{ baseurl string }
+
+func (e esplora) GetBlockHash(height int64) (*chainhash.Hash, error) {
+	resp, err := http.Get(e.baseurl + "/block-height/" + strconv.FormatInt(height, 10))
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	hexb, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	if _, err := hex.Decode(hexb, hexb); err != nil || len(hexb) != chainhash.HashSize {
+		return nil, err
+	}
+	var chash chainhash.Hash
+	copy(chash[:], hexb)
+	return &chash, nil
+}
+
+func (e esplora) GetBlockHeader(hash *chainhash.Hash) (*wire.BlockHeader, error) {
+	resp, err := http.Get(fmt.Sprintf("%s/block/%x/header", e.baseurl, hash))
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	hexb, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	if _, err := hex.Decode(hexb, hexb); err != nil {
+		return nil, err
+	}
+
+	header := &wire.BlockHeader{}
+	if err := header.BtcDecode(bytes.NewBuffer(hexb), 0, 0); err != nil {
+		return nil, err
+	}
+
+	return header, nil
+}