add new bitcoin electrum SPV provider

providers/bitcoinElectrum/providerImpl.go

@@ -0,0 +1,62 @@
+package bitcoinElectrum
+
+import (
+	"fmt"
+	"os"
+	"sync"
+	"sync/atomic"
+
+	"github.com/btcsuite/btcd/btcutil/hdkeychain"
+)
+
+type Provider struct {
+	masterKey       *hdkeychain.ExtendedKey
+	ynabAccountID   string // YNAB account ID this provider updates - all bitcoin addresses are summed up and mapped to this YNAB account
+	spvServer       string
+	gapLimit        int
+	coinGeckoApiKey string
+}
+
+func (p *Provider) Name() string {
+	return "Bitcoin - Electrum SPV"
+}
+
+func (p *Provider) Configure() error {
+	var err error
+	zpub := os.Getenv("bitcoin_zpub")
+	p.ynabAccountID = os.Getenv("bitcoin_ynab_account")
+	p.spvServer = os.Getenv("bitcoin_spv_server")
+	p.coinGeckoApiKey = os.Getenv("bitcoin_coingecko_api_key")
+	p.gapLimit = 20
+	if zpub == "" || p.ynabAccountID == "" || p.spvServer == "" || p.coinGeckoApiKey == "" {
+		return fmt.Errorf("this account provider is not configured")
+	}
+
+	p.masterKey, err = hdkeychain.NewKeyFromString(zpub)
+	if err != nil {
+		return fmt.Errorf("failed to obtain master key from zpub: %v", err)
+	}
+
+	return nil
+}
+
+// Returns slices of account balances and mapped YNAB account IDs, along with an error
+func (p *Provider) GetBalances() ([]int, []string, error) {
+	var totalSats int64
+	var wg sync.WaitGroup
+
+	// branch 0 = regular
+	// branch 1 = change addresses
+	for _, branch := range []uint32{0, 1} {
+		wg.Add(1)
+		go func(branch uint32) {
+			defer wg.Done()
+			branchSats := scanBranch(p.masterKey, branch, p.gapLimit, p.spvServer)
+			atomic.AddInt64(&branchSats, totalSats)
+		}(branch)
+	}
+
+	wg.Wait()
+
+	return nil, nil, nil
+}