ynab-portfolio-monitor/providers/bitcoin/providerImpl.go

package bitcoin

import (
	"fmt"
	"os"
	"sync"
)

type Provider struct {
	bitcoinAddresses []string // Slice of bitcoin addresses this provider monitors
	ynabAccountID    string   // YNAB account ID this provider updates - all bitcoin addresses are summed up and mapped to this YNAB account
	client           *client  // HTTP client for interacting with Questrade API
}

func (p *Provider) Name() string {
	return "Bitcoin - Blockstream.info / CoinGecko"
}

// Configures the provider for usage via environment variables and persistentData
// If an error is returned, the provider will not be used
func (p *Provider) Configure() error {
	// Load environment variables in continous series with suffix starting at 0
	// Multiple addresses can be configured, (eg _1, _2)
	// As soon as the series is interrupted, we assume we're done
	p.bitcoinAddresses = make([]string, 0)
	for i := 0; true; i++ {
		bitcoinAddress := os.Getenv(fmt.Sprintf("bitcoin_address_%d", i))
		if bitcoinAddress == "" {
			if i == 0 {
				return fmt.Errorf("this account provider is not configured")
			}
			break
		}
		p.bitcoinAddresses = append(p.bitcoinAddresses, bitcoinAddress)
	}
	p.ynabAccountID = os.Getenv("bitcoin_ynab_account")

	// Create new HTTP client
	p.client = newClient(os.Getenv("bitcoin_coingecko_api_key"))
	return nil
}

// Returns slices of account balances and mapped YNAB account IDs, along with an error
func (p *Provider) GetBalances() ([]int, []string, error) {

	balances := make([]int, 0)
	ynabAccountIDs := make([]string, 0)
	var satoshiBalance int
	wg := sync.WaitGroup{}
	var goErr *error

	for _, bitcoinAddress := range p.bitcoinAddresses {
		wg.Add(1)
		go func(goErr *error) {
			defer wg.Done()
			addressResponse, err := p.client.getAddress(bitcoinAddress)
			if err != nil {
				err := fmt.Errorf("failed to get bitcoin address '%s': %v", bitcoinAddress, err)
				goErr = &err
				return
			}
			satoshiBalance += addressResponse.ChainStats.FundedTxoSum - addressResponse.ChainStats.SpentTxoSum
		}(goErr)
	}
	wg.Wait()
	if *goErr != nil {
		return nil, nil, *goErr
	}

	fiatBalance, err := p.client.convertBTCToCAD(satoshiBalance)
	if err != nil {
		return balances, ynabAccountIDs, fmt.Errorf("failed to convert satoshi balance to fiat balance: %v", err)
	}

	balances = append(balances, fiatBalance)
	ynabAccountIDs = append(ynabAccountIDs, p.ynabAccountID)
	return balances, ynabAccountIDs, nil
}