app is now using historical exchange rates for transactions
This commit is contained in:
Matthias Hinrichs
+230
-16
@@ -17,32 +17,56 @@ type ExchangeRateResponse struct {
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Rates map[string]float64 `json:"rates"`
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}
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// HistoricalExchangeRateResponse represents historical rate response
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type HistoricalExchangeRateResponse struct {
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Success bool `json:"success"`
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Historical bool `json:"historical"`
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Base string `json:"base"`
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Date string `json:"date"`
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Rates map[string]float64 `json:"rates"`
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TimeLastUpdate int64 `json:"time_last_update_unix"`
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}
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// CachedRate stores exchange rate with timestamp
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type CachedRate struct {
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Rate float64
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Timestamp time.Time
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Date string // The date this rate is for (YYYY-MM-DD format)
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}
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// Currency conversion cache
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var (
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exchangeRateCache = make(map[string]CachedRate)
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cacheMutex sync.RWMutex
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cacheValidDuration = 1 * time.Hour // Cache rates for 1 hour
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cacheValidDuration = 24 * time.Hour // Cache historical rates for 24 hours
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currentRateCache = 1 * time.Hour // Cache current rates for 1 hour
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)
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// GetExchangeRate fetches the exchange rate from fromCurrency to toCurrency
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// GetExchangeRate fetches the current exchange rate from fromCurrency to toCurrency
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func GetExchangeRate(fromCurrency, toCurrency string) (float64, error) {
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return GetHistoricalExchangeRate(fromCurrency, toCurrency, time.Now())
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}
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// GetHistoricalExchangeRate fetches the exchange rate for a specific date
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func GetHistoricalExchangeRate(fromCurrency, toCurrency string, date time.Time) (float64, error) {
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// If currencies are the same, return 1.0
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if fromCurrency == toCurrency {
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return 1.0, nil
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}
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cacheKey := fmt.Sprintf("%s_%s", fromCurrency, toCurrency)
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dateStr := date.Format("2006-01-02")
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cacheKey := fmt.Sprintf("%s_%s_%s", fromCurrency, toCurrency, dateStr)
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// Check cache first
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cacheMutex.RLock()
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if cached, exists := exchangeRateCache[cacheKey]; exists {
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if time.Since(cached.Timestamp) < cacheValidDuration {
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// Determine cache validity based on whether it's historical or current
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validDuration := cacheValidDuration
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if isToday(date) {
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validDuration = currentRateCache
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}
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if time.Since(cached.Timestamp) < validDuration {
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cacheMutex.RUnlock()
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return cached.Rate, nil
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}
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@@ -50,7 +74,7 @@ func GetExchangeRate(fromCurrency, toCurrency string) (float64, error) {
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cacheMutex.RUnlock()
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// Fetch from API if not in cache or cache is expired
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rate, err := fetchExchangeRateFromAPI(fromCurrency, toCurrency)
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rate, err := fetchHistoricalExchangeRateFromAPI(fromCurrency, toCurrency, date)
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if err != nil {
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return 0, err
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}
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@@ -60,16 +84,27 @@ func GetExchangeRate(fromCurrency, toCurrency string) (float64, error) {
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exchangeRateCache[cacheKey] = CachedRate{
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Rate: rate,
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Timestamp: time.Now(),
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Date: dateStr,
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}
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cacheMutex.Unlock()
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return rate, nil
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}
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// fetchExchangeRateFromAPI fetches exchange rate from a free API
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func fetchExchangeRateFromAPI(fromCurrency, toCurrency string) (float64, error) {
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// Using exchangerate-api.com (completely free, no API key required)
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url := fmt.Sprintf("https://api.exchangerate-api.com/v4/latest/%s", fromCurrency)
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// fetchHistoricalExchangeRateFromAPI fetches exchange rate for a specific date
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func fetchHistoricalExchangeRateFromAPI(fromCurrency, toCurrency string, date time.Time) (float64, error) {
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var url string
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dateStr := date.Format("2006-01-02")
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today := time.Now().Format("2006-01-02")
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// Use different endpoints for historical vs current rates
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if dateStr == today {
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// Current rates
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url = fmt.Sprintf("https://api.exchangerate-api.com/v4/latest/%s", fromCurrency)
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} else {
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// Historical rates - try exchangerate-api.com historical endpoint
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url = fmt.Sprintf("https://api.exchangerate-api.com/v4/historical/%s/%s", fromCurrency, dateStr)
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}
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req, err := http.NewRequest("GET", url, nil)
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if err != nil {
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@@ -78,7 +113,7 @@ func fetchExchangeRateFromAPI(fromCurrency, toCurrency string) (float64, error)
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req.Header.Set("User-Agent", "Portfolio-Tracker/1.0")
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client := &http.Client{Timeout: 10 * time.Second}
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client := &http.Client{Timeout: 15 * time.Second}
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resp, err := client.Do(req)
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if err != nil {
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return 0, fmt.Errorf("error fetching exchange rate: %v", err)
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@@ -86,6 +121,10 @@ func fetchExchangeRateFromAPI(fromCurrency, toCurrency string) (float64, error)
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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// If historical API fails, try fallback strategy
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if dateStr != today {
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return fetchHistoricalRateFallback(fromCurrency, toCurrency, date)
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}
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return 0, fmt.Errorf("API returned status %d", resp.StatusCode)
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}
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@@ -94,7 +133,7 @@ func fetchExchangeRateFromAPI(fromCurrency, toCurrency string) (float64, error)
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return 0, fmt.Errorf("error reading response: %v", err)
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}
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// Parse exchangerate-api.com response format
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// Try parsing as standard response first
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var apiResp struct {
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Base string `json:"base"`
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Date string `json:"date"`
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@@ -113,13 +152,111 @@ func fetchExchangeRateFromAPI(fromCurrency, toCurrency string) (float64, error)
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return rate, nil
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}
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// ConvertCurrency converts an amount from one currency to another
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// fetchHistoricalRateFallback tries alternative methods for historical rates
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func fetchHistoricalRateFallback(fromCurrency, toCurrency string, date time.Time) (float64, error) {
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// Try frankfurter.app as fallback for historical rates (free and reliable)
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dateStr := date.Format("2006-01-02")
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url := fmt.Sprintf("https://api.frankfurter.app/%s?from=%s&to=%s", dateStr, fromCurrency, toCurrency)
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req, err := http.NewRequest("GET", url, nil)
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if err != nil {
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return 0, fmt.Errorf("error creating fallback request: %v", err)
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}
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req.Header.Set("User-Agent", "Portfolio-Tracker/1.0")
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client := &http.Client{Timeout: 15 * time.Second}
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resp, err := client.Do(req)
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if err != nil {
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// If historical rate fails, use current rate as last resort
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return getCurrentRateAsFallback(fromCurrency, toCurrency)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return getCurrentRateAsFallback(fromCurrency, toCurrency)
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}
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body, err := io.ReadAll(resp.Body)
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if err != nil {
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return getCurrentRateAsFallback(fromCurrency, toCurrency)
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}
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var fallbackResp struct {
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Amount float64 `json:"amount"`
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Base string `json:"base"`
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Date string `json:"date"`
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Rates map[string]float64 `json:"rates"`
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}
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if err := json.Unmarshal(body, &fallbackResp); err != nil {
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return getCurrentRateAsFallback(fromCurrency, toCurrency)
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}
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if rate, exists := fallbackResp.Rates[toCurrency]; exists {
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return rate, nil
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}
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return getCurrentRateAsFallback(fromCurrency, toCurrency)
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}
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// getCurrentRateAsFallback gets current rate when historical rate is unavailable
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func getCurrentRateAsFallback(fromCurrency, toCurrency string) (float64, error) {
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url := fmt.Sprintf("https://api.exchangerate-api.com/v4/latest/%s", fromCurrency)
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req, err := http.NewRequest("GET", url, nil)
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if err != nil {
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return 0, fmt.Errorf("error creating fallback request: %v", err)
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}
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req.Header.Set("User-Agent", "Portfolio-Tracker/1.0")
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client := &http.Client{Timeout: 10 * time.Second}
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resp, err := client.Do(req)
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if err != nil {
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return 0, fmt.Errorf("error fetching fallback rate: %v", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return 0, fmt.Errorf("fallback API returned status %d", resp.StatusCode)
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}
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body, err := io.ReadAll(resp.Body)
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if err != nil {
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return 0, fmt.Errorf("error reading fallback response: %v", err)
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}
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var apiResp struct {
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Base string `json:"base"`
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Date string `json:"date"`
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Rates map[string]float64 `json:"rates"`
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}
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if err := json.Unmarshal(body, &apiResp); err != nil {
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return 0, fmt.Errorf("error parsing fallback JSON: %v", err)
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}
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rate, exists := apiResp.Rates[toCurrency]
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if !exists {
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return 0, fmt.Errorf("currency %s not found in fallback response", toCurrency)
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}
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return rate, nil
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}
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// ConvertCurrency converts an amount from one currency to another using current rates
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func ConvertCurrency(amount float64, fromCurrency, toCurrency string) (float64, error) {
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return ConvertCurrencyHistorical(amount, fromCurrency, toCurrency, time.Now())
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}
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// ConvertCurrencyHistorical converts an amount using historical exchange rate for a specific date
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func ConvertCurrencyHistorical(amount float64, fromCurrency, toCurrency string, date time.Time) (float64, error) {
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if fromCurrency == toCurrency {
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return amount, nil
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}
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rate, err := GetExchangeRate(fromCurrency, toCurrency)
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rate, err := GetHistoricalExchangeRate(fromCurrency, toCurrency, date)
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if err != nil {
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return 0, err
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}
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@@ -178,11 +315,16 @@ func FormatCurrencyWithSymbol(amount float64, currency string) string {
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// ConvertAndFormat converts currency and formats it nicely
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func ConvertAndFormat(amount float64, fromCurrency, toCurrency string) string {
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return ConvertAndFormatHistorical(amount, fromCurrency, toCurrency, time.Now())
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}
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// ConvertAndFormatHistorical converts currency using historical rate and formats it
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func ConvertAndFormatHistorical(amount float64, fromCurrency, toCurrency string, date time.Time) string {
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if fromCurrency == toCurrency {
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return FormatCurrencyWithSymbol(amount, toCurrency)
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}
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convertedAmount, err := ConvertCurrency(amount, fromCurrency, toCurrency)
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convertedAmount, err := ConvertCurrencyHistorical(amount, fromCurrency, toCurrency, date)
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if err != nil {
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// If conversion fails, return original amount with note
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return fmt.Sprintf("%.2f %s (conv. error)", amount, fromCurrency)
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@@ -191,13 +333,18 @@ func ConvertAndFormat(amount float64, fromCurrency, toCurrency string) string {
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return FormatCurrencyWithSymbol(convertedAmount, toCurrency)
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}
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// BatchConvertCurrency converts multiple amounts in one API call for efficiency
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// BatchConvertCurrency converts multiple amounts in one API call for efficiency using current rates
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func BatchConvertCurrency(amounts []float64, fromCurrency, toCurrency string) ([]float64, error) {
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return BatchConvertCurrencyHistorical(amounts, fromCurrency, toCurrency, time.Now())
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}
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// BatchConvertCurrencyHistorical converts multiple amounts using historical rate for a specific date
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func BatchConvertCurrencyHistorical(amounts []float64, fromCurrency, toCurrency string, date time.Time) ([]float64, error) {
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if fromCurrency == toCurrency {
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return amounts, nil
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}
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rate, err := GetExchangeRate(fromCurrency, toCurrency)
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rate, err := GetHistoricalExchangeRate(fromCurrency, toCurrency, date)
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if err != nil {
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return nil, err
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}
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@@ -228,3 +375,70 @@ func GetCacheInfo() map[string]time.Time {
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}
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return info
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}
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// GetDetailedCacheInfo returns detailed information about cached exchange rates
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func GetDetailedCacheInfo() map[string]CachedRate {
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cacheMutex.RLock()
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defer cacheMutex.RUnlock()
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info := make(map[string]CachedRate)
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for key, cached := range exchangeRateCache {
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info[key] = cached
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}
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return info
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}
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// CleanExpiredCache removes expired cache entries
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func CleanExpiredCache() int {
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cacheMutex.Lock()
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defer cacheMutex.Unlock()
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removed := 0
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now := time.Now()
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for key, cached := range exchangeRateCache {
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// Determine if this is a current or historical rate
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validDuration := cacheValidDuration
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if isToday(parseDate(cached.Date)) {
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validDuration = currentRateCache
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}
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if now.Sub(cached.Timestamp) > validDuration {
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delete(exchangeRateCache, key)
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removed++
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}
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}
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return removed
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}
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// Helper functions
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// isToday checks if a date is today
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func isToday(date time.Time) bool {
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now := time.Now()
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return date.Year() == now.Year() && date.Month() == now.Month() && date.Day() == now.Day()
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}
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// parseDate parses a date string in YYYY-MM-DD format
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func parseDate(dateStr string) time.Time {
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date, err := time.Parse("2006-01-02", dateStr)
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if err != nil {
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return time.Time{}
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}
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return date
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}
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// GetExchangeRateWithFallback gets exchange rate with multiple fallback strategies
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func GetExchangeRateWithFallback(fromCurrency, toCurrency string, date time.Time) (float64, bool, error) {
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rate, err := GetHistoricalExchangeRate(fromCurrency, toCurrency, date)
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if err != nil {
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// Try with current date as fallback
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currentRate, currentErr := GetExchangeRate(fromCurrency, toCurrency)
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if currentErr != nil {
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return 0, false, fmt.Errorf("both historical (%v) and current (%v) rate fetching failed", err, currentErr)
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}
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return currentRate, false, nil // false indicates fallback was used
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}
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return rate, true, nil // true indicates historical rate was used
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}
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