feat(rate): support multi-currency forced rate list

src/config/config.go

@@ -8,7 +8,6 @@ import (
 	"net/url"
 	"os"
 	"path/filepath"
-	"strconv"
 	"strings"
 	"time"
 
@@ -17,12 +16,6 @@ import (
 	"github.com/tidwall/gjson"
 )
 
-// parseFloat is the minimal helper used by the settings bridge; kept
-// here so settings_bridge.go stays import-free.
-func parseFloat(s string) (float64, error) {
-	return strconv.ParseFloat(strings.TrimSpace(s), 64)
-}
-
 var (
 	HTTPAccessLog      bool
 	SQLDebug           bool
@@ -353,21 +346,25 @@ func GetRateForCoin(coin string, base string) float64 {
 	if coin == base {
 		return 1
 	}
-	if coin == "usdt" {
-		switch base {
-		case "usd":
-			return 1
-		case "cny":
-			usdtRate := GetUsdtRate()
-			if usdtRate > 0 {
-				return 1 / usdtRate
-			}
-			return 0
-		}
+	if forcedRate := getForcedRateForCoin(coin, base); forcedRate > 0 {
+		return forcedRate
+	}
+	if coin == "usdt" && base == "usd" {
+		return 1
 	}
 	return getRateForCoinFromAPI(coin, base)
 }
 
+func getForcedRateForCoin(coin string, base string) float64 {
+	raw := strings.TrimSpace(settingsForcedRateList())
+	if raw != "" {
+		if rate := gjson.Get(raw, base+"."+coin).Float(); rate > 0 {
+			return rate
+		}
+	}
+	return 0
+}
+
 func getRateForCoinFromAPI(coin string, base string) float64 {
 	baseURL := GetRateApiUrl()
 	if baseURL == "" {
@@ -401,17 +398,17 @@ func getRateForCoinFromAPI(coin string, base string) float64 {
 }
 
 func GetUsdtRate() float64 {
-	// Only the admin setting can force the USDT/CNY rate. When the
-	// setting is unset, zero, or negative, fall back to the rate API.
-	if forced := settingsForcedUsdtRate(); forced > 0 {
-		return forced
+	// rate.forced_rate_list stores token amount per one base currency unit.
+	// GetUsdtRate returns the inverse display value: CNY per USDT.
+	if forcedRate := getForcedRateForCoin("usdt", "cny"); forcedRate > 0 {
+		return 1 / forcedRate
 	}
 
 	apiRate := getRateForCoinFromAPI("usdt", "cny")
 	if apiRate > 0 {
 		return 1 / apiRate
 	}
-	log.Printf("usdt/cny rate unavailable: rate.forced_usdt_rate <= 0 and rate api returned no data")
+	log.Printf("usdt/cny rate unavailable: rate.forced_rate_list has no positive cny.usdt entry and rate api returned no data")
 	return 0
 }
 

src/config/config_test.go

@@ -231,7 +231,7 @@ func TestCopyMissingStaticFilesCopiesAssetsWithoutOverwriting(t *testing.T) {
 	}
 }
 
-func TestGetUsdtRatePrefersPositiveAdminOverride(t *testing.T) {
+func TestGetUsdtRatePrefersForcedRateList(t *testing.T) {
 	viper.Reset()
 	t.Cleanup(viper.Reset)
 	t.Setenv("API_RATE_URL", "")
@@ -249,16 +249,19 @@ func TestGetUsdtRatePrefersPositiveAdminOverride(t *testing.T) {
 	})
 
 	installSettingsGetter(t, map[string]string{
-		"rate.forced_usdt_rate": "7.25",
+		"rate.forced_rate_list": `{"cny":{"usdt":0.13793103448275862},"usd":{"trx":123.45}}`,
 		"rate.api_url":          "https://rate.example.test",
 	})
 
 	got := GetUsdtRate()
-	if got != 7.25 {
+	if math.Abs(got-7.25) > 1e-9 {
 		t.Fatalf("GetUsdtRate() = %v, want 7.25", got)
 	}
+	if rate := GetRateForCoin("trx", "usd"); rate != 123.45 {
+		t.Fatalf("GetRateForCoin(trx, usd) = %v, want 123.45", rate)
+	}
 	if apiCalled {
-		t.Fatalf("rate API should not be called when rate.forced_usdt_rate > 0")
+		t.Fatalf("rate API should not be called when rate.forced_rate_list has positive rate")
 	}
 }
 
@@ -281,7 +284,7 @@ func TestGetUsdtRateUsesAPIWhenAdminOverrideIsNotPositive(t *testing.T) {
 	})
 
 	installSettingsGetter(t, map[string]string{
-		"rate.forced_usdt_rate": "-1",
+		"rate.forced_rate_list": `{"cny":{"usdt":0}}`,
 		"rate.api_url":          "https://rate.example.test",
 	})
 
@@ -297,6 +300,35 @@ func TestGetUsdtRateUsesAPIWhenAdminOverrideIsNotPositive(t *testing.T) {
 	}
 }
 
+func TestGetRateForCoinUsesAPIWhenForcedPairMissing(t *testing.T) {
+	viper.Reset()
+	t.Cleanup(viper.Reset)
+	t.Setenv("API_RATE_URL", "")
+
+	installMockHTTPClient(t, func(r *http.Request) (*http.Response, error) {
+		if r.URL.Path != "/cny.json" {
+			t.Fatalf("rate api path = %s, want /cny.json", r.URL.Path)
+		}
+		return &http.Response{
+			StatusCode: http.StatusOK,
+			Status:     "200 OK",
+			Header:     http.Header{"Content-Type": []string{"application/json"}},
+			Body:       io.NopCloser(strings.NewReader(`{"cny":{"usdt":0.14635}}`)),
+			Request:    r,
+		}, nil
+	})
+
+	installSettingsGetter(t, map[string]string{
+		"rate.forced_rate_list": `{"usd":{"trx":123.45}}`,
+		"rate.api_url":          "https://rate.example.test",
+	})
+
+	rate := GetRateForCoin("usdt", "cny")
+	if math.Abs(rate-0.14635) > 1e-9 {
+		t.Fatalf("GetRateForCoin(usdt, cny) = %v, want 0.14635", rate)
+	}
+}
+
 func TestGetUsdtRateReturnsZeroWhenAPIUnavailableWithoutAdminOverride(t *testing.T) {
 	viper.Reset()
 	t.Cleanup(viper.Reset)
@@ -313,7 +345,7 @@ func TestGetUsdtRateReturnsZeroWhenAPIUnavailableWithoutAdminOverride(t *testing
 	})
 
 	installSettingsGetter(t, map[string]string{
-		"rate.forced_usdt_rate": "0",
+		"rate.forced_rate_list": `{"cny":{"usdt":0}}`,
 		"rate.api_url":          "https://rate.example.test",
 	})
 
@@ -343,7 +375,7 @@ func TestGetRateForCoinCallsRateAPIOnceForUsdtCnyFailure(t *testing.T) {
 	})
 
 	installSettingsGetter(t, map[string]string{
-		"rate.forced_usdt_rate": "0",
+		"rate.forced_rate_list": `{"cny":{"usdt":0}}`,
 		"rate.api_url":          "https://rate.example.test",
 	})
 

src/config/settings_bridge.go

@@ -18,17 +18,9 @@ func settingsRateApiUrl() string {
 	return SettingsGetString("rate.api_url")
 }
 
-func settingsForcedUsdtRate() float64 {
+func settingsForcedRateList() string {
 	if SettingsGetString == nil {
-		return 0
+		return ""
 	}
-	raw := SettingsGetString("rate.forced_usdt_rate")
-	if raw == "" {
-		return 0
-	}
-	f, err := parseFloat(raw)
-	if err != nil {
-		return 0
-	}
-	return f
+	return SettingsGetString("rate.forced_rate_list")
 }