Config: Refactor version packages (#1887)

* Config: Move config versions to separate pacakges

* Config: Move version tests to blackbox texts

* Config: Protect registerVersion from overflow

* Config: Protect against version already registered

config/versions/v4/v4.go

@@ -0,0 +1,76 @@
+package v4
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/buger/jsonparser"
+)
+
+// Version is an Exchange upgrade to move currencyPairs.assetTypes to currencyPairs.pairs.*.assetEnabled
+type Version struct{}
+
+// Exchanges returns all exchanges: "*"
+func (*Version) Exchanges() []string { return []string{"*"} }
+
+// UpgradeExchange sets AssetEnabled: true for all assets listed in assetTypes, and false for any with no field
+func (*Version) UpgradeExchange(_ context.Context, e []byte) ([]byte, error) {
+	toEnable := map[string]bool{}
+
+	assetTypesFn := func(asset []byte, valueType jsonparser.ValueType, _ int, _ error) {
+		if valueType == jsonparser.String {
+			toEnable[string(asset)] = true
+		}
+	}
+	_, err := jsonparser.ArrayEach(e, assetTypesFn, "currencyPairs", "assetTypes")
+	if err != nil && !errors.Is(err, jsonparser.KeyPathNotFoundError) {
+		return e, fmt.Errorf("error upgrading assetTypes: %w", err)
+	}
+
+	assetEnabledFn := func(assetBytes, v []byte, _ jsonparser.ValueType, _ int) (err error) {
+		asset := string(assetBytes)
+		if toEnable[asset] {
+			e, err = jsonparser.Set(e, []byte(`true`), "currencyPairs", "pairs", asset, "assetEnabled")
+		} else {
+			var vT jsonparser.ValueType
+			_, vT, _, err = jsonparser.Get(v, "assetEnabled")
+			switch {
+			case vT == jsonparser.Null, errors.Is(err, jsonparser.KeyPathNotFoundError):
+				e, err = jsonparser.Set(e, []byte(`false`), "currencyPairs", "pairs", asset, "assetEnabled")
+			case err == nil && vT != jsonparser.Boolean:
+				err = fmt.Errorf("assetEnabled: %w (`%s`)", jsonparser.UnknownValueTypeError, vT)
+			}
+		}
+		if err != nil {
+			err = fmt.Errorf("%w for asset `%s`", err, asset)
+		}
+		return err
+	}
+	if err = jsonparser.ObjectEach(bytes.Clone(e), assetEnabledFn, "currencyPairs", "pairs"); err != nil {
+		return e, fmt.Errorf("error upgrading currencyPairs.pairs: %w", err)
+	}
+	e = jsonparser.Delete(e, "currencyPairs", "assetTypes")
+	return e, err
+}
+
+// DowngradeExchange moves AssetEnabled assets into AssetType field
+func (*Version) DowngradeExchange(_ context.Context, e []byte) ([]byte, error) {
+	assetTypes := []string{}
+
+	assetEnabledFn := func(asset, v []byte, _ jsonparser.ValueType, _ int) error {
+		if b, err := jsonparser.GetBoolean(v, "assetEnabled"); err == nil {
+			if b {
+				assetTypes = append(assetTypes, fmt.Sprintf("%q", asset))
+			}
+			e = jsonparser.Delete(e, "currencyPairs", "pairs", string(asset), "assetEnabled")
+		}
+		return nil
+	}
+	if err := jsonparser.ObjectEach(bytes.Clone(e), assetEnabledFn, "currencyPairs", "pairs"); err != nil {
+		return e, err
+	}
+	return jsonparser.Set(e, []byte(`[`+strings.Join(assetTypes, ",")+`]`), "currencyPairs", "assetTypes")
+}