Add local-first race hub API

internal/query/metadata.go

@@ -0,0 +1,66 @@
+package query
+
+const (
+	DatasetStatusAvailable = "available"
+	DatasetStatusMissing   = "missing"
+
+	DataSourceLocal  = "local"
+	DataSourceNone   = "none"
+	DataSourceOpenF1 = "openf1"
+
+	ResponseSourceLocal   = "local"
+	ResponseSourceNone    = "none"
+	ResponseSourcePartial = "partial"
+)
+
+// DatasetInfo describes availability of a single dataset.
+type DatasetInfo struct {
+	Status string `json:"status"`
+	Source string `json:"source"`
+	Count  int    `json:"count,omitempty"`
+}
+
+func availableLocal(count int) DatasetInfo {
+	return DatasetInfo{
+		Status: DatasetStatusAvailable,
+		Source: DataSourceLocal,
+		Count:  count,
+	}
+}
+
+func missingDataset() DatasetInfo {
+	return DatasetInfo{
+		Status: DatasetStatusMissing,
+		Source: DataSourceNone,
+		Count:  0,
+	}
+}
+
+func responseSource(datasets map[string]DatasetInfo) string {
+	if len(datasets) == 0 {
+		return ResponseSourceNone
+	}
+
+	hasLocal := false
+	allMissing := true
+	for _, info := range datasets {
+		if info.Status == DatasetStatusAvailable && info.Source == DataSourceLocal {
+			hasLocal = true
+			allMissing = false
+		} else if info.Status == DatasetStatusAvailable {
+			allMissing = false
+		}
+	}
+	if allMissing {
+		return ResponseSourceNone
+	}
+	if hasLocal {
+		for _, info := range datasets {
+			if info.Status == DatasetStatusMissing {
+				return ResponseSourcePartial
+			}
+		}
+		return ResponseSourceLocal
+	}
+	return ResponseSourceNone
+}