feat: condition evaluator for rule filtering

internal/condition/evaluator.go

@@ -0,0 +1,98 @@
+package condition
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"aiaa-notification-service/internal/model"
+)
+
+// Evaluate checks all conditions against data. Returns true if ALL conditions pass.
+// An empty conditions slice always returns true.
+func Evaluate(conditions []model.Condition, data map[string]interface{}) bool {
+	if len(conditions) == 0 {
+		return true
+	}
+	for _, c := range conditions {
+		if !evaluateOne(c, data) {
+			return false
+		}
+	}
+	return true
+}
+
+func evaluateOne(c model.Condition, data map[string]interface{}) bool {
+	fieldVal, fieldExists := data[c.Field]
+
+	switch c.Op {
+	case "exists":
+		return fieldExists
+	case "not_exists":
+		return !fieldExists
+	case "eq":
+		if !fieldExists {
+			return false
+		}
+		return fmt.Sprintf("%v", fieldVal) == c.Value
+	case "ne":
+		if !fieldExists {
+			return false
+		}
+		return fmt.Sprintf("%v", fieldVal) != c.Value
+	case "contains":
+		if !fieldExists {
+			return false
+		}
+		return strings.Contains(fmt.Sprintf("%v", fieldVal), c.Value)
+	case "gt", "gte", "lt", "lte":
+		if !fieldExists {
+			return false
+		}
+		return compareNumeric(fieldVal, c.Value, c.Op)
+	default:
+		return false
+	}
+}
+
+func compareNumeric(fieldVal interface{}, value string, op string) bool {
+	fv, err := toFloat64(fieldVal)
+	if err != nil {
+		return false
+	}
+	cv, err := strconv.ParseFloat(value, 64)
+	if err != nil {
+		return false
+	}
+	switch op {
+	case "gt":
+		return fv > cv
+	case "gte":
+		return fv >= cv
+	case "lt":
+		return fv < cv
+	case "lte":
+		return fv <= cv
+	}
+	return false
+}
+
+func toFloat64(v interface{}) (float64, error) {
+	switch val := v.(type) {
+	case float64:
+		return val, nil
+	case float32:
+		return float64(val), nil
+	case int:
+		return float64(val), nil
+	case int64:
+		return float64(val), nil
+	case string:
+		return strconv.ParseFloat(val, 64)
+	case json.Number:
+		return val.Float64()
+	default:
+		return 0, fmt.Errorf("cannot convert %T to float64", v)
+	}
+}