class SegmentAdapter:
    def __init__(self, mapping=None):
        self.mapping = mapping or {
            "activation_rate": "activation_rate",
            "funnel_dropoff": "funnel_dropoff",
            "time_to_value": "time_to_value",
            "CAC": "cac",
            "LTV": "ltv",
        }

    def fill(self, source_metrics: dict) -> dict:
        result = {}
        for std_key, src_key in self.mapping.items():
            if isinstance(src_key, str) and src_key in source_metrics:
                result[std_key] = source_metrics[src_key]
        return result