import sys
from prometheus_client import CollectorRegistry, generate_latest

class BaseExporter():
    def __init__(self, args=[]):
        self.args = args

    def run(self):
        self.metrics = JobMetric(self.metric_config())
        return self.generate()

    def metric_config(self):
        return {}

class JobMetric():
    def __init__(self, stores={}):
        self._registry = CollectorRegistry()
        self.stores = stores
        self.metric_cache = {}

    def get(self, metric):
        if metric in self.metric_cache:
            return self.metric_cache[metric]
        else:
            try:
                store = self.stores[metric]
                mm = getattr(
                    sys.modules['prometheus_client'],
                    store['type']
                )
                mm_obj = mm(
                    metric,
                    '',
                    store['labels'],
                    registry=self._registry
                )
                self.metric_cache[metric] = mm_obj
                return mm_obj
            except Exception:
                raise Exception("failed to create metric %s" % self.stores[metric])

    def dump(self):
        return generate_latest(self._registry).decode('utf-8')