# -*- coding: utf-8 -*-
# Copyright 2015 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


class CounterMetric(object):

    def __init__(self, name, keys=[]):
        self.name = name
        self.keys = keys # OK not to clone as we never write it

        self.counts = {}

        # Scalar metrics are never empty
        if not len(keys):
            self.counts[()] = 0

    def inc(self, *values):
        if len(values) != len(self.keys):
            raise ValueError("Expected as many values to inc() as keys (%d)" %
                (len(self.keys))
            )

        # TODO: should assert that the tag values are all strings

        if values not in self.counts:
            self.counts[values] = 1
        else:
            self.counts[values] += 1

    def fetch(self):
        return dict(self.counts)

    def _render_key(self, values):
        # TODO: some kind of value escape
        return ",".join(["%s=%s" % kv for kv in zip(self.keys, values)])

    def render(self):
        if not len(self.keys):
            return ["%s %d" % (self.name, self.counts[()])]

        return ["%s{%s} %d" % (self.name, self._render_key(k), self.counts[k])
                for k in sorted(self.counts.keys())]