"""
Context
======

The purpose of Context is to provide a message-level context. For each message
taken from the queue, a Context should be created with the correlation_id in
that message. Context also provides a LoggerAdapter, which automatically
includes the correlation_id in logs.

Example:
    context.reset()  # always reset
    context.set('correlation_id', 'test_fp_correlation_id')
    context.logger.info("test fp log message")
"""

import json
import logging
import sys
from fpcapture import config
from fpcapture.connectors.logger import DSNHandler


logger = logging.getLogger(config.SERVICE_NAME)
logger.setLevel(config.LOGGER_LEVEL)

if config.environment in (config.TEST_ENVIRONMENT, config.DEV_ENVIRONMENT):
    # in TEST and DEV environments, log to STDOUT
    ch = logging.StreamHandler(sys.stdout)  # console handler
    payload = {
        'level': '%(levelname)s',
        'correlation_id': '%(correlation_id)s',
        'message': '%(message)s',
    }
    formatter = logging.Formatter(json.dumps(payload))
    ch.setFormatter(formatter)
    logger.addHandler(ch)
else:  # in QA and Prod environments, log to DSN
    logger.addHandler(DSNHandler(config.LOGGER_DSN))


class Context():

    def set(self, name, value):
        """Set an attribute of the context

        Args:
            name (str): name of attribute to set
            value: value to set attribute to
        """

        setattr(self, name, value)

    def reset(self):
        """Reset all attributes of the context
        """

        variables = vars(self)
        for i in variables.keys():
            variables[i] = None

    def get_correlation_id(self):
        """Get the Correlation ID. Raise an AttributeError if context
        has no correlation_id set
        """

        cid = getattr(self, 'correlation_id', None)
        if cid is not None:
            return cid
        else:
            raise AttributeError("Context has no correlation_id")

    @property
    def logger(self):
        """Get a logger with a context. The context provides additional
        information (such as the correlation_id)
        """

        extra = dict(correlation_id=self.get_correlation_id())
        return logging.LoggerAdapter(logger=logger, extra=extra)


context = Context()