config.py

from builtins import object
import logging
import os
import yaml
from yamlreader import yaml_load


def read_config(config_path, defaults):
    """Read config file from given location, and parse properties"""
    if not os.path.isdir(config_path):
        raise ValueError("{0} is not a directory".format(config_path))

    try:
        return yaml_load(config_path, defaults)
    except yaml.YAMLError:
        logging.exception("Failed to read YAML config from directory: {0}".format(config_path))


def strip_config(config, allowed_keys):
    return {k: v for k, v in config.items() if k in allowed_keys and v}


class Config(object):
    config = None

    def __init__(self, config_path, requirements, defaults):
        self.config = read_config(config_path, defaults)
        self.requirements = requirements
        self.valid = self.validator[type(self.config)](self, 'Base', self.config, self.requirements)

    def parse_config(self, config, requirements):
        return

    def validate_and_strip_dict(self, key, config_dict, config_requirements):
        specs = config_requirements['specs']
        required_entries = specs.get('required_entries', {})
        optional_entries = specs.get('optional_entries', {})
        config_dict = strip_config(config_dict, list(required_entries.keys()) + list(optional_entries.keys()))

        logging.debug("Validating dict {0} with specs: {1}".format(config_dict, specs))
        valid = True
        for required_key, required_type in required_entries.items():
            if required_key in config_dict:
                if not isinstance(config_dict[required_key], required_type):
                    logging.error("Config validation failed: Value of \'{0}\' must be {1}, was {2}".format(required_key, required_type,
                                                                                                           type(config_dict[
                                                                                                                    required_key])))
                    valid = False
            else:
                logging.error("Config validation failed: Missing required field \'{0}\' in \'{1}\'".format(required_key, key))
                valid = False

        for optional_key, optional_type in optional_entries.items():
            if optional_key in config_dict and not isinstance(config_dict[optional_key], optional_type):
                logging.error(
                    "Config validation failed: Value of optional entry \'{0}\' must be {1}, was {2}".format(optional_key, optional_type,
                                                                                                            type(config_dict[
                                                                                                                     optional_key])))
                valid = False

        if 'children' in config_requirements:
            for child_key, child_value in config_requirements['children'].items():
                if valid and child_key in config_dict:
                    valid = self.validator[type(config_dict[child_key])](self, child_key, config_dict[child_key], child_value)
        return valid

    def validate_list(self, key, value_list, specs):
        logging.debug("Validating list {0} with specs: {1}".format(value_list, specs))
        valid = True
        if 'minimum' in specs and len(value_list) < specs['minimum']:
            logging.error("Config validation failed: \'{0}\' needs to have at least {1} entries".format(key, specs['minimum']))
            valid = False

        for value in value_list:
            if valid:
                valid = self.validator[type(value)](self, key, value, specs)

        return valid

    validator = {dict: validate_and_strip_dict,
                 list: validate_list}

    def isvalid(self):
        return self.valid

    def get_config(self, key=None):
        if not key:
            return self.config
        elif key and key in self.config:
            return self.config[key]
        else:
            raise ValueError("Key {} not in config".format(key))