"""JSON Draft3 Schema Validators.

A collection of json_schema.Draft3Validator classes loaded with the different
endpoint validation schemas for our API
"""

import re

from jsonschema import Draft3Validator

from artist import config


def raml_header_to_json_schema(raml_headers):
    """Convert headers to JSON Draft 3 schema.

    Takes RAML specs for headers for an endpoint and converts to
    JSON Draft 3 schema to use with our validator
    NOTE: we have to filter out props with None as the value :(

    Args:
        raml_headers (collections.OrderedDict): the headers part of a RAML
            endpoint descriptor.

    Returns:
        dict: the dict representing JSON validation schema snippet.
    """
    properties = {}
    for item in raml_headers:
        raw_props = raml_headers[item]
        props = {}
        for prop in raw_props.__dict__:
            if raw_props.__dict__[prop] is not None:
                props[prop] = raw_props.__dict__[prop]
        properties[item] = props

    schema = {
        '$schema': 'http://json-schema.org/draft-03/schema',
        'type': 'object',
        'required': True,
        'properties': properties
    }
    return schema


def get_method_spec(resource_string, method):
    """Extract the section of the RAML spec for the given resource and method.

    Args:
        resource_string (str): resource name in the RAML spec.
        method (str): method name in the RAML spec.

    Returns:
        pyraml.entities.RamlMethod: spec for the given resource and method.
    """
    method_spec = config.API_DEFINITION
    resource_regex = r'(/{?\w+}?)'
    resources = re.findall(resource_regex, resource_string)

    for resource in resources:
        method_spec = method_spec.resources[resource]

    return method_spec.methods[method]


def query_args_validator(resource, method):
    """Construct a JSON args validator.

    JSON validator is based on the query parameters defined in the RAML
    spec for a particular resource and method.

    Args:
        resource (str): resource name in the RAML spec.
        method (str): method name in the RAML spec.

    Returns:
        Draft3Validator: schema validator object for query args
    """
    method_spec = get_method_spec(resource, method)
    return Draft3Validator(
        raml_header_to_json_schema(method_spec.queryParameters))


def headers_validator(resource, method):
    """Construct a JSON header validator.

    JSON validator is based on the query parameters defined in
    the RAML spec for a particular resource and method.

    Args:
        resource (str): resource name in the RAML spec.
        method (str): method name in the RAML spec.

    Returns:
        Draft3Validator: schema validator object for headers
    """
    method_spec = get_method_spec(resource, method)
    return Draft3Validator(
        raml_header_to_json_schema(method_spec.headers))


def body_validator(resource, method):
    """Construct a JSON body validator.

    JSON Validator is based on the the request body schema defined
    in the RAML spec for a particular resource and method (method will
    generally be POST or PUT).

    Args:
        resource (str): resource name in the RAML spec.
        method (str): method name in the RAML spec.

    Returns:
        Draft3Validator: schema validator object for request body
    """
    method_spec = get_method_spec(resource, method)
    return Draft3Validator(method_spec.body['application/json'].schema)