"""
MIT License

Copyright (c) 2020 Airbyte

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""


import json
import os
import pkgutil
from typing import Dict

import pkg_resources
from jsonschema import RefResolver


class JsonSchemaResolver:
    """Helper class to expand $ref items in json schema"""

    def __init__(self, shared_schemas_path: str):
        self._shared_refs = self._load_shared_schema_refs(shared_schemas_path)

    @staticmethod
    def _load_shared_schema_refs(shared_schemas_path: str):
        shared_file_names = [f for f in os.scandir(shared_schemas_path) if f.isfile()]

        shared_schema_refs = {}
        for shared_file in shared_file_names:
            with open(os.path.join(shared_schemas_path, shared_file)) as data_file:
                shared_schema_refs[shared_file] = json.load(data_file)

        return shared_schema_refs

    def _resolve_schema_references(self, schema: dict, resolver: RefResolver) -> dict:
        if "$ref" in schema:
            reference_path = schema.pop("$ref", None)
            resolved = resolver.resolve(reference_path)[1]
            schema.update(resolved)
            return self._resolve_schema_references(schema, resolver)

        if "properties" in schema:
            for k, val in schema["properties"].items():
                schema["properties"][k] = self._resolve_schema_references(val, resolver)

        if "patternProperties" in schema:
            for k, val in schema["patternProperties"].items():
                schema["patternProperties"][k] = self._resolve_schema_references(val, resolver)

        if "items" in schema:
            schema["items"] = self._resolve_schema_references(schema["items"], resolver)

        if "anyOf" in schema:
            for i, element in enumerate(schema["anyOf"]):
                schema["anyOf"][i] = self._resolve_schema_references(element, resolver)

        return schema

    def resolve(self, schema: dict, refs: Dict[str, dict] = None) -> dict:
        """Resolves and replaces json-schema $refs with the appropriate dict.
        Recursively walks the given schema dict, converting every instance
        of $ref in a 'properties' structure with a resolved dict.
        This modifies the input schema and also returns it.
        Arguments:
            schema:
                the schema dict
            refs:
                a dict of <string, dict> which forms a store of referenced schemata
        Returns:
            schema
        """
        refs = refs or {}
        refs = {**self._shared_refs, **refs}
        return self._resolve_schema_references(schema, RefResolver("", schema, store=refs))


class ResourceSchemaLoader:
    """JSONSchema loader from package resources"""

    def __init__(self, package_name: str):
        self.package_name = package_name

    def get_schema(self, name: str) -> dict:
        """
        This method retrieves a JSON schema from the schemas/ folder.


        The expected file structure is to have all top-level schemas (corresponding to streams) in the "schemas/" folder, with any shared $refs
        living inside the "schemas/shared/" folder. For example:

        schemas/shared/<shared_definition>.json
        schemas/<name>.json # contains a $ref to shared_definition
        schemas/<name2>.json # contains a $ref to shared_definition
        """

        schema_filename = f"schemas/{name}.json"
        raw_file = pkgutil.get_data(self.package_name, schema_filename)
        if not raw_file:
            raise IOError(f"Cannot find file {schema_filename}")
        try:
            raw_schema = json.loads(raw_file)
        except ValueError:
            # TODO use proper logging
            print(f"Invalid JSON file format for file {schema_filename}")
            raise

        shared_schemas_folder = pkg_resources.resource_filename(self.package_name, "schemas/shared/")
        if os.path.exists(shared_schemas_folder):
            return JsonSchemaResolver(shared_schemas_folder).resolve(raw_schema)
        return raw_schema