#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Thu Jan 31 11:41:48 2019

@author: tanya
"""

import os
import sys
from copy import deepcopy
import numpy as np
import json

import jsonref
from pathlib import Path

sys.path.append(os.getcwd())

from cdplib.db_migration.ParseDbSchema import ParseDbSchema


class ParseJsonSchema(ParseDbSchema):
    '''
    Class for retrieving column properties from mongodb jsonSchema
    '''

    def __init__(self, schema_paths: [list, str], log_file: str = None):
        '''
        '''
        from cdplib.log import Log

        super().__init__(schema_paths=schema_paths, log_file=log_file)

        self._log = Log(name="ParseJsonSchema", log_file=log_file)

        # load schemas to dictionaries if they are valid json files

        assert(isinstance(schema_paths, (list, str))),\
            "Schema paths must be either str or lists"

        if isinstance(schema_paths, str):
            schema_paths = [schema_paths]

        self._schema_paths = schema_paths

        self.schemas = []

        for schema_path in schema_paths:
            try:
                with open(schema_path, "r") as f:
                    schema = json.load(f)

                definitions_flag = self._analyze_schema(schema)
                
                if definitions_flag:
                    schema = self._clean_desciptions_tags_from_single_quotes(schema)
                    schema = self._dereference_schema(schema)
                    # Need to do it again since sub schema could also contain
                    # single quotes
                    schema = self._clean_desciptions_tags_from_single_quotes(schema)
                    self.schemas.append(schema)
                    
                else:
                    self.schemas.append(schema)

            except Exception as e:
                err = ("Could not load json schema:{1} , "
                       "Obtained error {0}".format(e,schema_path))

                self._log.error(err)
                raise Exception(err)

    @property
    def _collection_names(self) -> list:
        '''
        '''
        # Don't use strip() instaed of replace since schema_c.strip(schema_)
        # will discard the c as well which is not a appropriate output
        return [os.path.basename(p).replace("schema_","").split(".")[0] for p in self._schema_paths]

    def get_fields(self) -> list:
        '''
        '''
        return self._parse()

    def get_fields_restricted_to_collection(self, collection_name: str) -> list:
        '''
        '''
        schemas = [self.schemas[self._collection_names.index(collection_name)]]
        return self._parse(schemas=schemas)

    def get_required_fields(self) -> list:
        '''
        '''
        return self._parse(required_only=True)

    def get_mongo_types(self) -> dict:
        '''
        '''
        return self._parse(field_info="bsonType")

    def get_datetime_fields(self):
        '''
        '''
        mongo_types = self.get_mongo_types()

        return [k for k, v in mongo_types.items()
                if v in ["date", "timestamp", "Date", "Timestamp"]]

    def get_python_types(self) -> dict:
        '''
        '''
        mongo_types = self.get_mongo_types()
        python_types = {}
        bson_to_python_types = {"double": float,
                                "decimal": float,
                                "string": str,
                                "object": object,
                                "array": list,
                                "bool": bool,
                                "int": int,
                                "long": int,
                                "date": np.dtype('<M8[ns]'),
                                "timestamp": np.dtype('<M8[ns]')
                                }

        for k, v in mongo_types.items():

            if isinstance(v, list):
                if ("date" in v) or ("timestamp" in v):
                    v = "date"
                elif "string" in v:
                    v = "string"
                elif ("double" in v) or ("decimal" in v):
                    v = "double"
                elif ("null" in v) and (len(v) == 2) and ("int" not in v):
                    v = [t for t in v if type != "null"][0]
                else:
                    err = "Type {0}: {1} not convertibale".format(k, v)
                    self._log.error(err)
                    raise Exception(err)

            if v in bson_to_python_types:
                python_types[k] = bson_to_python_types[v]

        return python_types

    def get_patterns(self) -> dict:
        '''
        '''
        return self._parse(field_info="pattern")

    def get_default_values(self) -> dict:
        '''
        '''
        return self._parse(field_info="default")

    def get_allowed_values(self) -> dict:
        '''
        '''
        return self._parse(field_info="enum")

    def get_maximum_value(self) -> dict:
        '''
        '''
        return self._parse(field_info="maximum")

    def get_minimum_value(self) -> dict:
        '''
        '''
        return self._parse(field_info="minimum")

    def get_max_items(self) -> dict:
        '''
        '''
        return self._parse(field_info="maxItems")

    def get_min_items(self) -> dict:
        '''
        '''
        return self._parse(field_info="minItems")

    def get_field_descriptions(self) -> dict:
        '''
        '''
        return self._parse(field_info="description")

    def _parse(self,
               field_info: str = None,
               required_only: bool = False,
               schemas: list = None):
        '''
        '''
        if schemas is None:
            schemas = self.schemas

        result = self._parse_one(schema=schemas[0],
                                 field_info=field_info,
                                 required_only=required_only)
        
        for schema in schemas[1:]:
            
            next_result = self._parse_one(schema=schema,
                                          field_info=field_info,
                                          required_only=required_only)

            if isinstance(result, list):
                result.extend(next_result)
            else:
                result.update(next_result)

        return result

    def _parse_one(self,
                   schema: dict,
                   field_info: str = None,
                   required_only: bool = False,
                   super_field_name: str = None,
                   already_parsed: (list, dict) = None) -> (list, dict):
        '''
        Recursive function that returns a list of (nested) field names or
        a dictionary of (nested) field names with field characteristics.

        :param schema: if None => entire self.schema, or a sub-schema
            of self.schema

        :param field_info: optional, if provided a dictionary of field
            names with field characteristics is returned (for examples
            bsonType of each field), else a list of fields is returned

        :param required_only: when True, only returns fields marked as
            required in the mongo schema

        :param super_field_name: needed for recursion
            Example: the field 'article' has
            subfields 'id' and 'supplier'.
            If we parse the sub-document corresponding to article, then
            super_field_name is'article' and we might get an output like
            {'article.id': string, 'article.supplier': string}

        :param alread_parsed: needed for recursion

        '''
        schema = deepcopy(schema)

        assert(isinstance(schema, dict)),\
            "Parameter 'schema' must be a dict"

        if field_info is None:
            # parse a list of fields
            if already_parsed is None:
                already_parsed = []
            else:
                assert(isinstance(already_parsed, list)),\
                    "Parameter 'already_parsed' must be of type list"
        else:
            # parse a dictionary of field names with field characteristics
            if already_parsed is None:
                already_parsed = {}
            else:
                assert(isinstance(already_parsed, dict)),\
                    "Parameter 'already_parsed' must be of type dict"

        # If schema is nested, then
        # either it is of bsonType object
        # and the field information is stored under the key 'properties'
        # or it is of bsonType array
        # and the field information is stored in sub-schemas
        # under the key 'items'

        # if schema is of bsonType object
        if "properties" in schema.keys():
            if "required" in schema.keys():
                required_subfields = schema["required"]
            else:
                required_subfields = []

            for sub_field_name in schema["properties"].keys():

                sub_schema = schema["properties"][sub_field_name]

                # only process fields that are required
                if required_only and\
                        (sub_field_name not in required_subfields):
                    pass
                else:
                    if super_field_name is not None:
                        field_name = '.'.join([super_field_name,
                                               sub_field_name])
                    else:
                        field_name = sub_field_name

                    # if the given sub-field is nested, parse the
                    # sub-schema corresponding to this sub-field
                    self._parse_one(
                            schema=sub_schema,
                            super_field_name=field_name,
                            field_info=field_info,
                            already_parsed=already_parsed,
                            required_only=required_only)

        # if schema is of bsonType array
        elif "items" in schema.keys():
            # one schema for all items
            if isinstance(schema["items"], dict):

                sub_schema = schema["items"]

                self._parse_one(schema=sub_schema,
                                super_field_name=super_field_name,
                                field_info=field_info,
                                already_parsed=already_parsed,
                                required_only=required_only)

            # list of separate schemas for each item
            elif isinstance(schema["items"], list):

                for sub_schema in schema["items"]:
                    self._parse_one(schema=sub_schema,
                                    super_field_name=super_field_name,
                                    field_info=field_info,
                                    already_parsed=already_parsed,
                                    required_only=required_only)
            else:
                raise Exception(('Schema is not composed correctly: '
                                 'items must be a dictionary or a list'))
        else:
            # If neither properties nor items is in schema keys
            # we reached the last level of nestedness,
            # field information is stored in the schema keys.
            field_name = super_field_name

            if field_info is None:
                already_parsed.append(field_name)
            else:
                if field_info in schema.keys():
                    already_parsed[field_name] = schema[field_info]
                else:
                    pass

        return already_parsed

    def load_and_parse_schema_for_mongodb(self, schema_path: str) -> dict:
        '''
        We need to deference json before import to Mongo DB pymongo can't deal with references
        :param str schema_path: path to the schema file.
        '''

        assert(isinstance(schema_path, str)),\
            "Parameter 'schema_path must be a string type"

        with open(schema_path) as json_file:
            schema = json.load(json_file)

        definitions_flag = self._analyze_schema(schema)
        
        if definitions_flag:
            schema = self._clean_desciptions_tags_from_single_quotes(schema)
            schema = self._dereference_schema(schema)
             # Need to do it again since sub schema could also contain
             # single quotes
            schema = self._clean_desciptions_tags_from_single_quotes(schema)
            schema = self._format_schema_for_mongo(schema)
        else:
            schema = self._format_schema_for_mongo(schema)

        return schema

    def _analyze_schema (self, schema: dict, definitions_flag: bool = False) -> dict:

        for key in list(schema):

            if key == '$ref':
                definitions_flag = True
                return definitions_flag

            if type(schema[key]) == dict:
                definitions_flag = self._analyze_schema(schema[key], definitions_flag)

        return definitions_flag
    
    
    def _clean_desciptions_tags_from_single_quotes(self, schema: dict) -> dict:
        '''
        :param dict schema: dictonary containing schema
        '''

        for key in list(schema):

            if key == 'description':
                cleaned_description = self._remove_single_quotes_from_description_tag(schema[key])
                schema[key] = cleaned_description

            if type(schema[key]) == dict:
                self._clean_desciptions_tags_from_single_quotes(schema[key])
                
        return schema

    def _format_schema_for_mongo(self, schema: dict) -> dict:
        '''
        We use in the schema tags whih are not supported by mongo an threfore
        must be taken care of before setting the schema for mongo.
        :param str schema_path: path to the schema file.
        '''

        for key in list(schema):

            if type(schema[key]) == dict:
                self._format_schema_for_mongo(schema[key])

            if key == 'default' or key == 'default_values':
                self._remove_defaults(schema)
                
            if key == 'examples':
                self._remove_examples(schema)

        return schema

    def _dereference_schema(self, schema: dict) -> dict:
        '''
        :param dict schema: dictionary containing a schema which uses references.
        '''

        assert(isinstance(schema, dict)),\
            "Parameter 'schema' must be a dictionary type"

        base_dir_url = Path(os.path.join(os.getcwd(), "mongo_schema")).as_uri() + '/'
        # json.load(f) convert double quotes into singel quotes. jsonref expects
        # the json in string format with double quotes.
        schema = str(schema).replace("'", "\"")
        schema = jsonref.loads(schema, base_uri=base_dir_url)
        schema = deepcopy(schema)

        return schema

    def _remove_defaults(self, schema: dict) -> dict:
        '''
        :param dict schema: dictionary containing a schema which uses 'default' tags.
        '''
        assert(isinstance(schema, dict)),\
        "Parameter 'schema' must be a dictionary type"

        if 'default' in schema:
            del schema['default']
        if 'default_values' in schema:
            del schema['default_values']


    def _remove_examples(self, schema: dict) -> dict:
        '''
        :param dict schema: dictionary containing a schema with 'examples' tags.
        '''

        assert(isinstance(schema, dict)),\
        "Parameter 'schema' must be a dictionary type"

        if 'examples' in schema:
            del schema['examples']

        assert(isinstance(schema, dict)),\
        "Parameter 'schema' must be a dictionary type"

    def _remove_single_quotes_from_description_tag(self, description: str) -> str:
        '''
        :param dict schema: dictionary containing a schema with 'examples' tags.
        '''

        assert(isinstance(description, str)),\
        "Parameter 'description' must be a string type"

        description = description.replace("'", "")

        return description


if __name__ == "__main__":

#     Only for testing

    schema_path = os.path.join(".", "mongo_schema", "schema_components.json")

    if os.path.isfile(schema_path):

        parse_obj = ParseJsonSchema(schema_paths=schema_path)

        fields = parse_obj.get_fields()

        required_fileds = parse_obj.get_required_fields()

        patterns = parse_obj.get_patterns()

        mongo_types = parse_obj.get_mongo_types()

        python_types_except_dates = parse_obj.get_python_types()

        datetime_fields = parse_obj.get_datetime_fields()

        allowed_values = parse_obj.get_allowed_values()

        descriptions = parse_obj.get_field_descriptions()