import datetime as dt
import decimal
import json
import typing

from apistar import types, exceptions
from apistar.http import JSONResponse, Response, StrMapping, StrPairs, MutableHeaders
from werkzeug.http import HTTP_STATUS_CODES


class ExtJSONResponse(JSONResponse):
    """JSON Response with support for ISO 8601 datetime serialization and Decimal to float casting"""

    def default(self, obj: typing.Any) -> typing.Any:
        if isinstance(obj, types.Type):
            return dict(obj)
        if isinstance(obj, dt.datetime):
            return obj.isoformat()
        elif isinstance(obj, decimal.Decimal):
            return float(obj)
        error = "Object of type '%s' is not JSON serializable."
        return TypeError(error % type(obj).__name_)


class MetaJSONResponse(Response):
    """A JSONResponse that returns a meta, data, error on response"""
    media_type = 'application/json'
    charset = None
    options = {
        'ensure_ascii': False,
        'allow_nan': False,
        'indent': None,
        'separators': (',', ':'),
    }

    def __init__(self,
                 content: typing.Any,
                 status_code: int = 200,
                 headers: typing.Union[StrMapping, StrPairs] = None,
                 exc_info=None,
                 meta: typing.Any = None) -> None:
        self.status_code = status_code
        self.meta = self._build_meta(meta)
        self._content = content
        self.content = self.render(content)
        self.headers = MutableHeaders(headers)
        self.set_default_headers()
        self.exc_info = exc_info

    def render(self, content: typing.Any) -> bytes:
        """Builds a JSON response containing meta data. If the content is an `apistar.execption.HTTPException`
        then it will return the execption reason code"""
        error = {}
        if isinstance(content, exceptions.HTTPException):
            error["reason"] = content.detail

        options = {'default': self.default}
        options.update(self.options)
        response = dict(meta=self.meta)

        if error:
            response.update(dict(error=error))
            return json.dumps(response, **options).encode('utf-8')

        response.update(dict(data=content))
        return json.dumps(response, **options).encode('utf-8')

    def default(self, obj: typing.Any) -> typing.Any:
        if isinstance(obj, types.Type):
            return dict(obj)
        if isinstance(obj, dt.datetime):
            return obj.isoformat()
        elif isinstance(obj, decimal.Decimal):
            return float(obj)
        error = "Object of type '%s' is not JSON serializable."
        return TypeError(error % type(obj).__name_)

    def _build_meta(self, meta):
        _meta = {
            "status": self.status_code,
            "message": HTTP_STATUS_CODES.get(self.status_code)
        }
        if meta is None:
            return _meta
        return {**_meta, **meta}