import json

from rdflib.query import Result, ResultException, ResultSerializer, ResultParser
from rdflib import Literal, URIRef, BNode, Variable


"""A Serializer for SPARQL results in JSON:

http://www.w3.org/TR/rdf-sparql-json-res/

Bits and pieces borrowed from:
http://projects.bigasterisk.com/sparqlhttp/

Authors: Drew Perttula, Gunnar Aastrand Grimnes

"""


class JSONResultParser(ResultParser):
    def parse(self, source, content_type=None):
        inp = source.read()
        if isinstance(inp, bytes):
            inp = inp.decode("utf-8")
        return JSONResult(json.loads(inp))


class JSONResultSerializer(ResultSerializer):
    def __init__(self, result):
        ResultSerializer.__init__(self, result)

    def serialize(self, stream, encoding=None):

        res = {}
        if self.result.type == "ASK":
            res["head"] = {}
            res["boolean"] = self.result.askAnswer
        else:
            # select
            res["results"] = {}
            res["head"] = {}
            res["head"]["vars"] = self.result.vars
            res["results"]["bindings"] = [
                self._bindingToJSON(x) for x in self.result.bindings
            ]

        r = json.dumps(res, allow_nan=False, ensure_ascii=False)
        if encoding is not None:
            stream.write(r.encode(encoding))
        else:
            stream.write(r)

    def _bindingToJSON(self, b):
        res = {}
        for var in b:
            j = termToJSON(self, b[var])
            if j is not None:
                res[var] = termToJSON(self, b[var])
        return res


class JSONResult(Result):
    def __init__(self, json):
        self.json = json
        if "boolean" in json:
            type_ = "ASK"
        elif "results" in json:
            type_ = "SELECT"
        else:
            raise ResultException("No boolean or results in json!")

        Result.__init__(self, type_)

        if type_ == "ASK":
            self.askAnswer = bool(json["boolean"])
        else:
            self.bindings = self._get_bindings()
            self.vars = [Variable(x) for x in json["head"]["vars"]]

    def _get_bindings(self):
        ret = []
        for row in self.json["results"]["bindings"]:
            outRow = {}
            for k, v in row.items():
                outRow[Variable(k)] = parseJsonTerm(v)
            ret.append(outRow)
        return ret


def parseJsonTerm(d):
    """rdflib object (Literal, URIRef, BNode) for the given json-format dict.

    input is like:
      { 'type': 'uri', 'value': 'http://famegame.com/2006/01/username' }
      { 'type': 'literal', 'value': 'drewp' }
    """

    t = d["type"]
    if t == "uri":
        return URIRef(d["value"])
    elif t == "literal":
        return Literal(d["value"], datatype=d.get("datatype"), lang=d.get("xml:lang"))
    elif t == "typed-literal":
        return Literal(d["value"], datatype=URIRef(d["datatype"]))
    elif t == "bnode":
        return BNode(d["value"])
    else:
        raise NotImplementedError("json term type %r" % t)


def termToJSON(self, term):
    if isinstance(term, URIRef):
        return {"type": "uri", "value": str(term)}
    elif isinstance(term, Literal):
        r = {"type": "literal", "value": str(term)}

        if term.datatype is not None:
            r["datatype"] = str(term.datatype)
        if term.language is not None:
            r["xml:lang"] = term.language
        return r

    elif isinstance(term, BNode):
        return {"type": "bnode", "value": str(term)}
    elif term is None:
        return None
    else:
        raise ResultException("Unknown term type: %s (%s)" % (term, type(term)))
