import collections

from rdflib import Graph, Literal, URIRef
from rdflib.namespace import RDF, VOID


def generateVoID(  # noqa: N802
    g, dataset=None, res=None, distinctForPartitions=True  # noqa: N803
):
    """
    Returns a new graph with a VoID description of the passed dataset

    For more info on Vocabulary of Interlinked Datasets (VoID), see:
    http://vocab.deri.ie/void

    This only makes two passes through the triples (once to detect the types
    of things)

    The tradeoff is that lots of temporary structures are built up in memory
    meaning lots of memory may be consumed :)
    I imagine at least a few copies of your original graph.

    the distinctForPartitions parameter controls whether
    distinctSubjects/objects are tracked for each class/propertyPartition
    this requires more memory again

    """

    typeMap = collections.defaultdict(set)  # noqa: N806
    classes = collections.defaultdict(set)  # noqa: N806
    for e, c in g.subject_objects(RDF.type):
        classes[c].add(e)
        typeMap[e].add(c)

    triples = 0
    subjects = set()
    objects = set()
    properties = set()
    classCount = collections.defaultdict(int)  # noqa: N806
    propCount = collections.defaultdict(int)  # noqa: N806

    classProps = collections.defaultdict(set)  # noqa: N806
    classObjects = collections.defaultdict(set)  # noqa: N806
    propSubjects = collections.defaultdict(set)  # noqa: N806
    propObjects = collections.defaultdict(set)  # noqa: N806

    for s, p, o in g:

        triples += 1
        subjects.add(s)
        properties.add(p)
        objects.add(o)

        # class partitions
        if s in typeMap:
            for c in typeMap[s]:
                classCount[c] += 1
                if distinctForPartitions:
                    classObjects[c].add(o)
                    classProps[c].add(p)

        # property partitions
        propCount[p] += 1
        if distinctForPartitions:
            propObjects[p].add(o)
            propSubjects[p].add(s)

    if not dataset:
        dataset = URIRef("http://example.org/Dataset")

    if not res:
        res = Graph()

    res.add((dataset, RDF.type, VOID.Dataset))

    # basic stats
    res.add((dataset, VOID.triples, Literal(triples)))
    res.add((dataset, VOID.classes, Literal(len(classes))))

    res.add((dataset, VOID.distinctObjects, Literal(len(objects))))
    res.add((dataset, VOID.distinctSubjects, Literal(len(subjects))))
    res.add((dataset, VOID.properties, Literal(len(properties))))

    for i, c in enumerate(classes):
        part = URIRef(dataset + "_class%d" % i)
        res.add((dataset, VOID.classPartition, part))
        res.add((part, RDF.type, VOID.Dataset))

        res.add((part, VOID.triples, Literal(classCount[c])))
        res.add((part, VOID.classes, Literal(1)))

        res.add((part, VOID["class"], c))

        res.add((part, VOID.entities, Literal(len(classes[c]))))
        res.add((part, VOID.distinctSubjects, Literal(len(classes[c]))))

        if distinctForPartitions:
            res.add((part, VOID.properties, Literal(len(classProps[c]))))
            res.add((part, VOID.distinctObjects, Literal(len(classObjects[c]))))

    for i, p in enumerate(properties):
        part = URIRef(dataset + "_property%d" % i)
        res.add((dataset, VOID.propertyPartition, part))
        res.add((part, RDF.type, VOID.Dataset))

        res.add((part, VOID.triples, Literal(propCount[p])))
        res.add((part, VOID.properties, Literal(1)))

        res.add((part, VOID.property, p))

        if distinctForPartitions:

            entities = 0
            propClasses = set()  # noqa: N806
            for s in propSubjects[p]:
                if s in typeMap:
                    entities += 1
                for c in typeMap[s]:
                    propClasses.add(c)

            res.add((part, VOID.entities, Literal(entities)))
            res.add((part, VOID.classes, Literal(len(propClasses))))

            res.add((part, VOID.distinctSubjects, Literal(len(propSubjects[p]))))
            res.add((part, VOID.distinctObjects, Literal(len(propObjects[p]))))

    return res, dataset
