"""
The [`Resource`][rdflib.resource.Resource] class wraps a
[`Graph`][rdflib.graph.Graph]
and a resource reference (i.e. a [`URIRef`][rdflib.term.URIRef] or
[`BNode`][rdflib.term.BNode]) to support a resource-oriented way of
working with a graph.

It contains methods directly corresponding to those methods of the Graph
interface that relate to reading and writing data. The difference is that a
Resource also binds a resource identifier, making it possible to work without
tracking both the graph and a current subject. This makes for a "resource
oriented" style, as compared to the triple orientation of the Graph API.

Resulting generators are also wrapped so that any resource reference values
([`URIRef`][rdflib.term.URIRef] and [`BNode`][rdflib.term.BNode]) are in turn
wrapped as Resources. (Note that this behaviour differs from the corresponding
methods in [`Graph`][rdflib.graph.Graph], where no such conversion takes place.)


## Basic Usage Scenario

Start by importing things we need and define some namespaces:

```python
>>> from rdflib import *
>>> FOAF = Namespace("http://xmlns.com/foaf/0.1/")
>>> CV = Namespace("http://purl.org/captsolo/resume-rdf/0.2/cv#")

```

Load some RDF data:

```python
>>> graph = Graph().parse(format='n3', data='''
... @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
... @prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
... @prefix foaf: <http://xmlns.com/foaf/0.1/> .
... @prefix cv: <http://purl.org/captsolo/resume-rdf/0.2/cv#> .
...
... @base <http://example.org/> .
...
... </person/some1#self> a foaf:Person;
...     rdfs:comment "Just a Python & RDF hacker."@en;
...     foaf:depiction </images/person/some1.jpg>;
...     foaf:homepage <http://example.net/>;
...     foaf:name "Some Body" .
...
... </images/person/some1.jpg> a foaf:Image;
...     rdfs:label "some 1"@en;
...     rdfs:comment "Just an image"@en;
...     foaf:thumbnail </images/person/some1-thumb.jpg> .
...
... </images/person/some1-thumb.jpg> a foaf:Image .
...
... [] a cv:CV;
...     cv:aboutPerson </person/some1#self>;
...     cv:hasWorkHistory [ cv:employedIn </#company>;
...             cv:startDate "2009-09-04"^^xsd:date ] .
... ''')

```

Create a Resource:

```python
>>> person = Resource(
...     graph, URIRef("http://example.org/person/some1#self"))

```

Retrieve some basic facts:

```python
>>> person.identifier
rdflib.term.URIRef('http://example.org/person/some1#self')

>>> person.value(FOAF.name)
rdflib.term.Literal('Some Body')

>>> person.value(RDFS.comment)
rdflib.term.Literal('Just a Python & RDF hacker.', lang='en')

```

Resources can be sliced (like graphs, but the subject is fixed):

```python
>>> for name in person[FOAF.name]:
...     print(name)
Some Body
>>> person[FOAF.name : Literal("Some Body")]
True

```

Resources as unicode are represented by their identifiers as unicode:

```python
>>> %(unicode)s(person)  #doctest: +SKIP
'Resource(http://example.org/person/some1#self'

```

Resource references are also Resources, so you can easily get e.g. a qname
for the type of a resource, like:

```python
>>> person.value(RDF.type).qname()
'foaf:Person'

```

Or for the predicates of a resource:

```python
>>> sorted(
...     p.qname() for p in person.predicates()
... )  #doctest: +NORMALIZE_WHITESPACE +SKIP
['foaf:depiction', 'foaf:homepage',
 'foaf:name', 'rdf:type', 'rdfs:comment']

```

Follow relations and get more data from their Resources as well:

```python
>>> for pic in person.objects(FOAF.depiction):
...     print(pic.identifier)
...     print(pic.value(RDF.type).qname())
...     print(pic.value(FOAF.thumbnail).identifier)
http://example.org/images/person/some1.jpg
foaf:Image
http://example.org/images/person/some1-thumb.jpg

```

```python
>>> for cv in person.subjects(CV.aboutPerson):
...     work = list(cv.objects(CV.hasWorkHistory))[0]
...     print(work.value(CV.employedIn).identifier)
...     print(work.value(CV.startDate))
http://example.org/#company
2009-09-04

```

It's just as easy to work with the predicates of a resource:

```python
>>> for s, p in person.subject_predicates():
...     print(s.value(RDF.type).qname())
...     print(p.qname())
...     for s, o in p.subject_objects():
...         print(s.value(RDF.type).qname())
...         print(o.value(RDF.type).qname())
cv:CV
cv:aboutPerson
cv:CV
foaf:Person

```

This is useful for e.g. inspection:

```python
>>> thumb_ref = URIRef("http://example.org/images/person/some1-thumb.jpg")
>>> thumb = Resource(graph, thumb_ref)
>>> for p, o in thumb.predicate_objects():
...     print(p.qname())
...     print(o.qname())
rdf:type
foaf:Image

```

## Schema Example

With this artificial schema data:

```python
>>> graph = Graph().parse(format='n3', data='''
... @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
... @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
... @prefix owl: <http://www.w3.org/2002/07/owl#> .
... @prefix v: <http://example.org/def/v#> .
...
... v:Artifact a owl:Class .
...
... v:Document a owl:Class;
...     rdfs:subClassOf v:Artifact .
...
... v:Paper a owl:Class;
...     rdfs:subClassOf v:Document .
...
... v:Choice owl:oneOf (v:One v:Other) .
...
... v:Stuff a rdf:Seq; rdf:_1 v:One; rdf:_2 v:Other .
...
... ''')

```

From this class:

```python
>>> artifact = Resource(graph, URIRef("http://example.org/def/v#Artifact"))

```

we can get at subclasses:

```python
>>> subclasses = list(artifact.transitive_subjects(RDFS.subClassOf))
>>> [c.qname() for c in subclasses]
['v:Artifact', 'v:Document', 'v:Paper']

```

and superclasses from the last subclass:

```python
>>> [c.qname() for c in subclasses[-1].transitive_objects(RDFS.subClassOf)]
['v:Paper', 'v:Document', 'v:Artifact']

```

Get items from the Choice:

```python
>>> choice = Resource(graph, URIRef("http://example.org/def/v#Choice"))
>>> [it.qname() for it in choice.value(OWL.oneOf).items()]
['v:One', 'v:Other']

```

On add, other resources are auto-unboxed:

```python
>>> paper = Resource(graph, URIRef("http://example.org/def/v#Paper"))
>>> paper.add(RDFS.subClassOf, artifact)
>>> artifact in paper.objects(RDFS.subClassOf) # checks Resource instance
True
>>> (paper._identifier, RDFS.subClassOf, artifact._identifier) in graph
True

```

## Technical Details

Comparison is based on graph and identifier:

```python
>>> g1 = Graph()
>>> t1 = Resource(g1, URIRef("http://example.org/thing"))
>>> t2 = Resource(g1, URIRef("http://example.org/thing"))
>>> t3 = Resource(g1, URIRef("http://example.org/other"))
>>> t4 = Resource(Graph(), URIRef("http://example.org/other"))

>>> t1 is t2
False

>>> t1 == t2
True
>>> t1 != t2
False

>>> t1 == t3
False
>>> t1 != t3
True

>>> t3 != t4
True

>>> t3 < t1 and t1 > t3
True
>>> t1 >= t1 and t1 >= t3
True
>>> t1 <= t1 and t3 <= t1
True

>>> t1 < t1 or t1 < t3 or t3 > t1 or t3 > t3
False

```

Hash is computed from graph and identifier:

```python
>>> g1 = Graph()
>>> t1 = Resource(g1, URIRef("http://example.org/thing"))

>>> hash(t1) == hash(Resource(g1, URIRef("http://example.org/thing")))
True

>>> hash(t1) == hash(Resource(Graph(), t1.identifier))
False
>>> hash(t1) == hash(Resource(Graph(), URIRef("http://example.org/thing")))
False

```

The Resource class is suitable as a base class for mapper toolkits. For
example, consider this utility for accessing RDF properties via qname-like
attributes:

```python
>>> class Item(Resource):
...
...     def __getattr__(self, p):
...         return list(self.objects(self._to_ref(*p.split('_', 1))))
...
...     def _to_ref(self, pfx, name):
...         return URIRef(self._graph.store.namespace(pfx) + name)

```

It works as follows:

```python
>>> graph = Graph().parse(format='n3', data='''
... @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
... @prefix foaf: <http://xmlns.com/foaf/0.1/> .
...
... @base <http://example.org/> .
... </person/some1#self>
...     foaf:name "Some Body";
...     foaf:depiction </images/person/some1.jpg> .
... </images/person/some1.jpg> rdfs:comment "Just an image"@en .
... ''')

>>> person = Item(graph, URIRef("http://example.org/person/some1#self"))

>>> print(person.foaf_name[0])
Some Body

```

The mechanism for wrapping references as resources cooperates with subclasses.
Therefore, accessing referenced resources automatically creates new `Item`
objects:

```python
>>> isinstance(person.foaf_depiction[0], Item)
True

>>> print(person.foaf_depiction[0].rdfs_comment[0])
Just an image

```
"""

from rdflib.namespace import RDF
from rdflib.paths import Path
from rdflib.term import BNode, Node, URIRef

__all__ = ["Resource"]


class Resource:
    """A Resource is a wrapper for a graph and a resource identifier."""

    def __init__(self, graph, subject):
        self._graph = graph
        self._identifier = subject

    @property
    def graph(self):
        return self._graph

    @property
    def identifier(self):
        return self._identifier

    def __hash__(self):
        return hash(Resource) ^ hash(self._graph) ^ hash(self._identifier)

    def __eq__(self, other):
        return (
            isinstance(other, Resource)
            and self._graph == other._graph
            and self._identifier == other._identifier
        )

    def __ne__(self, other):
        return not self == other

    def __lt__(self, other):
        if isinstance(other, Resource):
            return self._identifier < other._identifier
        else:
            return False

    def __gt__(self, other):
        return not (self < other or self == other)

    def __le__(self, other):
        return self < other or self == other

    def __ge__(self, other):
        return not self < other

    def __unicode__(self):
        return str(self._identifier)

    def add(self, p, o):
        if isinstance(o, Resource):
            o = o._identifier

        self._graph.add((self._identifier, p, o))

    def remove(self, p, o=None):
        if isinstance(o, Resource):
            o = o._identifier

        self._graph.remove((self._identifier, p, o))

    def set(self, p, o):
        if isinstance(o, Resource):
            o = o._identifier

        self._graph.set((self._identifier, p, o))

    def subjects(self, predicate=None):  # rev
        return self._resources(self._graph.subjects(predicate, self._identifier))

    def predicates(self, o=None):
        if isinstance(o, Resource):
            o = o._identifier

        return self._resources(self._graph.predicates(self._identifier, o))

    def objects(self, predicate=None):
        return self._resources(self._graph.objects(self._identifier, predicate))

    def subject_predicates(self):
        return self._resource_pairs(self._graph.subject_predicates(self._identifier))

    def subject_objects(self):
        return self._resource_pairs(self._graph.subject_objects(self._identifier))

    def predicate_objects(self):
        return self._resource_pairs(self._graph.predicate_objects(self._identifier))

    def value(self, p=RDF.value, o=None, default=None, any=True):
        if isinstance(o, Resource):
            o = o._identifier

        return self._cast(self._graph.value(self._identifier, p, o, default, any))

    def items(self):
        return self._resources(self._graph.items(self._identifier))

    def transitive_objects(self, predicate, remember=None):
        return self._resources(
            self._graph.transitive_objects(self._identifier, predicate, remember)
        )

    def transitive_subjects(self, predicate, remember=None):
        return self._resources(
            self._graph.transitive_subjects(predicate, self._identifier, remember)
        )

    def qname(self):
        return self._graph.qname(self._identifier)

    def _resource_pairs(self, pairs):
        for s1, s2 in pairs:
            yield self._cast(s1), self._cast(s2)

    def _resource_triples(self, triples):
        for s, p, o in triples:
            yield self._cast(s), self._cast(p), self._cast(o)

    def _resources(self, nodes):
        for node in nodes:
            yield self._cast(node)

    def _cast(self, node):
        if isinstance(node, (BNode, URIRef)):
            return self._new(node)
        else:
            return node

    def __iter__(self):
        return self._resource_triples(
            self._graph.triples((self.identifier, None, None))
        )

    def __getitem__(self, item):
        if isinstance(item, slice):
            if item.step:
                raise TypeError(
                    "Resources fix the subject for slicing, and can only be sliced by predicate/object. "
                )
            p, o = item.start, item.stop
            if isinstance(p, Resource):
                p = p._identifier
            if isinstance(o, Resource):
                o = o._identifier
            if p is None and o is None:
                return self.predicate_objects()
            elif p is None:
                return self.predicates(o)
            elif o is None:
                return self.objects(p)
            else:
                return (self.identifier, p, o) in self._graph
        elif isinstance(item, (Node, Path)):
            return self.objects(item)
        else:
            raise TypeError(
                "You can only index a resource by a single rdflib term, a slice of rdflib terms, not %s (%s)"
                % (item, type(item))
            )

    def __setitem__(self, item, value):
        self.set(item, value)

    def _new(self, subject):
        return type(self)(self._graph, subject)

    def __str__(self):
        return "Resource(%s)" % self._identifier

    def __repr__(self):
        return "Resource(%s,%s)" % (self._graph, self._identifier)