import urllib
import urllib2
import json

# Helper functions
taskname = "test"
address = "http://localhost:8001"
last_output = None

def _input(value):
    # Ugly json encoding of primitives
    value = '"%s"' if type(value) == str else value
    urllib2.urlopen(urllib2.Request(address, urllib.urlencode({"op": "set_input", "value": value, "taskname": taskname})))

def _output():
    try:
        global last_output
        last_output = urllib2.urlopen(urllib2.Request(address, urllib.urlencode({"op": "get_output", "taskname": taskname})))
        return last_output
    except:
        raise UnknownError()

def _output_last():
    return last_output

# Exceptions
class UnknownError(Exception):
    pass

class UnknownIdentifier(Exception):
    pass

class UnknownType(Exception):
    pass

class UnsupportedValue(Exception):
    pass

class CompilationError(Exception):
    pass

class NoSuchAttribute(Exception):
    pass

# Actual functions to use for the wrapper
def list():
    """Return a list of all IDs and the type of the element"""
    pass
    # return [(name1, type1), (name2, type2), ...]
    # raises UnknownError

def types():
    """Return a list of all types usable in the model"""
    pass
    # return [type1, type2, ...]
    # raises UnknownError

def read(ID):
    """Return a tuple of information on the element: its type and source/target (None if not an edge)"""
    pass
    # return (type, (source, target))
    # raises UnknownError
    # raises UnknownIdentifier

def read_attrs(ID):
    """Return a dictionary of attribute value pairs"""
    pass
    # return {attr1: value1, attr2: value2, ...}
    # raises UnknownError

def verify():
    """Return the result of conformance checking (OK = conforms, otherwise error message)"""
    pass
    # return "OK"
    # raises UnknownError

def instantiate(typename, edge=None, ID=""):
    """Create a new instance of the specified typename, between the selected elements (if not None), and with the provided ID (if any)"""
    pass
    # return instantiated_ID
    # raises UnknownError
    # raises UnknownType
    # raises UnknownIdentifier

def delete(ID):
    """Delete the element with the given ID"""
    pass
    # return None
    # raises UnknownError
    # raises UnknownIdentifier

def attr_assign(ID, attr, value):
    """Assign a value to an attribute"""
    pass
    # return None
    # raises UnknownError
    # raises UnknownIdentifier
    # raises NoSuchAttribute
    # raises UnsupportedValue

def attr_assign_code(ID, attr, code):
    """Assign a piece of Action Language code to the attribute"""
    pass
    # return None
    # raises UnknownError
    # raises UnknownIdentifier
    # raises NoSuchAttribute
    # raises UnsupportedValue

def upload(new_model):
    """Overwrite the current model with the provided model"""
    pass
    # return None
    # raises UnknownError
    # raises CompilationError

def read_outgoing(ID, typename):
    """Returns a list of all outgoing associations of a specific type ("" = all)"""
    pass
    # return [name1, name2, ...]
    # raises UnknownError
    # raises UnknownIdentifier
    # raises UnknownType

def read_incoming(ID, typename):
    """Returns a list of all incoming associations of a specific type ("" = all)"""
    pass
    # return [name1, name2, ...]
    # raises UnknownError
    # raises UnknownIdentifier
    # raises UnknownType