From 120c785bbce8ffad75ee39c523ba0fa3222df8bf Mon Sep 17 00:00:00 2001
From: Jonathan Beezley <jonathan.beezley@kitware.com>
Date: Fri, 9 Feb 2018 09:47:33 -0500
Subject: [PATCH] Refactor type annotation decorators to use click

This commit rewrites how item_tasks decorators is implemented to use
click primatives rather than custom logic.  The primary advantage is to
the new implementation is that the commandline interface comes with the
item_task annotations for free.  Also, much of the decorating and
conversion logic is handled by click classes directly which
significantly reduces the number of lines of code.

Signed-off-by: Jonathan Beezley <jonathan.beezley@kitware.com>
---
 girder_worker_utils/command.py                |  76 ++++++++++
 girder_worker_utils/decorators.py             | 138 ++++--------------
 girder_worker_utils/input.py                  |  67 +++++++++
 girder_worker_utils/output.py                 |   5 +
 girder_worker_utils/parameter.py              |  20 +++
 girder_worker_utils/tests/decorators_test.py  |  98 +++----------
 girder_worker_utils/tests/types_test.py       |  41 ------
 girder_worker_utils/types/__init__.py         |  31 ++--
 girder_worker_utils/types/base.py             |  67 ---------
 girder_worker_utils/types/boolean.py          |  22 +--
 girder_worker_utils/types/choice.py           |  47 ++----
 girder_worker_utils/types/color.py            |  21 +--
 girder_worker_utils/types/file.py             |  28 ++++
 girder_worker_utils/types/girder.py           |   5 -
 girder_worker_utils/types/girder_folder.py    |  11 --
 girder_worker_utils/types/girder_item.py      |  11 --
 girder_worker_utils/types/integer.py          |  20 ---
 girder_worker_utils/types/number.py           |  99 ++++---------
 girder_worker_utils/types/number_choice.py    |  12 --
 .../types/number_multichoice.py               |  16 --
 girder_worker_utils/types/number_vector.py    |  14 --
 girder_worker_utils/types/range.py            |  12 --
 girder_worker_utils/types/string.py           |  25 +---
 girder_worker_utils/types/string_choice.py    |  12 --
 .../types/string_multichoice.py               |  16 --
 girder_worker_utils/types/string_vector.py    |  14 --
 girder_worker_utils/types/vector.py           |  45 ------
 requirements.in                               |   1 +
 28 files changed, 310 insertions(+), 664 deletions(-)
 create mode 100644 girder_worker_utils/command.py
 create mode 100644 girder_worker_utils/input.py
 create mode 100644 girder_worker_utils/output.py
 create mode 100644 girder_worker_utils/parameter.py
 delete mode 100644 girder_worker_utils/tests/types_test.py
 delete mode 100644 girder_worker_utils/types/base.py
 create mode 100644 girder_worker_utils/types/file.py
 delete mode 100644 girder_worker_utils/types/girder.py
 delete mode 100644 girder_worker_utils/types/girder_folder.py
 delete mode 100644 girder_worker_utils/types/girder_item.py
 delete mode 100644 girder_worker_utils/types/integer.py
 delete mode 100644 girder_worker_utils/types/number_choice.py
 delete mode 100644 girder_worker_utils/types/number_multichoice.py
 delete mode 100644 girder_worker_utils/types/number_vector.py
 delete mode 100644 girder_worker_utils/types/range.py
 delete mode 100644 girder_worker_utils/types/string_choice.py
 delete mode 100644 girder_worker_utils/types/string_multichoice.py
 delete mode 100644 girder_worker_utils/types/string_vector.py
 delete mode 100644 girder_worker_utils/types/vector.py

diff --git a/girder_worker_utils/command.py b/girder_worker_utils/command.py
new file mode 100644
index 0000000..f2cc8d6
--- /dev/null
+++ b/girder_worker_utils/command.py
@@ -0,0 +1,76 @@
+import json
+
+import click
+
+from .parameter import Parameter
+
+
+class Command(click.Command):
+
+    def __init__(self, *args, **kwargs):
+        params = kwargs.pop('params', None) or []
+        input_params = []
+        output_params = []
+        other_params = []
+        for param in params:
+            if isinstance(param, Parameter) and param.is_input():
+                input_params.append(param)
+            elif isinstance(param, Parameter) and param.is_output():
+                output_params.append(param)
+            else:
+                other_params.append(param)
+        other_params += [
+            click.Option(('--item-tasks-json',), is_flag=True, default=False)
+        ]
+        kwargs['params'] = input_params + other_params
+        self._input_params = input_params
+        self._output_params = output_params
+        self._other_params = other_params
+        super(Command, self).__init__(*args, **kwargs)
+
+    def invoke(self, ctx):
+        if ctx.params.pop('item_tasks_json', False):
+            return self._print_item_tasks_json(ctx)
+        return super(Command, self).invoke(ctx)
+
+    def invoke_item_task(self, bindings):
+        # parse the input bindings to construct an argument list
+        kwargs = {}
+
+        # We need to loop through all of the input_params to get default values
+        # because we are bypassing the part of click that does this by calling
+        # ctx.invoke directly.  This is done because there is no way to
+        # construct CLI argument list from bindings (the name munging logic in
+        # click is strictly one directional).
+        #
+        # Alternatively, we might store the commandline argument name in addition
+        # to the bound variable name so we *can* generate a valid CLI argument
+        # list... this could potentially remove some of the custom logic present
+        # in girder's item_tasks plugin.
+        with self.make_context(self.name, [], resilient_parsing=True) as ctx:
+            for param in self._input_params:
+                kwargs.update(param.get_kwargs_from_input_bindings(bindings, ctx))
+
+            return ctx.invoke(self.callback, **kwargs)
+
+    def item_tasks_json(self, ctx=None):
+        spec = {
+            'name': self.name,
+            'description': self.help or '',
+            'inputs': [],
+            'outputs': []
+        }
+        for param in self._input_params:
+            spec['inputs'].append(param.item_tasks_json(ctx))
+        for param in self._output_params:
+            spec['outputs'].append(param.item_tasks_json(ctx))
+        return spec
+
+    def make_context(self, info_name, args, **kwargs):
+        if '--item-tasks-json' in args:
+            kwargs.setdefault('resilient_parsing', True)
+        return super(Command, self).make_context(info_name, args, **kwargs)
+
+    def _print_item_tasks_json(self, ctx=None):
+        spec = self.item_tasks_json(ctx)
+        click.echo(json.dumps(spec, indent=2))
diff --git a/girder_worker_utils/decorators.py b/girder_worker_utils/decorators.py
index ca21847..3d6824a 100644
--- a/girder_worker_utils/decorators.py
+++ b/girder_worker_utils/decorators.py
@@ -1,121 +1,33 @@
-from inspect import getdoc
-try:
-    from inspect import signature
-except ImportError:  # pragma: nocover
-    from funcsigs import signature
-import six
+import click
 
+from .command import Command
+from .input import Input
+from .output import Output
+from .types import String
 
-class MissingDescriptionException(Exception):
-    """Raised when a function is missing description decorators."""
-
-
-class MissingInputException(Exception):
-    """Raised when a required input is missing."""
-
-
-def get_description_attribute(func):
-    """Get the private description attribute from a function."""
-    func = getattr(func, 'run', func)
-    description = getattr(func, '_girder_description', None)
-    if description is None:
-        raise MissingDescriptionException('Function is missing description decorators')
-    return description
-
-
-def argument(name, data_type, *args, **kwargs):
-    """Describe an argument to a function as a function decorator.
-
-    Additional arguments are passed to the type class constructor.
-
-    :param str name: The parameter name from the function declaration
-    :param type: A type class derived from ``girder_worker_utils.types.Base``
-    """
-    if not isinstance(name, six.string_types):
-        raise TypeError('Expected argument name to be a string')
-
-    if callable(data_type):
-        data_type = data_type(name, *args, **kwargs)
-
-    def argument_wrapper(func):
-        func._girder_description = getattr(func, '_girder_description', {})
-        args = func._girder_description.setdefault('arguments', [])
-        sig = signature(func)
-
-        if name not in sig.parameters:
-            raise ValueError('Invalid argument name "%s"' % name)
-
-        data_type.set_parameter(sig.parameters[name], signature=sig)
-        args.insert(0, data_type)
-
-        def call_item_task(inputs, outputs={}):
-            args, kwargs = parse_inputs(func, inputs)
-            return func(*args, **kwargs)
-
-        def describe():
-            return describe_function(func)
-
-        func.call_item_task = call_item_task
-        func.describe = describe
 
+def task(name=None, cls=Command, **attrs):
+    def wrapper(func):
+        cmd_wrapper = click.command(name, cls, **attrs)
+        func.main = cmd_wrapper(func)
+        func.call_item_task = func.main.invoke_item_task
+        func.describe = func.main.item_tasks_json
         return func
+    return wrapper
 
-    return argument_wrapper
-
-
-def describe_function(func):
-    """Return a json description from a decorated function."""
-    description = get_description_attribute(func)
-
-    inputs = [arg.describe() for arg in description.get('arguments', [])]
-    spec = {
-        'name': description.get('name', func.__name__),
-        'inputs': inputs,
-        'mode': 'girder_worker'
-    }
-    desc = description.get('description', getdoc(func))
-    if desc:
-        spec['description'] = desc
-
-    return spec
-
-
-def get_input_data(arg, input_binding):
-    """Parse an input binding from a function argument description.
-
-    :param arg: An instantiated type description
-    :param input_binding: An input binding object
-    :returns: The parameter value
-    """
-    mode = input_binding.get('mode', 'inline')
-    if mode == 'inline' and 'data' in input_binding:
-        value = arg.deserialize(input_binding['data'])
-    elif mode == 'girder':
-        value = input_binding.get('id')
-    else:
-        raise ValueError('Unhandled input mode')
-
-    arg.validate(value)
-    return value
 
+def task_input(*param_decls, **attrs):
+    attrs.setdefault('cls', Input)
+    attrs.setdefault('type', String())
+    return click.option(*param_decls, **attrs)
 
-def parse_inputs(func, inputs):
-    """Parse an object of input bindings from item_tasks.
 
-    :param func: The task function
-    :param dict inputs: The input task bindings object
-    :returns: args and kwargs objects to call the function with
-    """
-    description = get_description_attribute(func)
-    arguments = description.get('arguments', [])
-    args = []
-    kwargs = {}
-    for arg in arguments:
-        desc = arg.describe()
-        input_id = desc['id']
-        name = desc['name']
-        if input_id not in inputs and not arg.has_default():
-            raise MissingInputException('Required input "%s" not provided' % name)
-        if input_id in inputs:
-            kwargs[name] = get_input_data(arg, inputs[input_id])
-    return args, kwargs
+def task_output(*param_decls, **attrs):
+    decls = []
+    for decl in param_decls:
+        if not decl.startswith('-'):
+            decl = '--' + decl
+        decls.append(decl)
+    attrs.setdefault('cls', Output)
+    attrs.setdefault('type', String())
+    return click.argument(*decls, **attrs)
diff --git a/girder_worker_utils/input.py b/girder_worker_utils/input.py
new file mode 100644
index 0000000..0c4679a
--- /dev/null
+++ b/girder_worker_utils/input.py
@@ -0,0 +1,67 @@
+try:
+    from inspect import signature
+except ImportError:
+    from funcsigs import signature
+
+from click.exceptions import BadParameter
+
+from .parameter import Parameter
+
+
+class Input(Parameter):
+    _item_tasks_type = 'input'
+
+    # TODO: Currently, the context argument exists entirely to provide the function
+    #       signature for providing default values.  Click on it's own expects that
+    #       defaults are provided by the @option decorators.  It could be that parsing
+    #       the function signature for default values is a bad idea, and we should
+    #       remove the context argument here.
+    #
+    #       As an additional implementation note, there is some confusion as to
+    #       exactly methods need to have access to the context.  In most cases,
+    #       click uses the context optionally inside it's API.  In the item_tasks
+    #       use case, it is complicated because we cannot create a context (which
+    #       requires the argument list) before parsing the input bindings.  This
+    #       will almost certainly cause pain down the road as code is created that
+    #       *needs* access to the context for special processing.
+    def item_tasks_json(self, ctx=None):
+        spec = super(Input, self).item_tasks_json(ctx)
+
+        # get default from the decorator
+        default = self.get_default(ctx)
+
+        # get default from the function definition
+        if ctx and self.default is None:
+            default = self._get_default_from_function(ctx.command)
+
+        if default is not None:
+            spec['default'] = {
+                'data': default
+            }
+        spec.update(self.type.item_tasks_json(self, ctx))
+        return spec
+
+    def get_kwargs_from_input_bindings(self, bindings, ctx):
+        value = self.default
+        if self.name in bindings:
+            binding = bindings[self.name]
+            if not isinstance(binding, dict) or 'data' not in binding:
+                raise BadParameter('Invalid input binding', ctx=ctx, param=self)
+            value = binding['data']
+
+        if value is None:
+            return {}
+
+        return {self.name: value}
+
+    def _get_default_from_function(self, command):
+        if command is None:
+            return
+        func = command.callback
+        sig = signature(func)
+        if self.name not in sig.parameters:
+            return
+        param = sig.parameters[self.name]
+        if param.default == param.empty:
+            return
+        return param.default
diff --git a/girder_worker_utils/output.py b/girder_worker_utils/output.py
new file mode 100644
index 0000000..dfcc387
--- /dev/null
+++ b/girder_worker_utils/output.py
@@ -0,0 +1,5 @@
+from .parameter import Parameter
+
+
+class Output(Parameter):
+    _item_tasks_type = 'output'
diff --git a/girder_worker_utils/parameter.py b/girder_worker_utils/parameter.py
new file mode 100644
index 0000000..eff266e
--- /dev/null
+++ b/girder_worker_utils/parameter.py
@@ -0,0 +1,20 @@
+import click
+
+
+class Parameter(click.Option):
+    _item_tasks_type = None
+
+    def item_tasks_json(self, command=None):
+        spec = {
+            'id': self.name,
+            'name': self.name,
+            'description': self.help or ''
+        }
+        spec.update(self.type.item_tasks_json(self))
+        return spec
+
+    def is_input(self):
+        return self._item_tasks_type == 'input'
+
+    def is_output(self):
+        return self._item_tasks_type == 'output'
diff --git a/girder_worker_utils/tests/decorators_test.py b/girder_worker_utils/tests/decorators_test.py
index 85a9c78..d3eb2c0 100644
--- a/girder_worker_utils/tests/decorators_test.py
+++ b/girder_worker_utils/tests/decorators_test.py
@@ -1,11 +1,12 @@
 import pytest
 
-from girder_worker_utils import decorators
 from girder_worker_utils import types
-from girder_worker_utils.decorators import argument
+from girder_worker_utils.decorators import task, task_input, task_output
 
 
-@argument('n', types.Integer, help='The element to return')
+@task()
+@task_input('-n', type=types.Integer(), help='The element to return')
+@task_output('value', type=types.Integer())
 def fibonacci(n):
     """Compute a fibonacci number."""
     if n <= 2:
@@ -13,18 +14,21 @@ def fibonacci(n):
     return fibonacci(n - 1) + fibonacci(n - 2)
 
 
-@argument('val', types.String, help='The value to return')
+@task()
+@task_input('--val', help='The value to return')
+@task_output('noop_value')
 def keyword_func(val='test'):
     """Return a value."""
     return val
 
 
-@argument('arg1', types.String)
-@argument('arg2', types.StringChoice, choices=('a', 'b'))
-@argument('kwarg1', types.StringVector)
-@argument('kwarg2', types.Number, min=0, max=10)
-@argument('kwarg3', types.NumberMultichoice, choices=(1, 2, 3, 4, 5))
-def complex_func(arg1, arg2, kwarg1=('one',), kwarg2=4, kwarg3=(1, 2)):
+@task()
+@task_input('--arg1')
+@task_input('--arg2', type=types.Choice(('a', 'b')))
+@task_input('--kwarg1', nargs=2)
+@task_input('--kwarg2', type=types.Integer(min=0, max=10))
+@task_input('--kwarg3', type=types.Choice((1, 2, 3, 4, 5)), multiple=True)
+def complex_func(arg1, arg2, kwarg1=('one', 'two'), kwarg2=4, kwarg3=(1, 2)):
     return {
         'arg1': arg1,
         'arg2': arg2,
@@ -34,12 +38,6 @@ def complex_func(arg1, arg2, kwarg1=('one',), kwarg2=4, kwarg3=(1, 2)):
     }
 
 
-@argument('item', types.GirderItem)
-@argument('folder', types.GirderFolder)
-def girder_types_func(item, folder):
-    return item, folder
-
-
 def test_positional_argument():
     desc = fibonacci.describe()
     assert len(desc['inputs']) == 1
@@ -52,7 +50,7 @@ def test_positional_argument():
         'The element to return'
 
     assert fibonacci.call_item_task({'n': {'data': 10}}) == 55
-    with pytest.raises(decorators.MissingInputException):
+    with pytest.raises(TypeError):
         fibonacci.call_item_task({})
 
 
@@ -82,25 +80,12 @@ def test_multiple_arguments():
     assert desc['inputs'][3]['name'] == 'kwarg2'
     assert desc['inputs'][4]['name'] == 'kwarg3'
 
-    with pytest.raises(decorators.MissingInputException):
+    with pytest.raises(TypeError):
         complex_func.call_item_task({})
 
-    with pytest.raises(decorators.MissingInputException):
-        complex_func.call_item_task({
-            'arg1': {'data': 'value'}
-        })
-
-    with pytest.raises(ValueError):
-        complex_func.call_item_task({
-            'arg1': {'data': 'value'},
-            'arg2': {'data': 'invalid'}
-        })
-
     with pytest.raises(TypeError):
         complex_func.call_item_task({
-            'arg1': {'data': 'value'},
-            'arg2': {'data': 'a'},
-            'kwarg2': {'data': 'foo'}
+            'arg1': {'data': 'value'}
         })
 
     assert complex_func.call_item_task({
@@ -109,7 +94,7 @@ def test_multiple_arguments():
     }) == {
         'arg1': 'value',
         'arg2': 'a',
-        'kwarg1': ('one',),
+        'kwarg1': ('one', 'two'),
         'kwarg2': 4,
         'kwarg3': (1, 2)
     }
@@ -117,7 +102,7 @@ def test_multiple_arguments():
     assert complex_func.call_item_task({
         'arg1': {'data': 'value'},
         'arg2': {'data': 'b'},
-        'kwarg1': {'data': 'one,two'},
+        'kwarg1': {'data': ['one', 'two']},
         'kwarg2': {'data': 10},
         'kwarg3': {'data': (1, 4)}
     }) == {
@@ -127,48 +112,3 @@ def test_multiple_arguments():
         'kwarg2': 10,
         'kwarg3': (1, 4)
     }
-
-
-def test_girder_input_mode():
-    item, folder = girder_types_func.call_item_task({
-        'item': {
-            'mode': 'girder',
-            'id': 'itemid',
-            'resource_type': 'item',
-            'fileName': 'file.txt'
-        },
-        'folder': {
-            'mode': 'girder',
-            'id': 'folderid',
-            'resource_type': 'folder'
-        }
-    })
-
-    assert item == 'itemid'
-    assert folder == 'folderid'
-
-
-def test_missing_description_exception():
-    def func():
-        pass
-
-    with pytest.raises(decorators.MissingDescriptionException):
-        decorators.get_description_attribute(func)
-
-
-def test_argument_name_not_string():
-    with pytest.raises(TypeError):
-        argument(0, types.Integer)
-
-
-def test_argument_name_not_a_parameter():
-    with pytest.raises(ValueError):
-        @argument('notarg', types.Integer)
-        def func(arg):
-            pass
-
-
-def test_unhandled_input_binding():
-    arg = argument('arg', types.Integer)
-    with pytest.raises(ValueError):
-        decorators.get_input_data(arg, {})
diff --git a/girder_worker_utils/tests/types_test.py b/girder_worker_utils/tests/types_test.py
deleted file mode 100644
index c9a26d4..0000000
--- a/girder_worker_utils/tests/types_test.py
+++ /dev/null
@@ -1,41 +0,0 @@
-import pytest
-
-from girder_worker_utils import types
-
-
-def test_serialize_boolean():
-    arg = types.Boolean('arg')
-    assert arg.serialize(None) is False
-    assert arg.serialize(1) is True
-
-
-def test_validate_choice_value():
-    arg = types.StringMultichoice('arg')
-    with pytest.raises(TypeError):
-        arg.validate('not a list')
-
-
-def test_serialize_integer():
-    arg = types.Integer('arg')
-    assert arg.serialize(1.0) is 1
-
-
-def test_validate_integer_range():
-    arg = types.Integer('arg', min=0, max=10)
-    with pytest.raises(ValueError):
-        arg.validate(-1)
-
-    with pytest.raises(ValueError):
-        arg.validate(11)
-
-
-def test_validate_string():
-    arg = types.String('arg')
-    with pytest.raises(TypeError):
-        arg.validate(1)
-
-
-def test_validate_number_vector():
-    arg = types.NumberVector('arg')
-    with pytest.raises(TypeError):
-        arg.validate('not a list')
diff --git a/girder_worker_utils/types/__init__.py b/girder_worker_utils/types/__init__.py
index a3dd2cb..fa9ed0b 100644
--- a/girder_worker_utils/types/__init__.py
+++ b/girder_worker_utils/types/__init__.py
@@ -1,31 +1,18 @@
 from .boolean import Boolean
+from .choice import Choice
 from .color import Color
-from .girder_folder import GirderFolder
-from .girder_item import GirderItem
-from .integer import Integer
-from .number import Number
-from .number_choice import NumberChoice
-from .number_multichoice import NumberMultichoice
-from .number_vector import NumberVector
-from .range import Range
+from .file import File, Folder, Image
+from .number import Float, Integer
 from .string import String
-from .string_choice import StringChoice
-from .string_multichoice import StringMultichoice
-from .string_vector import StringVector
 
 __all__ = (
     Boolean,
+    Choice,
     Color,
-    GirderFolder,
-    GirderItem,
+    File,
+    Float,
+    Folder,
+    Image,
     Integer,
-    Number,
-    NumberChoice,
-    NumberMultichoice,
-    NumberVector,
-    Range,
-    String,
-    StringChoice,
-    StringMultichoice,
-    StringVector
+    String
 )
diff --git a/girder_worker_utils/types/base.py b/girder_worker_utils/types/base.py
deleted file mode 100644
index f213550..0000000
--- a/girder_worker_utils/types/base.py
+++ /dev/null
@@ -1,67 +0,0 @@
-from copy import deepcopy
-
-
-class Base(object):
-    """Define an abstract type class.
-
-    This class defines the interface expected by the functions in
-    :py:mod:`girder_worker.describe`.  All autodescribing parameter
-    types should derive from this class.
-    """
-
-    #: This is used as a base description object for all types.
-    description = {}
-
-    def __init__(self, name, **kwargs):
-        """Construct a task description.
-
-        Subclasses can define additional keyword arguments.
-
-        :param str name: The argument name in the task function.
-        :param str id: An optional id (defaults to the argument name)
-        :param str help: A help string (defaults to the function docstring)
-        """
-        self.id = kwargs.get('id', name)
-        self.name = name
-        self.help = kwargs.get('help')
-
-    def set_parameter(self, parameter, **kwargs):
-        """Store a parameter instance from a function signature.
-
-        This method is called internally by description decorators.
-
-        :param parameter: The parameter signature from the task
-        :type parameter: inspect.Parameter
-        """
-        self.parameter = parameter
-
-    def has_default(self):
-        """Return true if the parameter has a default value."""
-        return self.parameter.default is not self.parameter.empty
-
-    def describe(self):
-        """Return a type description serialization."""
-        copy = deepcopy(self.description)
-        copy.setdefault('id', self.id)
-        copy.setdefault('name', self.name)
-        if self.has_default():
-            copy.setdefault('default', {
-                'data': self.serialize(self.parameter.default)
-            })
-        if self.help is not None:
-            copy['description'] = self.help
-        return copy
-
-    def serialize(self, value):
-        """Serialize a python value into a format expected by item_tasks."""
-        return value
-
-    def deserialize(self, value):
-        """Deserialize a python value from a format provided by item_tasks."""
-        return value
-
-    def validate(self, value):
-        """Validate a parameter value.
-
-        :raises Exception: if the value is not valid
-        """
diff --git a/girder_worker_utils/types/boolean.py b/girder_worker_utils/types/boolean.py
index 896f033..0dc019e 100644
--- a/girder_worker_utils/types/boolean.py
+++ b/girder_worker_utils/types/boolean.py
@@ -1,18 +1,8 @@
-from .base import Base
+import click
 
 
-class Boolean(Base):
-    """Define a boolean task parameter.
-
-    >>> @argument('debug', types.Boolean)
-    ... def func(debug=False):
-    ...     pass
-    """
-
-    description = {
-        'type': 'boolean',
-        'description': 'Provide a boolean value'
-    }
-
-    def serialize(self, value):
-        return bool(value)
+class Boolean(click.types.BoolParamType):
+    def item_tasks_json(self, param, ctx=None):
+        return {
+            'type': 'boolean'
+        }
diff --git a/girder_worker_utils/types/choice.py b/girder_worker_utils/types/choice.py
index 462d145..04c51b8 100644
--- a/girder_worker_utils/types/choice.py
+++ b/girder_worker_utils/types/choice.py
@@ -1,40 +1,13 @@
-from .base import Base
+import click
 
 
-class Choice(Base):
-    """Define base functionality for multi choice parameter."""
+class Choice(click.Choice):
 
-    #: The explicit type provided by the subclass
-    paramType = None
-
-    #: Whether the parameter accepts multiple values from the choices
-    multiple = False
-
-    def __init__(self, *args, **kwargs):
-        """Construct a choice parameter.
-
-        :param list choices: A list of valid values.
-        """
-        self.choices = kwargs.get('choices', [])
-        super(Choice, self).__init__(*args, **kwargs)
-
-    def describe(self, *args, **kwargs):
-        desc = super(Choice, self).describe(*args, **kwargs)
-        desc['type'] = self.paramType
-        desc['values'] = self.choices
-        desc['description'] = 'Choose from a list of values'
-        return desc
-
-    def _validate_one(self, value):
-        if value not in self.choices:
-            raise ValueError('Invalid value provided for "%s"' % self.name)
-
-    def validate(self, value):
-        if not self.multiple:
-            value = [value]
-
-        if not isinstance(value, (list, tuple)):
-            raise TypeError(
-                'Expected a list or tuple for "%s"' % self.name)
-        for v in value:
-            self._validate_one(v)
+    def item_tasks_json(self, param, ctx=None):
+        multiple = ''
+        if param.multiple:
+            multiple = '-multiple'
+        return {
+            'type': 'string-choice' + multiple,
+            'values': self.choices
+        }
diff --git a/girder_worker_utils/types/color.py b/girder_worker_utils/types/color.py
index be7d6b0..986794a 100644
--- a/girder_worker_utils/types/color.py
+++ b/girder_worker_utils/types/color.py
@@ -1,17 +1,8 @@
-from .base import Base
+import click
 
 
-class Color(Base):
-    """Define a task parameter expecting a color value.
-
-    >>> @argument('background', types.Color)
-    ... def func(background):
-    ...     pass
-    """
-
-    description = {
-        'type': 'color',
-        'description': 'Provide a color value'
-    }
-
-    # TODO: handle normalization and validation
+class Color(click.types.StringParamType):
+    def item_tasks_json(self, param, ctx=None):
+        return {
+            'type': 'color'
+        }
diff --git a/girder_worker_utils/types/file.py b/girder_worker_utils/types/file.py
new file mode 100644
index 0000000..ed0337c
--- /dev/null
+++ b/girder_worker_utils/types/file.py
@@ -0,0 +1,28 @@
+import click
+
+
+class File(click.types.File):
+    def item_tasks_json(self, param, ctx=None):
+        widget = 'file'
+        if param.is_output():
+            widget = 'new-file'
+        return {
+            'type': widget
+        }
+
+
+class Image(click.types.File):
+    def item_tasks_json(self, param, ctx=None):
+        return {
+            'type': 'image'
+        }
+
+
+class Folder(click.types.Path):
+    def item_tasks_json(self, param, ctx=None):
+        widget = 'directory'
+        if param.is_output():
+            widget = 'new-folder'
+        return {
+            'type': widget
+        }
diff --git a/girder_worker_utils/types/girder.py b/girder_worker_utils/types/girder.py
deleted file mode 100644
index 866165c..0000000
--- a/girder_worker_utils/types/girder.py
+++ /dev/null
@@ -1,5 +0,0 @@
-from .base import Base
-
-
-class Girder(Base):
-    """Define a base parameter type representing a Girder Id."""
diff --git a/girder_worker_utils/types/girder_folder.py b/girder_worker_utils/types/girder_folder.py
deleted file mode 100644
index a07c6f3..0000000
--- a/girder_worker_utils/types/girder_folder.py
+++ /dev/null
@@ -1,11 +0,0 @@
-from .girder import Girder
-
-
-class GirderFolder(Girder):
-    """Define a parameter representing a girder folder id."""
-
-    def describe(self, **kwargs):
-        desc = super(GirderFolder, self).describe(**kwargs)
-        desc['type'] = 'directory'
-        desc['description'] = self.help or 'Select a folder'
-        return desc
diff --git a/girder_worker_utils/types/girder_item.py b/girder_worker_utils/types/girder_item.py
deleted file mode 100644
index 9937bb9..0000000
--- a/girder_worker_utils/types/girder_item.py
+++ /dev/null
@@ -1,11 +0,0 @@
-from .girder import Girder
-
-
-class GirderItem(Girder):
-    """Define a parameter representing a girder item id."""
-
-    def describe(self, **kwargs):
-        desc = super(GirderItem, self).describe(**kwargs)
-        desc['type'] = 'file'
-        desc['description'] = self.help or 'Select an item'
-        return desc
diff --git a/girder_worker_utils/types/integer.py b/girder_worker_utils/types/integer.py
deleted file mode 100644
index 17aa943..0000000
--- a/girder_worker_utils/types/integer.py
+++ /dev/null
@@ -1,20 +0,0 @@
-from .number import Number
-
-
-class Integer(Number):
-    """Define an integer task parameter.
-
-    >>> @argument('iterations', types.Integer)
-    ... def func(iterations=3):
-    ...     pass
-    """
-
-    paramType = 'integer'
-
-    def __init__(self, *args, **kwargs):
-        kwargs['step'] = 1
-        super(Integer, self).__init__(*args, **kwargs)
-
-    def serialize(self, value):
-        value = super(Integer, self).serialize(value)
-        return int(value)
diff --git a/girder_worker_utils/types/number.py b/girder_worker_utils/types/number.py
index 0ee9ea7..f7ccecd 100644
--- a/girder_worker_utils/types/number.py
+++ b/girder_worker_utils/types/number.py
@@ -1,67 +1,32 @@
-import numbers
-
-from .base import Base
-
-
-class Number(Base):
-    """Define a numeric parameter type optionally in a given range.
-
-    Values accepted by this parameter can be any numeric value.
-    If min/max/step are provided, then the values must be a float
-    or int.
-
-    >>> @argument('value', types.Number, min=10, max=100, step=10)
-    ... def func(value):
-    ...     pass
-    """
-
-    paramType = 'number'
-
-    def __init__(self, *args, **kwargs):
-        """Construct a new numeric parameter type.
-
-        :param float min: The minimum valid value
-        :param float max: The maximum valid value
-        :param float step: The resolution of valid values
-        """
-        super(Number, self).__init__(*args, **kwargs)
-        self.min = kwargs.get('min')
-        self.max = kwargs.get('max')
-        self.step = kwargs.get('step')
-
-    def describe(self, **kwargs):
-        desc = super(Number, self).describe(**kwargs)
-
-        if self.min is not None:
-            desc['min'] = self.min
-        if self.max is not None:
-            desc['max'] = self.max
-        if self.step is not None:
-            desc['step'] = self.step
-
-        desc['type'] = self.paramType
-        desc['description'] = self.help or 'Select a number'
-        return desc
-
-    def validate(self, value):
-        if not isinstance(value, numbers.Number):
-            raise TypeError('Expected a number for parameter "%s"' % self.name)
-
-        if self.min is not None and value < self.min:
-            raise ValueError('Expected %s <= %s' % (str(self.min), str(value)))
-
-        if self.max is not None and value > self.max:
-            raise ValueError('Expected %s >= %s' % (str(self.max), str(value)))
-
-    def serialize(self, value):
-        if self.step is not None:
-            n = round(float(value) / self.step)
-            value = n * self.step
-        return value
-
-    def deserialize(self, value):
-        try:
-            value = float(value)
-        except ValueError:
-            pass
-        return value
+import click
+
+
+class Integer(click.types.IntRange):
+    def __init__(self, widget='number', step=1, **kwargs):
+        self.widget = widget
+        self.step = step
+        super(Integer, self).__init__(**kwargs)
+
+    def item_tasks_json(self, param, ctx=None):
+        widget = self.widget
+        if param.nargs > 1:
+            widget = 'number-vector'
+        return {
+            'type': widget,
+            'min': self.min,
+            'max': self.max,
+            'step': self.step
+        }
+
+
+# click.FloatRange is created in click master, but not released.
+# We could consider backporting it to support min/max arguments
+# and slider widgets.
+class Float(click.types.FloatParamType):
+    def item_tasks_json(self, param, ctx=None):
+        widget = 'number'
+        if param.nargs > 1:
+            widget = 'number-vector'
+        return {
+            'type': widget
+        }
diff --git a/girder_worker_utils/types/number_choice.py b/girder_worker_utils/types/number_choice.py
deleted file mode 100644
index 377b856..0000000
--- a/girder_worker_utils/types/number_choice.py
+++ /dev/null
@@ -1,12 +0,0 @@
-from .choice import Choice
-
-
-class NumberChoice(Choice):
-    """Define a numeric parameter with a set of valid values.
-
-    >>> @argument('address', types.NumberChoice, choices=(5, 10, 15))
-    ... def func(address):
-    ...     pass
-    """
-
-    paramType = 'number-enumeration'
diff --git a/girder_worker_utils/types/number_multichoice.py b/girder_worker_utils/types/number_multichoice.py
deleted file mode 100644
index a0bc95d..0000000
--- a/girder_worker_utils/types/number_multichoice.py
+++ /dev/null
@@ -1,16 +0,0 @@
-from .choice import Choice
-
-
-class NumberMultichoice(Choice):
-    """Define a multichose numeric parameter type.
-
-    Values of this type are iterable sequences of numbers
-    all of which must be an element of a predefined set.
-
-    >>> @argument('images', types.NumberMultichoice, choices=(5, 10, 15))
-    ... def func(images=(5, 10)):
-    ...     pass
-    """
-
-    paramType = 'number-enumeration-multiple'
-    multiple = True
diff --git a/girder_worker_utils/types/number_vector.py b/girder_worker_utils/types/number_vector.py
deleted file mode 100644
index f9ed0e0..0000000
--- a/girder_worker_utils/types/number_vector.py
+++ /dev/null
@@ -1,14 +0,0 @@
-from .number import Number
-from .vector import Vector
-
-
-class NumberVector(Vector):
-    """Define a parameter accepting a list of numbers.
-
-    >>> @argument('value', types.NumberVector, min=10, max=100, step=10)
-    ... def func(value=(10, 11)):
-    ...     pass
-    """
-
-    paramType = 'number-vector'
-    elementClass = Number
diff --git a/girder_worker_utils/types/range.py b/girder_worker_utils/types/range.py
deleted file mode 100644
index 5081014..0000000
--- a/girder_worker_utils/types/range.py
+++ /dev/null
@@ -1,12 +0,0 @@
-from .number import Number
-
-
-class Range(Number):
-    """Define numeric parameter with valid values in a given range.
-
-    >>> @argument('value', types.Range, min=10, max=100, step=10)
-    ... def func(value):
-    ...     pass
-    """
-
-    paramType = 'range'
diff --git a/girder_worker_utils/types/string.py b/girder_worker_utils/types/string.py
index a5b11f0..57704c6 100644
--- a/girder_worker_utils/types/string.py
+++ b/girder_worker_utils/types/string.py
@@ -1,21 +1,8 @@
-import six
+import click
 
-from .base import Base
 
-
-class String(Base):
-    """Define a parameter that can be an arbitrary string.
-
-    >>> @argument('person', types.String)
-    ... def func(person='eve'):
-    ...     pass
-    """
-
-    description = {
-        'type': 'string',
-        'description': 'Provide a string value'
-    }
-
-    def validate(self, value):
-        if not isinstance(value, six.string_types):
-            raise TypeError('Expected a string value for "%s"' % self.name)
+class String(click.types.StringParamType):
+    def item_tasks_json(self, param, ctx=None):
+        return {
+            'type': 'string'
+        }
diff --git a/girder_worker_utils/types/string_choice.py b/girder_worker_utils/types/string_choice.py
deleted file mode 100644
index 4397f61..0000000
--- a/girder_worker_utils/types/string_choice.py
+++ /dev/null
@@ -1,12 +0,0 @@
-from .choice import Choice
-
-
-class StringChoice(Choice):
-    """Define a string parameter with a list of valid values.
-
-    >>> @argument('person', types.StringChoice, choices=('alice', 'bob', 'charlie'))
-    ... def func(person):
-    ...     pass
-    """
-
-    paramType = 'string-enumeration'
diff --git a/girder_worker_utils/types/string_multichoice.py b/girder_worker_utils/types/string_multichoice.py
deleted file mode 100644
index ce0fe47..0000000
--- a/girder_worker_utils/types/string_multichoice.py
+++ /dev/null
@@ -1,16 +0,0 @@
-from .choice import Choice
-
-
-class StringMultichoice(Choice):
-    """Define a multichose string parameter type.
-
-    Values of this type are iterable sequences of strings
-    all of which must be an element of a predefined set.
-
-    >>> @argument('people', types.StringMultichoice, choices=('alice', 'bob', 'charlie'))
-    ... def func(people=('alice', 'bob')):
-    ...     pass
-    """
-
-    paramType = 'string-enumeration-multiple'
-    multiple = True
diff --git a/girder_worker_utils/types/string_vector.py b/girder_worker_utils/types/string_vector.py
deleted file mode 100644
index bd8d5a5..0000000
--- a/girder_worker_utils/types/string_vector.py
+++ /dev/null
@@ -1,14 +0,0 @@
-from .string import String
-from .vector import Vector
-
-
-class StringVector(Vector):
-    """Define a parameter which takes a list of strings.
-
-    >>> @argument('people', types.StringVector)
-    ... def func(people=('alice', 'bob')):
-    ...     pass
-    """
-
-    paramType = 'string-vector'
-    elementClass = String
diff --git a/girder_worker_utils/types/vector.py b/girder_worker_utils/types/vector.py
deleted file mode 100644
index 7d68332..0000000
--- a/girder_worker_utils/types/vector.py
+++ /dev/null
@@ -1,45 +0,0 @@
-import six
-
-from .base import Base
-
-
-class Vector(Base):
-    """Define a base class that accepts an iterable object."""
-
-    #: The explicit type provided by the subclass
-    paramType = None
-
-    #: The class of the elements of the vector
-    elementClass = None
-
-    #: A list seperator for serialization
-    seperator = ','
-
-    def __init__(self, *args, **kwargs):
-        if self.paramType is None:  # pragma: nocover
-            raise NotImplementedError('Subclasses should define paramType')
-
-        if self.elementClass is None:  # pragma: nocover
-            raise NotImplementedError('Subclasses should define elementClass')
-
-        self.element = self.elementClass(*args, **kwargs)
-        super(Vector, self).__init__(*args, **kwargs)
-
-    def describe(self, *args, **kwargs):
-        desc = super(Vector, self).describe(*args, **kwargs)
-        desc['type'] = self.paramType
-        desc['description'] = 'Provide a list of values'
-        return desc
-
-    def validate(self, value):
-        if not isinstance(value, (list, tuple)):
-            raise TypeError('Expected a list or tuple for "%s"' % self.name)
-
-        for elementValue in value:
-            self.element.validate(elementValue)
-
-    def deserialize(self, value):
-        if isinstance(value, six.string_types):
-            value = value.split(self.seperator)
-
-        return [self.element.deserialize(v) for v in value]
diff --git a/requirements.in b/requirements.in
index 23a8c80..4e30c00 100644
--- a/requirements.in
+++ b/requirements.in
@@ -1,3 +1,4 @@
+click
 funcsigs ; python_version < '3.5'
 girder-client>=2
 jsonpickle