Add support for multiple file attachments.

This is a breaking change. No longer does Messageable.send have a
filename keyword argument, instead this is all handled through the
discord.File model. To upload many files you must specify a list
of discord.File objects.

5 files changed, 122 insertions, 31 deletions

diff --git a/discord/__init__.py b/discord/__init__.py
index 7b31c7f8..53016f43 100644
--- a/discord/__init__.py
+++ b/discord/__init__.py
@@ -30,6 +30,7 @@ from .errors import *
 from .calls import CallMessage, GroupCall
 from .permissions import Permissions, PermissionOverwrite
 from .role import Role
+from .file import File
 from .colour import Color, Colour
 from .invite import Invite
 from .object import Object
diff --git a/discord/abc.py b/discord/abc.py
index 7472c103..9c94c5dc 100644
--- a/discord/abc.py
+++ b/discord/abc.py
@@ -37,6 +37,7 @@ from .errors import InvalidArgument
 from .permissions import PermissionOverwrite, Permissions
 from .role import Role
 from .invite import Invite
+from .file import File
 from . import utils, compat
 
 class _Undefined:
@@ -536,7 +537,7 @@ class Messageable(metaclass=abc.ABCMeta):
         raise NotImplementedError
 
     @asyncio.coroutine
-    def send(self, content=None, *, tts=False, embed=None, file=None, filename=None, delete_after=None):
+    def send(self, content=None, *, tts=False, embed=None, file=None, files=None, delete_after=None):
         """|coro|
 
         Sends a message to the destination with the content given.
@@ -545,19 +546,10 @@ class Messageable(metaclass=abc.ABCMeta):
         If the content is set to ``None`` (the default), then the ``embed`` parameter must
         be provided.
 
-        The ``file`` parameter should be either a string denoting the location for a
-        file or a *file-like object*. The *file-like object* passed is **not closed**
-        at the end of execution. You are responsible for closing it yourself.
-
-        .. note::
-
-            If the file-like object passed is opened via ``open`` then the modes
-            'rb' should be used.
-
-        The ``filename`` parameter is the filename of the file.
-        If this is not given then it defaults to ``file.name`` or if ``file`` is a string
-        then the ``filename`` will default to the string given. You can overwrite
-        this value by passing this in.
+        To upload a single file, the ``file`` parameter should be used with a
+        single :class:`File` object. To upload multiple files, the ``files``
+        parameter should be used with a list of :class:`File` objects.
+        **Specifying both parameters will lead to an exception**.
 
         If the ``embed`` parameter is provided, it must be of type :class:`Embed` and
         it must be a rich embed type.
@@ -570,12 +562,11 @@ class Messageable(metaclass=abc.ABCMeta):
             Indicates if the message should be sent using text-to-speech.
         embed: :class:`Embed`
             The rich embed for the content.
-        file: file-like object or filename
-            The *file-like object* or file path to send.
-        filename: str
-            The filename of the file. Defaults to ``file.name`` if it's available.
-            If this is provided, you must also provide the ``file`` parameter or it
-            is silently ignored.
+        file: :class:`File`
+            The file to upload.
+        files: List[:class:`File`]
+            A list of files to upload. Must be a minimum of 2 and a
+            maximum of 10.
         delete_after: float
             If provided, the number of seconds to wait in the background
             before deleting the message we just sent. If the deletion fails,
@@ -587,6 +578,9 @@ class Messageable(metaclass=abc.ABCMeta):
             Sending the message failed.
         Forbidden
             You do not have the proper permissions to send the message.
+        InvalidArgument
+            The ``files`` list is not of the appropriate size or
+            you specified both ``file`` and ``files``.
 
         Returns
         ---------
@@ -600,17 +594,29 @@ class Messageable(metaclass=abc.ABCMeta):
         if embed is not None:
             embed = embed.to_dict()
 
+        if file is not None and files is not None:
+            raise InvalidArgument('cannot pass both file and files parameter to send()')
+
         if file is not None:
+            if not isinstance(file, File):
+                raise InvalidArgument('file parameter must be File')
+
+            try:
+                data = yield from state.http.send_files(channel.id, files=[(file.open_file(), file.filename)],
+                                                        content=content, tts=tts, embed=embed)
+            finally:
+                file.close()
+
+        elif files is not None:
+            if len(files) < 2 or len(files) > 10:
+                raise InvalidArgument('files parameter must be a list of 2 to 10 elements')
+
             try:
-                with open(file, 'rb') as f:
-                    buffer = io.BytesIO(f.read())
-                    if filename is None:
-                        _, filename = os.path.split(file)
-            except TypeError:
-                buffer = file
-
-            data = yield from state.http.send_file(channel.id, buffer, filename=filename, content=content,
-                                                   tts=tts, embed=embed)
+                param = [(f.open_file(), f.filename) for f in files]
+                data = yield from state.http.send_files(channel.id, files=param, content=content, tts=tts, embed=embed)
+            finally:
+                for f in files:
+                    f.close()
         else:
             data = yield from state.http.send_message(channel.id, content, tts=tts, embed=embed)
 
diff --git a/discord/file.py b/discord/file.py
new file mode 100644
index 00000000..98d11412
--- /dev/null
+++ b/discord/file.py
@@ -0,0 +1,73 @@
+# -*- coding: utf-8 -*-
+
+"""
+The MIT License (MIT)
+
+Copyright (c) 2015-2017 Rapptz
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the "Software"),
+to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense,
+and/or sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+"""
+
+import os.path
+
+class File:
+    """A parameter object used for :meth:`abc.Messageable.send`
+    for sending file objects.
+
+    Attributes
+    -----------
+    fp: Union[str, BinaryIO]
+        A file-like object opened in binary mode and read mode
+        or a filename representing a file in the hard drive to
+        open.
+
+        .. note::
+
+            If the file-like object passed is opened via ``open`` then the
+            modes 'rb' should be used.
+
+            To pass binary data, consider usage of ``io.BytesIO``.
+
+    filename: Optional[str]
+        The filename to display when uploading to Discord.
+        If this is not given then it defaults to ``fp.name`` or if ``fp`` is
+        a string then the ``filename`` will default to the string given.
+    """
+
+    __slots__ = ('fp', 'filename', '_true_fp')
+
+    def __init__(self, fp, filename=None):
+        self.fp = fp
+        self._true_fp = None
+
+        if filename is None:
+            if isinstance(fp, str):
+                _, self.filename = os.path.split(fp)
+            else:
+                self.filename = getattr(fp, 'name', None)
+
+    def open_file(self):
+        fp = self.fp
+        if isinstance(fp, str):
+            self._true_fp = fp = open(fp, 'rb')
+        return fp
+
+    def close(self):
+        if self._true_fp:
+            self._true_fp.close()
diff --git a/discord/http.py b/discord/http.py
index 9f43faad..e5d0c094 100644
--- a/discord/http.py
+++ b/discord/http.py
@@ -306,7 +306,7 @@ class HTTPClient:
     def send_typing(self, channel_id):
         return self.request(Route('POST', '/channels/{channel_id}/typing', channel_id=channel_id))
 
-    def send_file(self, channel_id, buffer, *, filename=None, content=None, tts=False, embed=None):
+    def send_files(self, channel_id, *, files, content=None, tts=False, embed=None):
         r = Route('POST', '/channels/{channel_id}/messages', channel_id=channel_id)
         form = aiohttp.FormData()
 
@@ -317,7 +317,12 @@ class HTTPClient:
             payload['embed'] = embed
 
         form.add_field('payload_json', utils.to_json(payload))
-        form.add_field('file', buffer, filename=filename, content_type='application/octet-stream')
+        if len(files) == 1:
+            fp = files[0]
+            form.add_field('file', fp[0], filename=fp[1], content_type='application/octet-stream')
+        else:
+            for index, (buffer, filename) in enumerate(files):
+                form.add_field('file%s' % index, buffer, filename=filename, content_type='application/octet-stream')
 
         return self.request(r, data=form)
 
diff --git a/docs/api.rst b/docs/api.rst
index 6da9c1ed..6581cc97 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -827,6 +827,12 @@ Embed
 .. autoclass:: Embed
     :members:
 
+File
+~~~~~
+
+.. autoclass:: File
+    :members:
+
 CallMessage
 ~~~~~~~~~~~~