Save content using original filenames (#893)

Add feature from issue #892 (Save content using original filenames)

- The new feature would download posts and save the images/videos with the original filenames.
- The implementation follows the other options for the filename-pattern parameter. As filename is related to a single file and not the whole post, for sidecar nodes the filename is calculated again.
- Using this option media from one post is only grouped together by the file modification timestamp.

docs/basic-usage.rst

@@ -171,6 +171,9 @@ dirname pattern. The following tokens are defined for usage with
 - ``{mediaid}``
    Integer representation of shortcode.
 
+- ``{filename}``
+   Instagram's internal filename.
+
 - ``{date_utc}`` (same as ``{date}``)
    Creation time in UTC timezone.
    `strftime()-style formatting options <https://docs.python.org/3/library/datetime.html#strftime-and-strptime-behavior>`__

instaloader/instaloader.py

@@ -14,6 +14,7 @@ from hashlib import md5
 from io import BytesIO
 from pathlib import Path
 from typing import Any, Callable, IO, Iterator, List, Optional, Set, Union, cast
+from urllib.parse import urlparse
 
 import requests
 import urllib3  # type: ignore
@@ -22,7 +23,7 @@ from .exceptions import *
 from .instaloadercontext import InstaloaderContext, RateController
 from .nodeiterator import NodeIterator, resumable_iteration
 from .structures import (Hashtag, Highlight, JsonExportable, Post, PostLocation, Profile, Story, StoryItem,
-                         load_structure_from_file, save_structure_to_file)
+                         load_structure_from_file, save_structure_to_file, PostSidecarNode)
 
 
 def get_default_session_filename(username: str) -> str:
@@ -101,6 +102,8 @@ class _ArbitraryItemFormatter(string.Formatter):
 
     def get_value(self, key, args, kwargs):
         """Override to substitute {ATTRIBUTE} by attributes of our _item."""
+        if key == 'filename' and isinstance(self._item, (Post, StoryItem, PostSidecarNode)):
+            return "{filename}"
         if hasattr(self._item, key):
             return getattr(self._item, key)
         return super().get_value(key, args, kwargs)
@@ -492,7 +495,16 @@ class Instaloader:
         .. versionadded:: 4.2"""
         self.context.two_factor_login(two_factor_code)
 
-    def format_filename(self, item: Union[Post, StoryItem], target: Optional[Union[str, Path]] = None):
+    @staticmethod
+    def __prepare_filename(filename_template: str, url: str) -> str:
+        """Replace filename token inside filename_template with url's filename and assure the directories exist.
+
+        .. versionadded:: 4.6"""
+        filename = filename_template.replace("{filename}", os.path.splitext(os.path.basename(urlparse(url).path))[0])
+        os.makedirs(os.path.dirname(filename), exist_ok=True)
+        return filename
+
+    def format_filename(self, item: Union[Post, StoryItem, PostSidecarNode], target: Optional[Union[str, Path]] = None):
         """Format filename of a :class:`Post` or :class:`StoryItem` according to ``filename-pattern`` parameter.
 
         .. versionadded:: 4.1"""
@@ -508,8 +520,8 @@ class Instaloader:
         """
 
         dirname = _PostPathFormatter(post).format(self.dirname_pattern, target=target)
-        filename = os.path.join(dirname, self.format_filename(post, target=target))
+        filename_template = os.path.join(dirname, self.format_filename(post, target=target))
-        os.makedirs(os.path.dirname(filename), exist_ok=True)
+        filename = self.__prepare_filename(filename_template, post.url)
 
         # Download the image(s) / video thumbnail and videos within sidecars if desired
         downloaded = True
@@ -517,13 +529,21 @@ class Instaloader:
             if self.download_pictures or self.download_videos:
                 for edge_number, sidecar_node in enumerate(post.get_sidecar_nodes(), start=1):
                     if self.download_pictures and (not sidecar_node.is_video or self.download_video_thumbnails):
+                        suffix = str(edge_number)
+                        if '{filename}' in self.filename_pattern:
+                            suffix = ''
+                        filename = self.__prepare_filename(filename_template, sidecar_node.display_url)
                         # Download sidecar picture or video thumbnail (--no-pictures implies --no-video-thumbnails)
                         downloaded &= self.download_pic(filename=filename, url=sidecar_node.display_url,
-                                                        mtime=post.date_local, filename_suffix=str(edge_number))
+                                                        mtime=post.date_local, filename_suffix=suffix)
                     if sidecar_node.is_video and self.download_videos:
+                        suffix = str(edge_number)
+                        if '{filename}' in self.filename_pattern:
+                            suffix = ''
+                        filename = self.__prepare_filename(filename_template, sidecar_node.video_url)
                         # Download sidecar video if desired
                         downloaded &= self.download_pic(filename=filename, url=sidecar_node.video_url,
-                                                        mtime=post.date_local, filename_suffix=str(edge_number))
+                                                        mtime=post.date_local, filename_suffix=suffix)
         elif post.typename == 'GraphImage':
             # Download picture
             if self.download_pictures:
@@ -638,13 +658,14 @@ class Instaloader:
 
         date_local = item.date_local
         dirname = _PostPathFormatter(item).format(self.dirname_pattern, target=target)
-        filename = os.path.join(dirname, self.format_filename(item, target=target))
+        filename_template = os.path.join(dirname, self.format_filename(item, target=target))
-        os.makedirs(os.path.dirname(filename), exist_ok=True)
+        filename = self.__prepare_filename(filename_template, item.url)
         downloaded = False
         if not item.is_video or self.download_video_thumbnails is True:
             url = item.url
             downloaded = self.download_pic(filename=filename, url=url, mtime=date_local)
         if item.is_video and self.download_videos is True:
+            filename = self.__prepare_filename(filename_template, str(item.video_url))
             downloaded |= self.download_pic(filename=filename, url=item.video_url, mtime=date_local)
         # Save caption if desired
         metadata_string = _ArbitraryItemFormatter(item).format(self.storyitem_metadata_txt_pattern).strip()