slack_data_import: Support converting integration bot users.

Currently, we're unable to convert messages from Slack's integration
bots because this message subtype doesn't come from a Slack "user", that
is they don't have a Slack user profile.

This is a preparatory change to support converting Slack's integration
bot messages. This commit artificially creates Slack user data from the
integration bot's "profile" so that we can create a corresponding Zulip
user for them.

Part of #31311.

zerver/data_import/slack.py

@@ -50,7 +50,7 @@ from zerver.lib.emoji import codepoint_to_name, get_emoji_file_name
 from zerver.lib.export import MESSAGE_BATCH_CHUNK_SIZE, do_common_export_processes
 from zerver.lib.mime_types import guess_type
 from zerver.lib.storage import static_path
-from zerver.lib.thumbnail import resize_realm_icon
+from zerver.lib.thumbnail import THUMBNAIL_ACCEPT_IMAGE_TYPES, resize_realm_icon
 from zerver.lib.upload import sanitize_name
 from zerver.models import (
     CustomProfileField,
@@ -472,6 +472,19 @@ def build_avatar_url(slack_user_id: str, user: ZerverFieldsT) -> tuple[str, str]
         avatar_hash = user["profile"]["avatar_hash"]
         avatar_url = f"https://ca.slack-edge.com/{team_id}-{slack_user_id}-{avatar_hash}"
         avatar_source = UserProfile.AVATAR_FROM_USER
+    elif user.get("is_integration_bot"):
+        # Unlike other Slack user types, Slacks integration bot avatar URL ends with
+        # a file type extension (.png, in this case).
+        # e.g https://avatars.slack-edge.com/2024-05-01/7218497908_deb94eac4c_512.png
+        avatar_url = user["profile"]["image_72"]
+        content_type = guess_type(avatar_url)[0]
+        if content_type not in THUMBNAIL_ACCEPT_IMAGE_TYPES:
+            logging.info(
+                "Unsupported avatar type (%s) for user -> %s\n", content_type, user.get("name")
+            )
+            avatar_source = UserProfile.AVATAR_FROM_GRAVATAR
+        else:
+            avatar_source = UserProfile.AVATAR_FROM_USER
     else:
         logging.info("Failed to process avatar for user -> %s\n", user.get("name"))
     return avatar_source, avatar_url
@@ -1262,12 +1275,39 @@ def get_timestamp_from_message(message: ZerverFieldsT) -> float:
     return float(message["ts"])
 
 
+def is_integration_bot_message(message: ZerverFieldsT) -> bool:
+    return message.get("subtype") == "bot_message" and "user" not in message and "bot_id" in message
+
+
+def convert_bot_info_to_slack_user(bot_info: dict[str, Any]) -> ZerverFieldsT:
+    # We use "image_72," an icon-sized 72x72 pixel image, for the Slack integration
+    # bots avatar because it is the best available option. As a consequence, this
+    # will make the avatar appear blurry in places where a medium-sized avatar
+    # (500x500px) is expected, such as in the user profile menu.
+
+    bot_user = {
+        "id": bot_info["id"],
+        "name": bot_info["name"],
+        "deleted": bot_info["deleted"],
+        "is_mirror_dummy": False,
+        "real_name": bot_info["name"],
+        "is_integration_bot": True,
+        "profile": {
+            "image_72": bot_info["icons"]["image_72"],
+            "bot_id": bot_info["id"],
+            "first_name": bot_info["name"],
+        },
+    }
+    return bot_user
+
+
 def fetch_shared_channel_users(
     user_list: list[ZerverFieldsT], slack_data_dir: str, token: str
 ) -> None:
     normal_user_ids = set()
     mirror_dummy_user_ids = set()
     added_channels = {}
+    integration_bot_users: list[str] = []
     team_id_to_domain: dict[str, str] = {}
     for user in user_list:
         user["is_mirror_dummy"] = False
@@ -1296,10 +1336,25 @@ def fetch_shared_channel_users(
 
     all_messages = get_messages_iterator(slack_data_dir, added_channels, {}, {})
     for message in all_messages:
-        user_id = get_message_sending_user(message)
-        if user_id is None or user_id in normal_user_ids:
-            continue
-        mirror_dummy_user_ids.add(user_id)
+        if is_integration_bot_message(message):
+            # This message is likely from an integration bot. Since Slack's integration
+            # bots doesn't have user profiles, we need to artificially create users for
+            # them to convert their messages.
+            bot_id = message["bot_id"]
+            if bot_id in integration_bot_users:
+                continue
+            bot_info = get_slack_api_data(
+                "https://slack.com/api/bots.info", "bot", token=token, bot=bot_id
+            )
+            bot_user = convert_bot_info_to_slack_user(bot_info)
+
+            user_list.append(bot_user)
+            integration_bot_users.append(bot_id)
+        else:
+            user_id = get_message_sending_user(message)
+            if user_id is None or user_id in normal_user_ids:
+                continue
+            mirror_dummy_user_ids.add(user_id)
 
     # Fetch data on the mirror_dummy_user_ids from the Slack API (it's
     # not included in the data export file).