Read toot lenght limit from mastodon instances

fixes #369

toot/tui/app.py

@@ -14,13 +14,16 @@ from .overlays import ExceptionStackTrace, GotoMenu, Help, StatusSource, StatusL
 from .overlays import StatusDeleteConfirmation, Account
 from .poll import Poll
 from .timeline import Timeline
-from .utils import parse_content_links, show_media, copy_to_clipboard
+from .utils import get_max_toot_chars, parse_content_links, show_media, copy_to_clipboard
 
 logger = logging.getLogger(__name__)
 
 urwid.set_encoding('UTF-8')
 
 
+DEFAULT_MAX_TOOT_CHARS = 500
+
+
 class Header(urwid.WidgetWrap):
     def __init__(self, app, user):
         self.app = app
@@ -112,7 +115,7 @@ class TUI(urwid.Frame):
         self.footer.set_status("Loading...")
 
         # Default max status length, updated on startup
-        self.max_toot_chars = 500
+        self.max_toot_chars = DEFAULT_MAX_TOOT_CHARS
 
         self.timeline = None
         self.overlay = None
@@ -289,8 +292,8 @@ class TUI(urwid.Frame):
             return api.get_instance(self.app.base_url)
 
         def _done(instance):
-            if "max_toot_chars" in instance:
-                self.max_toot_chars = instance["max_toot_chars"]
+            self.max_toot_chars = get_max_toot_chars(instance, DEFAULT_MAX_TOOT_CHARS)
+            logger.info(f"Max toot chars set to: {self.max_toot_chars}")
 
             if "translation" in instance:
                 # instance is advertising translation service

toot/tui/utils.py

@@ -1,13 +1,14 @@
 import base64
-import urwid
-from html.parser import HTMLParser
 import math
 import os
 import re
 import shutil
 import subprocess
+import urwid
 
 from datetime import datetime, timezone
+from functools import reduce
+from html.parser import HTMLParser
 
 HASHTAG_PATTERN = re.compile(r'(?<!\w)(#\w+)\b')
 SECOND = 1
@@ -163,3 +164,26 @@ def copy_to_clipboard(screen: urwid.raw_display.Screen, text: str):
 
     screen.write(f"\033]52;c;{b64_text}\a")
     screen.flush()
+
+
+def get_max_toot_chars(instance, default=500):
+    # Mastodon
+    # https://docs.joinmastodon.org/entities/Instance/#max_characters
+    max_toot_chars = deep_get(instance, ["configuration", "statuses", "max_characters"])
+    if isinstance(max_toot_chars, int):
+        return max_toot_chars
+
+    # Pleroma
+    max_toot_chars = instance.get("max_toot_chars")
+    if isinstance(max_toot_chars, int):
+        return max_toot_chars
+
+    return default
+
+
+def deep_get(adict: dict, path: list[str], default=None):
+    return reduce(
+        lambda d, key: d.get(key, default) if isinstance(d, dict) else default,
+        path,
+        adict
+    )