Add chat command

pyproject.toml

@@ -34,6 +34,13 @@ packages = [
 [tool.setuptools_scm]
 
 [project.optional-dependencies]
+# This is made optional because it is not pure python, and when used prevents
+# distribution of twitch-dl as a pyz archive while keeping it cross-platform.
+chat = [
+    "pillow>=9",
+    "fonttools>=4,<5",
+]
+
 dev = [
     "build",
     "pytest",

twitchdl/cache.py

@@ -0,0 +1,71 @@
+import hashlib
+import logging
+import os
+import sys
+from pathlib import Path
+from typing import Optional
+
+from twitchdl.http import download_file
+
+CACHE_SUBFOLDER = "twitch-dl"
+
+
+logger = logging.getLogger(__name__)
+
+
+def download_cached(
+    url: str,
+    *,
+    filename: Optional[str] = None,
+    subfolder: Optional[str] = None,
+) -> Optional[Path]:
+    base = get_cache_dir()
+    if not filename:
+        filename = hashlib.sha256(url.encode()).hexdigest()
+    target = base / subfolder / filename if subfolder else base / filename
+
+    if not target.exists():
+        download_file(url, target)
+
+    return target
+
+
+def get_text_font() -> Path:
+    url = "https://cdn.jsdelivr.net/gh/notofonts/notofonts.github.io/fonts/NotoSans/full/ttf/NotoSans-Light.ttf"
+    path = download_cached(url, subfolder="fonts", filename="NotoSans-Light.ttf")
+    if not path:
+        raise ValueError(f"Failed downloading font from {url}")
+    return path
+
+
+def get_noto_color_emoji_font() -> Path:
+    url = "https://github.com/googlefonts/noto-emoji/raw/main/fonts/NotoColorEmoji.ttf"
+    path = download_cached(url, subfolder="fonts", filename="NotoColorEmoji.ttf")
+    if not path:
+        raise ValueError(f"Failed downloading font from {url}")
+    return path
+
+
+def get_cache_dir() -> Path:
+    path = _cache_dir_path()
+    path.mkdir(parents=True, exist_ok=True)
+    return path
+
+
+def _cache_dir_path() -> Path:
+    """Returns the path to the cache directory"""
+
+    # Windows
+    if sys.platform == "win32" and "APPDATA" in os.environ:
+        return Path(os.environ["APPDATA"], CACHE_SUBFOLDER, "cache")
+
+    # Mac OS
+    if sys.platform == "darwin":
+        return Path.home() / "Library" / "Caches" / CACHE_SUBFOLDER
+
+    # Respect XDG_CONFIG_HOME env variable if set
+    # https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
+    if "XDG_CACHE_HOME" in os.environ:
+        return Path(os.environ["XDG_CACHE_HOME"], CACHE_SUBFOLDER)
+
+    return Path.home() / ".cache" / CACHE_SUBFOLDER