Added basic downloading ability

downloader.py

@@ -0,0 +1,50 @@
+import asyncio
+import tempfile
+import signal
+import os
+from pathlib import Path
+from dataclasses import dataclass
+
+class Downloader:
+    """Class that performs content download."""
+
+    #
+    # PUBLIC
+    #
+    def __init__(self, url: str):
+        self._url = url
+
+    async def download_video(self, directory: str | Path) -> Path:
+        directory = Path(directory).resolve()
+        directory.mkdir(parents=True, exist_ok=True)
+
+        with tempfile.TemporaryDirectory(dir=directory, prefix=".ytdlp-") as tmp:
+            proc = await asyncio.create_subprocess_exec(
+                "yt-dlp",
+                "-f", "bv*+ba/b",
+                "-P", f"home:{directory}",
+                "-P", f"temp:{tmp}",
+                "--no-playlist",
+                "--print", "after_move:filepath",
+                self._url,
+                stdout=asyncio.subprocess.PIPE,
+                stderr=asyncio.subprocess.PIPE,
+                start_new_session=True,
+            )
+
+            try:
+                stdout, stderr = await proc.communicate()
+
+            except asyncio.CancelledError:
+                try:
+                    os.killpg(proc.pid, signal.SIGKILL)
+                except ProcessLookupError:
+                    pass
+
+                await asyncio.shield(proc.wait())
+                raise
+
+            if proc.returncode != 0:
+                raise RuntimeError(stderr.decode(errors="replace"))
+
+            return Path(stdout.decode().strip())