first commit

swingmusic/services/download_provider_adapters.py

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+from __future__ import annotations
+
+import os
+import shlex
+import shutil
+import subprocess
+import time
+from dataclasses import dataclass
+from pathlib import Path
+
+SUPPORTED_AUDIO_EXTENSIONS = {
+    ".flac",
+    ".mp3",
+    ".m4a",
+    ".ogg",
+    ".opus",
+    ".wav",
+    ".aac",
+}
+
+
+@dataclass
+class AdapterDownloadResult:
+    file_path: str
+    codec: str
+    bitrate: int
+    provider: str
+
+
+def _quality_to_bitrate(quality: str, codec: str) -> int:
+    quality = (quality or "high").lower()
+    codec = (codec or "mp3").lower()
+
+    if codec == "flac" or quality == "lossless":
+        return 1411
+    if quality == "high":
+        return 320
+    if quality == "medium":
+        return 192
+    return 128
+
+
+class CommandFallbackAdapter:
+    """
+    Generic command adapter used as fallback when the primary SpotiFLAC
+    provider is not available or fails.
+
+    Configure with:
+    - SWINGMUSIC_FALLBACK_DOWNLOAD_CMD
+      Default: disabled.
+      Example:
+      '{url}' -> source URL
+      '{output_dir}' -> destination directory
+      '{codec}' / '{quality}' / '{item_type}' / '{target_path}'
+    """
+
+    def __init__(self) -> None:
+        self.name = os.getenv("SWINGMUSIC_FALLBACK_PROVIDER_NAME", "fallback-command")
+        self.command_template = os.getenv(
+            "SWINGMUSIC_FALLBACK_DOWNLOAD_CMD", ""
+        ).strip()
+        self.timeout_seconds = int(
+            os.getenv("SWINGMUSIC_FALLBACK_TIMEOUT_SECONDS", "3600")
+        )
+
+    def is_available(self) -> bool:
+        if not self.command_template:
+            return False
+
+        try:
+            command = shlex.split(self.command_template)
+        except ValueError:
+            return False
+
+        if not command:
+            return False
+
+        executable = command[0]
+        return shutil.which(executable) is not None
+
+    @staticmethod
+    def _list_audio_files(output_dir: str) -> set[Path]:
+        directory = Path(output_dir)
+        if not directory.exists():
+            return set()
+
+        files: set[Path] = set()
+        for path in directory.rglob("*"):
+            if path.is_file() and path.suffix.lower() in SUPPORTED_AUDIO_EXTENSIONS:
+                files.add(path.resolve())
+        return files
+
+    def _build_command(
+        self,
+        *,
+        source_url: str,
+        output_dir: str,
+        codec: str,
+        quality: str,
+        item_type: str,
+        target_path: str | None,
+    ) -> list[str]:
+        command = self.command_template.format(
+            url=source_url,
+            output_dir=output_dir,
+            codec=codec,
+            quality=quality,
+            item_type=item_type,
+            target_path=target_path or "",
+        )
+        return shlex.split(command)
+
+    def download(
+        self,
+        *,
+        source_url: str,
+        output_dir: str,
+        codec: str,
+        quality: str,
+        item_type: str,
+        target_path: str | None = None,
+    ) -> AdapterDownloadResult:
+        if not source_url:
+            raise RuntimeError("Fallback adapter requires source_url")
+
+        if not self.is_available():
+            raise RuntimeError(
+                "Fallback adapter command is not configured or unavailable"
+            )
+
+        os.makedirs(output_dir, exist_ok=True)
+        before = self._list_audio_files(output_dir)
+        command = self._build_command(
+            source_url=source_url,
+            output_dir=output_dir,
+            codec=codec,
+            quality=quality,
+            item_type=item_type,
+            target_path=target_path,
+        )
+
+        process = subprocess.run(
+            command,
+            capture_output=True,
+            text=True,
+            timeout=self.timeout_seconds,
+            check=False,
+        )
+        if process.returncode != 0:
+            err = (
+                process.stderr.strip()
+                or process.stdout.strip()
+                or "Fallback command failed"
+            )
+            raise RuntimeError(err)
+
+        if target_path and Path(target_path).exists():
+            resolved = str(Path(target_path).resolve())
+            return AdapterDownloadResult(
+                file_path=resolved if item_type == "track" else output_dir,
+                codec=Path(resolved).suffix.lstrip(".") or codec,
+                bitrate=_quality_to_bitrate(quality, codec),
+                provider=self.name,
+            )
+
+        after = self._list_audio_files(output_dir)
+        new_files = list(after - before)
+        if not new_files:
+            new_files = list(after)
+        if not new_files:
+            raise RuntimeError(
+                "Fallback adapter finished without producing audio files"
+            )
+
+        newest = max(
+            new_files,
+            key=lambda path: path.stat().st_mtime if path.exists() else time.time(),
+        )
+        resolved = str(newest.resolve())
+        resolved_codec = newest.suffix.lstrip(".") or codec
+
+        return AdapterDownloadResult(
+            file_path=resolved if item_type == "track" else output_dir,
+            codec=resolved_codec,
+            bitrate=_quality_to_bitrate(quality, resolved_codec),
+            provider=self.name,
+        )
+
+
+fallback_download_adapter = CommandFallbackAdapter()