"""Shard downloader for distributed model loading."""

from typing import Optional, Dict, Any
from pathlib import Path


class ShardDownloader:
    """Downloads and manages model shards for distributed inference."""

    def __init__(self, cache_dir: Optional[Path] = None):
        """Initialize shard downloader.

        Args:
            cache_dir: Directory to cache downloaded shards
        """
        self.cache_dir = cache_dir or Path.home() / ".hanzo" / "models"
        self.cache_dir.mkdir(parents=True, exist_ok=True)
        self._downloads = {}

    async def download_shard(self, model_id: str, shard_id: str) -> Path:
        """Download a model shard.

        Args:
            model_id: Model identifier
            shard_id: Shard identifier

        Returns:
            Path to downloaded shard
        """
        # For now, return a dummy path
        shard_path = self.cache_dir / model_id / f"{shard_id}.shard"
        shard_path.parent.mkdir(parents=True, exist_ok=True)

        # In real implementation, this would download from hanzo/net
        # For testing, just create an empty file
        if not shard_path.exists():
            shard_path.touch()

        return shard_path

    async def get_shard_info(self, model_id: str) -> Dict[str, Any]:
        """Get information about available shards for a model.

        Args:
            model_id: Model identifier

        Returns:
            Dictionary with shard information
        """
        # Mock shard info
        return {
            "model_id": model_id,
            "total_shards": 1,
            "shard_size": 1024 * 1024 * 100,  # 100MB
            "shards": [{"id": "shard_0", "layers": [0, 31], "size": 1024 * 1024 * 100}],
        }

    def is_cached(self, model_id: str, shard_id: str) -> bool:
        """Check if a shard is already cached.

        Args:
            model_id: Model identifier
            shard_id: Shard identifier

        Returns:
            True if shard is cached
        """
        shard_path = self.cache_dir / model_id / f"{shard_id}.shard"
        return shard_path.exists()
