#!/usr/bin/env python3
# /// script
# requires-python = ">=3.9"
# dependencies = [
#     "aiohttp",
#     "typer>=0.9",
#     "rich",
#     "PyYAML",
#     "pyarrow",
# ]
# ///
"""Download ColliderML dataset assets and manage README URL updates."""

from __future__ import annotations

import asyncio
import contextlib
import hashlib
import logging
import os
import re
import shutil
import tempfile
from dataclasses import dataclass
from pathlib import Path
from typing import Annotated, Any, Dict, List, Sequence
from urllib.parse import urlparse

import aiohttp
import pyarrow.parquet as pq
import typer
import yaml
from rich.console import Console
from rich.logging import RichHandler
from rich.progress import (
    BarColumn,
    DownloadColumn,
    Progress,
    TextColumn,
    TimeElapsedColumn,
    TransferSpeedColumn,
)
from rich.table import Table


console = Console()
app = typer.Typer()

# Set up logging with rich handler
logging.basicConfig(
    level=logging.INFO,
    format="%(message)s",
    datefmt="[%X]",
    handlers=[RichHandler(console=console, show_path=False)],
)
logger = logging.getLogger(__name__)


@app.callback()
def main_callback(
    verbose: Annotated[
        bool,
        typer.Option(
            "--verbose",
            "-v",
            help="Enable verbose logging.",
        ),
    ] = False,
) -> None:
    """Manage dataset file URLs declared in README front matter."""
    if verbose:
        logging.getLogger().setLevel(logging.DEBUG)
        logger.debug("Verbose logging enabled")


@dataclass
class DataFileEntry:
    config_name: str
    path: Sequence[str]
    url: str

    def parsed(self) -> tuple[str, str]:
        parsed = urlparse(self.url)
        return parsed.netloc, parsed.path.lstrip("/")

    def relative_path(self) -> Path:
        netloc, remainder = self.parsed()
        return Path(netloc) / Path(remainder)


@dataclass
class DownloadResult:
    entry: DataFileEntry
    path: Path
    success: bool
    skipped: bool
    error: Exception | None = None
    order: int = 0


@dataclass
class VerifyResult:
    entry: DataFileEntry
    ok: bool
    status: int | None
    detail: str = ""
    order: int = 0


@dataclass
class ChecksumResult:
    entry: DataFileEntry
    filename: str
    computed_hash: str | None
    expected_hash: str | None
    matches: bool
    success: bool
    error: Exception | None = None
    order: int = 0


@dataclass
class SchemaInfo:
    config_name: str
    filename: str
    columns: List[tuple[str, str]]  # (column_name, data_type)
    num_rows: int | None
    success: bool
    error: Exception | None = None


def read_front_matter(readme_path: Path) -> tuple[str, str]:
    text = readme_path.read_text(encoding="utf-8")
    if not text.startswith("---\n"):
        raise ValueError("README.md does not start with YAML front matter.")
    try:
        front_matter, body = text[4:].split("\n---\n", 1)
    except ValueError as exc:
        raise ValueError("README.md front matter is not terminated by '---'.") from exc
    return front_matter, body


def load_data_file_entries(front_matter_text: str) -> List[DataFileEntry]:
    data = yaml.safe_load(front_matter_text)
    configs = data.get("configs", []) if isinstance(data, dict) else []
    entries: List[DataFileEntry] = []

    def _walk(value: Any, path: list[str]) -> None:
        if value is None:
            return
        if isinstance(value, str):
            entries.append(
                DataFileEntry(config_name=current_config, path=tuple(path), url=value)
            )
        elif isinstance(value, list):
            for idx, item in enumerate(value):
                _walk(item, [*path, str(idx)])
        elif isinstance(value, dict):
            for key, item in value.items():
                _walk(item, [*path, str(key)])

    for config in configs:
        if not isinstance(config, dict):
            continue
        current_config = str(config.get("config_name", "<unnamed>"))
        _walk(config.get("data_files"), ["data_files"])

    return entries


def replace_once(text: str, old: str, new: str) -> str:
    index = text.find(old)
    if index == -1:
        raise ValueError(f"Value '{old}' was not found in front matter.")
    return f"{text[:index]}{new}{text[index + len(old):]}"


def build_rewritten_url(
    result: DownloadResult, output_dir: Path, base_url: str
) -> str:
    """Build new URL by replacing output_dir with base_url in the file path.

    For example:
    - File path: /data/output/particles/file.parquet
    - Output dir: /data/output
    - Base URL: https://example.com/files
    - Result: https://example.com/files/particles/file.parquet
    """
    relative_path = result.path.relative_to(output_dir)
    # Ensure base_url doesn't end with slash, relative_path is POSIX-style
    base_url = base_url.rstrip("/")
    return f"{base_url}/{relative_path.as_posix()}"


def resolve_destination(entry: DataFileEntry, output_dir: Path) -> Path:
    _, remote_path = entry.parsed()
    filename = Path(remote_path).name or remote_path
    base_dir = output_dir / entry.config_name
    return (base_dir / filename).resolve()


def move_with_progress(src: Path, dst: Path, progress: Progress, task_id: int) -> None:
    """Move file with progress tracking for cross-filesystem moves."""
    # Try fast rename first (works if same filesystem)
    try:
        os.rename(src, dst)
        return
    except OSError:
        # Cross-filesystem move - need to copy with progress
        pass

    # Get file size for progress tracking
    file_size = src.stat().st_size
    progress.update(task_id, total=file_size)

    # Copy with progress tracking - use larger buffers for remote filesystems
    buffer_size = 8 << 20  # 8 MB chunks for better performance on remote FS
    with src.open("rb") as fsrc, dst.open("wb") as fdst:
        copied = 0
        while True:
            buf = fsrc.read(buffer_size)
            if not buf:
                break
            fdst.write(buf)
            copied += len(buf)
            progress.update(task_id, completed=copied)

        # Ensure data is flushed to disk (critical for remote filesystems)
        fdst.flush()
        os.fsync(fdst.fileno())

    # Verify file was written correctly before removing source
    if dst.stat().st_size != file_size:
        raise IOError(
            f"File size mismatch after copy: expected {file_size}, got {dst.stat().st_size}"
        )

    # Remove source after successful copy
    src.unlink()


async def download_one(
    entry: DataFileEntry,
    output_dir: Path,
    session: aiohttp.ClientSession,
    semaphore: asyncio.Semaphore,
    skip_existing: bool,
    progress: Progress,
    order: int,
    staging_dir: Path | None = None,
) -> DownloadResult:
    _, remote_path = entry.parsed()
    filename = Path(remote_path).name or remote_path
    terse_name = (filename[:32] + "…") if len(filename) > 33 else filename
    description = f"{entry.config_name}: {terse_name}"
    async with semaphore:
        task_id: int | None = None
        destination = resolve_destination(entry, output_dir)

        # Determine download location (staging or direct)
        if staging_dir:
            download_dest = resolve_destination(entry, staging_dir)
            tmp_path = download_dest.parent / f"{download_dest.name}.part"
        else:
            download_dest = destination
            tmp_path = destination.parent / f"{destination.name}.part"

        try:
            destination.parent.mkdir(parents=True, exist_ok=True)
            download_dest.parent.mkdir(parents=True, exist_ok=True)
            task_id = progress.add_task(description, total=0, start=False)
            progress.start_task(task_id)
            async with session.get(entry.url) as response:
                response.raise_for_status()
                total_bytes = response.content_length or 0

                # Check if we can skip this file
                if skip_existing and destination.exists():
                    local_size = destination.stat().st_size
                    if total_bytes and local_size == total_bytes:
                        if task_id is not None:
                            progress.remove_task(task_id)
                            task_id = None
                        logger.info(
                            f"Skipped {destination.name} ({total_bytes:,} bytes) - already exists with correct size"
                        )
                        return DownloadResult(
                            entry=entry,
                            path=destination,
                            success=True,
                            skipped=True,
                            order=order,
                        )
                    else:
                        # File exists but needs re-download
                        if not total_bytes:
                            reason = f"remote size unknown, local size is {local_size:,} bytes"
                        else:
                            reason = f"size mismatch (local: {local_size:,} bytes, remote: {total_bytes:,} bytes)"
                        logger.info(f"Downloading {destination.name} - {reason}")
                else:
                    # File doesn't exist or skip_existing is disabled
                    if not destination.exists():
                        size_info = f" ({total_bytes:,} bytes)" if total_bytes else ""
                        logger.info(
                            f"Downloading {destination.name}{size_info} - file not found locally"
                        )
                    else:
                        size_info = f" ({total_bytes:,} bytes)" if total_bytes else ""
                        logger.info(
                            f"Downloading {destination.name}{size_info} - skip_existing is disabled"
                        )

                if total_bytes:
                    progress.update(task_id, total=total_bytes)
                with tmp_path.open("wb") as handle:
                    async for chunk in response.content.iter_chunked(1 << 17):
                        handle.write(chunk)
                        progress.update(task_id, advance=len(chunk))

                    # Flush and sync to ensure data is written (critical for remote filesystems)
                    handle.flush()
                    os.fsync(handle.fileno())

            # Move from .part to final location
            tmp_path.rename(download_dest)

            # If using staging, move from staging to final destination with progress
            if staging_dir:
                logger.info(
                    f"Moving {download_dest.name} from staging to {destination.parent.name}/"
                )
                # Update progress bar description for move operation
                if task_id is not None:
                    progress.update(
                        task_id, description=f"{entry.config_name}: Moving {terse_name}"
                    )
                await asyncio.to_thread(
                    move_with_progress, download_dest, destination, progress, task_id
                )

            return DownloadResult(
                entry=entry,
                path=destination,
                success=True,
                skipped=False,
                order=order,
            )
        except Exception as exc:  # noqa: BLE001
            # Report error immediately
            logger.error(f"Failed to download {entry.config_name}/{filename}: {exc}")
            with contextlib.suppress(FileNotFoundError):
                tmp_path.unlink()
            return DownloadResult(
                entry=entry,
                path=destination,
                success=False,
                skipped=False,
                error=exc,
                order=order,
            )
        finally:
            if task_id is not None:
                progress.remove_task(task_id)


async def perform_downloads(
    entries: Sequence[DataFileEntry],
    output_dir: Path,
    max_concurrency: int,
    timeout: float,
    skip_existing: bool,
    use_staging: bool = False,
) -> List[DownloadResult]:
    if not entries:
        return []

    with contextlib.ExitStack() as stack:
        # Create staging directory if needed
        staging_dir: Path | None = None
        if use_staging:
            staging_tmp = stack.enter_context(
                tempfile.TemporaryDirectory(prefix="dataset_staging_")
            )
            staging_dir = Path(staging_tmp)
            logger.info(f"Using staging directory: {staging_dir}")

        semaphore = asyncio.Semaphore(max_concurrency)
        results: List[DownloadResult] = []
        timeout_cfg = aiohttp.ClientTimeout(total=timeout)
        progress = Progress(
            TextColumn("{task.description}"),
            BarColumn(bar_width=None),
            DownloadColumn(),
            TransferSpeedColumn(),
            TimeElapsedColumn(),
            console=console,
        )

        async with aiohttp.ClientSession(timeout=timeout_cfg) as session:
            with progress:
                tasks: list[asyncio.Task[DownloadResult]] = []
                for order, entry in enumerate(entries):
                    task = asyncio.create_task(
                        download_one(
                            entry=entry,
                            output_dir=output_dir,
                            session=session,
                            semaphore=semaphore,
                            skip_existing=skip_existing,
                            progress=progress,
                            order=order,
                            staging_dir=staging_dir,
                        )
                    )
                    tasks.append(task)

                for future in asyncio.as_completed(tasks):
                    result = await future
                    results.append(result)

        results.sort(key=lambda item: item.order)
        return results


async def get_remote_file_size(
    entry: DataFileEntry,
    session: aiohttp.ClientSession,
    semaphore: asyncio.Semaphore,
) -> int | None:
    """Get remote file size via HEAD request."""
    async with semaphore:
        try:
            async with session.head(entry.url, allow_redirects=True) as response:
                if response.status < 400:
                    return response.content_length
        except Exception:  # noqa: BLE001
            pass
    return None


async def fetch_remote_sizes(
    entries: Sequence[DataFileEntry],
    max_concurrency: int,
    timeout: float,
) -> Dict[str, int | None]:
    """Fetch remote file sizes for all entries."""
    semaphore = asyncio.Semaphore(max_concurrency)
    timeout_cfg = aiohttp.ClientTimeout(total=timeout)
    sizes: Dict[str, int | None] = {}

    progress = Progress(
        TextColumn("Fetching remote file sizes..."),
        BarColumn(),
        TextColumn("{task.completed}/{task.total}"),
        TimeElapsedColumn(),
        console=console,
    )

    async with aiohttp.ClientSession(timeout=timeout_cfg) as session:
        with progress:
            task_id = progress.add_task("Fetching sizes", total=len(entries))
            tasks = {
                entry.url: asyncio.create_task(
                    get_remote_file_size(entry, session, semaphore)
                )
                for entry in entries
            }
            for url, task in tasks.items():
                size = await task
                sizes[url] = size
                progress.advance(task_id)

    return sizes


async def verify_one(
    entry: DataFileEntry,
    session: aiohttp.ClientSession,
    semaphore: asyncio.Semaphore,
    order: int,
) -> VerifyResult:
    async with semaphore:
        last_error: str = ""
        for method in ("HEAD", "GET"):
            try:
                async with session.request(
                    method, entry.url, allow_redirects=True
                ) as response:
                    status = response.status
                    if status < 400:
                        return VerifyResult(
                            entry=entry, ok=True, status=status, order=order
                        )
                    if method == "HEAD" and status in {405, 501}:
                        last_error = f"{method} returned {status}; retrying with GET."
                        continue
                    return VerifyResult(
                        entry=entry,
                        ok=False,
                        status=status,
                        detail=f"{method} -> {status}",
                        order=order,
                    )
            except Exception as exc:  # noqa: BLE001
                last_error = str(exc)
        return VerifyResult(
            entry=entry,
            ok=False,
            status=None,
            detail=last_error or "Unknown error",
            order=order,
        )


async def perform_verification(
    entries: Sequence[DataFileEntry],
    max_concurrency: int,
    timeout: float,
) -> List[VerifyResult]:
    if not entries:
        return []

    semaphore = asyncio.Semaphore(max_concurrency)
    timeout_cfg = aiohttp.ClientTimeout(total=timeout)
    results: List[VerifyResult] = []
    progress = Progress(
        TextColumn("{task.description}"),
        BarColumn(),
        TextColumn("{task.completed}/{task.total}"),
        TimeElapsedColumn(),
        console=console,
    )

    async with aiohttp.ClientSession(timeout=timeout_cfg) as session:
        with progress:
            task_id = progress.add_task("Verifying dataset URLs", total=len(entries))
            tasks = [
                asyncio.create_task(verify_one(entry, session, semaphore, order=order))
                for order, entry in enumerate(entries)
            ]
            for future in asyncio.as_completed(tasks):
                result = await future
                results.append(result)
                progress.advance(task_id)

    results.sort(key=lambda item: item.order)
    return results


async def compute_file_hash(
    entry: DataFileEntry,
    session: aiohttp.ClientSession,
    semaphore: asyncio.Semaphore,
    progress: Progress,
    order: int,
) -> ChecksumResult:
    """Download file to temp location and compute SHA256 hash."""
    # Extract filename from URL
    _, remote_path = entry.parsed()
    filename = Path(remote_path).name or remote_path
    terse_name = (filename[:32] + "…") if len(filename) > 33 else filename
    description = f"{entry.config_name}: {terse_name}"

    async with semaphore:
        task_id: int | None = None
        try:
            task_id = progress.add_task(description, total=0, start=False)
            progress.start_task(task_id)

            async with session.get(entry.url) as response:
                response.raise_for_status()
                total_bytes = response.content_length or 0

                if total_bytes:
                    progress.update(task_id, total=total_bytes)

                hasher = hashlib.sha256()
                async for chunk in response.content.iter_chunked(1 << 17):
                    hasher.update(chunk)
                    progress.update(task_id, advance=len(chunk))

                computed_hash = hasher.hexdigest()
                return ChecksumResult(
                    entry=entry,
                    filename=filename,
                    computed_hash=computed_hash,
                    expected_hash=None,  # Will be filled in later
                    matches=False,  # Will be determined later
                    success=True,
                    order=order,
                )
        except Exception as exc:  # noqa: BLE001
            return ChecksumResult(
                entry=entry,
                filename=filename,
                computed_hash=None,
                expected_hash=None,
                matches=False,
                success=False,
                error=exc,
                order=order,
            )
        finally:
            if task_id is not None:
                progress.remove_task(task_id)


async def perform_checksum_verification(
    entries: Sequence[DataFileEntry],
    expected_hashes_by_config: Dict[str, Dict[str, str]],
    max_concurrency: int,
    timeout: float,
) -> List[ChecksumResult]:
    """Download files and verify their checksums.

    expected_hashes_by_config: dict mapping config_name -> (filename -> hash)
    """
    if not entries:
        return []

    semaphore = asyncio.Semaphore(max_concurrency)
    timeout_cfg = aiohttp.ClientTimeout(total=timeout)
    results: List[ChecksumResult] = []
    progress = Progress(
        TextColumn("{task.description}"),
        BarColumn(),
        DownloadColumn(),
        TransferSpeedColumn(),
        TimeElapsedColumn(),
        console=console,
    )

    async with aiohttp.ClientSession(timeout=timeout_cfg) as session:
        with progress:
            tasks = [
                asyncio.create_task(
                    compute_file_hash(
                        entry, session, semaphore, order=order, progress=progress
                    )
                )
                for order, entry in enumerate(entries)
            ]
            for future in asyncio.as_completed(tasks):
                result = await future
                # Fill in expected hash and match status
                config_hashes = expected_hashes_by_config.get(
                    result.entry.config_name, {}
                )
                result.expected_hash = config_hashes.get(result.filename)
                if result.success and result.expected_hash:
                    result.matches = result.computed_hash == result.expected_hash
                results.append(result)

    results.sort(key=lambda item: item.order)
    return results


def load_checksums_for_config(checksum_dir: Path, config_name: str) -> Dict[str, str]:
    """Load expected hashes from SHA256SUM-style file for a specific config.

    Returns a dict mapping filename -> hash.
    """
    checksum_file = checksum_dir / f"{config_name}.sha256"
    if not checksum_file.exists():
        return {}

    hashes: Dict[str, str] = {}
    try:
        with checksum_file.open("r", encoding="utf-8") as f:
            for line in f:
                line = line.strip()
                if not line or line.startswith("#"):
                    continue
                # Format: <hash>  <filename>
                parts = line.split(None, 1)
                if len(parts) == 2:
                    hash_value, filename = parts
                    hashes[filename] = hash_value
    except OSError as exc:
        logger.warning(f"Failed to load checksum file {checksum_file}: {exc}")

    return hashes


def save_checksums_for_config(
    checksum_dir: Path, config_name: str, file_hashes: Dict[str, str]
) -> None:
    """Save hashes to SHA256SUM-style file for a specific config.

    file_hashes: dict mapping filename -> hash
    """
    checksum_dir.mkdir(parents=True, exist_ok=True)
    checksum_file = checksum_dir / f"{config_name}.sha256"

    with checksum_file.open("w", encoding="utf-8") as f:
        for filename in sorted(file_hashes.keys()):
            hash_value = file_hashes[filename]
            f.write(f"{hash_value}  {filename}\n")

    logger.info(f"Saved {len(file_hashes)} checksums to {checksum_file}")




@app.command()
def download(
    output_dir: Annotated[
        Path,
        typer.Option(
            "--output-dir",
            "-o",
            help="Directory where files will be stored.",
            resolve_path=True,
        ),
    ],
    readme_path: Annotated[
        Path,
        typer.Option(
            "--readme-path",
            "-r",
            help="Path to the README file with YAML front matter.",
            exists=True,
            resolve_path=True,
            dir_okay=False,
        ),
    ] = Path("README.md"),
    max_concurrency: Annotated[
        int,
        typer.Option(
            "--max-concurrency",
            "-c",
            min=1,
            show_default=True,
            help="Maximum number of concurrent downloads.",
        ),
    ] = 4,
    timeout: Annotated[
        float,
        typer.Option(
            "--timeout",
            min=1.0,
            show_default=True,
            help="Request timeout in seconds.",
        ),
    ] = 600.0,
    dry_run: Annotated[
        bool,
        typer.Option(
            "--dry-run/--no-dry-run",
            show_default=True,
            help="Preview downloads and README rewrites without performing any changes.",
        ),
    ] = False,
    skip_existing: Annotated[
        bool,
        typer.Option(
            "--skip-existing/--no-skip-existing",
            show_default=True,
            help="Skip downloading files that already exist locally.",
        ),
    ] = True,
    use_staging: Annotated[
        bool,
        typer.Option(
            "--stage/--no-stage",
            show_default=True,
            help="Download to a temporary staging directory first, then move to final destination.",
        ),
    ] = False,
    clean_invalid: Annotated[
        bool,
        typer.Option(
            "--clean-invalid",
            help="Delete files with incorrect sizes but don't download. Useful for cleaning up failed downloads.",
        ),
    ] = False,
) -> None:
    front_matter_text, body_text = read_front_matter(readme_path)
    entries = load_data_file_entries(front_matter_text)
    if not entries:
        logger.warning("No data_files entries found in README front matter.")
        raise typer.Exit(code=0)

    logger.info(f"Found {len(entries)} data file URLs across {readme_path}.")
    output_dir = output_dir.resolve()

    if clean_invalid:
        # Fetch remote file sizes
        logger.info("Fetching remote file sizes to check for invalid files...")
        remote_sizes = asyncio.run(
            fetch_remote_sizes(
                entries=entries,
                max_concurrency=max_concurrency,
                timeout=timeout,
            )
        )

        # Check and delete invalid files
        deleted = 0
        skipped = 0
        missing = 0
        size_unknown = 0

        table = Table(title="Cleaning invalid files")
        table.add_column("Config")
        table.add_column("File")
        table.add_column("Status")
        table.add_column("Local size")
        table.add_column("Remote size")

        for entry in entries:
            destination = resolve_destination(entry, output_dir)
            _, remote_path = entry.parsed()
            filename = Path(remote_path).name or remote_path

            if not destination.exists():
                missing += 1
                table.add_row(
                    entry.config_name,
                    filename,
                    "[dim]Not found[/dim]",
                    "-",
                    "-",
                )
                continue

            local_size = destination.stat().st_size
            remote_size = remote_sizes.get(entry.url)

            if not remote_size:
                size_unknown += 1
                table.add_row(
                    entry.config_name,
                    filename,
                    "[cyan]Skipped (remote size unknown)[/cyan]",
                    f"{local_size:,}",
                    "Unknown",
                )
                continue

            if local_size == remote_size:
                skipped += 1
                table.add_row(
                    entry.config_name,
                    filename,
                    "[green]Valid[/green]",
                    f"{local_size:,}",
                    f"{remote_size:,}",
                )
            else:
                # Size mismatch - delete the file
                destination.unlink()
                deleted += 1
                logger.warning(
                    f"Deleted {destination} (size mismatch: {local_size:,} != {remote_size:,})"
                )
                table.add_row(
                    entry.config_name,
                    filename,
                    "[red]Deleted (size mismatch)[/red]",
                    f"{local_size:,}",
                    f"{remote_size:,}",
                )

        console.print(table)
        logger.info(
            f"Summary: {deleted} deleted, {skipped} valid, {missing} missing, {size_unknown} unknown size"
        )
        return

    if dry_run:
        # Fetch remote file sizes
        logger.info("Fetching remote file sizes for dry-run preview...")
        remote_sizes = asyncio.run(
            fetch_remote_sizes(
                entries=entries,
                max_concurrency=max_concurrency,
                timeout=timeout,
            )
        )

        preview = Table(title="Download plan (dry-run)")
        preview.add_column("Config")
        preview.add_column("Local file", overflow="fold")
        preview.add_column("Status")
        preview.add_column("Local size")
        preview.add_column("Remote size")
        preview.add_column("Source URL", overflow="fold")

        for order, entry in enumerate(entries):
            destination = resolve_destination(entry, output_dir)
            try:
                relative = destination.relative_to(output_dir)
            except ValueError:
                relative = Path(destination)

            # Check local file
            local_exists = destination.exists()
            local_size = destination.stat().st_size if local_exists else None
            remote_size = remote_sizes.get(entry.url)

            # Determine status
            if not local_exists:
                status = "[yellow]Will download[/yellow]"
                local_size_str = "-"
            elif not skip_existing:
                status = "[red]Will overwrite[/red]"
                local_size_str = f"{local_size:,}"
            elif remote_size and local_size == remote_size:
                status = "[green]Will skip (exists)[/green]"
                local_size_str = f"{local_size:,}"
            elif not remote_size:
                status = "[cyan]Will skip (exists, size unknown)[/cyan]"
                local_size_str = f"{local_size:,}"
            else:
                # skip_existing=True but sizes don't match
                status = "[red]Will overwrite (size mismatch)[/red]"
                local_size_str = f"{local_size:,}"

            remote_size_str = f"{remote_size:,}" if remote_size else "Unknown"

            row_data = [
                entry.config_name,
                relative.as_posix(),
                status,
                local_size_str,
                remote_size_str,
                entry.url,
            ]

            preview.add_row(*row_data)

        console.print(preview)

        # Summary statistics
        will_download = 0
        will_skip = 0
        will_overwrite = 0

        for entry in entries:
            dest = resolve_destination(entry, output_dir)
            local_exists = dest.exists()
            local_size = dest.stat().st_size if local_exists else None
            remote_size = remote_sizes.get(entry.url)

            if not local_exists:
                will_download += 1
            elif not skip_existing:
                will_overwrite += 1
            elif remote_size and local_size == remote_size:
                will_skip += 1
            elif not remote_size:
                will_skip += 1
            else:
                will_overwrite += 1

        logger.info(
            f"Summary: {will_download} new, {will_skip} will skip, {will_overwrite} will overwrite"
        )
        logger.info("Dry run: no files downloaded and README left unchanged.")
        return

    output_dir.mkdir(parents=True, exist_ok=True)

    results = asyncio.run(
        perform_downloads(
            entries=entries,
            output_dir=output_dir,
            max_concurrency=max_concurrency,
            timeout=timeout,
            skip_existing=skip_existing,
            use_staging=use_staging,
        )
    )

    successes = sum(1 for item in results if item.success)
    failures = len(results) - successes
    skipped = sum(1 for item in results if item.skipped)
    logger.info(f"{successes} succeeded, {failures} failed, {skipped} skipped.")

    if failures:
        for item in results:
            if not item.success:
                logger.error(f"Error: {item.entry.url} -> {item.error}")
        raise typer.Exit(code=1)


@app.command()
def rewrite(
    output_dir: Annotated[
        Path,
        typer.Option(
            "--output-dir",
            "-o",
            help="Directory where downloaded files are stored.",
            resolve_path=True,
        ),
    ],
    base_url: Annotated[
        str,
        typer.Option(
            "--base-url",
            "-u",
            help=(
                "Base URL for rewriting URLs in README. Files under output_dir will be rewritten "
                "to use this base URL. Example: if output_dir=/data/files and base_url=https://example.com/dataset, "
                "then /data/files/particles/file.parquet becomes https://example.com/dataset/particles/file.parquet"
            ),
        ),
    ],
    readme_path: Annotated[
        Path,
        typer.Option(
            "--readme-path",
            "-r",
            help="Path to the README file with YAML front matter.",
            exists=True,
            resolve_path=True,
            dir_okay=False,
        ),
    ] = Path("README.md"),
    dry_run: Annotated[
        bool,
        typer.Option(
            "--dry-run/--no-dry-run",
            show_default=True,
            help="Preview URL rewrites without modifying the README.",
        ),
    ] = False,
    skip_missing: Annotated[
        bool,
        typer.Option(
            "--skip-missing/--no-skip-missing",
            show_default=True,
            help="Skip rewriting URLs for files that don't exist locally.",
        ),
    ] = True,
) -> None:
    """Rewrite URLs in README to point to local files served at a base URL."""
    front_matter_text, body_text = read_front_matter(readme_path)
    entries = load_data_file_entries(front_matter_text)
    if not entries:
        logger.warning("No data_files entries found in README front matter.")
        raise typer.Exit(code=0)

    logger.info(f"Found {len(entries)} data file URLs in {readme_path}.")
    output_dir = output_dir.resolve()

    # Build list of results for files that exist
    results: List[DownloadResult] = []
    missing_files = []

    for order, entry in enumerate(entries):
        destination = resolve_destination(entry, output_dir)
        if destination.exists():
            results.append(
                DownloadResult(
                    entry=entry,
                    path=destination,
                    success=True,
                    skipped=False,
                    order=order,
                )
            )
        else:
            missing_files.append((entry, destination))

    if missing_files:
        if not skip_missing:
            logger.error(f"Found {len(missing_files)} missing files:")
            for entry, dest in missing_files:
                logger.error(f"  {entry.config_name}: {dest}")
            logger.error(
                "Use --skip-missing to rewrite URLs only for existing files, "
                "or download the missing files first."
            )
            raise typer.Exit(code=1)
        else:
            logger.warning(
                f"Skipping {len(missing_files)} missing files "
                f"(rewriting {len(results)} existing files)"
            )

    if not results:
        logger.error("No files found to rewrite URLs for.")
        raise typer.Exit(code=1)

    # Preview or perform rewrite
    table = Table(title="URL rewrite preview" if dry_run else "README URL updates")
    table.add_column("Config")
    table.add_column("Local file", overflow="fold")
    table.add_column("Old URL", overflow="fold")
    table.add_column("New URL", overflow="fold")

    replacements: list[tuple[DownloadResult, str]] = []
    for result in results:
        relative_path = result.path.relative_to(output_dir)
        new_url = build_rewritten_url(result, output_dir, base_url)
        replacements.append((result, new_url))
        table.add_row(
            result.entry.config_name,
            relative_path.as_posix(),
            result.entry.url,
            new_url,
        )

    console.print(table)

    if dry_run:
        logger.info(
            f"Dry run: would rewrite {len(results)} URLs. "
            "Remove --dry-run to apply changes."
        )
        return

    # Apply rewrites
    updated_front = front_matter_text
    for result, new_url in replacements:
        updated_front = replace_once(updated_front, result.entry.url, new_url)

    readme_path.write_text(f"---\n{updated_front}\n---\n{body_text}", encoding="utf-8")
    logger.info(f"Successfully rewrote {len(results)} URLs in {readme_path}")


@app.command()
def verify(
    readme_path: Annotated[
        Path,
        typer.Option(
            "--readme-path",
            "-r",
            help="Path to the README file with YAML front matter.",
            exists=True,
            resolve_path=True,
            dir_okay=False,
        ),
    ] = Path("README.md"),
    max_concurrency: Annotated[
        int,
        typer.Option(
            "--max-concurrency",
            "-c",
            min=1,
            show_default=True,
            help="Maximum concurrent verification requests.",
        ),
    ] = 8,
    timeout: Annotated[
        float,
        typer.Option(
            "--timeout",
            min=1.0,
            show_default=True,
            help="Request timeout in seconds.",
        ),
    ] = 60.0,
) -> None:
    front_matter_text, _ = read_front_matter(readme_path)
    entries = load_data_file_entries(front_matter_text)
    if not entries:
        logger.warning("No data_files entries found in README front matter.")
        raise typer.Exit(code=0)

    logger.info(f"Verifying {len(entries)} URLs from {readme_path}.")
    results = asyncio.run(
        perform_verification(
            entries=entries,
            max_concurrency=max_concurrency,
            timeout=timeout,
        )
    )

    table = Table(title="URL verification results")
    table.add_column("Config")
    table.add_column("Status")
    table.add_column("Detail", overflow="fold")
    failed = 0
    for result in sorted(results, key=lambda r: (not r.ok, r.order)):
        status_text = str(result.status) if result.status is not None else "-"
        if result.ok:
            table.add_row(
                result.entry.config_name,
                f"[green]{status_text}[/green]",
                result.entry.url,
            )
        else:
            failed += 1
            detail = result.detail or result.entry.url
            table.add_row(
                result.entry.config_name,
                f"[red]{status_text}[/red]",
                f"{result.entry.url}\n{detail}",
            )

    console.print(table)
    if failed:
        logger.error(f"{failed} URLs failed verification.")
        raise typer.Exit(code=1)
    logger.info("All URLs verified successfully.")


@app.command()
def checksum(
    readme_path: Annotated[
        Path,
        typer.Option(
            "--readme-path",
            "-r",
            help="Path to the README file with YAML front matter.",
            exists=True,
            resolve_path=True,
            dir_okay=False,
        ),
    ] = Path("README.md"),
    checksum_dir: Annotated[
        Path,
        typer.Option(
            "--checksum-dir",
            "-d",
            help="Directory containing SHA256 checksum files (one per config).",
            resolve_path=True,
        ),
    ] = Path("checksums"),
    max_concurrency: Annotated[
        int,
        typer.Option(
            "--max-concurrency",
            "-c",
            min=1,
            show_default=True,
            help="Maximum concurrent checksum operations.",
        ),
    ] = 8,
    timeout: Annotated[
        float,
        typer.Option(
            "--timeout",
            min=1.0,
            show_default=True,
            help="Request timeout in seconds.",
        ),
    ] = 300.0,
    generate: Annotated[
        bool,
        typer.Option(
            "--generate",
            help="Generate/update checksum files with current remote file checksums.",
        ),
    ] = False,
    update_mismatches: Annotated[
        bool,
        typer.Option(
            "--update-mismatches",
            help="Update checksum files with new hashes for files that don't match.",
        ),
    ] = False,
) -> None:
    """Verify file integrity using SHA256 checksums."""
    front_matter_text, _ = read_front_matter(readme_path)
    entries = load_data_file_entries(front_matter_text)
    if not entries:
        logger.warning("No data_files entries found in README front matter.")
        raise typer.Exit(code=0)

    logger.info(f"Computing checksums for {len(entries)} files from {readme_path}.")

    # Get unique config names
    config_names = sorted(set(entry.config_name for entry in entries))

    # Load existing hashes per config unless we're regenerating
    expected_hashes_by_config: Dict[str, Dict[str, str]] = {}
    if not generate:
        for config_name in config_names:
            expected_hashes_by_config[config_name] = load_checksums_for_config(
                checksum_dir, config_name
            )

    # Compute checksums
    results = asyncio.run(
        perform_checksum_verification(
            entries=entries,
            expected_hashes_by_config=expected_hashes_by_config,
            max_concurrency=max_concurrency,
            timeout=timeout,
        )
    )

    # Display results
    table = Table(title="Checksum verification results")
    table.add_column("Config")
    table.add_column("Filename")
    table.add_column("Status")
    table.add_column("SHA256", overflow="fold")

    failed = 0
    mismatched = 0
    # new_hashes_by_config: config_name -> (filename -> hash)
    new_hashes_by_config: Dict[str, Dict[str, str]] = {}

    for result in results:
        if not result.success:
            failed += 1
            error_msg = str(result.error) if result.error else "Unknown error"
            table.add_row(
                result.entry.config_name,
                result.filename,
                "[red]ERROR[/red]",
                error_msg,
            )
        elif generate:
            # In generate mode, just collect all hashes
            if result.entry.config_name not in new_hashes_by_config:
                new_hashes_by_config[result.entry.config_name] = {}
            new_hashes_by_config[result.entry.config_name][result.filename] = (
                result.computed_hash or ""
            )
            table.add_row(
                result.entry.config_name,
                result.filename,
                "[cyan]COMPUTED[/cyan]",
                result.computed_hash or "-",
            )
        elif result.expected_hash is None:
            # No expected hash available
            table.add_row(
                result.entry.config_name,
                result.filename,
                "[yellow]NEW[/yellow]",
                result.computed_hash or "-",
            )
            if update_mismatches and result.computed_hash:
                if result.entry.config_name not in new_hashes_by_config:
                    new_hashes_by_config[result.entry.config_name] = {}
                new_hashes_by_config[result.entry.config_name][
                    result.filename
                ] = result.computed_hash
        elif result.matches:
            # Hash matches
            table.add_row(
                result.entry.config_name,
                result.filename,
                "[green]OK[/green]",
                result.computed_hash or "-",
            )
        else:
            # Hash mismatch
            mismatched += 1
            table.add_row(
                result.entry.config_name,
                result.filename,
                "[red]MISMATCH[/red]",
                f"Expected: {result.expected_hash}\nComputed: {result.computed_hash}",
            )
            if update_mismatches and result.computed_hash:
                if result.entry.config_name not in new_hashes_by_config:
                    new_hashes_by_config[result.entry.config_name] = {}
                new_hashes_by_config[result.entry.config_name][
                    result.filename
                ] = result.computed_hash

    console.print(table)

    # Handle checksum file updates
    if generate:
        total_saved = 0
        for config_name, file_hashes in new_hashes_by_config.items():
            save_checksums_for_config(checksum_dir, config_name, file_hashes)
            total_saved += len(file_hashes)
        logger.info(
            f"Generated {len(new_hashes_by_config)} checksum files with {total_saved} total checksums."
        )
    elif update_mismatches and new_hashes_by_config:
        total_updated = 0
        for config_name, new_file_hashes in new_hashes_by_config.items():
            # Merge with existing hashes for this config
            all_hashes = load_checksums_for_config(checksum_dir, config_name)
            all_hashes.update(new_file_hashes)
            save_checksums_for_config(checksum_dir, config_name, all_hashes)
            total_updated += len(new_file_hashes)
        logger.warning(
            f"Updated {total_updated} checksums across {len(new_hashes_by_config)} checksum files."
        )

    # Exit with appropriate code
    if failed:
        logger.error(f"{failed} files failed checksum computation.")
        raise typer.Exit(code=1)
    if mismatched and not update_mismatches:
        logger.error(f"{mismatched} files have checksum mismatches.")
        logger.warning("Use --update-mismatches to update the checksum files.")
        raise typer.Exit(code=1)
    if not generate and not mismatched and not failed:
        logger.info("All checksums verified successfully.")


def clean_arrow_type(type_str: str) -> str:
    """Clean up Arrow type string for display."""
    # Remove "element: " from list types
    # Pattern: list<element: TYPE> -> list<TYPE>
    cleaned = re.sub(r"list<element:\s*", "list<", type_str)
    return cleaned


def escape_latex(text: str) -> str:
    """Escape special LaTeX characters."""
    # Map of characters to escape
    replacements = {
        "\\": r"\\",  # Backslash must be first to avoid double-escaping
        "&": r"\&",
        "%": r"\%",
        "$": r"\$",
        "#": r"\#",
        "_": r"\_",
        "{": r"\{",
        "}": r"\}",
        "~": r"\textasciitilde{}",
        "^": r"\^{}",
    }
    for char, escaped in replacements.items():
        text = text.replace(char, escaped)
    return text


async def inspect_file_schema(
    entry: DataFileEntry,
    session: aiohttp.ClientSession,
    semaphore: asyncio.Semaphore,
    progress: Progress,
) -> SchemaInfo:
    """Download file and extract schema information using PyArrow."""
    _, remote_path = entry.parsed()
    filename = Path(remote_path).name or remote_path
    terse_name = (filename[:32] + "…") if len(filename) > 33 else filename
    description = f"{entry.config_name}: {terse_name}"

    async with semaphore:
        task_id: int | None = None
        temp_file = None
        try:
            task_id = progress.add_task(description, total=0, start=False)
            progress.start_task(task_id)

            # Download to temporary file
            async with session.get(entry.url) as response:
                response.raise_for_status()
                total_bytes = response.content_length or 0

                if total_bytes:
                    progress.update(task_id, total=total_bytes)

                with tempfile.NamedTemporaryFile(delete=False, suffix=".parquet") as f:
                    temp_file = Path(f.name)
                    async for chunk in response.content.iter_chunked(1 << 17):
                        f.write(chunk)
                        progress.update(task_id, advance=len(chunk))

                    # Read schema with PyArrow
                    parquet_file = pq.read_table(temp_file)
                    schema = parquet_file.schema

            columns = [
                (field.name, clean_arrow_type(str(field.type))) for field in schema
            ]
            num_rows = len(parquet_file)

            return SchemaInfo(
                config_name=entry.config_name,
                filename=filename,
                columns=columns,
                num_rows=num_rows,
                success=True,
            )

        except Exception as exc:  # noqa: BLE001
            return SchemaInfo(
                config_name=entry.config_name,
                filename=filename,
                columns=[],
                num_rows=None,
                success=False,
                error=exc,
            )
        finally:
            if task_id is not None:
                progress.remove_task(task_id)
            # Clean up temp file
            if temp_file and temp_file.exists():
                temp_file.unlink()


async def perform_schema_inspection(
    entries: Sequence[DataFileEntry],
    max_concurrency: int,
    timeout: float,
) -> List[SchemaInfo]:
    """Download first file from each config and inspect schema."""
    if not entries:
        return []

    semaphore = asyncio.Semaphore(max_concurrency)
    timeout_cfg = aiohttp.ClientTimeout(total=timeout)
    results: List[SchemaInfo] = []
    progress = Progress(
        TextColumn("{task.description}"),
        BarColumn(bar_width=None),
        DownloadColumn(),
        TransferSpeedColumn(),
        TimeElapsedColumn(),
        console=console,
    )

    async with aiohttp.ClientSession(timeout=timeout_cfg) as session:
        with progress:
            tasks = [
                asyncio.create_task(
                    inspect_file_schema(entry, session, semaphore, progress)
                )
                for entry in entries
            ]
            for future in asyncio.as_completed(tasks):
                result = await future
                results.append(result)

    # Sort by config name for consistent output
    results.sort(key=lambda r: r.config_name)
    return results


@app.command()
def schema(
    readme_path: Annotated[
        Path,
        typer.Option(
            "--readme-path",
            "-r",
            help="Path to the README file with YAML front matter.",
            exists=True,
            resolve_path=True,
            dir_okay=False,
        ),
    ] = Path("README.md"),
    output_file: Annotated[
        Path | None,
        typer.Option(
            "--output-file",
            "-o",
            help="Write schema information to plain text file.",
            resolve_path=True,
            dir_okay=False,
        ),
    ] = None,
    latex: Annotated[
        bool,
        typer.Option(
            "--latex",
            help="Output schema in LaTeX format (requires --output-file).",
        ),
    ] = False,
    max_concurrency: Annotated[
        int,
        typer.Option(
            "--max-concurrency",
            "-c",
            min=1,
            show_default=True,
            help="Maximum concurrent downloads.",
        ),
    ] = 4,
    timeout: Annotated[
        float,
        typer.Option(
            "--timeout",
            min=1.0,
            show_default=True,
            help="Request timeout in seconds.",
        ),
    ] = 300.0,
    types: Annotated[bool, typer.Option(help="Add column type info")] = True,
) -> None:
    """Inspect schema of first file from each dataset config."""
    # Validate options
    if latex and not output_file:
        logger.error("--latex requires --output-file to be specified.")
        raise typer.Exit(code=1)

    front_matter_text, _ = read_front_matter(readme_path)
    entries = load_data_file_entries(front_matter_text)
    if not entries:
        logger.warning("No data_files entries found in README front matter.")
        raise typer.Exit(code=0)

    # Get first file from each config
    configs_seen = set()
    first_files = []
    for entry in entries:
        if entry.config_name not in configs_seen:
            first_files.append(entry)
            configs_seen.add(entry.config_name)

    logger.info(f"Inspecting schema for {len(first_files)} configs.")

    # Perform schema inspection
    results = asyncio.run(
        perform_schema_inspection(
            entries=first_files,
            max_concurrency=max_concurrency,
            timeout=timeout,
        )
    )

    # Display results
    failed = 0
    text_output_lines = []
    latex_items = []

    for result in results:
        if not result.success:
            failed += 1
            error_msg = str(result.error) if result.error else "Unknown error"
            logger.error(
                f"Failed to inspect {result.config_name}/{result.filename}: {error_msg}"
            )
            continue

        # Prepare output file content
        if output_file:
            if latex:
                # LaTeX format: \item \textbf{CONFIG}: \texttt{col1} (\texttt{type1}), ...
                escaped_config = escape_latex(result.config_name)
                column_parts = []
                for col_name, col_type in result.columns:
                    escaped_col = escape_latex(col_name)
                    escaped_type = escape_latex(col_type)
                    part = f"\\texttt{{{escaped_col}}}"
                    if types:
                        part += f" (\\texttt{{{escaped_type}}})"
                    column_parts.append(part)
                columns_str = ", ".join(column_parts)
                latex_items.append(
                    f"\\item \\textbf{{{escaped_config}}}: {columns_str}"
                )
            else:
                # Plain text format
                text_output_lines.append(f"# {result.config_name} — {result.filename}")
                if result.num_rows is not None:
                    text_output_lines.append(
                        f"# {len(result.columns)} columns, {result.num_rows:,} rows"
                    )
                text_output_lines.append("")
                for col_name, col_type in result.columns:
                    text_output_lines.append(f"{col_name}: {col_type}")
                text_output_lines.append("")

        # Create table for console display
        table = Table(title=f"[bold]{result.config_name}[/bold] — {result.filename}")
        table.add_column("Column", style="cyan")
        table.add_column("Type", style="yellow")

        for col_name, col_type in result.columns:
            table.add_row(col_name, col_type)

        console.print(table)
        if result.num_rows is not None:
            logger.info(
                f"{result.config_name}: {len(result.columns)} columns, {result.num_rows:,} rows"
            )
        console.print()  # Empty line between configs

    # Write to output file if specified
    if output_file:
        if latex and latex_items:
            latex_content = (
                "\\begin{itemize}\n" + "\n".join(latex_items) + "\n\\end{itemize}"
            )
            output_file.write_text(latex_content, encoding="utf-8")
            logger.info(f"Wrote LaTeX schema to {output_file}")
        elif text_output_lines:
            output_file.write_text("\n".join(text_output_lines), encoding="utf-8")
            logger.info(f"Wrote schema information to {output_file}")

    if failed:
        logger.error(f"{failed} configs failed schema inspection.")
        raise typer.Exit(code=1)
    logger.info("Schema inspection completed successfully.")


if __name__ == "__main__":
    app()