"""Scan command implementation."""

from pathlib import Path
from typing import Optional

import click

from vlm.context import CLIContext
from vlm.scanner import load_inventory_csv, save_inventory_csv, scan_library
from vlm.utils import format_size


def scan_cmd(
    ctx: CLIContext,
    output: Path,
    metadata: bool,
    reuse_from: Optional[Path],
    force_refresh_metadata: bool,
) -> None:
    """Run scan: discover video files and save inventory."""
    config = ctx.config
    logger = ctx.logger

    click.echo(f"Scanning library at: {config.library_root}")
    click.echo("This may take a while for large libraries...")
    click.echo()

    progress_state: dict[str, Optional[click.ProgressBar]] = {"bar": None}
    progress_position = {"current": 0}

    def _scan_progress(processed: int, total: int) -> None:
        if total <= 0:
            return
        if progress_state["bar"] is None:
            bar = click.progressbar(
                length=total,
                label="Scanning files",
                show_pos=True,
            )
            progress_state["bar"] = bar.__enter__()
        step = processed - progress_position["current"]
        if step > 0 and progress_state["bar"] is not None:
            progress_state["bar"].update(step)
            progress_position["current"] = processed

    metadata_cache = None
    cache_source = None
    if not force_refresh_metadata:
        cache_source = reuse_from if reuse_from is not None else (output if output.exists() else None)

    if metadata and force_refresh_metadata:
        click.echo("Forcing metadata refresh for all files (cache disabled).")
        click.echo()

    if metadata and cache_source is not None:
        click.echo(f"Loading metadata cache from: {cache_source}")
        try:
            cached_files = load_inventory_csv(cache_source)
            metadata_cache = {str(vf.path): vf for vf in cached_files}
            click.echo(f"Loaded metadata cache entries: {len(metadata_cache)}")
            click.echo()
        except Exception as e:
            click.echo(f"Warning: could not load metadata cache: {e}")
            click.echo("Continuing without cache.")
            click.echo()

    try:
        video_files = scan_library(
            config.library_root,
            config,
            progress_callback=_scan_progress,
            include_video_metadata=metadata,
            metadata_cache=metadata_cache,
        )
    finally:
        if progress_state["bar"] is not None:
            progress_state["bar"].__exit__(None, None, None)
            click.echo()

    click.echo("Scan complete!")
    click.echo(f"  Total files found: {len(video_files)}")
    categories = {}
    total_size = 0
    for vf in video_files:
        categories[vf.category] = categories.get(vf.category, 0) + 1
        total_size += vf.size_bytes
    click.echo(f"  Total size: {format_size(total_size)}")
    click.echo()
    click.echo("Files by category:")
    for category in sorted(categories.keys()):
        click.echo(f"  {category}: {categories[category]}")
    click.echo()
    click.echo(f"Saving inventory to: {output}")
    save_inventory_csv(video_files, output, config.library_root)
    click.echo("Inventory saved successfully!")
    logger.info(f"Scan completed: {len(video_files)} files found, saved to {output}")