flow-pixl 0.1.6

mod cli;
#[cfg(feature = "view")]
mod tui;

use std::io::IsTerminal;
use std::path::{Path, PathBuf};

use anyhow::{Context, Result};
use clap::Parser;
use cli::{Cli, Command, GenerateArgs, ModelsCmd, PixelizeArgs};
use image::imageops::FilterType;
use pixl_pixelize::{pixelize, PixelizeParams};

fn main() -> Result<()> {
    let cli = Cli::parse();
    match cli.command {
        Some(Command::Pixelize(args)) => run_pixelize(args),
        Some(Command::Models { action }) => run_models(action),
        Some(Command::Gen(args)) => run_generate(args),
        Some(Command::View(args)) => run_view(args),
        None => run_generate(cli.generate),
    }
}

/// Lower this process to background priority (on macOS, equivalent to
/// `taskpolicy -b`) and cap the pixelize thread pool to one, so a batch stays out
/// of the way of the rest of the machine.
fn apply_low_priority() {
    let _ = rayon::ThreadPoolBuilder::new()
        .num_threads(1)
        .build_global();
    #[cfg(target_os = "macos")]
    unsafe {
        const PRIO_DARWIN_PROCESS: libc::c_int = 4;
        const PRIO_DARWIN_BG: libc::c_int = 0x1000;
        libc::setpriority(PRIO_DARWIN_PROCESS, 0, PRIO_DARWIN_BG);
    }
}

fn run_pixelize(args: PixelizeArgs) -> Result<()> {
    let multi = args.inputs.len() > 1;
    if multi {
        if let Some(out) = &args.out {
            std::fs::create_dir_all(out)
                .with_context(|| format!("creating output dir {}", out.display()))?;
        }
    }
    for input in &args.inputs {
        let img = image::open(input)
            .with_context(|| format!("opening {}", input.display()))?
            .to_rgba8();
        let params = PixelizeParams {
            pixel_size: args.pixel_size,
            target_cells: Some(args.target_cells),
            max_colors: args.colors,
            ..Default::default()
        };
        let (small, report) =
            pixelize(&img, &params).with_context(|| format!("pixelizing {}", input.display()))?;
        let out_img = if args.scale > 1 {
            image::imageops::resize(
                &small,
                small.width() * args.scale,
                small.height() * args.scale,
                FilterType::Nearest,
            )
        } else {
            small
        };
        let out_path = resolve_out(input, &args.out, multi);
        out_img
            .save(&out_path)
            .with_context(|| format!("saving {}", out_path.display()))?;
        println!(
            "{} -> {}  [{}x{} cells, {} colors, cell {:.1}px{}]",
            input.display(),
            out_path.display(),
            report.out_cells.0,
            report.out_cells.1,
            report.palette_len,
            report.detected_cell_px.0,
            if report.low_confidence {
                ", low-confidence grid"
            } else {
                ""
            },
        );
    }
    Ok(())
}

fn resolve_out(input: &Path, out: &Option<PathBuf>, multi: bool) -> PathBuf {
    let stem = input.file_stem().and_then(|s| s.to_str()).unwrap_or("out");
    match out {
        Some(p) if multi => p.join(format!("{stem}.png")),
        Some(p) => p.clone(),
        None => input.with_file_name(format!("{stem}.pixl.png")),
    }
}

const DEFAULT_COUNT: u32 = 4;

/// Resolve `[COUNT] PROMPT [OUT_DIR]`: a leading numeric arg is COUNT (default 4
/// when absent), the next is the prompt, the last is an optional output dir.
fn resolve_positionals(pos: &[String]) -> Result<(u32, String, Option<PathBuf>)> {
    match pos {
        [] => anyhow::bail!("missing PROMPT (usage: pixl [COUNT] <PROMPT> [OUT_DIR])"),
        [a] => {
            if a.parse::<u32>().is_ok() {
                anyhow::bail!("missing PROMPT (got only a count)");
            }
            Ok((DEFAULT_COUNT, a.clone(), None))
        }
        [a, b] => {
            if let Ok(n) = a.parse::<u32>() {
                Ok((n, b.clone(), None))
            } else {
                Ok((DEFAULT_COUNT, a.clone(), Some(PathBuf::from(b))))
            }
        }
        [a, b, c] => {
            let n = a
                .parse::<u32>()
                .map_err(|_| anyhow::anyhow!("COUNT must be a number, got {a:?}"))?;
            Ok((n, b.clone(), Some(PathBuf::from(c))))
        }
        _ => anyhow::bail!("too many positional arguments (expected [COUNT] <PROMPT> [OUT_DIR])"),
    }
}

fn run_generate(args: GenerateArgs) -> Result<()> {
    if args.low_prio {
        apply_low_priority();
    }
    let (count, prompt, out_dir) = resolve_positionals(&args.positional)?;
    let (w, h) = cli::parse_size(&args.size).map_err(anyhow::Error::msg)?;

    #[cfg(feature = "gen")]
    {
        if should_launch_gallery(&args) {
            let out = out_dir.clone().unwrap_or_else(|| default_out_dir(&prompt));
            let saved_dir = args
                .saved_dir
                .clone()
                .unwrap_or_else(tui::gallery::default_saved_dir);
            if tui::run_live(&prompt, count, out.clone(), w, h, &args, saved_dir)? {
                return Ok(());
            }
            return generate_metal(&prompt, count, Some(out), w, h, &args);
        }
        generate_metal(&prompt, count, out_dir, w, h, &args)
    }
    #[cfg(not(feature = "gen"))]
    {
        let _ = (w, h, count, &prompt, &out_dir);
        anyhow::bail!(
            "this build has no generation backend. Rebuild with --features gen (Metal on macOS, CPU elsewhere) or --features cuda (NVIDIA). `pixl pixelize <img>` works without it."
        )
    }
}

fn run_view(args: cli::ViewArgs) -> Result<()> {
    #[cfg(feature = "view")]
    {
        let saved_dir = args
            .saved_dir
            .clone()
            .unwrap_or_else(tui::gallery::default_saved_dir);
        tui::run_static(args.dir, saved_dir)
    }
    #[cfg(not(feature = "view"))]
    {
        let _ = args;
        anyhow::bail!("this build has no gallery; rebuild with --features view")
    }
}

#[cfg(feature = "gen")]
fn gallery_allowed(no_view: bool, json: bool, quiet: bool, is_tty: bool) -> bool {
    is_tty && !no_view && !json && !quiet
}

#[cfg(feature = "gen")]
fn should_launch_gallery(args: &GenerateArgs) -> bool {
    gallery_allowed(
        args.no_view,
        args.json,
        args.quiet,
        std::io::stdout().is_terminal(),
    )
}

#[cfg(feature = "gen")]
fn model_and_loras(args: &GenerateArgs) -> (pixl_gen::BaseModel, Vec<pixl_gen::LoraRef>) {
    use pixl_gen::{BaseModel, LoraRef};
    let model = match args.model {
        cli::ModelArg::Sdxl => BaseModel::Sdxl,
        cli::ModelArg::Turbo => BaseModel::SdxlTurbo,
    };
    let loras = if args.no_lora {
        Vec::new()
    } else {
        vec![LoraRef {
            repo: "nerijs/pixel-art-xl".into(),
            file: "pixel-art-xl.safetensors".into(),
            scale: args.lora_weight,
        }]
    };
    (model, loras)
}

#[cfg(feature = "gen")]
fn resolve_steps(args: &GenerateArgs) -> u32 {
    args.steps.unwrap_or(match args.model {
        cli::ModelArg::Sdxl => 25,
        cli::ModelArg::Turbo => 8,
    })
}

#[cfg(feature = "gen")]
fn resolve_cfg(args: &GenerateArgs) -> f32 {
    args.cfg.unwrap_or(match args.model {
        cli::ModelArg::Sdxl => 7.0,
        cli::ModelArg::Turbo => 1.0,
    })
}

#[cfg(feature = "gen")]
fn gen_params(args: &GenerateArgs) -> pixl_gen::GenParams {
    pixl_gen::GenParams {
        steps: resolve_steps(args),
        guidance: resolve_cfg(args),
        base_seed: args.seed,
    }
}

#[cfg(feature = "gen")]
fn push_fail(failures: &std::sync::Mutex<Vec<(usize, String)>>, i: usize, msg: String) {
    failures
        .lock()
        .unwrap_or_else(|e| e.into_inner())
        .push((i, msg));
}

#[cfg(feature = "gen")]
fn generate_metal(
    prompt: &str,
    count: u32,
    out_dir: Option<PathBuf>,
    w: u32,
    h: u32,
    args: &GenerateArgs,
) -> Result<()> {
    use indicatif::{MultiProgress, ProgressBar, ProgressDrawTarget, ProgressStyle};
    use pixl_gen::{BaseModel, CandleSdxlGenerator, GenImage, GenRequest, Generator};
    use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
    use std::sync::{Arc, Mutex};
    use std::time::{Duration, Instant};

    let out_dir = out_dir.unwrap_or_else(|| default_out_dir(prompt));
    std::fs::create_dir_all(&out_dir)
        .with_context(|| format!("creating output dir {}", out_dir.display()))?;
    if !args.quiet {
        eprintln!("{:<8} {}", "output", out_dir.display());
    }

    if !args.lora_weight.is_finite() {
        anyhow::bail!("--lora-weight must be a finite number");
    }
    let (model, loras) = model_and_loras(args);

    let (mut generator, report) = CandleSdxlGenerator::load(model, w, h, &loras, None)
        .map_err(|e| anyhow::anyhow!("loading generator: {e}"))?;

    if !args.quiet {
        eprintln!(
            "{:<8} {} ({})",
            "model",
            report.model,
            if report.weights_cached {
                "cached"
            } else {
                "fetched"
            }
        );
        if let Some((name, scale)) = &report.lora {
            eprintln!("{:<8} {name} @ {scale}", "lora");
        }
        match report.merge {
            pixl_gen::MergeState::Cached => eprintln!("{:<8} merged (cached)", "unet"),
            pixl_gen::MergeState::Merged(n) => eprintln!("{:<8} merged ({n} modules)", "unet"),
            pixl_gen::MergeState::None => {}
        }
        if args.no_lora && !args.no_postprocess {
            eprintln!("note: --no-lora produces a non-pixel-art image; the pixelize pass has no grid to snap (looks like noise). Drop --no-lora, or add --no-postprocess for the raw render.");
        }
        if resolve_cfg(args) > 1.0 && matches!(model, BaseModel::SdxlTurbo) {
            eprintln!("note: --cfg > 1 has no effect on SDXL-Turbo (CFG-distilled); use --model sdxl for guidance");
        }
    }

    let draw = if args.quiet {
        ProgressDrawTarget::hidden()
    } else {
        ProgressDrawTarget::stderr()
    };
    let mp = MultiProgress::with_draw_target(draw);
    let overall = mp.add(ProgressBar::new(count as u64));
    overall.set_style(
        ProgressStyle::with_template(
            "{prefix:>8.cyan.bold} [{bar:28.cyan/blue}] {pos}/{len} · {elapsed_precise} · eta {eta}",
        )
        .unwrap()
        .progress_chars("=> "),
    );
    overall.set_prefix("pixl");
    let gen_spin = mp.add(ProgressBar::new_spinner());
    gen_spin.enable_steady_tick(Duration::from_millis(100));
    gen_spin.set_style(ProgressStyle::with_template("{spinner:.green} {msg}").unwrap());

    let cur = Arc::new(AtomicUsize::new(0));
    {
        let spin = gen_spin.clone();
        let cur = cur.clone();
        generator.set_step_callback(Box::new(move |step, steps| {
            spin.set_message(format!(
                "image {}/{count} · diffusing {step}/{steps}",
                cur.load(Ordering::Relaxed) + 1
            ));
        }));
    }

    let cancel = Arc::new(AtomicBool::new(false));
    {
        let cancel = cancel.clone();
        let _ = ctrlc::set_handler(move || cancel.store(true, Ordering::Relaxed));
    }

    let req = GenRequest {
        prompt: prompt.to_string(),
        negative: args.negative.clone(),
        params: gen_params(args),
    };
    let slug = slugify(prompt);
    let jobs = if args.jobs > 0 {
        args.jobs
    } else {
        std::thread::available_parallelism()
            .map(|n| n.get().min(2))
            .unwrap_or(1)
    };

    let (tx, rx) = crossbeam_channel::bounded::<(usize, GenImage)>(jobs);
    let failures: Arc<Mutex<Vec<(usize, String)>>> = Arc::new(Mutex::new(Vec::new()));
    let saved = Arc::new(AtomicUsize::new(0));
    let abort = Arc::new(AtomicBool::new(false)); // fail-fast (distinct from Ctrl-C cancel)
    let started = Instant::now();

    std::thread::scope(|scope| {
        for _ in 0..jobs {
            let rx = rx.clone();
            let overall = overall.clone();
            let failures = failures.clone();
            let out_dir = out_dir.to_path_buf();
            let slug = slug.clone();
            let args = args.clone();
            let saved = saved.clone();
            scope.spawn(move || {
                for (i, gi) in rx.iter() {
                    let r = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
                        pixelize_and_save(gi, i, &out_dir, &slug, &args)
                    }));
                    match r {
                        Ok(Ok(s)) => {
                            saved.fetch_add(1, Ordering::Relaxed);
                            if args.json {
                                println!("{}", s.json(i));
                            }
                        }
                        Ok(Err(e)) => push_fail(&failures, i, e.to_string()),
                        Err(_) => push_fail(&failures, i, "panicked during pixelize/save".into()),
                    }
                    overall.inc(1);
                }
            });
        }
        drop(rx);

        for i in 0..count as usize {
            if cancel.load(Ordering::Relaxed) || abort.load(Ordering::Relaxed) {
                break;
            }
            cur.store(i, Ordering::Relaxed);
            match generator.generate(&req, i) {
                Ok(gi) => {
                    if tx.send((i, gi)).is_err() {
                        break;
                    }
                }
                Err(e) => {
                    push_fail(&failures, i, e.to_string());
                    if args.fail_fast {
                        abort.store(true, Ordering::Relaxed);
                        break;
                    }
                }
            }
        }
        drop(tx);
    });

    gen_spin.finish_and_clear();
    overall.finish_and_clear();

    let fails = failures.lock().unwrap_or_else(|e| e.into_inner());
    let ok = saved.load(Ordering::Relaxed);
    let cancelled = cancel.load(Ordering::Relaxed);
    if !args.quiet {
        let secs = started.elapsed().as_secs_f32();
        eprintln!(
            "{} {ok}/{count} saved · {secs:.1}s · {:.1}s/img{}{} -> {}",
            if fails.is_empty() && !cancelled {
                "✓"
            } else {
                "•"
            },
            if ok > 0 { secs / ok as f32 } else { 0.0 },
            if cancelled { " · cancelled" } else { "" },
            if fails.is_empty() {
                String::new()
            } else {
                format!(" · {} failed", fails.len())
            },
            out_dir.display(),
        );
        for (i, e) in fails.iter() {
            eprintln!("  image {i}: {e}");
        }
        if ok > 0 && std::io::stderr().is_terminal() {
            eprintln!("  {}", open_link(&out_dir));
        }
    }
    if cancelled {
        std::process::exit(130);
    }
    if !fails.is_empty() {
        anyhow::bail!("{} image(s) failed", fails.len());
    }
    Ok(())
}

/// One saved image's metadata, for JSON output and the gallery.
#[cfg(feature = "gen")]
pub(crate) struct Saved {
    pub path: PathBuf,
    pub seed: u64,
    pub cells: (u32, u32),
    pub colors: u16,
}

#[cfg(feature = "gen")]
impl Saved {
    fn json(&self, i: usize) -> String {
        serde_json::json!({
            "index": i,
            "seed": self.seed,
            "path": self.path.to_string_lossy(),
            "cells": [self.cells.0, self.cells.1],
            "colors": self.colors,
        })
        .to_string()
    }
}

/// Pixelize (unless disabled) + save one generated image.
#[cfg(feature = "gen")]
fn pixelize_and_save(
    gi: pixl_gen::GenImage,
    i: usize,
    out_dir: &Path,
    slug: &str,
    args: &GenerateArgs,
) -> Result<Saved> {
    let path = out_dir.join(format!("{slug}_{i:03}.png"));
    let (cells, colors) = if args.no_postprocess {
        gi.image
            .save(&path)
            .with_context(|| format!("saving {}", path.display()))?;
        ((gi.image.width(), gi.image.height()), 0u16)
    } else {
        let (out, report) = postprocess(&gi.image, args)?;
        out.save(&path)
            .with_context(|| format!("saving {}", path.display()))?;
        (report.out_cells, report.palette_len)
    };
    Ok(Saved {
        path,
        seed: gi.seed,
        cells,
        colors,
    })
}

#[cfg(feature = "gen")]
fn postprocess(
    img: &image::RgbImage,
    args: &GenerateArgs,
) -> Result<(image::RgbImage, pixl_pixelize::PixelizeReport)> {
    let (w, h) = img.dimensions();
    let rgba = image::RgbaImage::from_fn(w, h, |x, y| {
        let p = img.get_pixel(x, y).0;
        image::Rgba([p[0], p[1], p[2], 255])
    });
    let params = PixelizeParams {
        pixel_size: args.pixel_size,
        max_colors: args.colors,
        ..Default::default()
    };
    let (small, report) = pixelize(&rgba, &params)?;
    let scale = (512 / small.width().max(1)).max(1);
    let up = image::imageops::resize(
        &small,
        small.width() * scale,
        small.height() * scale,
        FilterType::Nearest,
    );
    Ok((up, report))
}

/// UTC `YYYYMMDD-HHMMSS` (civil date from days-since-epoch; no date crate).
#[cfg(feature = "gen")]
fn timestamp() -> String {
    let secs = std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .map(|d| d.as_secs())
        .unwrap_or(0);
    let days = (secs / 86400) as i64;
    let tod = secs % 86400;
    let (hh, mm, ss) = (tod / 3600, (tod % 3600) / 60, tod % 60);
    let z = days + 719468;
    let era = (if z >= 0 { z } else { z - 146096 }) / 146097;
    let doe = z - era * 146097;
    let yoe = (doe - doe / 1460 + doe / 36524 - doe / 146096) / 365;
    let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
    let mp = (5 * doy + 2) / 153;
    let d = doy - (153 * mp + 2) / 5 + 1;
    let m = if mp < 10 { mp + 3 } else { mp - 9 };
    let y = yoe + era * 400 + if m <= 2 { 1 } else { 0 };
    format!("{y:04}{m:02}{d:02}-{hh:02}{mm:02}{ss:02}")
}

/// First few prompt words as a dash-slug, capped to 40 chars.
#[cfg(feature = "gen")]
fn short_slug(prompt: &str) -> String {
    let mut out = String::new();
    let mut prev_dash = true;
    for c in prompt.chars() {
        if c.is_ascii_alphanumeric() {
            out.push(c.to_ascii_lowercase());
            prev_dash = false;
        } else if !prev_dash {
            out.push('-');
            prev_dash = true;
        }
        if out.len() >= 40 {
            break;
        }
    }
    let t = out.trim_matches('-').to_string();
    if t.is_empty() {
        "img".into()
    } else {
        t
    }
}

/// Default per-run output dir: `~/.pixl/<timestamp>-<prompt-words>`.
#[cfg(feature = "gen")]
fn default_out_dir(prompt: &str) -> PathBuf {
    std::env::var_os("HOME")
        .map(PathBuf::from)
        .unwrap_or_else(std::env::temp_dir)
        .join(".pixl")
        .join(format!("{}-{}", timestamp(), short_slug(prompt)))
}

/// An OSC-8 terminal hyperlink to `path` (clickable; opens the folder in Finder).
#[cfg(feature = "gen")]
fn open_link(path: &Path) -> String {
    let abs = std::fs::canonicalize(path).unwrap_or_else(|_| path.to_path_buf());
    let uri = format!("file://{}", abs.to_string_lossy().replace(' ', "%20"));
    let esc = char::from(0x1b);
    let bs = char::from(0x5c);
    format!(
        "open: {esc}]8;;{uri}{esc}{bs}{}{esc}]8;;{esc}{bs}",
        abs.display()
    )
}

#[cfg(feature = "gen")]
fn slugify(s: &str) -> String {
    let out: String = s
        .chars()
        .map(|c| {
            if c.is_ascii_alphanumeric() {
                c.to_ascii_lowercase()
            } else {
                '_'
            }
        })
        .collect();
    let trimmed = out[..out.len().min(40)].trim_matches('_').to_string();
    if trimmed.is_empty() {
        "img".into()
    } else {
        trimmed
    }
}

fn run_models(action: ModelsCmd) -> Result<()> {
    let merged = pixl_gen::merged_cache_dir();
    match action {
        ModelsCmd::Path => {
            println!("merged cache: {}", merged.display());
            println!("hf weights  : {}", pixl_gen::hf_cache_dir().display());
        }
        ModelsCmd::Ls => {
            let (files, total) = list_merged(&merged);
            println!("merged-LoRA cache ({}):", merged.display());
            if files.is_empty() {
                println!("  (empty)");
            } else {
                for (name, sz) in &files {
                    println!("  {:>9}  {name}", human(*sz));
                }
                println!("  {:>9}  total", human(total));
            }

            let hf = pixl_gen::hf_cache_dir();
            let mut models = dir_entries_by_size(&hf);
            let hf_total: u64 = models.iter().map(|(_, s)| s).sum();
            println!("hf weights cache ({}):", hf.display());
            if models.is_empty() {
                println!("  (empty)");
            } else {
                for (name, sz) in models.drain(..) {
                    let pretty = name
                        .strip_prefix("models--")
                        .map(|r| r.replace("--", "/"))
                        .unwrap_or(name);
                    println!("  {:>9}  {pretty}", human(sz));
                }
                println!("  {:>9}  total", human(hf_total));
            }
        }
        ModelsCmd::Clear { yes } => {
            let (files, total) = list_merged(&merged);
            if files.is_empty() {
                println!("nothing to clear ({})", merged.display());
                return Ok(());
            }
            // structural guard: the path must end in exactly .../pixl/merged and not be a symlink
            let tail: Vec<String> = merged
                .components()
                .rev()
                .take(2)
                .map(|c| c.as_os_str().to_string_lossy().into_owned())
                .collect();
            if tail != ["merged", "pixl"] {
                anyhow::bail!(
                    "refusing to clear unexpected cache path {}",
                    merged.display()
                );
            }
            if std::fs::symlink_metadata(&merged)
                .map(|m| m.file_type().is_symlink())
                .unwrap_or(false)
            {
                anyhow::bail!(
                    "cache path is a symlink, refusing to clear {}",
                    merged.display()
                );
            }
            if !yes {
                if !std::io::stdin().is_terminal() {
                    anyhow::bail!(
                        "not a terminal; pass --yes to clear {} ({})",
                        merged.display(),
                        human(total)
                    );
                }
                eprint!(
                    "delete {} merged file(s) ({}) from {}? [y/N] ",
                    files.len(),
                    human(total),
                    merged.display()
                );
                std::io::Write::flush(&mut std::io::stderr())?;
                let mut line = String::new();
                if std::io::stdin().read_line(&mut line).is_err()
                    || !line.trim().eq_ignore_ascii_case("y")
                {
                    println!("aborted");
                    return Ok(());
                }
            }
            // remove only the known cache files, then the now-empty dir
            for (name, _) in &files {
                let f = merged.join(name);
                std::fs::remove_file(&f).with_context(|| format!("removing {}", f.display()))?;
            }
            let _ = std::fs::remove_dir(&merged);
            println!("cleared {} ({})", human(total), merged.display());
        }
    }
    Ok(())
}

/// Top-level entries of `dir` with their on-disk size, largest first.
fn dir_entries_by_size(dir: &Path) -> Vec<(String, u64)> {
    let mut out = Vec::new();
    if let Ok(rd) = std::fs::read_dir(dir) {
        for e in rd.flatten() {
            out.push((
                e.file_name().to_string_lossy().into_owned(),
                dir_size(&e.path()),
            ));
        }
    }
    out.sort_by_key(|b| std::cmp::Reverse(b.1));
    out
}

/// Recursive on-disk size. Symlinks count as 0 so HF's snapshot symlinks-to-blobs
/// are not double-counted (the real bytes live once in `blobs/`).
fn dir_size(path: &Path) -> u64 {
    let md = match std::fs::symlink_metadata(path) {
        Ok(m) => m,
        Err(_) => return 0,
    };
    if md.file_type().is_symlink() {
        return 0;
    }
    if md.is_file() {
        return md.len();
    }
    let mut total = 0;
    if let Ok(rd) = std::fs::read_dir(path) {
        for e in rd.flatten() {
            total += dir_size(&e.path());
        }
    }
    total
}

fn list_merged(dir: &Path) -> (Vec<(String, u64)>, u64) {
    let mut out = Vec::new();
    let mut total = 0u64;
    if let Ok(rd) = std::fs::read_dir(dir) {
        for e in rd.flatten() {
            if let Ok(md) = e.metadata() {
                if md.is_file() {
                    total += md.len();
                    out.push((e.file_name().to_string_lossy().into_owned(), md.len()));
                }
            }
        }
    }
    out.sort();
    (out, total)
}

fn human(bytes: u64) -> String {
    const U: [&str; 5] = ["B", "KB", "MB", "GB", "TB"];
    let mut b = bytes as f64;
    let mut i = 0;
    while b >= 1024.0 && i < U.len() - 1 {
        b /= 1024.0;
        i += 1;
    }
    if i == 0 {
        format!("{bytes} B")
    } else {
        format!("{b:.1} {}", U[i])
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn r(v: &[&str]) -> (u32, String, Option<PathBuf>) {
        resolve_positionals(&v.iter().map(|s| s.to_string()).collect::<Vec<_>>()).unwrap()
    }

    #[test]
    fn resolves_optional_count() {
        assert_eq!(r(&["a cozy tavern"]), (4, "a cozy tavern".into(), None));
        assert_eq!(r(&["8", "tavern"]), (8, "tavern".into(), None));
        assert_eq!(
            r(&["tavern", "out"]),
            (4, "tavern".into(), Some(PathBuf::from("out")))
        );
        assert_eq!(
            r(&["8", "tavern", "out"]),
            (8, "tavern".into(), Some(PathBuf::from("out")))
        );
        assert!(resolve_positionals(&["8".to_string()]).is_err());
        assert!(resolve_positionals(&[]).is_err());
    }

    #[cfg(feature = "gen")]
    #[test]
    fn gallery_decision() {
        assert!(gallery_allowed(false, false, false, true));
        assert!(!gallery_allowed(false, false, false, false));
        assert!(!gallery_allowed(true, false, false, true));
        assert!(!gallery_allowed(false, true, false, true));
        assert!(!gallery_allowed(false, false, true, true));
    }
}