//! `lightcraft-cli`: headless LightCraft.
//!
//! ```text
//! lightcraft-cli run [--demo | --library DIR | --connect [ADDR]] [--import PATH]… CMD [key=value…]…
//! lightcraft-cli mcp [--connect [ADDR]] [--demo] [--compact] [FILES/FOLDERS…]
//! lightcraft-cli render <in> -o <out> [--set control=value]… [--settings FILE.json] [--preset ID] [--size N] [--quality Q]
//! lightcraft-cli snapshot [--library DIR | --demo] [--script FILE.jsonl] [-o OUT.png] [--size WxH] [--scale S] [FILES…]
//! lightcraft-cli merge hdr|panorama|hdr-panorama [OPTIONS] FILES…
//! lightcraft-cli synth-merge hdr|panorama -o DIR
//! lightcraft-cli commands [--json]
//! lightcraft-cli controls [--json]
//! lightcraft-cli calibrate [--max N] [--out DIR] FOLDERS/FILES…
//! ```
#![forbid(unsafe_code)]
#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]

mod alloc_release;

use std::io::{BufReader, Write};
use std::path::Path;
use std::process::ExitCode;

use lightcraft_engine::Session;
use lightcraft_mcp::{Backend, DEFAULT_ADDR, Headless, Remote, Server, expand_paths};
use serde_json::{Value, json};

const USAGE: &str = "\
lightcraft-cli — headless LightCraft (photo library + raw developer)

USAGE:
  lightcraft-cli run [OPTIONS] COMMAND [key=value | '{json}']… [COMMAND …]…
      Run one or more commands (ids from `commands`, or control-protocol methods such as
      engine.commands / ui.inspect / ui.screenshot) and print one JSON line per command:
      {\"command\", \"ok\", \"result\" | \"error\", \"ms\"}. A word without `=` starts the next
      command; values are JSON when they parse (1, true, [1,2], {…}), else strings. Exit status
      is non-zero when a command fails. Example:
        lightcraft-cli run --import ~/Photos/a.jpg develop.set control=light.exposure value=0.7 \\
            develop.auto app.export path=/tmp/a.jpg longEdge=1600
      Options:
        --demo            headless, the procedural demo library
        --library DIR     headless, open (or create) a LightCraft library; edits are saved
        --import PATH     headless, import a file or folder first (repeatable)
        --connect [ADDR]  drive the running app (`lightcraft --control 7980`; default 127.0.0.1:7980)
        --script FILE|-   also run JSON lines {\"command\": id, \"params\": {…}} (or {\"method\": …})
        --keep-going      continue after a failed command
  lightcraft-cli mcp [OPTIONS] [FILES/FOLDERS…]
      MCP server (JSON-RPC 2.0 over stdio). Headless by default: an in-process session with the
      given files imported. Options:
        --connect [ADDR]  drive a running app instead (`lightcraft --control 7980`; default 127.0.0.1:7980)
        --demo            headless: start with the procedurally generated demo library
        --library DIR     headless: open (or create) a persistent LightCraft library; edits are saved
        --compact         list only the helper tools (every command stays reachable via run_command)
  lightcraft-cli render <IN> -o <OUT> [OPTIONS]
      Develop one file and export it (.jpg, .png, .tif, .webp, .avif or .dng by extension) with the
      same encoder as the app's Export dialog. Options:
        --set CONTROL=VALUE  set a develop slider, repeatable (e.g. --set light.exposure=0.5)
        --settings FILE      merge a partial develop-settings JSON file
        --preset ID          apply a preset (see `commands`/presets.list)
        --size N             long edge in pixels (default: full size, cropped)
        --quality Q          JPEG/AVIF quality 1..100 (default 92)
        --opt KEY=VALUE      any export option of `app.export`, repeatable (VALUE is JSON or a
                             string), e.g. --opt colorSpace=displayP3 --opt bitDepth=16
                             --opt percent=50 --opt shortEdge=1080 --opt ppi=300
                             --opt format=original (copy + XMP sidecar) --opt metadata=none
  lightcraft-cli snapshot [OPTIONS] [FILES/FOLDERS…]
      Run the full app UI headlessly (no window, no GPU: CPU-rasterized egui) and write PNGs.
      Options:
        --demo            the procedural demo library (default unless --library or FILES)
        --library DIR     open (or create) a LightCraft library
        --script FILE     JSON-lines control-protocol requests (docs/control-protocol.md), one
                          per line: {\"method\": \"ui.set\", \"params\": {\"view\": \"detail\"}}.
                          Replies go to stdout. `ui.screenshot` without a path writes -o (then
                          OUT-2.png, OUT-3.png…); `ui.settle {timeoutMs?}` waits for renders.
                          A failed request (\"ok\": false) does not stop the script, but the exit
                          status is non-zero when any request failed.
        -o, --output OUT  PNG path (a final screenshot is written here if the script took none)
        --size WxH        window size in points (default 1600x1000)
        --scale S         pixels per point (default 1)
  lightcraft-cli merge hdr|panorama|hdr-panorama [OPTIONS] FILES…
      Photo Merge: writes <first>-HDR.dng / -Pano.dng / -HDR-Pano.dng next to the first file and
      prints the result as JSON. Options:
        --deghost none|low|medium|high   --no-align   --bracket N (HDR panorama)
        --projection auto|spherical|cylindrical|perspective   --boundary-warp 0..100
        --auto-crop   --fill-edges   --no-auto-settings
        --preview OUT.png   only render a ≤ 1024 px preview (nothing written next to the files)
  lightcraft-cli synth-merge hdr|panorama -o DIR
      Write synthetic merge inputs (procedural scene; bracketed DNGs or overlapping PNG views).
  lightcraft-cli commands [--json]   list every command id with its parameters
  lightcraft-cli controls [--json]   list every develop control id with its range
  lightcraft-cli calibrate [--max N] [--out DIR] FOLDERS/FILES…
      Fit a colour profile per camera model from raw files and their embedded camera JPEGs
      (Sony ARW, Nikon NEF): up to N files spread over the folders (default 300; 0 = all), pooled per
      model, written as <model>.json to DIR (default: the profiles folder LightCraft reads,
      <config>/camera-profiles, or $LIGHTCRAFT_CAMERA_PROFILES). Raws of a profiled model then
      take their colour from the profile and only their tone from their own JPEG.
  lightcraft-cli --version | --help
";

#[cfg(feature = "dhat-heap")]
#[global_allocator]
static ALLOC: dhat::Alloc = dhat::Alloc;

/// Why `--library DIR` can't be opened; for a library open in another program, how to work with
/// that one instead (issue #99).
fn library_error(dir: &str, e: lightcraft_engine::EngineError) -> String {
    match e {
        lightcraft_engine::EngineError::LibraryInUse(why) => format!(
            "{dir}: {why}\nTo work with the library while the app has it open, start the app with `--control PORT` and use `lightcraft-cli mcp --connect 127.0.0.1:PORT`."
        ),
        e => format!("{dir}: {e}"),
    }
}

fn main() -> ExitCode {
    // `--features dhat-heap`: count allocations; the profile is written when `_heap` drops
    // (LIGHTCRAFT_DHAT_FILE, default dhat-heap.json).
    #[cfg(feature = "dhat-heap")]
    let _heap = {
        let file = std::env::var("LIGHTCRAFT_DHAT_FILE").unwrap_or_else(|_| "dhat-heap.json".into());
        lightcraft_engine::memory::set_heap_stats(|| {
            let s = dhat::HeapStats::get();
            lightcraft_engine::memory::HeapUsage { current: s.curr_bytes as u64, peak: s.max_bytes as u64 }
        });
        dhat::Profiler::builder().file_name(file).build()
    };
    alloc_release::install();
    let args: Vec<String> = std::env::args().skip(1).collect();
    let r = match args.first().map(String::as_str) {
        Some("run") => run(&args[1..]),
        Some("mcp") => mcp(&args[1..]),
        Some("render") => render(&args[1..]),
        Some("snapshot") => snapshot(&args[1..]),
        Some("commands") => commands(&args[1..]),
        Some("merge") => merge(&args[1..]),
        Some("synth-merge") => synth_merge(&args[1..]),
        Some("controls") => controls(&args[1..]),
        Some("calibrate") => calibrate(&args[1..]),
        Some("--version" | "-V" | "version") => {
            println!("lightcraft-cli {}", env!("CARGO_PKG_VERSION"));
            Ok(())
        }
        Some("--help" | "-h" | "help") | None => {
            print!("{USAGE}");
            Ok(())
        }
        Some(other) => Err(format!("unknown subcommand `{other}`\n\n{USAGE}")),
    };
    match r {
        Ok(()) => ExitCode::SUCCESS,
        Err(e) => {
            eprintln!("lightcraft-cli: {e}");
            ExitCode::FAILURE
        }
    }
}

/// Raw files below `path` (or `path` itself), skipping hidden and NAS metadata folders.
fn raw_files(path: &Path, out: &mut Vec<std::path::PathBuf>, depth: usize) {
    let is_raw = |p: &Path| p.extension().and_then(|e| e.to_str()).is_some_and(|e| ["arw", "nef", "nrw"].iter().any(|x| e.eq_ignore_ascii_case(x)));
    if path.is_file() {
        if is_raw(path) {
            out.push(path.to_path_buf());
        }
        return;
    }
    let Ok(entries) = std::fs::read_dir(path) else { return };
    if depth > 32 {
        return;
    }
    for entry in entries.flatten() {
        let name = entry.file_name();
        if name.to_string_lossy().starts_with(['.', '@']) {
            continue;
        }
        raw_files(&entry.path(), out, depth + 1);
    }
}

fn calibrate(args: &[String]) -> Result<(), String> {
    let mut max = 300usize;
    let mut out: Option<std::path::PathBuf> = None;
    let mut inputs = Vec::new();
    let mut i = 0;
    while i < args.len() {
        match args[i].as_str() {
            "--max" => max = take_value(args, &mut i, "--max")?.parse().map_err(|_| "--max needs a number".to_string())?,
            "--out" => out = Some(take_value(args, &mut i, "--out")?.into()),
            a if a.starts_with("--") => return Err(format!("unknown option `{a}`")),
            f => inputs.push(f.to_string()),
        }
        i += 1;
    }
    if inputs.is_empty() {
        return Err("calibrate needs folders or raw files".into());
    }
    let mut files = Vec::new();
    for input in &inputs {
        raw_files(Path::new(input), &mut files, 0);
    }
    files.sort();
    files.dedup();
    let found = files.len();
    if max > 0 && files.len() > max {
        // spread over all folders (dates, scenes) rather than the first N
        files = (0..max).filter_map(|k| files.get(k * found / max).cloned()).collect();
    }
    eprintln!("calibrate: {} of {found} raw files", files.len());
    let dir = out.or_else(lightcraft_engine::camera_profiles::dir).ok_or("no profiles folder: pass --out DIR")?;
    let workers = std::thread::available_parallelism().map_or(4, |n| n.get()).clamp(1, 6);
    let next = std::sync::atomic::AtomicUsize::new(0);
    let done = std::sync::atomic::AtomicUsize::new(0);
    let pools: Vec<lightcraft_engine::camera_profiles::Pool> = std::thread::scope(|scope| {
        let handles: Vec<_> = (0..workers)
            .map(|_| {
                scope.spawn(|| {
                    let mut pool = lightcraft_engine::camera_profiles::Pool::default();
                    while let Some(path) = files.get(next.fetch_add(1, std::sync::atomic::Ordering::Relaxed)) {
                        let result = std::fs::read(path).map_err(|e| e.to_string()).and_then(|bytes| pool.add(&bytes));
                        let n = done.fetch_add(1, std::sync::atomic::Ordering::Relaxed) + 1;
                        match result {
                            Ok(Some(model)) => eprintln!("[{n}/{}] {} ({model})", files.len(), path.display()),
                            Ok(None) => eprintln!("[{n}/{}] {}: skipped (no usable camera JPEG or colour)", files.len(), path.display()),
                            Err(e) => eprintln!("[{n}/{}] {}: {e}", files.len(), path.display()),
                        }
                    }
                    pool
                })
            })
            .collect();
        handles.into_iter().filter_map(|h| h.join().ok()).collect()
    });
    let mut pool = lightcraft_engine::camera_profiles::Pool::default();
    for p in pools {
        pool.merge(p);
    }
    let mut written = 0;
    for result in pool.fit(5) {
        match result {
            Ok(profile) => {
                let path = lightcraft_engine::camera_profiles::save(&profile, &dir)?;
                println!(
                    "{}: {} photos, {} colour pairs, hue/saturation table {} → {}",
                    profile.model,
                    profile.files,
                    profile.samples,
                    profile.hue_sat.is_some(),
                    path.display()
                );
                written += 1;
            }
            Err(e) => eprintln!("calibrate: {e}"),
        }
    }
    for (model, n) in pool.files() {
        if n < 5 {
            eprintln!("calibrate: {model}: only {n} usable photo(s), at least 5 needed");
        }
    }
    if written == 0 {
        return Err("no profile written".into());
    }
    Ok(())
}

fn mcp(args: &[String]) -> Result<(), String> {
    let mut connect: Option<String> = None;
    let mut demo = false;
    let mut library: Option<String> = None;
    let mut compact = false;
    let mut files = Vec::new();
    let mut i = 0;
    while i < args.len() {
        match args[i].as_str() {
            "--connect" => {
                // Optional address argument.
                match args.get(i + 1).filter(|a| !a.starts_with("--") && a.contains(':')) {
                    Some(a) => {
                        connect = Some(a.clone());
                        i += 1;
                    }
                    None => connect = Some(DEFAULT_ADDR.to_string()),
                }
            }
            a if a.starts_with("--connect=") => connect = Some(a["--connect=".len()..].to_string()),
            "--headless" => connect = None,
            "--demo" => demo = true,
            "--compact" => compact = true,
            "--library" => library = Some(take_value(args, &mut i, "--library")?.to_string()),
            a if a.starts_with("--") => return Err(format!("unknown option `{a}`")),
            f => files.push(f.to_string()),
        }
        i += 1;
    }
    let backend: Box<dyn Backend> = match connect {
        Some(addr) => {
            if !files.is_empty() || demo || library.is_some() {
                return Err("FILES, --demo and --library apply to headless mode only (import through the `import` tool instead)".into());
            }
            match Remote::connect(&addr) {
                Ok(r) => {
                    eprintln!("lightcraft-cli mcp: connected to LightCraft at {addr}");
                    Box::new(r)
                }
                Err(e) => {
                    eprintln!("lightcraft-cli mcp: LightCraft is not reachable at {addr} yet ({e}); will retry on each call");
                    Box::new(Remote::lazy(&addr))
                }
            }
        }
        None => {
            let mut h = match &library {
                Some(dir) => {
                    let mut h = Headless::default();
                    let r = h.session.open_library(dir, demo).map_err(|e| library_error(dir, e))?;
                    eprintln!("lightcraft-cli mcp: opened library {dir} ({r:?})");
                    h
                }
                None if demo => Headless::demo(),
                None => Headless::default(),
            };
            if !files.is_empty() {
                let paths = expand_paths(&files);
                let r = h.session.execute("library.import", &json!({"paths": paths})).map_err(|e| e.to_string())?;
                eprintln!("lightcraft-cli mcp: imported {} photo(s)", r["imported"].as_array().map_or(0, Vec::len));
            }
            Box::new(h)
        }
    };
    eprintln!("lightcraft-cli mcp: serving MCP on stdio ({})", backend.describe());
    let mut server = Server::new(backend).with_command_tools(!compact);
    let stdin = std::io::stdin();
    server.serve(BufReader::new(stdin.lock()), std::io::stdout().lock()).map_err(|e| e.to_string())
}

fn merge(args: &[String]) -> Result<(), String> {
    let cmd = match args.first().map(String::as_str) {
        Some("hdr") => "merge.hdr",
        Some("panorama" | "pano") => "merge.panorama",
        Some("hdr-panorama") => "merge.hdrPanorama",
        _ => return Err("merge: expected hdr, panorama or hdr-panorama".into()),
    };
    let mut p = serde_json::Map::new();
    let mut files = Vec::new();
    let mut i = 1;
    while i < args.len() {
        match args[i].as_str() {
            "--deghost" => {
                p.insert("deghost".into(), json!(take_value(args, &mut i, "--deghost")?));
            }
            "--no-align" => {
                p.insert("align".into(), json!(false));
            }
            "--bracket" => {
                p.insert("bracket".into(), json!(take_value(args, &mut i, "--bracket")?.parse::<u64>().map_err(|e| e.to_string())?));
            }
            "--projection" => {
                p.insert("projection".into(), json!(take_value(args, &mut i, "--projection")?));
            }
            "--boundary-warp" => {
                p.insert("boundaryWarp".into(), json!(take_value(args, &mut i, "--boundary-warp")?.parse::<f64>().map_err(|e| e.to_string())?));
            }
            "--auto-crop" => {
                p.insert("autoCrop".into(), json!(true));
            }
            "--fill-edges" => {
                p.insert("fillEdges".into(), json!(true));
            }
            "--no-auto-settings" => {
                p.insert("autoSettings".into(), json!(false));
            }
            "--preview" => {
                p.insert("preview".into(), json!(true));
                p.insert("previewPath".into(), json!(take_value(args, &mut i, "--preview")?));
                p.insert("showOverlay".into(), json!(true));
            }
            a if a.starts_with("--") => return Err(format!("unknown option `{a}`")),
            f => files.push(f.to_string()),
        }
        i += 1;
    }
    let mut s = Session::new().with_fs();
    let paths = expand_paths(&files);
    let r = s.execute("library.import", &json!({"paths": paths})).map_err(|e| e.to_string())?;
    let mut ids: Vec<u64> = r["imported"].as_array().map(|a| a.iter().filter_map(Value::as_u64).collect()).unwrap_or_default();
    // keep the command line's order
    ids.sort_by_key(|id| {
        paths.iter().position(|f| {
            s.catalog
                .photo(lightcraft_engine::catalog::PhotoId(*id))
                .is_some_and(|ph| matches!(&ph.source, lightcraft_engine::catalog::Source::File { path } if path == f))
        })
    });
    p.insert("ids".into(), json!(ids));
    let t0 = std::time::Instant::now();
    let mut out = s.execute(cmd, &Value::Object(p)).map_err(|e| e.to_string())?;
    out["seconds"] = json!(t0.elapsed().as_secs_f64());
    println!("{}", serde_json::to_string_pretty(&out).unwrap_or_default());
    Ok(())
}

fn synth_merge(args: &[String]) -> Result<(), String> {
    let kind = args.first().map(String::as_str).unwrap_or("");
    let mut dir = None;
    let mut i = 1;
    while i < args.len() {
        match args[i].as_str() {
            "-o" | "--output" => dir = Some(take_value(args, &mut i, "-o")?.to_string()),
            a => return Err(format!("unknown option `{a}`")),
        }
        i += 1;
    }
    let dir = dir.ok_or("synth-merge needs -o DIR")?;
    std::fs::create_dir_all(&dir).map_err(|e| e.to_string())?;
    let mut written = Vec::new();
    match kind {
        "hdr" => {
            for (k, b) in lightcraft_merge::synth::bracket_dngs(1800, 1200, &[-2.0, 0.0, 2.0]).map_err(|e| e.to_string())?.into_iter().enumerate() {
                let p = Path::new(&dir).join(format!("bracket-{k}.dng"));
                std::fs::write(&p, b).map_err(|e| e.to_string())?;
                written.push(p);
            }
        }
        "panorama" | "pano" => {
            for (k, v) in lightcraft_merge::synth::pano_views(1200, 900, 1000.0, &[-50.0, -25.0, 0.0, 25.0, 50.0])
                .map_err(|e| e.to_string())?
                .into_iter()
                .enumerate()
            {
                let p = Path::new(&dir).join(format!("view-{k}.png"));
                let img = v.to_srgb8();
                let png = lightcraft_codecs::encode_png(&lightcraft_codecs::EncodeImage::rgba8(&img), &lightcraft_codecs::EncodeMeta::default())
                    .map_err(|e| e.to_string())?;
                std::fs::write(&p, png).map_err(|e| e.to_string())?;
                written.push(p);
            }
        }
        _ => return Err("synth-merge: expected hdr or panorama".into()),
    }
    for p in written {
        println!("{}", p.display());
    }
    Ok(())
}

/// One step of `lightcraft-cli run`: a command id (or control-protocol method) and its params.
#[derive(Debug, PartialEq)]
struct Step {
    id: String,
    params: Value,
}

/// Parse `CMD [key=value | {json}]… CMD …` into steps. A token without `=` that doesn't start
/// with `{` begins a new command; values are JSON when they parse, else strings.
fn parse_steps(tokens: &[String]) -> Result<Vec<Step>, String> {
    let mut steps: Vec<Step> = Vec::new();
    for t in tokens {
        if t.starts_with('{') {
            let v: Value = serde_json::from_str(t).map_err(|e| format!("bad JSON params `{t}`: {e}"))?;
            let step = steps.last_mut().ok_or_else(|| format!("params `{t}` before any command"))?;
            match (step.params.as_object_mut(), v) {
                (Some(o), Value::Object(m)) => o.extend(m),
                _ => return Err(format!("params `{t}` must be a JSON object")),
            }
        } else if let Some((k, v)) = t.split_once('=') {
            let step = steps.last_mut().ok_or_else(|| format!("param `{t}` before any command"))?;
            let v = serde_json::from_str(v).unwrap_or_else(|_| json!(v));
            step.params[k.trim()] = v;
        } else {
            steps.push(Step { id: t.clone(), params: json!({}) });
        }
    }
    Ok(steps)
}

/// Run one step: control-protocol methods (`ui.*`, `engine.*`) directly, everything else as a
/// command through `engine.execute`.
fn run_step(b: &mut dyn Backend, s: &Step) -> Result<Value, String> {
    let direct = s.id.starts_with("ui.") || s.id.starts_with("engine.") || s.id == "app.quit";
    if direct { b.call(&s.id, s.params.clone()) } else { b.call("engine.execute", json!({"command": s.id, "params": s.params})) }
}

fn run(args: &[String]) -> Result<(), String> {
    let mut connect: Option<String> = None;
    let mut demo = false;
    let mut library: Option<String> = None;
    let mut imports = Vec::new();
    let mut script: Option<String> = None;
    let mut keep_going = false;
    let mut i = 0;
    while i < args.len() && args[i].starts_with("--") {
        match args[i].as_str() {
            "--" => {
                i += 1;
                break;
            }
            "--connect" => match args.get(i + 1).filter(|a| a.contains(':') && !a.contains('=')) {
                Some(a) => {
                    connect = Some(a.clone());
                    i += 1;
                }
                None => connect = Some(DEFAULT_ADDR.to_string()),
            },
            a if a.starts_with("--connect=") => connect = Some(a["--connect=".len()..].to_string()),
            "--demo" => demo = true,
            "--library" => library = Some(take_value(args, &mut i, "--library")?.to_string()),
            "--import" => imports.push(take_value(args, &mut i, "--import")?.to_string()),
            "--script" => script = Some(take_value(args, &mut i, "--script")?.to_string()),
            "--keep-going" => keep_going = true,
            a => return Err(format!("unknown option `{a}`")),
        }
        i += 1;
    }
    let mut steps = parse_steps(&args[i..])?;
    if let Some(path) = &script {
        let text = if path == "-" {
            let mut s = String::new();
            std::io::Read::read_to_string(&mut std::io::stdin(), &mut s).map_err(|e| e.to_string())?;
            s
        } else {
            std::fs::read_to_string(path).map_err(|e| format!("{path}: {e}"))?
        };
        for (n, line) in text.lines().enumerate().filter(|(_, l)| !l.trim().is_empty() && !l.trim_start().starts_with('#')) {
            let v: Value = serde_json::from_str(line).map_err(|e| format!("{path}:{}: {e}", n + 1))?;
            // `{"command": id, "params": …}` or a control request `{"method": m, "params": …}`
            let id = v
                .get("command")
                .or(v.get("method"))
                .and_then(Value::as_str)
                .ok_or_else(|| format!("{path}:{}: needs `command` or `method`", n + 1))?;
            let params = v.get("params").cloned().filter(|p| p.is_object()).unwrap_or_else(|| json!({}));
            steps.push(Step { id: id.to_string(), params });
        }
    }
    if steps.is_empty() {
        return Err("run: no command given (see `lightcraft-cli commands`)".into());
    }
    let mut backend: Box<dyn Backend> =
        match connect {
            Some(addr) => {
                if demo || library.is_some() || !imports.is_empty() {
                    return Err("--demo, --library and --import apply to headless mode only".into());
                }
                Box::new(Remote::connect(&addr).map_err(|e| {
                    format!("LightCraft is not reachable at {addr} ({e}); start it with `lightcraft --control {}`", connect_port(&addr))
                })?)
            }
            None => {
                let mut h = match &library {
                    Some(dir) => {
                        let mut h = Headless::default();
                        h.session.open_library(dir, demo).map_err(|e| library_error(dir, e))?;
                        h
                    }
                    None if demo => Headless::demo(),
                    None => Headless::default(),
                };
                if !imports.is_empty() {
                    let paths = expand_paths(&imports);
                    let r = h.session.execute("library.import", &json!({"paths": paths})).map_err(|e| e.to_string())?;
                    // what follows acts on the imported photos (already-known files are reported as duplicates)
                    let mut ids: Vec<Value> = r["imported"].as_array().cloned().unwrap_or_default();
                    ids.extend(r["duplicates"].as_array().into_iter().flatten().filter_map(|d| d.get("existing").filter(|v| v.is_u64()).cloned()));
                    if let Some(first) = ids.first().cloned() {
                        h.session.execute("library.select", &json!({"ids": ids, "active": first})).map_err(|e| e.to_string())?;
                    }
                }
                Box::new(h)
            }
        };
    let mut out = std::io::stdout().lock();
    let mut failed = 0;
    for s in &steps {
        let t = std::time::Instant::now();
        let line = match run_step(backend.as_mut(), s) {
            Ok(r) => json!({"command": s.id, "ok": true, "result": r, "ms": (t.elapsed().as_secs_f64() * 1e4).round() / 10.0}),
            Err(e) => {
                failed += 1;
                json!({"command": s.id, "ok": false, "error": e})
            }
        };
        writeln!(out, "{line}").map_err(|e| e.to_string())?;
        if failed > 0 && !keep_going {
            break;
        }
    }
    drop(backend); // a library session is flushed here
    if failed > 0 { Err(format!("{failed} command(s) failed")) } else { Ok(()) }
}

fn take_value<'a>(args: &'a [String], i: &mut usize, flag: &str) -> Result<&'a str, String> {
    *i += 1;
    args.get(*i).map(String::as_str).ok_or_else(|| format!("{flag} needs a value"))
}

/// The port an `--connect` address names, for the recovery hint. The whole address when it has
/// no port, so a hint is never built from a guess.
fn connect_port(addr: &str) -> &str {
    addr.rsplit_once(':').map_or(addr, |(_, port)| port)
}

fn render(args: &[String]) -> Result<(), String> {
    let mut input = None;
    let mut output = None;
    let mut values = serde_json::Map::new();
    let mut settings: Option<Value> = None;
    let mut preset = None;
    let mut size: Option<u64> = None;
    let mut quality = 92u8;
    let mut opts = serde_json::Map::new();
    let mut i = 0;
    while i < args.len() {
        match args[i].as_str() {
            "-o" | "--output" => output = Some(take_value(args, &mut i, "-o")?.to_string()),
            "--set" => {
                let kv = take_value(args, &mut i, "--set")?;
                let (k, v) = kv.split_once('=').ok_or_else(|| format!("--set expects control=value, got `{kv}`"))?;
                let v: f64 = v.trim().parse().map_err(|_| format!("--set {k}: `{v}` is not a number"))?;
                values.insert(k.trim().to_string(), json!(v));
            }
            "--settings" => {
                let p = take_value(args, &mut i, "--settings")?;
                let text = std::fs::read_to_string(p).map_err(|e| format!("{p}: {e}"))?;
                settings = Some(serde_json::from_str(&text).map_err(|e| format!("{p}: {e}"))?);
            }
            "--preset" => preset = Some(take_value(args, &mut i, "--preset")?.to_string()),
            "--size" => size = Some(take_value(args, &mut i, "--size")?.parse().map_err(|_| "--size expects a number")?),
            "--quality" => quality = take_value(args, &mut i, "--quality")?.parse().map_err(|_| "--quality expects 1..100")?,
            "--opt" => {
                let kv = take_value(args, &mut i, "--opt")?;
                let (k, v) = kv.split_once('=').ok_or_else(|| format!("--opt expects key=value, got `{kv}`"))?;
                opts.insert(k.trim().to_string(), serde_json::from_str(v).unwrap_or_else(|_| json!(v)));
            }
            a if a.starts_with('-') => return Err(format!("unknown option `{a}`")),
            f if input.is_none() => input = Some(f.to_string()),
            f => return Err(format!("unexpected argument `{f}`")),
        }
        i += 1;
    }
    let input = input.ok_or("render: missing input file")?;
    let output = output.ok_or("render: missing -o OUTPUT")?;
    let mut s = Session::new().with_fs();
    let abs = expand_paths(std::slice::from_ref(&input));
    let r = s.execute("library.import", &json!({"paths": abs})).map_err(|e| e.to_string())?;
    let id = r["imported"][0].as_u64().ok_or_else(|| format!("{input}: not a readable photo"))?;
    let run = |s: &mut Session, cmd: &str, p: Value| s.execute(cmd, &p).map(|_| ()).map_err(|e| e.to_string());
    run(&mut s, "library.select", json!({"ids": [id], "active": id}))?;
    if let Some(p) = preset {
        run(&mut s, "preset.apply", json!({"id": p}))?;
    }
    if let Some(st) = settings {
        run(&mut s, "develop.merge", json!({"settings": st}))?;
    }
    if !values.is_empty() {
        run(&mut s, "develop.set", json!({"values": values}))?;
    }
    use lightcraft_engine::export::{ExportFormat, ExportOptions, export_photo};
    let mut p = json!({"quality": quality});
    if let Some(n) = size {
        p["longEdge"] = json!(n);
    }
    for (k, v) in opts {
        p[k] = v;
    }
    let mut o = ExportOptions::from_json(&p);
    if p.get("format").is_none() {
        let ext = Path::new(&output).extension().map(|e| e.to_string_lossy().to_string()).unwrap_or_default();
        o.format = ExportFormat::parse(&ext)
            .ok_or_else(|| format!("{output}: unknown extension (use .jpg .png .tif .webp .avif .dng or --opt format=…)"))?;
    }
    let e = export_photo(&mut s, lightcraft_engine::catalog::PhotoId(id), &o, 1)?;
    // never over the input (or its sidecar), however it is spelled: `render IMG.jpg -o IMG.jpg`
    let sidecars: Vec<(String, &Vec<u8>)> =
        e.sidecars.iter().map(|(ext, bytes)| (Path::new(&output).with_extension(ext).to_string_lossy().to_string(), bytes)).collect();
    let guard = s.original_guard();
    for p in std::iter::once(&output).chain(sidecars.iter().map(|(p, _)| p)) {
        guard.check(Path::new(p)).map_err(|err| format!("render: {err}"))?;
    }
    lightcraft_engine::export::write_file(&output, &e.bytes)?;
    for (sc, bytes) in &sidecars {
        lightcraft_engine::export::write_file(sc, bytes)?;
        eprintln!("lightcraft-cli: wrote {sc}");
    }
    eprintln!("lightcraft-cli: wrote {output} ({}×{})", e.width, e.height);
    Ok(())
}

fn snapshot(args: &[String]) -> Result<(), String> {
    use lightcraft_ui_egui::headless::Headless;
    use std::time::{Duration, Instant};
    let mut library: Option<String> = None;
    let mut script: Option<String> = None;
    let mut output: Option<String> = None;
    let mut size = [1600.0f32, 1000.0];
    let mut scale = 1.0f32;
    let mut files = Vec::new();
    let mut i = 0;
    while i < args.len() {
        match args[i].as_str() {
            "--demo" => {}
            "--library" => library = Some(take_value(args, &mut i, "--library")?.to_string()),
            "--script" => script = Some(take_value(args, &mut i, "--script")?.to_string()),
            "-o" | "--output" => output = Some(take_value(args, &mut i, "-o")?.to_string()),
            "--size" => {
                let v = take_value(args, &mut i, "--size")?;
                let (w, h) = v.split_once(['x', 'X']).ok_or("--size expects WxH, e.g. 1600x1000")?;
                size = [w.trim().parse().map_err(|_| "--size: bad width")?, h.trim().parse().map_err(|_| "--size: bad height")?];
            }
            "--scale" => scale = take_value(args, &mut i, "--scale")?.parse().map_err(|_| "--scale expects a number")?,
            a if a.starts_with('-') => return Err(format!("unknown option `{a}`")),
            f => files.push(f.to_string()),
        }
        i += 1;
    }
    if script.is_none() && output.is_none() {
        return Err("snapshot: give -o OUT.png and/or --script FILE".into());
    }
    if !(scale > 0.0 && size[0] >= 1.0 && size[1] >= 1.0) {
        return Err("snapshot: bad --size/--scale".into());
    }
    let t0 = Instant::now();
    let mut session = match &library {
        Some(dir) => {
            let mut s = Session::new().with_fs();
            s.open_library(dir, false).map_err(|e| library_error(dir, e))?;
            s
        }
        None if files.is_empty() => Session::with_demo().with_fs(),
        None => Session::new().with_fs(),
    };
    if !files.is_empty() {
        let ti = Instant::now();
        let r = session.execute("library.import", &json!({"paths": expand_paths(&files)})).map_err(|e| e.to_string())?;
        let n = r["imported"].as_array().map_or(0, Vec::len);
        eprintln!("lightcraft-cli snapshot: imported {n} files in {:.0} ms", ti.elapsed().as_secs_f64() * 1e3);
    }
    let services = lightcraft_ui_egui::Services {
        write_shared: Some(std::sync::Arc::new(lightcraft_engine::export::write_file)),
        write: Some(Box::new(lightcraft_engine::export::write_file)),
        png: Some(Box::new(|img: &lightcraft_raster::Rgba8| {
            lightcraft_codecs::encode_png(&lightcraft_codecs::EncodeImage::rgba8(img), &lightcraft_codecs::EncodeMeta::default()).unwrap_or_default()
        })),
        ..Default::default()
    };
    let app = lightcraft_ui_egui::LightcraftApp::new(session, services);
    let mut h = Headless::new(app, size, scale);
    let timeout = Duration::from_secs(60);
    let mut shots = 0usize;
    let next_path = |shots: &mut usize| -> Option<String> {
        let out = output.as_deref()?;
        *shots += 1;
        if *shots == 1 {
            return Some(out.to_string());
        }
        let p = Path::new(out);
        let stem = p.file_stem().map(|s| s.to_string_lossy().to_string()).unwrap_or_default();
        let ext = p.extension().map(|e| e.to_string_lossy().to_string()).unwrap_or_else(|| "png".into());
        Some(p.with_file_name(format!("{stem}-{shots}.{ext}")).to_string_lossy().to_string())
    };
    let mut wrote_output = false;
    // Issue #166: a scripted request that fails still gets its reply printed and the run carries
    // on (like `run --keep-going`), but the exit status reports it — CI judges by exit status.
    let mut failed = 0usize;
    if let Some(script) = &script {
        let text = std::fs::read_to_string(script).map_err(|e| format!("{script}: {e}"))?;
        let mut out = std::io::stdout().lock();
        for (n, line) in text.lines().enumerate() {
            let line = line.trim();
            if line.is_empty() || line.starts_with('#') || line.starts_with("//") {
                continue;
            }
            let msg: Value = serde_json::from_str(line).map_err(|e| format!("{script}:{}: {e}", n + 1))?;
            let id = msg.get("id").cloned().unwrap_or(json!(n + 1));
            let method = msg.get("method").and_then(Value::as_str).unwrap_or("").to_string();
            let mut params = msg.get("params").cloned().unwrap_or(json!({}));
            let ts = Instant::now();
            let mut reply = match method.as_str() {
                "ui.settle" => {
                    let ms = params.get("timeoutMs").and_then(Value::as_u64).unwrap_or(20_000);
                    json!({"ok": true, "result": {"settled": h.settle(Duration::from_millis(ms))}})
                }
                "ui.screenshot" => {
                    if params.get("path").and_then(Value::as_str).is_none() {
                        match next_path(&mut shots) {
                            Some(p) => {
                                wrote_output = true;
                                params["path"] = json!(p);
                            }
                            None => return Err(format!("{script}:{}: ui.screenshot needs a `path` (or give -o)", n + 1)),
                        }
                    }
                    h.request(&method, params, timeout)
                }
                _ => h.request(&method, params, timeout),
            };
            if reply["ok"] != true {
                failed += 1;
            }
            if let Some(o) = reply.as_object_mut() {
                o.insert("id".into(), id);
                // wall time of the request (incl. the frames it ran), and since the start
                o.insert("ms".into(), json!((ts.elapsed().as_secs_f64() * 1e4).round() / 10.0));
                o.insert("t".into(), json!((t0.elapsed().as_secs_f64() * 1e4).round() / 10.0));
            }
            writeln!(out, "{reply}").map_err(|e| e.to_string())?;
            if method == "ui.screenshot" {
                eprintln!(
                    "lightcraft-cli snapshot: {} ({:.0} ms)",
                    reply["result"]["path"].as_str().unwrap_or("?"),
                    ts.elapsed().as_secs_f64() * 1000.0
                );
            }
            if h.quit_requested() {
                break;
            }
        }
    }
    if !wrote_output && let Some(path) = next_path(&mut shots) {
        let r = h.request("ui.screenshot", json!({"path": path}), timeout);
        if r["ok"] != true {
            return Err(format!("screenshot failed: {}", r["error"]));
        }
        eprintln!("lightcraft-cli snapshot: wrote {path} ({}×{})", r["result"]["width"], r["result"]["height"]);
    }
    // a background export started by the script finishes before we exit (its files would be cut off)
    if h.app.export.is_some() {
        eprintln!("lightcraft-cli snapshot: waiting for the background export");
        let te = std::time::Instant::now();
        while h.app.export.is_some() && te.elapsed() < std::time::Duration::from_secs(3600) {
            h.step();
            std::thread::sleep(std::time::Duration::from_millis(20));
        }
    }
    eprintln!("lightcraft-cli snapshot: done in {:.2} s ({} frames)", t0.elapsed().as_secs_f64(), h.frames());
    if failed > 0 { Err(format!("{failed} scripted request(s) failed")) } else { Ok(()) }
}

fn commands(args: &[String]) -> Result<(), String> {
    let mut h = Headless::demo();
    let cmds = h.call("engine.commands", json!({}))?;
    let mut out = std::io::stdout().lock();
    if args.iter().any(|a| a == "--json") {
        writeln!(out, "{}", serde_json::to_string_pretty(&cmds).unwrap_or_default()).map_err(|e| e.to_string())?;
        return Ok(());
    }
    for c in cmds.as_array().into_iter().flatten() {
        let sc = c["shortcut"].as_str().map(|s| format!("  [{s}]")).unwrap_or_default();
        writeln!(
            out,
            "{:<28} {}{sc}\n{:<28} params: {}",
            c["id"].as_str().unwrap_or(""),
            c["label"].as_str().unwrap_or(""),
            "",
            c["params"].as_str().unwrap_or("")
        )
        .map_err(|e| e.to_string())?;
    }
    Ok(())
}

fn controls(args: &[String]) -> Result<(), String> {
    let mut s = Session::new();
    let v = s.execute("develop.controls", &json!({})).map_err(|e| e.to_string())?;
    let mut out = std::io::stdout().lock();
    if args.iter().any(|a| a == "--json") {
        writeln!(out, "{}", serde_json::to_string_pretty(&v).unwrap_or_default()).map_err(|e| e.to_string())?;
        return Ok(());
    }
    for c in v.as_array().into_iter().flatten() {
        writeln!(
            out,
            "{:<28} {:<22} {} .. {} (default {})",
            c["id"].as_str().unwrap_or(""),
            c["label"].as_str().unwrap_or(""),
            c["min"],
            c["max"],
            c["default"]
        )
        .map_err(|e| e.to_string())?;
    }
    Ok(())
}