//! TRACES: FR-CAT-11a | FR-CAT-15 | FR-UI-4 | NFR-P9
//! The duplicate originals review: which groups there are, which copy stays,
//! what the check found, and the button that consolidates them.
//!
//! The page is a view of [`Reviewed`] groups held here. The catalog is read
//! on the UI thread only for what one query answers — the groups themselves,
//! and a merge preview for the thirty rows on the page — and every read of a
//! file happens on a worker (`crate::duplicates`), which reports per group.

use std::cell::{Cell, RefCell};
use std::collections::HashMap;
use std::rc::Rc;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::mpsc::Receiver;
use std::sync::Arc;

use dr_catalog::duplicates::Outcome;
use dr_catalog::Catalog;
use dr_types::ImageId;
use slint::{ComponentHandle, ModelRc, VecModel};

use crate::activity::{Activity, ActivityLog};
use crate::duplicates::{self as dups, Check, DupMessage, Reviewed};
use crate::library_ui::LibraryController;
use crate::{AppWindow, DuplicateCopy, DuplicateRow, Duplicates, Library, Page};

/// Groups on one page of the review. A page is what gets a thumbnail and a
/// merge preview, so this bounds the work a redraw does whatever the size
/// of the library.
pub const PAGE: usize = 30;

/// What runs when a consolidation ends: the grid, the sidebar and the trash
/// brought up to date.
pub type After = Rc<dyn Fn(&AppWindow)>;

/// How a group ended in this session.
#[derive(Debug, Clone)]
enum Ended {
    Done(String),
    Failed(String),
}

/// What the review holds between redraws.
pub struct DuplicatesController {
    review: RefCell<Vec<Reviewed>>,
    page: Cell<usize>,
    ended: RefCell<HashMap<usize, Ended>>,
    /// Pictures for the page on screen, by `oc:fileid`.
    thumbs: RefCell<HashMap<u64, slint::Image>>,
    running: Cell<bool>,
    consolidating: Cell<bool>,
    stop: RefCell<Arc<AtomicBool>>,
    timer: RefCell<Option<slint::Timer>>,
    activity: Rc<ActivityLog>,
    /// Survivors consolidated by the running job, whose sidecars are written
    /// when it ends.
    survivors: RefCell<Vec<ImageId>>,
    counts: Cell<(usize, usize, usize)>,
}

impl DuplicatesController {
    pub fn new(activity: Rc<ActivityLog>) -> Rc<Self> {
        Rc::new(Self {
            review: RefCell::default(),
            page: Cell::new(0),
            ended: RefCell::default(),
            thumbs: RefCell::default(),
            running: Cell::new(false),
            consolidating: Cell::new(false),
            stop: RefCell::default(),
            timer: RefCell::default(),
            activity,
            survivors: RefCell::default(),
            counts: Cell::new((0, 0, 0)),
        })
    }
}

/// TRACES: FR-CAT-11a
/// Put the number of duplicate groups where the sidebar and settings show
/// it. One `COUNT` query; called when the catalog is opened, after a scan,
/// and after anything moves files in or out of the trash — the events that
/// can change the answer.
pub fn refresh_count(window: &AppWindow, catalog: &Catalog) {
    let (groups, _) = dr_catalog::duplicates::count(catalog.connection()).unwrap_or((0, 0));
    window.global::<Duplicates>().set_group_count(groups as i32);
}

/// Wire the page. `after` runs when a consolidation ends, to bring the grid,
/// the sidebar and the trash up to date.
pub fn wire(
    window: &AppWindow,
    ctl: Rc<DuplicatesController>,
    library: Rc<LibraryController>,
    after: After,
) {
    let g = window.global::<Duplicates>();

    {
        let (weak, ctl, library) = (window.as_weak(), ctl.clone(), library.clone());
        g.on_open(move || {
            let Some(w) = weak.upgrade() else { return };
            open(&w, &ctl, &library);
        });
    }
    {
        let (weak, ctl, library) = (window.as_weak(), ctl.clone(), library.clone());
        g.on_close(move || {
            let Some(w) = weak.upgrade() else { return };
            // A running job carries on and reports to the register; the
            // page can be opened again to watch it.
            w.set_active_page(Page::None);
            if !ctl.running.get() {
                ctl.thumbs.borrow_mut().clear();
                if let Some(cat) = library.catalog().borrow().as_ref() {
                    refresh_count(&w, cat);
                }
            }
        });
    }
    {
        let (weak, ctl, library) = (window.as_weak(), ctl.clone(), library.clone());
        g.on_check(move || {
            let Some(w) = weak.upgrade() else { return };
            start_check(&w, &ctl, &library);
        });
    }
    {
        let ctl = ctl.clone();
        g.on_stop(move || {
            ctl.stop.borrow().store(true, Ordering::Relaxed);
        });
    }
    {
        let (weak, ctl, library, after) = (
            window.as_weak(),
            ctl.clone(),
            library.clone(),
            after.clone(),
        );
        g.on_confirm(move || {
            let Some(w) = weak.upgrade() else { return };
            start_consolidate(&w, &ctl, &library, after.clone());
        });
    }
    {
        let (weak, ctl, library) = (window.as_weak(), ctl.clone(), library.clone());
        g.on_prev_page(move || {
            let Some(w) = weak.upgrade() else { return };
            ctl.page.set(ctl.page.get().saturating_sub(1));
            ctl.thumbs.borrow_mut().clear();
            show(&w, &ctl, &library);
        });
    }
    {
        let (weak, ctl, library) = (window.as_weak(), ctl.clone(), library.clone());
        g.on_next_page(move || {
            let Some(w) = weak.upgrade() else { return };
            let last = ctl.review.borrow().len().saturating_sub(1) / PAGE;
            ctl.page.set((ctl.page.get() + 1).min(last));
            ctl.thumbs.borrow_mut().clear();
            show(&w, &ctl, &library);
        });
    }
    {
        let (weak, ctl, library) = (window.as_weak(), ctl.clone(), library.clone());
        g.on_pick_survivor(move |row, copy| {
            let Some(w) = weak.upgrade() else { return };
            if ctl.running.get() {
                return;
            }
            let index = ctl.page.get() * PAGE + row.max(0) as usize;
            {
                let mut review = ctl.review.borrow_mut();
                let Some(r) = review.get_mut(index) else {
                    return;
                };
                if (copy as usize) < r.group.copies.len() {
                    r.survivor = copy as usize;
                }
            }
            show(&w, &ctl, &library);
        });
    }
    {
        let (weak, ctl, library) = (window.as_weak(), ctl.clone(), library.clone());
        g.on_toggle(move |row, on| {
            let Some(w) = weak.upgrade() else { return };
            if ctl.running.get() {
                return;
            }
            let index = ctl.page.get() * PAGE + row.max(0) as usize;
            if let Some(r) = ctl.review.borrow_mut().get_mut(index) {
                r.include = on;
            }
            show(&w, &ctl, &library);
        });
    }
}

/// Open the page on a fresh read of the groups.
///
/// What was decided about a group that is still the same group — its check,
/// the copy chosen to stay, whether it is in — is carried over, so leaving
/// the page and coming back loses nothing.
fn open(window: &AppWindow, ctl: &Rc<DuplicatesController>, library: &Rc<LibraryController>) {
    window.set_active_page(Page::Duplicates);
    if ctl.running.get() {
        show(window, ctl, library);
        return;
    }
    let groups = {
        let catalog = library.catalog();
        let borrow = catalog.borrow();
        let Some(cat) = borrow.as_ref() else {
            window
                .global::<Duplicates>()
                .set_error("Open a library first.".into());
            return;
        };
        refresh_count(window, cat);
        match dr_catalog::duplicates::candidates(cat.connection()) {
            Ok(g) => g,
            Err(e) => {
                window
                    .global::<Duplicates>()
                    .set_error(format!("Reading duplicates: {e}").into());
                return;
            }
        }
    };

    let before: HashMap<Vec<ImageId>, Reviewed> = ctl
        .review
        .borrow_mut()
        .drain(..)
        .map(|r| (ids(&r), r))
        .collect();
    let review: Vec<Reviewed> = groups
        .into_iter()
        .map(|g| {
            let fresh = Reviewed::new(g);
            match before.get(&ids(&fresh)) {
                Some(old) => Reviewed {
                    group: fresh.group,
                    survivor: old.survivor,
                    include: old.include,
                    check: old.check.clone(),
                },
                None => fresh,
            }
        })
        .collect();
    *ctl.review.borrow_mut() = review;
    ctl.ended.borrow_mut().clear();
    ctl.thumbs.borrow_mut().clear();
    ctl.page.set(0);
    window.global::<Duplicates>().set_error("".into());
    show(window, ctl, library);
}

fn ids(r: &Reviewed) -> Vec<ImageId> {
    r.group.copies.iter().map(|c| c.image).collect()
}

/// Megabytes or gigabytes, as a transfer is quoted.
fn quote_bytes(bytes: u64) -> String {
    let mb = bytes as f64 / (1024.0 * 1024.0);
    if mb >= 1024.0 {
        format!("{:.1} GB", mb / 1024.0)
    } else {
        format!("{mb:.0} MB")
    }
}

fn plural(n: usize, one: &str, many: &str) -> String {
    format!("{n} {}", if n == 1 { one } else { many })
}

/// Redraw the page from what the controller holds.
fn show(window: &AppWindow, ctl: &Rc<DuplicatesController>, library: &Rc<LibraryController>) {
    let g = window.global::<Duplicates>();
    let review = ctl.review.borrow();
    let summary = dups::summarise(&review);
    let total = review.len();

    // The dry run, and what the check would cost.
    let text = if total == 0 {
        "No duplicate originals: every file is in the library once.".to_string()
    } else if summary.unchecked == total {
        format!(
            "{} of the same file in more than one folder, {} spare. \
             Check them before anything moves.",
            plural(total, "group", "groups"),
            plural(
                review.iter().map(|r| r.group.copies.len() - 1).sum(),
                "copy",
                "copies"
            ),
        )
    } else {
        let mut t = format!(
            "{}, {} to trash, {} skipped",
            plural(summary.groups, "group", "groups"),
            plural(summary.files, "file", "files"),
            summary.skipped
        );
        if summary.excluded > 0 {
            t.push_str(&format!(", {} left out", summary.excluded));
        }
        if summary.unchecked > 0 {
            t.push_str(&format!(", {} not checked yet", summary.unchecked));
        }
        t.push('.');
        t
    };
    g.set_summary(text.into());

    let unread: Vec<&Reviewed> = review
        .iter()
        .filter(|r| r.check == Check::Unchecked)
        .collect();
    let to_read: usize = unread
        .iter()
        .filter(|r| !r.group.copies.iter().all(|c| c.content_hash.is_some()))
        .flat_map(|r| r.group.copies.iter())
        .filter(|c| c.probe.is_none())
        .map(|c| c.file_size.min(2 * dr_catalog::duplicates::PROBE_WINDOW) as usize)
        .sum();
    g.set_can_check(!unread.is_empty() && !ctl.running.get());
    g.set_check_label(format!("Check {}", plural(unread.len(), "group", "groups")).into());
    g.set_check_cost(if unread.is_empty() {
        "".into()
    } else if to_read == 0 {
        "The check reads each copy's sidecar; the files were read before.".into()
    } else {
        format!(
            "The check reads the first and last megabyte of each copy not read \
             before — about {} — and each copy's sidecar. What it reads is kept, \
             so a second check costs nothing.",
            quote_bytes(to_read as u64)
        )
        .into()
    });
    g.set_can_confirm(summary.files > 0 && !ctl.running.get());
    g.set_confirm_label(
        if summary.files == 1 {
            "Move 1 copy to trash".to_string()
        } else {
            format!("Move {} copies to trash", summary.files)
        }
        .into(),
    );

    // The page.
    let pages = total.div_ceil(PAGE).max(1);
    let page = ctl.page.get().min(pages - 1);
    let first = page * PAGE;
    let last = (first + PAGE).min(total);
    g.set_has_prev(page > 0);
    g.set_has_next(page + 1 < pages);
    g.set_page_label(if total == 0 {
        "".into()
    } else {
        format!("Groups {}–{} of {}", first + 1, last, total).into()
    });

    let catalog = library.catalog();
    let borrow = catalog.borrow();
    let store = library
        .session()
        .and_then(|c| dr_thumbs::ThumbStore::open(&crate::library::thumbs_dir(&c.account)).ok());
    let ended = ctl.ended.borrow();
    let mut rows = Vec::with_capacity(last - first);
    for (index, r) in review.iter().enumerate().take(last).skip(first) {
        let (thumb, has_thumb) = thumbnail(ctl, store.as_ref(), r);
        let done = matches!(ended.get(&index), Some(Ended::Done(_)));
        let (status, warn) = match (ended.get(&index), &r.check) {
            (Some(Ended::Done(s)), _) => (s.clone(), false),
            (Some(Ended::Failed(s)), _) => (format!("Left as it was: {s}"), true),
            (None, Check::Unchecked) => ("Not checked yet".to_string(), false),
            (None, Check::Skip(why)) => (format!("Skipped: {why}"), true),
            (None, Check::Same(_)) if !r.include => (
                "The same file · left out: nothing will move".to_string(),
                false,
            ),
            (None, Check::Same(edits)) => (
                if edits.edited.iter().any(|e| *e) {
                    "The same file, with one edit between them".to_string()
                } else {
                    "The same file".to_string()
                },
                false,
            ),
        };
        let detail = match (&r.check, borrow.as_ref()) {
            (Check::Same(edits), Some(cat)) if r.include && !done => {
                let survivor = r.group.copies[r.survivor].image;
                let others: Vec<ImageId> = r
                    .group
                    .copies
                    .iter()
                    .enumerate()
                    .filter(|(i, _)| *i != r.survivor)
                    .map(|(_, c)| c.image)
                    .collect();
                let carried = edits
                    .source_for(r.survivor)
                    .map(|i| r.group.copies[i].file_name().to_string());
                match dr_catalog::duplicates::preview(cat.connection(), survivor, &others) {
                    Ok(o) => describe(&o, carried.as_deref()),
                    Err(e) => format!("Cannot preview the merge: {e}"),
                }
            }
            _ => String::new(),
        };
        let title = format!(
            "{} · {} · {:.1} MB",
            r.group.camera,
            dr_types::format_date(r.group.captured_at),
            r.group.file_size as f64 / (1024.0 * 1024.0)
        );
        rows.push(DuplicateRow {
            title: title.into(),
            thumb,
            has_thumb,
            copies: ModelRc::new(VecModel::from(
                r.group
                    .copies
                    .iter()
                    .enumerate()
                    .map(|(i, c)| DuplicateCopy {
                        path: c.source_ref.clone().into(),
                        survivor: i == r.survivor,
                    })
                    .collect::<Vec<_>>(),
            )),
            status: status.into(),
            detail: detail.into(),
            warn,
            include: r.include,
            can_include: matches!(r.check, Check::Same(_) | Check::Unchecked),
            done,
        });
    }
    g.set_rows(ModelRc::new(VecModel::from(rows)));
}

/// One picture for a group, from the first copy the thumbnail store holds.
fn thumbnail(
    ctl: &Rc<DuplicatesController>,
    store: Option<&dr_thumbs::ThumbStore>,
    r: &Reviewed,
) -> (slint::Image, bool) {
    let mut thumbs = ctl.thumbs.borrow_mut();
    for id in r.group.copies.iter().filter_map(|c| c.file_id) {
        if let Some(img) = thumbs.get(&id) {
            return (img.clone(), true);
        }
    }
    let Some(store) = store else {
        return (slint::Image::default(), false);
    };
    for id in r.group.copies.iter().filter_map(|c| c.file_id) {
        let Ok(Some(t)) = store.get(id, dr_thumbs::ThumbSize::Grid) else {
            continue;
        };
        let Ok((w, h, rgba)) = dr_thumbs::codec::decode_rgba(&t.bytes) else {
            continue;
        };
        let mut buf = slint::SharedPixelBuffer::<slint::Rgba8Pixel>::new(w, h);
        let n = buf.make_mut_bytes().len().min(rgba.len());
        buf.make_mut_bytes()[..n].copy_from_slice(&rgba[..n]);
        let img = slint::Image::from_rgba8(buf);
        thumbs.insert(id, img.clone());
        return (img, true);
    }
    (slint::Image::default(), false)
}

/// What a consolidation brings to the survivor, in words.
pub fn describe(o: &Outcome, carried_edit: Option<&str>) -> String {
    let mut parts: Vec<String> = Vec::new();
    if o.rating.1 != o.rating.0 {
        parts.push(format!("rating {}★ (was {}★)", o.rating.1, o.rating.0));
    }
    if o.flag.1 != o.flag.0 {
        parts.push(
            match o.flag.1 {
                1 => "the pick flag",
                2 => "the reject flag",
                _ => "no flag",
            }
            .to_string(),
        );
    }
    if o.label.1 != o.label.0 {
        parts.push("a colour label".into());
    }
    if o.keywords_added > 0 {
        parts.push(plural(o.keywords_added, "keyword", "keywords"));
    }
    if o.collections_joined > 0 {
        parts.push(plural(o.collections_joined, "collection", "collections"));
    }
    if o.faces.moved > 0 {
        parts.push(plural(o.faces.moved, "face", "faces"));
    }
    if o.faces.named > 0 {
        parts.push(plural(o.faces.named, "name", "names"));
    }
    if let Some(from) = carried_edit {
        parts.push(format!("the edit from {from}"));
    }
    let mut out = if parts.is_empty() {
        "Nothing to merge: the copy that stays already has it all.".to_string()
    } else {
        format!("The copy that stays gains {}.", parts.join(", "))
    };
    let mut conflicts = Vec::new();
    if o.flag_conflict {
        conflicts.push("flags");
    }
    if o.label_conflict {
        conflicts.push("colour labels");
    }
    if !conflicts.is_empty() {
        out.push_str(&format!(
            " The copies disagree on {}; the one that stays keeps its own.",
            conflicts.join(" and ")
        ));
    }
    if o.faces.conflicts > 0 {
        out.push_str(&format!(
            " {} named differently; the one that stays keeps its names.",
            plural(o.faces.conflicts, "face is", "faces are")
        ));
    }
    if o.faces.unmatched_named > 0 {
        out.push_str(&format!(
            " {} stay with the copies in the trash.",
            plural(o.faces.unmatched_named, "named face", "named faces")
        ));
    }
    out
}

fn start_check(
    window: &AppWindow,
    ctl: &Rc<DuplicatesController>,
    library: &Rc<LibraryController>,
) {
    if ctl.running.get() {
        return;
    }
    let Some(conn) = library.session() else {
        return;
    };
    let Some(cache_dir) = library.sidecar_cache_dir() else {
        return;
    };
    let groups: Vec<(usize, dr_catalog::duplicates::Group)> = ctl
        .review
        .borrow()
        .iter()
        .enumerate()
        .filter(|(_, r)| r.check == Check::Unchecked)
        .map(|(i, r)| (i, r.group.clone()))
        .collect();
    if groups.is_empty() {
        return;
    }
    let stop = Arc::new(AtomicBool::new(false));
    *ctl.stop.borrow_mut() = stop.clone();
    let count = groups.len();
    let rx = dups::spawn_check(
        conn.clone(),
        crate::library::catalog_path(&conn.account),
        cache_dir,
        groups,
        stop,
    );
    let job = ctl.activity.begin(
        crate::activity::Kind::Download,
        format!(
            "Checking {}",
            plural(count, "duplicate group", "duplicate groups")
        ),
    );
    ctl.consolidating.set(false);
    ctl.counts.set((0, 0, 0));
    drain(window, ctl, library, rx, job, None);
}

fn start_consolidate(
    window: &AppWindow,
    ctl: &Rc<DuplicatesController>,
    library: &Rc<LibraryController>,
    after: After,
) {
    if ctl.running.get() {
        return;
    }
    let Some(conn) = library.session() else {
        return;
    };
    let Some(cache_dir) = library.sidecar_cache_dir() else {
        return;
    };
    let plans = {
        let catalog = library.catalog();
        let borrow = catalog.borrow();
        let Some(cat) = borrow.as_ref() else { return };
        match dups::plan(cat, &conn.account.root, &ctl.review.borrow()) {
            Ok(p) => p,
            Err(e) => {
                window
                    .global::<Duplicates>()
                    .set_error(format!("Planning: {e}").into());
                return;
            }
        }
    };
    if plans.is_empty() {
        return;
    }
    let files: usize = plans.iter().map(|p| p.copies.len()).sum();
    log::info!(
        "duplicates: consolidating {} group(s), {files} copies to the trash",
        plans.len()
    );
    let stop = Arc::new(AtomicBool::new(false));
    *ctl.stop.borrow_mut() = stop.clone();
    let rx = dups::spawn_consolidate(
        conn.clone(),
        crate::library::catalog_path(&conn.account),
        cache_dir,
        plans,
        stop,
    );
    let job = ctl.activity.begin(
        crate::activity::Kind::Trash,
        format!(
            "Moving {} to the trash",
            plural(files, "duplicate copy", "duplicate copies")
        ),
    );
    ctl.consolidating.set(true);
    ctl.survivors.borrow_mut().clear();
    ctl.counts.set((0, 0, 0));
    window
        .global::<Library>()
        .set_library_status(format!("Moving {files} duplicate copies to the trash…").into());
    drain(window, ctl, library, rx, job, Some(after));
}

/// Take a worker's reports on the UI thread, as every job here does: a
/// channel polled by a timer, so nothing waits on a file.
fn drain(
    window: &AppWindow,
    ctl: &Rc<DuplicatesController>,
    library: &Rc<LibraryController>,
    rx: Receiver<DupMessage>,
    job: Activity,
    after: Option<After>,
) {
    ctl.running.set(true);
    let g = window.global::<Duplicates>();
    g.set_running(true);
    g.set_fraction(0.0);
    g.set_progress_label(
        if ctl.consolidating.get() {
            "Consolidating…"
        } else {
            "Checking…"
        }
        .into(),
    );
    show(window, ctl, library);

    let (weak, ctl_cb, library) = (window.as_weak(), ctl.clone(), library.clone());
    let timer = slint::Timer::default();
    timer.start(
        slint::TimerMode::Repeated,
        std::time::Duration::from_millis(150),
        move || {
            let Some(w) = weak.upgrade() else { return };
            let ctl = &ctl_cb;
            let mut changed = false;
            loop {
                let msg = match rx.try_recv() {
                    Ok(m) => m,
                    Err(std::sync::mpsc::TryRecvError::Empty) => break,
                    Err(std::sync::mpsc::TryRecvError::Disconnected) => {
                        finish(&w, ctl, &library, &job, Some("stopped without finishing".into()), after.as_ref());
                        return;
                    }
                };
                changed = true;
                match msg {
                    DupMessage::Checked { index, check } => {
                        if let Some(r) = ctl.review.borrow_mut().get_mut(index) {
                            r.check = check;
                        }
                    }
                    DupMessage::Consolidated {
                        index,
                        survivor,
                        outcome,
                    } => {
                        ctl.survivors.borrow_mut().push(survivor);
                        let (ok, files, bad) = ctl.counts.get();
                        ctl.counts.set((ok + 1, files + outcome.trashed, bad));
                        ctl.ended.borrow_mut().insert(
                            index,
                            Ended::Done(format!(
                                "Consolidated: {} in the trash",
                                plural(outcome.trashed, "copy", "copies")
                            )),
                        );
                    }
                    DupMessage::Failed { index, reason } => {
                        let (ok, files, bad) = ctl.counts.get();
                        ctl.counts.set((ok, files, bad + 1));
                        ctl.ended.borrow_mut().insert(index, Ended::Failed(reason));
                    }
                    DupMessage::Progress { done, total } => {
                        job.progress(done, total);
                        let g = w.global::<Duplicates>();
                        g.set_fraction(done as f32 / total.max(1) as f32);
                        g.set_progress_label(
                            format!(
                                "{} {done} of {total} groups",
                                if ctl.consolidating.get() {
                                    "Consolidated"
                                } else {
                                    "Checked"
                                }
                            )
                            .into(),
                        );
                        if ctl.consolidating.get() {
                            let (_, files, _) = ctl.counts.get();
                            w.global::<Library>().set_library_status(
                                format!("Duplicates: {done} of {total} groups · {files} copies in the trash")
                                    .into(),
                            );
                        }
                    }
                    DupMessage::Finished { stopped } => {
                        finish(&w, ctl, &library, &job, stopped, after.as_ref());
                        return;
                    }
                }
            }
            // One redraw per tick, and only of the page on screen.
            if changed && w.get_active_page() == Page::Duplicates {
                show(&w, ctl, &library);
            }
        },
    );
    *ctl.timer.borrow_mut() = Some(timer);
}

fn finish(
    w: &AppWindow,
    ctl: &Rc<DuplicatesController>,
    library: &Rc<LibraryController>,
    job: &Activity,
    stopped: Option<String>,
    after: Option<&After>,
) {
    ctl.running.set(false);
    let g = w.global::<Duplicates>();
    g.set_running(false);

    if ctl.consolidating.get() {
        let (ok, files, bad) = ctl.counts.get();
        let skipped = dups::summarise(&ctl.review.borrow()).skipped;
        let mut status = format!(
            "Duplicates: {} consolidated, {} in the trash, {} skipped",
            plural(ok, "group", "groups"),
            plural(files, "copy", "copies"),
            skipped + bad
        );
        if let Some(why) = &stopped {
            status.push_str(&format!(" · {why}"));
        }
        if bad > 0 || stopped.is_some() {
            job.fail(status.clone());
        } else {
            job.finish(status.clone());
        }
        w.global::<Library>().set_library_status(status.into());

        // The consolidated groups leave the review: they are no longer
        // duplicates, and their rows would only offer to do it again. A
        // failed group stays, with its reason, under its new index.
        {
            let old_ended = std::mem::take(&mut *ctl.ended.borrow_mut());
            let old = std::mem::take(&mut *ctl.review.borrow_mut());
            let mut review = Vec::with_capacity(old.len());
            let mut ended = HashMap::new();
            for (i, r) in old.into_iter().enumerate() {
                match old_ended.get(&i) {
                    Some(Ended::Done(_)) => continue,
                    Some(e) => {
                        ended.insert(review.len(), e.clone());
                    }
                    None => {}
                }
                review.push(r);
            }
            *ctl.review.borrow_mut() = review;
            *ctl.ended.borrow_mut() = ended;
        }

        let survivors = std::mem::take(&mut *ctl.survivors.borrow_mut());
        crate::library_ui::save_judgements(w, library, &survivors);
        if let Some(after) = after {
            after(w);
        }
        if let Some(cat) = library.catalog().borrow().as_ref() {
            refresh_count(w, cat);
        }
    } else {
        let s = dups::summarise(&ctl.review.borrow());
        let note = format!(
            "{} the same, {} skipped",
            plural(s.groups + s.excluded, "group", "groups"),
            s.skipped
        );
        match &stopped {
            Some(why) => {
                job.fail(format!("{note} · {why}"));
                g.set_error(why.as_str().into());
            }
            None => job.finish(note),
        }
    }
    if let Some(t) = ctl.timer.borrow().as_ref() {
        t.stop();
    }
    ctl.thumbs.borrow_mut().clear();
    show(w, ctl, library);
}

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

    #[test]
    fn a_merge_is_described_in_words_with_its_conflicts() {
        let mut o = Outcome {
            rating: (2, 4),
            keywords_added: 1,
            collections_joined: 2,
            flag_conflict: true,
            ..Default::default()
        };
        o.faces.named = 1;
        let s = describe(&o, Some("_MG_4623.CR2"));
        assert!(s.contains("rating 4★ (was 2★)"), "{s}");
        assert!(s.contains("1 keyword,"), "{s}");
        assert!(s.contains("2 collections"), "{s}");
        assert!(s.contains("1 name"), "{s}");
        assert!(s.contains("the edit from _MG_4623.CR2"), "{s}");
        assert!(s.contains("disagree on flags"), "{s}");
    }

    #[test]
    fn nothing_to_merge_says_so() {
        let s = describe(&Outcome::default(), None);
        assert!(s.starts_with("Nothing to merge"), "{s}");
    }

    #[test]
    fn transfers_are_quoted_in_the_unit_a_person_reads() {
        assert_eq!(quote_bytes(10 * 1024 * 1024 * 1024), "10.0 GB");
        assert_eq!(quote_bytes(6 * 1024 * 1024), "6 MB");
    }
}