use std::time::{Duration, Instant};

use super::action::Action;
use crate::api::models::TrackItem;

use super::state::{
    AppState, GlobalView, Loadable, OpenedPlaylist, SearchState, Tab, TILE_HEIGHT, TILE_WIDTH,
    ViewMode, release_display_order, release_rows,
};

pub const QUIT_CONFIRM_WINDOW: Duration = Duration::from_millis(1500);
pub const QUIT_CONFIRM_HINT: &str = "press quit again to exit";

/// Side effects requested by `update()`; executed by the app loop, which
/// owns the Runtime (audio controller, API client). Keeps update() pure.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Effect {
    /// (Re)start playback of `queue[queue_pos]`.
    PlayCurrent,
    TogglePause,
    StopPlayback,
    /// Seek relative to the current position, in seconds.
    SeekBy(i64),
    SetVolume(u8),
    /// Fetch a release and append all its tracks to the queue.
    EnqueueRelease { id: i64, next: bool },
    ToggleLike { track_id: i64 },
}

pub fn update(state: &mut AppState, action: Action) -> Option<Effect> {
    // Any action other than a second Quit press disarms the confirmation.
    let quit_armed = state
        .quit_armed_until
        .take()
        .is_some_and(|deadline| Instant::now() <= deadline);
    state.status_message = None;
    match action {
        Action::Quit => {
            if quit_armed {
                state.should_quit = true;
            } else {
                state.quit_armed_until = Some(Instant::now() + QUIT_CONFIRM_WINDOW);
                state.status_message = Some(QUIT_CONFIRM_HINT.to_string());
            }
            None
        }
        Action::ToggleHelp => {
            state.help_visible = !state.help_visible;
            None
        }
        Action::Back if state.help_visible => {
            state.help_visible = false;
            None
        }
        Action::NextTab => {
            switch_tab(state, state.active_tab.next());
            None
        }
        Action::PrevTab => {
            switch_tab(state, state.active_tab.prev());
            None
        }
        Action::GoToTab(index) => {
            if let Some(tab) = Tab::from_index(index) {
                // Pressing the current tab's number again resets it to its
                // top level (closes drill-down views).
                if tab == state.active_tab {
                    reset_tab(state, tab);
                } else {
                    switch_tab(state, tab);
                }
            }
            None
        }
        Action::PlayPause => {
            if state.player.current.is_some() {
                state.player.paused = !state.player.paused;
                Some(Effect::TogglePause)
            } else if state.player.queue.is_empty() {
                state.status_message = Some("nothing queued — open a track and press enter".into());
                None
            } else {
                Some(Effect::PlayCurrent)
            }
        }
        Action::NextTrack => queue_step(state, 1),
        Action::PrevTrack => queue_step(state, -1),
        Action::SeekForward { seconds } => {
            state.player.current.is_some().then_some(Effect::SeekBy(seconds as i64))
        }
        Action::SeekBackward { seconds } => state
            .player
            .current
            .is_some()
            .then_some(Effect::SeekBy(-(seconds as i64))),
        Action::VolumeUp => {
            state.player.volume = (state.player.volume + 5).min(100);
            Some(Effect::SetVolume(state.player.volume))
        }
        Action::VolumeDown => {
            state.player.volume = state.player.volume.saturating_sub(5);
            Some(Effect::SetVolume(state.player.volume))
        }
        Action::ToggleShuffle => {
            state.player.shuffle = !state.player.shuffle;
            None
        }
        Action::CycleRepeat => {
            state.player.repeat = state.player.repeat.next();
            None
        }
        Action::MoveUp => {
            move_selection(state, 0, -1);
            None
        }
        Action::MoveDown => {
            move_selection(state, 0, 1);
            None
        }
        Action::MoveLeft => {
            move_selection(state, -1, 0);
            None
        }
        Action::MoveRight => {
            move_selection(state, 1, 0);
            None
        }
        Action::PageUp => {
            move_selection(state, 0, -page_step(state));
            None
        }
        Action::PageDown => {
            move_selection(state, 0, page_step(state));
            None
        }
        Action::SelectFirst => {
            jump_selection(state, true);
            None
        }
        Action::SelectLast => {
            jump_selection(state, false);
            None
        }
        Action::ToggleViewMode => {
            match state.active_tab {
                Tab::Global => state.global.view = state.global.view.toggle(),
                // On the Logs tab the same key cycles the severity filter.
                Tab::Logs => {
                    state.logs.level_index =
                        (state.logs.level_index + 1) % super::state::LOG_LEVELS.len();
                    state.logs.scroll_from_end = 0;
                    state.logs.follow = true;
                }
                _ => {}
            }
            None
        }
        Action::OpenCommandLine => {
            state.cmdline.active = true;
            state.cmdline.input.clear();
            None
        }
        Action::Select => select_current(state),
        Action::Back => {
            go_back(state);
            None
        }
        Action::ToggleLike => {
            let target = selected_track(state)
                .map(|t| t.id)
                .or(state.player.current.as_ref().map(|t| t.id));
            match target {
                Some(track_id) => Some(Effect::ToggleLike { track_id }),
                None => {
                    state.status_message = Some("no track selected".into());
                    None
                }
            }
        }
        Action::QueueAddNext => queue_add(state, true),
        Action::QueueAddLast => queue_add(state, false),
        // Needs the Runtime, so it is intercepted in app::handle_main_key
        // before reaching update().
        Action::Logout => None,
    }
}

/// The track under the cursor in whatever view is showing tracks.
pub fn selected_track(state: &AppState) -> Option<TrackItem> {
    match state.active_tab {
        Tab::Global => match state.global.stack.last()? {
            GlobalView::Artist { id, cursor } => match state.artist_views.get(id)? {
                Loadable::Ready(detail) => detail.top_tracks.get(*cursor).cloned(),
                _ => None,
            },
            GlobalView::Release { id, cursor } => match state.release_views.get(id)? {
                Loadable::Ready(detail) => detail.tracks.get(*cursor).cloned(),
                _ => None,
            },
            GlobalView::Search { cursor } => {
                let results = state.search.results.as_ref()?;
                let offset = cursor.checked_sub(results.artists.len() + results.releases.len())?;
                results.tracks.get(offset).cloned()
            }
        },
        Tab::Playlists => {
            let opened = state.playlists.opened.as_ref()?;
            playlist_tracks(state, opened.id)?.get(opened.cursor).cloned()
        }
        Tab::Queue => state
            .player
            .queue
            .get(state.player.queue_pos)
            .cloned(),
        Tab::Devices | Tab::Logs => None,
    }
}

/// Tracks backing an opened playlist, if loaded.
pub fn playlist_tracks(state: &AppState, id: i64) -> Option<&Vec<TrackItem>> {
    match state.playlist_views.get(&id)? {
        Loadable::Ready(detail) => Some(&detail.tracks),
        _ => None,
    }
}

/// A *release* under the cursor (artist-view tile/row or a search release).
fn selected_release_id(state: &AppState) -> Option<i64> {
    if state.active_tab != Tab::Global {
        return None;
    }
    match state.global.stack.last()? {
        GlobalView::Artist { id, cursor } => match state.artist_views.get(id)? {
            Loadable::Ready(detail) => {
                let position = cursor.checked_sub(detail.top_tracks.len())?;
                let order = release_display_order(&detail.releases);
                order.get(position).map(|&i| detail.releases[i].id)
            }
            _ => None,
        },
        GlobalView::Search { cursor } => {
            let results = state.search.results.as_ref()?;
            let offset = cursor.checked_sub(results.artists.len())?;
            results.releases.get(offset).map(|r| r.id)
        }
        GlobalView::Release { .. } => None,
    }
}

/// a / shift-a: queue the selection — a single track directly, a release via
/// an async fetch effect.
fn queue_add(state: &mut AppState, next: bool) -> Option<Effect> {
    if let Some(track) = selected_track(state) {
        let title = track.title.clone();
        enqueue_tracks(state, vec![track], next);
        state.status_message = Some(if next {
            format!("queued next: {title}")
        } else {
            format!("queued: {title}")
        });
        return None;
    }
    if let Some(id) = selected_release_id(state) {
        return Some(Effect::EnqueueRelease { id, next });
    }
    state.status_message = Some("nothing to queue here".into());
    None
}

/// Insert tracks after the playing one (`next`) or at the end. Keeps the
/// gapless prefetch index pointing at the same track if items shift.
pub fn enqueue_tracks(state: &mut AppState, tracks: Vec<TrackItem>, next: bool) {
    let player = &mut state.player;
    if tracks.is_empty() {
        return;
    }
    let insert_at = if next && !player.queue.is_empty() {
        (player.queue_pos + 1).min(player.queue.len())
    } else if next {
        0
    } else {
        player.queue.len()
    };
    let count = tracks.len();
    for (offset, track) in tracks.into_iter().enumerate() {
        player.queue.insert(insert_at + offset, track);
    }
    if let Some(prefetched) = &mut player.prefetched_pos {
        if insert_at <= *prefetched {
            *prefetched += count;
        }
    }
    if insert_at <= player.queue_pos && player.current.is_some() {
        player.queue_pos += count;
    }
}

/// Manual queue navigation (n / p).
fn queue_step(state: &mut AppState, direction: isize) -> Option<Effect> {
    let player = &mut state.player;
    if player.queue.is_empty() {
        state.status_message = Some("queue is empty".into());
        return None;
    }
    let len = player.queue.len();
    if player.shuffle && direction > 0 {
        player.queue_pos = pseudo_random(len);
        return Some(Effect::PlayCurrent);
    }
    let next = player.queue_pos as isize + direction;
    if next < 0 {
        player.queue_pos = 0;
    } else if next >= len as isize {
        if player.repeat == super::state::RepeatMode::All {
            player.queue_pos = 0;
        } else {
            state.status_message = Some("end of queue".into());
            return None;
        }
    } else {
        player.queue_pos = next as usize;
    }
    Some(Effect::PlayCurrent)
}

/// What plays after the current track, without mutating anything — used to
/// pick the gapless prefetch target. Mirrors `advance_after_finish`.
pub fn peek_next_pos(player: &super::state::PlayerBar) -> Option<usize> {
    if player.queue.is_empty() {
        return None;
    }
    match player.repeat {
        super::state::RepeatMode::One => Some(player.queue_pos),
        _ if player.shuffle => Some(pseudo_random(player.queue.len())),
        repeat => {
            if player.queue_pos + 1 < player.queue.len() {
                Some(player.queue_pos + 1)
            } else if repeat == super::state::RepeatMode::All {
                Some(0)
            } else {
                None
            }
        }
    }
}

/// The current track finished: pick what plays next according to
/// repeat/shuffle, or stop at the end of the queue.
pub fn advance_after_finish(state: &mut AppState) -> Option<Effect> {
    let player = &mut state.player;
    if player.queue.is_empty() {
        player.playing = false;
        player.current = None;
        return None;
    }
    match player.repeat {
        super::state::RepeatMode::One => Some(Effect::PlayCurrent),
        _ if player.shuffle => {
            player.queue_pos = pseudo_random(player.queue.len());
            Some(Effect::PlayCurrent)
        }
        repeat => {
            if player.queue_pos + 1 < player.queue.len() {
                player.queue_pos += 1;
                Some(Effect::PlayCurrent)
            } else if repeat == super::state::RepeatMode::All {
                player.queue_pos = 0;
                Some(Effect::PlayCurrent)
            } else {
                player.playing = false;
                player.paused = false;
                Some(Effect::StopPlayback)
            }
        }
    }
}

/// Shuffle pick without a rand dependency: clock-derived index.
fn pseudo_random(len: usize) -> usize {
    let nanos = std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .map(|d| d.subsec_nanos())
        .unwrap_or(0);
    nanos as usize % len.max(1)
}

/// Columns of the Global tile grid. Derived from the terminal width the same
/// way ui::global does (full width minus the surrounding block's borders),
/// so selection math and rendering agree.
pub fn grid_columns() -> usize {
    let width = crossterm::terminal::size().map(|(w, _)| w).unwrap_or(80);
    usize::from((width.saturating_sub(2) / TILE_WIDTH).max(1))
}

/// Lines of content visible in the main area (terminal height minus the tab
/// bar, status bar and the view's borders).
fn viewport_lines() -> isize {
    let height = crossterm::terminal::size().map(|(_, h)| h).unwrap_or(24);
    height.saturating_sub(5).max(1) as isize
}

/// One PageUp/PageDown step in MoveUp/MoveDown units for the current view:
/// move_selection() multiplies vertical steps by the column count in tile
/// zones, so tile views page by visible tile rows, line views by visible
/// lines.
fn page_step(state: &AppState) -> isize {
    let lines = viewport_lines();
    if state.active_tab != Tab::Global {
        return lines;
    }
    let tile_rows = (lines / TILE_HEIGHT as isize).max(1);
    match state.global.stack.last() {
        None => match state.global.view {
            ViewMode::Tiles => tile_rows,
            ViewMode::Table => lines,
        },
        Some(GlobalView::Artist { id, cursor }) => {
            let in_tracks = match state.artist_views.get(id) {
                Some(Loadable::Ready(detail)) => *cursor < detail.top_tracks.len(),
                _ => true,
            };
            if in_tracks || state.global.view == ViewMode::Table {
                lines
            } else {
                tile_rows
            }
        }
        Some(GlobalView::Release { .. }) | Some(GlobalView::Search { .. }) => lines,
    }
}

fn move_selection(state: &mut AppState, dx: isize, dy: isize) {
    if state.active_tab == Tab::Logs {
        let total = crate::config::logging::buffer().map_or(0, |b| b.len());
        let logs = &mut state.logs;
        if dy < 0 {
            logs.follow = false;
            logs.scroll_from_end = (logs.scroll_from_end + dy.unsigned_abs()).min(total);
        } else if dy > 0 {
            logs.scroll_from_end = logs.scroll_from_end.saturating_sub(dy as usize);
            if logs.scroll_from_end == 0 {
                logs.follow = true;
            }
        }
        return;
    }
    if state.active_tab == Tab::Playlists {
        let len = playlists_view_len(state);
        if len == 0 {
            return;
        }
        let last = len as isize - 1;
        match &mut state.playlists.opened {
            Some(opened) => {
                opened.cursor = (opened.cursor as isize + dy).clamp(0, last) as usize;
            }
            None => {
                state.playlists.selected =
                    (state.playlists.selected as isize + dy).clamp(0, last) as usize;
            }
        }
        return;
    }
    if state.active_tab != Tab::Global {
        return not_yet(state, "Navigation in this view");
    }
    match state.global.stack.last().copied() {
        None => {
            let global = &mut state.global;
            if global.artists.is_empty() {
                return;
            }
            let step = match global.view {
                ViewMode::Tiles => dx + dy * grid_columns() as isize,
                ViewMode::Table => dy,
            };
            let last = global.artists.len() as isize - 1;
            global.selected = (global.selected as isize + step).clamp(0, last) as usize;
        }
        Some(GlobalView::Artist { id, cursor }) => {
            let Some(Loadable::Ready(detail)) = state.artist_views.get(&id) else {
                return;
            };
            let tracks = detail.top_tracks.len();
            let total = tracks + detail.releases.len();
            if total == 0 {
                return;
            }
            let next = if cursor < tracks {
                // Top-tracks zone: vertical only; stepping past the last
                // track enters the releases zone (its first item).
                (cursor as isize + dy).clamp(0, total as isize - 1) as usize
            } else if state.global.view == ViewMode::Table {
                let next = cursor as isize + dy;
                if next < tracks as isize && dy < 0 && tracks > 0 {
                    tracks - 1
                } else {
                    next.clamp(0, total as isize - 1) as usize
                }
            } else {
                // Tiles: move by visual rows (groups break rows), keeping
                // the column, so Up lands on the tile directly above.
                let rows = release_rows(&detail.releases, grid_columns());
                let position = cursor - tracks;
                let (row, column) = rows
                    .iter()
                    .enumerate()
                    .find_map(|(r, items)| {
                        items.iter().position(|p| *p == position).map(|c| (r, c))
                    })
                    .unwrap_or((0, 0));
                if dx != 0 {
                    let last = detail.releases.len() as isize - 1;
                    tracks + (position as isize + dx).clamp(0, last) as usize
                } else {
                    let target = row as isize + dy;
                    if target < 0 {
                        if tracks > 0 {
                            tracks - 1
                        } else {
                            cursor
                        }
                    } else {
                        let items = &rows[(target as usize).min(rows.len() - 1)];
                        tracks + items[column.min(items.len() - 1)]
                    }
                }
            };
            set_view_cursor(state, next);
        }
        Some(GlobalView::Release { id, cursor }) => {
            let Some(Loadable::Ready(detail)) = state.release_views.get(&id) else {
                return;
            };
            let total = detail.tracks.len() as isize;
            if total == 0 {
                return;
            }
            let next = (cursor as isize + dy).clamp(0, total - 1);
            set_view_cursor(state, next as usize);
        }
        Some(GlobalView::Search { cursor }) => {
            let total = state.search.results.as_ref().map_or(0, |r| r.len()) as isize;
            if total == 0 {
                return;
            }
            let next = (cursor as isize + dy).clamp(0, total - 1);
            set_view_cursor(state, next as usize);
        }
    }
}

fn set_view_cursor(state: &mut AppState, value: usize) {
    if let Some(view) = state.global.stack.last_mut() {
        match view {
            GlobalView::Artist { cursor, .. }
            | GlobalView::Release { cursor, .. }
            | GlobalView::Search { cursor } => *cursor = value,
        }
    }
}

/// Items in the playlists tab's current view (list or opened playlist).
fn playlists_view_len(state: &AppState) -> usize {
    match &state.playlists.opened {
        Some(opened) => playlist_tracks(state, opened.id).map_or(0, Vec::len),
        None => match &state.playlists.list {
            Some(Loadable::Ready(list)) => list.len(),
            _ => 0,
        },
    }
}

fn current_view_len(state: &AppState) -> usize {
    if state.active_tab == Tab::Playlists {
        return playlists_view_len(state);
    }
    match state.global.stack.last() {
        None => state.global.artists.len(),
        Some(GlobalView::Artist { id, .. }) => match state.artist_views.get(id) {
            Some(Loadable::Ready(d)) => d.top_tracks.len() + d.releases.len(),
            _ => 0,
        },
        Some(GlobalView::Release { id, .. }) => match state.release_views.get(id) {
            Some(Loadable::Ready(d)) => d.tracks.len(),
            _ => 0,
        },
        Some(GlobalView::Search { .. }) => state.search.results.as_ref().map_or(0, |r| r.len()),
    }
}

fn jump_selection(state: &mut AppState, first: bool) {
    if state.active_tab == Tab::Logs {
        if first {
            state.logs.follow = false;
            state.logs.scroll_from_end = crate::config::logging::buffer().map_or(0, |b| b.len());
        } else {
            state.logs.follow = true;
            state.logs.scroll_from_end = 0;
        }
        return;
    }
    if state.active_tab != Tab::Global && state.active_tab != Tab::Playlists {
        return not_yet(state, "Navigation in this view");
    }
    let len = current_view_len(state);
    if len == 0 {
        return;
    }
    let target = if first { 0 } else { len - 1 };
    if state.active_tab == Tab::Playlists {
        match &mut state.playlists.opened {
            Some(opened) => opened.cursor = target,
            None => state.playlists.selected = target,
        }
    } else if state.global.stack.is_empty() {
        state.global.selected = target;
    } else {
        set_view_cursor(state, target);
    }
}

/// Enter on the Playlists tab: open a playlist from the list, or play the
/// selected track with the playlist as the queue.
fn select_playlist(state: &mut AppState) -> Option<Effect> {
    match state.playlists.opened {
        Some(opened) => {
            let tracks = playlist_tracks(state, opened.id)?.clone();
            if tracks.is_empty() {
                return None;
            }
            state.player.queue = tracks;
            state.player.queue_pos = opened.cursor.min(state.player.queue.len() - 1);
            Some(Effect::PlayCurrent)
        }
        None => {
            let id = match &state.playlists.list {
                Some(Loadable::Ready(list)) => list.get(state.playlists.selected)?.id,
                _ => return None,
            };
            state.playlists.opened = Some(OpenedPlaylist { id, cursor: 0 });
            None
        }
    }
}

/// Enter: drill down (grid → artist → release) or play the selected track
/// with its surrounding list as the queue.
fn select_current(state: &mut AppState) -> Option<Effect> {
    if state.active_tab == Tab::Playlists {
        return select_playlist(state);
    }
    if state.active_tab != Tab::Global {
        not_yet(state, "Navigation in this view");
        return None;
    }
    enum Outcome {
        Push(GlobalView),
        Play { tracks: Vec<crate::api::models::TrackItem>, start: usize },
        Nothing,
    }
    let outcome = match state.global.stack.last().copied() {
        None => match state.global.artists.get(state.global.selected) {
            Some(artist) => Outcome::Push(GlobalView::Artist {
                id: artist.id,
                cursor: 0,
            }),
            None => Outcome::Nothing,
        },
        Some(GlobalView::Artist { id, cursor }) => match state.artist_views.get(&id) {
            Some(Loadable::Ready(detail)) => {
                let tracks = detail.top_tracks.len();
                if cursor < tracks {
                    Outcome::Play {
                        tracks: detail.top_tracks.clone(),
                        start: cursor,
                    }
                } else {
                    let order = release_display_order(&detail.releases);
                    match order.get(cursor - tracks) {
                        Some(&original) => Outcome::Push(GlobalView::Release {
                            id: detail.releases[original].id,
                            cursor: 0,
                        }),
                        None => Outcome::Nothing,
                    }
                }
            }
            _ => Outcome::Nothing,
        },
        Some(GlobalView::Release { id, cursor }) => match state.release_views.get(&id) {
            Some(Loadable::Ready(detail)) if !detail.tracks.is_empty() => Outcome::Play {
                tracks: detail.tracks.clone(),
                start: cursor.min(detail.tracks.len() - 1),
            },
            _ => Outcome::Nothing,
        },
        Some(GlobalView::Search { cursor }) => match &state.search.results {
            Some(results) => {
                let artists = results.artists.len();
                let releases = results.releases.len();
                if cursor < artists {
                    Outcome::Push(GlobalView::Artist {
                        id: results.artists[cursor].id,
                        cursor: 0,
                    })
                } else if cursor < artists + releases {
                    Outcome::Push(GlobalView::Release {
                        id: results.releases[cursor - artists].id,
                        cursor: 0,
                    })
                } else if results.tracks.get(cursor - artists - releases).is_some() {
                    Outcome::Play {
                        tracks: results.tracks.clone(),
                        start: cursor - artists - releases,
                    }
                } else {
                    Outcome::Nothing
                }
            }
            None => Outcome::Nothing,
        },
    };
    match outcome {
        Outcome::Push(view) => {
            state.global.stack.push(view);
            None
        }
        Outcome::Play { tracks, start } => {
            state.player.queue = tracks;
            state.player.queue_pos = start;
            Some(Effect::PlayCurrent)
        }
        Outcome::Nothing => None,
    }
}

/// Esc/Backspace: pop the navigation stack; leaving a search view resets the
/// search so the next `:/` starts clean.
fn go_back(state: &mut AppState) {
    match state.active_tab {
        Tab::Playlists => {
            state.playlists.opened = None;
        }
        Tab::Global => {
            if let Some(popped) = state.global.stack.pop() {
                if matches!(popped, GlobalView::Search { .. }) {
                    state.search = SearchState::default();
                }
            }
        }
        _ => {}
    }
}

fn switch_tab(state: &mut AppState, tab: Tab) {
    state.active_tab = tab;
    state.help_visible = false;
}

fn reset_tab(state: &mut AppState, tab: Tab) {
    match tab {
        Tab::Global => {
            if state
                .global
                .stack
                .iter()
                .any(|v| matches!(v, GlobalView::Search { .. }))
            {
                state.search = SearchState::default();
            }
            state.global.stack.clear();
        }
        Tab::Playlists => state.playlists.opened = None,
        Tab::Logs => {
            state.logs.follow = true;
            state.logs.scroll_from_end = 0;
        }
        Tab::Queue | Tab::Devices => {}
    }
}

fn not_yet(state: &mut AppState, what: &str) {
    state.status_message = Some(format!("{what}: coming in a later milestone"));
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::api::models::ArtistCard;

    fn with_artists(n: usize) -> AppState {
        let mut state = AppState::default();
        state.global.artists = (0..n)
            .map(|i| ArtistCard {
                id: i as i64,
                name: format!("artist {i}"),
                image_url: None,
                release_count: 1,
                track_count: 2,
            })
            .collect();
        state
    }

    #[test]
    fn quit_needs_double_press() {
        let mut state = AppState::default();
        update(&mut state, Action::Quit);
        assert!(!state.should_quit);
        assert_eq!(state.status_message.as_deref(), Some(QUIT_CONFIRM_HINT));
        update(&mut state, Action::Quit);
        assert!(state.should_quit);
    }

    #[test]
    fn other_action_disarms_quit() {
        let mut state = AppState::default();
        update(&mut state, Action::Quit);
        update(&mut state, Action::NextTab);
        update(&mut state, Action::Quit);
        assert!(!state.should_quit);
    }

    #[test]
    fn expired_quit_confirmation_rearms() {
        let mut state = AppState::default();
        update(&mut state, Action::Quit);
        state.quit_armed_until = Some(Instant::now() - Duration::from_secs(1));
        update(&mut state, Action::Quit);
        assert!(!state.should_quit);
        assert_eq!(state.status_message.as_deref(), Some(QUIT_CONFIRM_HINT));
    }

    #[test]
    fn tab_cycling_wraps() {
        let mut state = AppState::default();
        update(&mut state, Action::PrevTab);
        assert_eq!(state.active_tab, Tab::Logs);
        update(&mut state, Action::NextTab);
        assert_eq!(state.active_tab, Tab::Global);
    }

    #[test]
    fn volume_clamps() {
        let mut state = AppState::default();
        for _ in 0..30 {
            update(&mut state, Action::VolumeUp);
        }
        assert_eq!(state.player.volume, 100);
        for _ in 0..30 {
            update(&mut state, Action::VolumeDown);
        }
        assert_eq!(state.player.volume, 0);
    }

    #[test]
    fn back_closes_help_first() {
        let mut state = AppState::default();
        update(&mut state, Action::ToggleHelp);
        assert!(state.help_visible);
        update(&mut state, Action::Back);
        assert!(!state.help_visible);
    }

    #[test]
    fn grid_movement_clamps_and_wraps_rows() {
        let mut state = with_artists(10);
        let cols = grid_columns();
        update(&mut state, Action::MoveDown);
        assert_eq!(state.global.selected, cols.min(9));
        update(&mut state, Action::MoveUp);
        assert_eq!(state.global.selected, 0);
        update(&mut state, Action::MoveLeft);
        assert_eq!(state.global.selected, 0);
        update(&mut state, Action::MoveRight);
        assert_eq!(state.global.selected, 1);
    }

    #[test]
    fn table_mode_moves_one_row() {
        let mut state = with_artists(10);
        state.global.view = ViewMode::Table;
        update(&mut state, Action::MoveDown);
        assert_eq!(state.global.selected, 1);
        // Left/right are meaningless in the table.
        update(&mut state, Action::MoveRight);
        assert_eq!(state.global.selected, 1);
    }

    #[test]
    fn page_down_moves_a_page_and_clamps() {
        let mut state = with_artists(200);
        let cols = grid_columns() as isize;
        let expected = (page_step(&state) * cols).min(199) as usize;
        update(&mut state, Action::PageDown);
        assert_eq!(state.global.selected, expected);
        update(&mut state, Action::PageUp);
        assert_eq!(state.global.selected, 0);

        state.global.view = ViewMode::Table;
        update(&mut state, Action::PageDown);
        assert_eq!(state.global.selected, page_step(&state).min(199) as usize);
    }

    #[test]
    fn jump_first_last() {
        let mut state = with_artists(10);
        update(&mut state, Action::SelectLast);
        assert_eq!(state.global.selected, 9);
        update(&mut state, Action::SelectFirst);
        assert_eq!(state.global.selected, 0);
    }

    #[test]
    fn artist_tiles_move_by_visual_rows_across_groups() {
        use crate::api::models::{ArtistDetail, ReleaseCard};

        let release = |id: i64, kind: &str| ReleaseCard {
            id,
            title: format!("r{id}"),
            release_type: kind.to_string(),
            year: None,
            cover_url: None,
            track_count: 1,
        };
        // columns = 3 in tests (no tty → 80 wide): albums rows [0,1,2],[3],
        // compilations row [4,5].
        let detail = ArtistDetail {
            id: 1,
            name: "a".into(),
            image_url: None,
            total_track_count: 0,
            total_play_count: 0,
            top_tracks: vec![],
            releases: vec![
                release(10, "album"),
                release(11, "album"),
                release(12, "album"),
                release(13, "album"),
                release(14, "compilation"),
                release(15, "compilation"),
            ],
        };
        let mut state = AppState::default();
        state.artist_views.insert(1, Loadable::Ready(detail));
        state.global.stack.push(GlobalView::Artist { id: 1, cursor: 4 });

        // Up from the first compilation lands on the album row directly
        // above (position 3), not three flat items back.
        update(&mut state, Action::MoveUp);
        assert_eq!(
            state.global.stack.last(),
            Some(&GlobalView::Artist { id: 1, cursor: 3 })
        );
        // And back down returns to the compilation row, same column.
        update(&mut state, Action::MoveDown);
        assert_eq!(
            state.global.stack.last(),
            Some(&GlobalView::Artist { id: 1, cursor: 4 })
        );
        // Up from the second compilation clamps to the single tile above.
        state.global.stack.pop();
        state.global.stack.push(GlobalView::Artist { id: 1, cursor: 5 });
        update(&mut state, Action::MoveUp);
        assert_eq!(
            state.global.stack.last(),
            Some(&GlobalView::Artist { id: 1, cursor: 3 })
        );
    }

    #[test]
    fn select_opens_artist_and_back_returns() {
        let mut state = with_artists(3);
        state.global.selected = 2;
        update(&mut state, Action::Select);
        assert_eq!(
            state.global.stack.last(),
            Some(&GlobalView::Artist { id: 2, cursor: 0 })
        );
        update(&mut state, Action::Back);
        assert!(state.global.stack.is_empty());
        assert_eq!(state.global.selected, 2);
    }

    #[test]
    fn back_from_search_resets_search_state() {
        let mut state = AppState::default();
        state.global.stack.push(GlobalView::Search { cursor: 0 });
        state.search.query = "abc".to_string();
        update(&mut state, Action::Back);
        assert!(state.global.stack.is_empty());
        assert!(state.search.query.is_empty());
    }

    #[test]
    fn queue_advances_and_respects_repeat() {
        use crate::api::models::TrackItem;
        use crate::app::state::RepeatMode;

        let track = |id: i64| TrackItem {
            id,
            title: format!("t{id}"),
            track_number: None,
            duration_seconds: 1.0,
            artists: vec![],
            featured_artists: vec![],
            release_id: 1,
            release_title: "r".into(),
            release_year: None,
            cover_url: None,
            stream_url: format!("/api/player/stream/{id}"),
            audio_format: None,
            audio_bitrate: None,
            audio_sample_rate: None,
            file_size_bytes: None,
            lastfm_playcount: None,
        };
        let mut state = AppState::default();
        state.player.queue = vec![track(1), track(2)];
        state.player.playing = true;

        // Track 1 finishes → play track 2.
        assert_eq!(advance_after_finish(&mut state), Some(Effect::PlayCurrent));
        assert_eq!(state.player.queue_pos, 1);
        // Last track, repeat off → stop.
        assert_eq!(advance_after_finish(&mut state), Some(Effect::StopPlayback));
        assert!(!state.player.playing);
        // Repeat all wraps to the start.
        state.player.playing = true;
        state.player.repeat = RepeatMode::All;
        assert_eq!(advance_after_finish(&mut state), Some(Effect::PlayCurrent));
        assert_eq!(state.player.queue_pos, 0);
        // Repeat one replays the same position.
        state.player.repeat = RepeatMode::One;
        assert_eq!(advance_after_finish(&mut state), Some(Effect::PlayCurrent));
        assert_eq!(state.player.queue_pos, 0);
    }

    #[test]
    fn same_tab_number_resets_to_root() {
        let mut state = with_artists(3);
        update(&mut state, Action::Select);
        assert!(!state.global.stack.is_empty());
        update(&mut state, Action::GoToTab(0));
        assert!(state.global.stack.is_empty());

        state.playlists.opened = Some(OpenedPlaylist {
            id: crate::app::state::LIKES_PLAYLIST_ID,
            cursor: 0,
        });
        update(&mut state, Action::GoToTab(1));
        assert_eq!(state.active_tab, Tab::Playlists);
        assert!(state.playlists.opened.is_some());
        update(&mut state, Action::GoToTab(1));
        assert!(state.playlists.opened.is_none());
    }

    #[test]
    fn view_toggle() {
        let mut state = AppState::default();
        update(&mut state, Action::ToggleViewMode);
        assert_eq!(state.global.view, ViewMode::Table);
        update(&mut state, Action::ToggleViewMode);
        assert_eq!(state.global.view, ViewMode::Tiles);
    }
}