// app lifecycle manager: nav stack, dispatch, font propagation, draw
//
// all dispatch is static (monomorphized via with_app!); no dyn, no vtable
// loading indicator is drawn between app content and overlays so it
// sits on top of page content but under quick menu and button bumps

use crate::apps::files::FilesApp;
use crate::apps::home::HomeApp;
use crate::apps::reader::ReaderApp;
use crate::apps::settings::SettingsApp;
use crate::apps::stats::StatsApp;
use crate::apps::{
    App, AppContext, AppId, DeferredPersistenceReason, Launcher, PendingSetting, Redraw, Transition,
};
use esp_hal::delay::Delay;

use crate::apps::widgets::quick_menu::{MAX_APP_ACTIONS, QuickMenuResult};
use crate::apps::widgets::{ButtonFeedback, QuickMenu};
use crate::board::action::{Action, ActionEvent, ButtonMapper};
use crate::board::{Epd, SCREEN_H, SCREEN_W};
use crate::drivers::input::Event;
use crate::drivers::sdcard::SdStorage;
use crate::drivers::strip::StripBuffer;
use crate::fonts;
use crate::kernel::KernelHandle;
use crate::kernel::app::AppLayer;
use crate::kernel::bookmarks::BookmarkCache;
use crate::kernel::config::{SystemSettings, WifiConfig};
use crate::kernel::input_policy::SemanticInput;
use crate::ui::Region;

// monomorphized dispatch from AppId to concrete app type
macro_rules! with_app {
    ($id:expr, $mgr:expr, |$app:ident| $body:expr) => {
        match $id {
            AppId::Home => {
                let $app = &mut *$mgr.home;
                $body
            }
            AppId::Files => {
                let $app = &mut *$mgr.files;
                $body
            }
            AppId::Reader => {
                let $app = &mut *$mgr.reader;
                $body
            }
            AppId::Settings => {
                let $app = &mut *$mgr.settings;
                $body
            }
            AppId::Stats => {
                let $app = &mut *$mgr.stats;
                $body
            }
            AppId::Upload => {
                unreachable!("Upload mode is handled outside the app dispatch loop");
            }
        }
    };
}

// shared-ref variant for read-only dispatch (draw, quick_actions)
macro_rules! with_app_ref {
    ($id:expr, $mgr:expr, |$app:ident| $body:expr) => {
        match $id {
            AppId::Home => {
                let $app = &*$mgr.home;
                $body
            }
            AppId::Files => {
                let $app = &*$mgr.files;
                $body
            }
            AppId::Reader => {
                let $app = &*$mgr.reader;
                $body
            }
            AppId::Settings => {
                let $app = &*$mgr.settings;
                $body
            }
            AppId::Stats => {
                let $app = &*$mgr.stats;
                $body
            }
            AppId::Upload => {
                unreachable!("Upload mode is handled outside the app dispatch loop");
            }
        }
    };
}

#[allow(unused_imports)]
pub(crate) use with_app;
#[allow(unused_imports)]
pub(crate) use with_app_ref;

pub struct AppManager {
    pub launcher: &'static mut Launcher,

    pub home: &'static mut HomeApp,
    pub files: &'static mut FilesApp,
    pub reader: &'static mut ReaderApp,
    pub settings: &'static mut SettingsApp,
    pub stats: &'static mut StatsApp,

    pub quick_menu: &'static mut QuickMenu,
    pub bumps: &'static mut ButtonFeedback,

    pub mapper: ButtonMapper,
}

impl AppManager {
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        launcher: &'static mut Launcher,
        home: &'static mut HomeApp,
        files: &'static mut FilesApp,
        reader: &'static mut ReaderApp,
        settings: &'static mut SettingsApp,
        stats: &'static mut StatsApp,
        quick_menu: &'static mut QuickMenu,
        bumps: &'static mut ButtonFeedback,
        mapper: ButtonMapper,
    ) -> Self {
        Self {
            launcher,
            home,
            files,
            reader,
            settings,
            stats,
            quick_menu,
            bumps,
            mapper,
        }
    }

    #[inline]
    pub fn active(&self) -> AppId {
        self.launcher.active()
    }

    #[inline]
    pub fn ctx(&self) -> &AppContext {
        &self.launcher.ctx
    }

    #[inline]
    pub fn ctx_mut(&mut self) -> &mut AppContext {
        &mut self.launcher.ctx
    }

    #[inline]
    pub fn has_redraw(&self) -> bool {
        self.launcher.ctx.has_redraw()
    }

    #[inline]
    pub fn take_redraw(&mut self) -> Redraw {
        self.launcher.ctx.take_redraw()
    }

    #[inline]
    pub fn request_full_redraw(&mut self) {
        self.launcher.ctx.request_full_redraw();
    }

    #[inline]
    pub fn apply_nav(&mut self, transition: Transition) -> Option<crate::apps::NavEvent> {
        self.launcher.apply(transition)
    }

    pub fn load_eager_settings(&mut self, k: &mut KernelHandle<'_>) {
        self.settings.load_eager(k);
        self.propagate_fonts();
        self.sync_button_config();
    }

    // sync button mapper and label widget from settings
    fn sync_button_config(&mut self) {
        let swap = self.settings.system_settings().swap_buttons;
        self.mapper.set_swap(swap);
        if self.bumps.set_swap(swap) {
            // labels changed, need to redraw the button bar
            self.launcher.ctx.mark_dirty(crate::ui::Region::new(
                0,
                crate::board::SCREEN_H - crate::ui::BUTTON_BAR_H,
                crate::board::SCREEN_W,
                crate::ui::BUTTON_BAR_H,
            ));
        }
    }

    pub fn load_home_recent(&mut self, k: &mut KernelHandle<'_>) {
        self.home.load_recent(k);
    }

    pub fn enter_initial(&mut self, k: &mut KernelHandle<'_>) {
        self.home.on_enter(&mut self.launcher.ctx, k);
    }

    // save active app state to bookmark cache before sleep
    pub fn save_active_state(&mut self, bm: &mut crate::kernel::bookmarks::BookmarkCache) {
        let active = self.launcher.active();
        with_app!(active, self, |app| app.save_state(bm));
    }

    // collect session state to RTC memory struct before sleep
    pub fn collect_session(&self, session: &mut crate::kernel::rtc_session::RtcSession) {
        use crate::kernel::rtc_session::MAX_NAV_STACK;

        // save navigation stack
        session.nav_depth = self.launcher.depth() as u8;
        for i in 0..MAX_NAV_STACK {
            session.nav_stack[i] = if i < self.launcher.depth() {
                self.launcher.stack_at(i) as u8
            } else {
                0
            };
        }

        // save reader state
        session.reader_filename_len = self.reader.filename_len() as u8;
        let len = session.reader_filename_len as usize;
        session.reader_filename[..len].copy_from_slice(self.reader.filename_bytes());
        session.reader_is_epub = self.reader.is_epub() as u8;
        session.reader_chapter = self.reader.chapter();
        session.reader_page = self.reader.page() as u16;
        session.reader_byte_offset = self.reader.byte_offset();
        session.reader_font_size = self.reader.font_size_idx();

        // save files state
        session.files_scroll = self.files.scroll() as u16;
        session.files_selected = self.files.selected() as u8;
        session.files_total = self.files.total() as u16;

        // save home state
        session.home_state = self.home.state_id();
        session.home_selected = self.home.selected() as u8;
        session.home_bm_selected = self.home.bm_selected() as u8;
        session.home_bm_scroll = self.home.bm_scroll() as u8;

        // save settings cache
        let ss = self.settings.system_settings();
        session.settings_sleep_timeout = ss.sleep_timeout;
        session.settings_ghost_clear = ss.ghost_clear_every;
        session.settings_book_font = ss.book_font_size_idx;
        session.settings_ui_font = ss.ui_font_size_idx;
        session.settings_valid = 1;

        log::debug!(
            "session: collected nav_depth={} active={:?}",
            session.nav_depth,
            self.launcher.active()
        );
    }

    // restore session from RTC memory; returns true if successful
    //
    // IMPORTANT: this does NOT call on_enter() on any app. the previous
    // code called on_enter() after restore_state(), which clobbered the
    // restored values (home.selected, files.scroll, reader.chapter, etc).
    // instead, each app's restore_state() is now responsible for setting
    // up ALL state needed to resume, and the reader enters at NeedBookmark
    // with its chapter/offset pre-populated from the RTC session.
    pub fn apply_session(
        &mut self,
        session: &crate::kernel::rtc_session::RtcSession,
        k: &mut KernelHandle<'_>,
    ) -> bool {
        // validate session data
        if session.nav_depth == 0 || session.nav_depth > 4 {
            log::warn!("session: invalid nav_depth {}", session.nav_depth);
            return false;
        }

        // restore navigation stack
        self.launcher.restore_stack(
            session.nav_depth as usize,
            &session.nav_stack,
            |id| match id {
                0 => AppId::Home,
                1 => AppId::Files,
                2 => AppId::Reader,
                3 => AppId::Settings,
                4 => AppId::Stats,
                _ => AppId::Home,
            },
        );

        log::debug!(
            "session: restored nav stack depth={} active={:?}",
            session.nav_depth,
            self.launcher.active()
        );

        // restore home state (always in stack)
        // restore_state sets state/selected/bm cursors without
        // resetting them like on_enter() would
        self.home.restore_state(
            session.home_state,
            session.home_selected as usize,
            session.home_bm_selected as usize,
            session.home_bm_scroll as usize,
        );
        // battery percentage for status display
        self.home.set_battery(k.battery_mv());

        // restore files state if in stack
        if self.launcher.contains(AppId::Files) {
            self.files.restore_state(
                session.files_scroll as usize,
                session.files_selected as usize,
                session.files_total as usize,
            );
        }

        // restore reader state if active or in stack
        if self.launcher.active() == AppId::Reader || self.launcher.contains(AppId::Reader) {
            let filename = &session.reader_filename[..session.reader_filename_len as usize];
            self.reader.restore_state(
                filename,
                session.reader_is_epub != 0,
                session.reader_chapter,
                session.reader_page as usize,
                session.reader_byte_offset,
                session.reader_font_size,
            );

            // Wake-to-reader should use the rich cover loading screen on
            // the very first frame instead of flashing a generic resume
            // screen before background restore reloads cached assets.
            if self.launcher.active() == AppId::Reader {
                self.reader.prepare_restore_loading_screen(k);
            }
        }

        // propagate fonts (uses settings already loaded)
        self.propagate_fonts();

        // set loading indicator for reader if it's the active app,
        // so the first frame shows "Opening" instead of blank content
        if self.launcher.active() == AppId::Reader {
            self.launcher
                .ctx
                .set_loading(crate::apps::reader::LOADING_REGION, "Resuming", 0);
        }

        // mark full redraw needed — the next render will draw the
        // active app's content using the restored state
        self.launcher.ctx.request_full_redraw();

        log::debug!(
            "session: restore complete, active={:?}",
            self.launcher.active()
        );

        true
    }

    /// Open the quick menu for the active app.
    fn open_quick_menu(&mut self) {
        let active = self.launcher.active();
        let actions: &[_] = with_app!(active, self, |app| app.quick_actions());
        self.quick_menu.show(actions);
        self.launcher.ctx.mark_dirty(self.quick_menu.region());
    }

    /// Close the quick menu, propagating any changed cycle values
    /// and pending settings to the active app.
    ///
    /// Idempotent: safe to call even if `hide()` was already called
    /// (e.g. from `QuickMenu::on_action`).
    fn close_quick_menu(&mut self) {
        let region = self.quick_menu.region();
        self.quick_menu.hide();
        self.sync_quick_menu();
        self.launcher.ctx.mark_dirty(region);
    }

    /// Handle a semantic input from the input policy layer.
    pub fn dispatch_semantic_input(&mut self, input: SemanticInput) -> Transition {
        match input {
            SemanticInput::MenuTap => {
                if self.quick_menu.open {
                    self.close_quick_menu();
                } else {
                    self.open_quick_menu();
                }
                Transition::None
            }
        }
    }

    // power-button long-press must be intercepted by the scheduler
    // before calling this method
    pub fn dispatch_event(&mut self, hw_event: Event, bm_cache: &mut BookmarkCache) -> Transition {
        let event = self.mapper.map_event(hw_event);

        if self.quick_menu.open {
            return self.handle_quick_menu(event, bm_cache);
        }

        if matches!(event, ActionEvent::Press(Action::Menu)) {
            self.open_quick_menu();
            return Transition::None;
        }

        let active = self.launcher.active();
        with_app!(active, self, |app| {
            app.on_event(event, &mut self.launcher.ctx)
        })
    }

    fn handle_quick_menu(
        &mut self,
        event: ActionEvent,
        bm_cache: &mut BookmarkCache,
    ) -> Transition {
        let action = match event {
            ActionEvent::Press(a) | ActionEvent::Repeat(a) => a,
            _ => return Transition::None,
        };

        let result = self.quick_menu.on_action(action);

        match result {
            QuickMenuResult::Consumed => {
                if self.quick_menu.dirty {
                    self.launcher.ctx.mark_dirty(self.quick_menu.region());
                    self.quick_menu.dirty = false;
                }
                Transition::None
            }

            QuickMenuResult::Close => {
                // hide() already called by on_action; close_quick_menu
                // is idempotent and handles sync + dirty marking
                self.close_quick_menu();
                Transition::None
            }

            QuickMenuResult::RefreshScreen => {
                self.close_quick_menu();
                self.launcher.ctx.request_full_redraw();
                Transition::None
            }

            QuickMenuResult::GoHome => {
                self.close_quick_menu();
                Transition::Home
            }

            QuickMenuResult::AppTrigger(id) => {
                let active = self.launcher.active();
                self.close_quick_menu();

                with_app!(active, self, |app| {
                    app.on_quick_trigger(id, &mut self.launcher.ctx);
                    // Save app state after trigger (e.g. font change
                    // may invalidate the reader's current page offset).
                    app.save_state(bm_cache);
                });

                Transition::None
            }
        }
    }

    /// Flush deferred persistence for all app singletons.
    ///
    /// Dispatches to every concrete app so that failed flushes can
    /// retry even when the owning app is suspended (e.g. reader
    /// dirty state retries while Home is active).
    pub fn flush_deferred_persistence(
        &mut self,
        k: &mut KernelHandle<'_>,
        reason: DeferredPersistenceReason,
    ) -> crate::error::Result<()> {
        // today only ReaderApp does real work; others inherit the
        // default no-op. iterate all singletons for retry semantics.
        let mut first_error = None;
        for &id in &[
            AppId::Home,
            AppId::Files,
            AppId::Reader,
            AppId::Settings,
            AppId::Stats,
        ] {
            let result = with_app!(id, self, |app| app.flush_deferred_persistence(k, reason));
            if let Err(e) = result {
                log::warn!("flush_deferred_persistence({:?}): {}", id, e);
                first_error.get_or_insert(e);
            }
        }

        if let Some(err) = first_error {
            Err(err)
        } else {
            Ok(())
        }
    }

    pub fn apply_transition(&mut self, transition: Transition, k: &mut KernelHandle<'_>) {
        if let Some(nav) = self.launcher.apply(transition) {
            log::debug!("app: {:?} -> {:?}", nav.from, nav.to);

            if nav.from != AppId::Upload {
                with_app!(nav.from, self, |app| app.save_state(k.bookmark_cache_mut()));

                // force flush deferred persistence for all app singletons
                // before leaving the current app so inactive retries still
                // run and reader dirty state gets one last chance before the
                // singleton is potentially reused for another book.
                if let Err(e) =
                    self.flush_deferred_persistence(k, DeferredPersistenceReason::Transition)
                {
                    log::warn!("flush on leave {:?}: {}", nav.from, e);
                }

                with_app!(nav.from, self, |app| {
                    if nav.suspend {
                        app.on_suspend();
                    } else {
                        app.on_exit();
                    }
                });
            }

            self.propagate_fonts();
            self.launcher.ctx.clear_loading();

            if nav.to != AppId::Upload {
                if nav.resume {
                    with_app!(nav.to, self, |app| {
                        app.on_resume(&mut self.launcher.ctx, k)
                    });
                } else {
                    with_app!(nav.to, self, |app| {
                        app.on_enter(&mut self.launcher.ctx, k)
                    });
                }
            }

            if nav.resume {
                self.launcher
                    .ctx
                    .mark_dirty(Region::new(0, 0, SCREEN_W, SCREEN_H));
            } else {
                self.launcher.ctx.request_full_redraw();
            }
        }
    }

    pub async fn run_background(&mut self, k: &mut KernelHandle<'_>) {
        let active = self.launcher.active();
        with_app!(active, self, |app| {
            app.background(&mut self.launcher.ctx, k).await
        });

        for &id in &[AppId::Home, AppId::Files, AppId::Reader, AppId::Settings] {
            if id != active {
                with_app!(id, self, |app| {
                    if app.has_background_when_suspended() {
                        app.background_suspended(k);
                    }
                });
            }
        }
    }

    pub fn draw(&self, strip: &mut StripBuffer) {
        let active = self.launcher.active();
        with_app_ref!(active, self, |app| app.draw(strip));

        // loading indicator: after app content, before overlays.
        // the reader draws its own centered loading screen while a
        // book is opening, so suppress the generic indicator there.
        let suppress_loading = active == AppId::Reader && self.reader.shows_loading_screen();
        if self.launcher.ctx.loading_active() && !suppress_loading {
            let region = self.launcher.ctx.loading_region();
            if region.intersects(strip.logical_window()) {
                crate::ui::LoadingIndicator::new(
                    region,
                    self.launcher.ctx.loading_msg(),
                    self.launcher.ctx.loading_pct(),
                )
                .draw(strip);
            }
        }

        if self.quick_menu.open {
            self.quick_menu.draw(strip);
        }

        let hide = with_app_ref!(active, self, |app| app.hide_button_bar());
        if !hide {
            self.bumps.draw(strip);
        }
    }

    pub fn propagate_fonts(&mut self) {
        let ss = self.settings.system_settings();
        let ui_idx = ss.ui_font_size_idx;
        let book_idx = ss.book_font_size_idx;
        let theme_idx = ss.reading_theme;
        let reader_status = ss.reader_status;
        let text_alignment = ss.text_alignment;

        self.home.set_ui_font_size(ui_idx);
        self.files.set_ui_font_size(ui_idx);
        self.settings.set_ui_font_size(ui_idx);
        self.stats.set_ui_font_size(ui_idx);
        self.reader.set_book_font_size(book_idx);
        self.reader.set_reading_theme(theme_idx);
        self.reader.set_show_chrome(reader_status);
        self.reader.set_text_alignment(text_alignment);

        let chrome = fonts::chrome_font();
        self.reader.set_chrome_font(chrome);
        self.quick_menu.set_chrome_font(chrome);
        self.bumps.set_chrome_font(chrome);
    }

    fn sync_quick_menu(&mut self) {
        let active = self.launcher.active();

        for id in 0..MAX_APP_ACTIONS as u8 {
            if let Some(value) = self.quick_menu.app_cycle_value(id) {
                with_app!(active, self, |app| {
                    app.on_quick_cycle_update(id, value, &mut self.launcher.ctx);
                });
            }
        }

        let pending = with_app!(active, self, |app| app.pending_setting());
        if let Some(setting) = pending {
            match setting {
                PendingSetting::BookFontSize(idx) => {
                    let ss = self.settings.system_settings_mut();
                    if ss.book_font_size_idx != idx {
                        ss.book_font_size_idx = idx;
                        self.settings.mark_save_needed();
                    }
                }
            }
        }
    }

    #[inline]
    pub fn system_settings(&self) -> &crate::kernel::config::SystemSettings {
        self.settings.system_settings()
    }

    #[inline]
    pub fn settings_loaded(&self) -> bool {
        self.settings.is_loaded()
    }

    #[inline]
    pub fn settings_generation(&self) -> u32 {
        self.settings.generation()
    }

    #[inline]
    pub fn wifi_config(&self) -> &crate::kernel::config::WifiConfig {
        self.settings.wifi_config()
    }

    pub fn ghost_clear_every(&self) -> u32 {
        if self.settings.is_loaded() {
            self.settings.system_settings().ghost_clear_every as u32
        } else {
            crate::kernel::DEFAULT_GHOST_CLEAR_EVERY
        }
    }
}

impl AppLayer for AppManager {
    type Id = AppId;

    #[inline]
    fn active(&self) -> AppId {
        self.launcher.active()
    }

    fn dispatch_event(&mut self, event: Event, bm: &mut BookmarkCache) -> Transition {
        AppManager::dispatch_event(self, event, bm)
    }

    fn dispatch_semantic(&mut self, input: SemanticInput) -> Transition {
        AppManager::dispatch_semantic_input(self, input)
    }

    fn apply_transition(&mut self, t: Transition, k: &mut KernelHandle<'_>) {
        AppManager::apply_transition(self, t, k);
    }

    async fn run_background(&mut self, k: &mut KernelHandle<'_>) {
        AppManager::run_background(self, k).await;
    }

    fn draw(&self, strip: &mut StripBuffer) {
        AppManager::draw(self, strip);
    }

    #[inline]
    fn has_redraw(&self) -> bool {
        self.launcher.ctx.has_redraw()
    }

    #[inline]
    fn take_redraw(&mut self) -> Redraw {
        self.launcher.ctx.take_redraw()
    }

    #[inline]
    fn request_full_redraw(&mut self) {
        self.launcher.ctx.request_full_redraw();
    }

    #[inline]
    fn ctx_mut(&mut self) -> &mut AppContext {
        &mut self.launcher.ctx
    }

    fn system_settings(&self) -> &SystemSettings {
        self.settings.system_settings()
    }

    fn settings_loaded(&self) -> bool {
        self.settings.is_loaded()
    }

    fn settings_generation(&self) -> u32 {
        self.settings.generation()
    }

    fn on_swap_buttons_changed(&mut self, swap: bool) {
        self.mapper.set_swap(swap);
        if self.bumps.set_swap(swap) {
            self.launcher.ctx.mark_dirty(crate::ui::Region::new(
                0,
                crate::board::SCREEN_H - crate::ui::BUTTON_BAR_H,
                crate::board::SCREEN_W,
                crate::ui::BUTTON_BAR_H,
            ));
        }
    }

    fn ghost_clear_every(&self) -> u32 {
        AppManager::ghost_clear_every(self)
    }

    fn wants_grayscale(&self) -> bool {
        self.launcher.active() == AppId::Reader
            && !self.quick_menu.open
            && self.reader.wants_grayscale()
    }

    fn wifi_config(&self) -> &WifiConfig {
        self.settings.wifi_config()
    }

    fn load_eager_settings(&mut self, k: &mut KernelHandle<'_>) {
        AppManager::load_eager_settings(self, k);
    }

    fn load_initial_state(&mut self, k: &mut KernelHandle<'_>) {
        AppManager::load_home_recent(self, k);
    }

    fn enter_initial(&mut self, k: &mut KernelHandle<'_>) {
        AppManager::enter_initial(self, k);
    }

    fn save_active_state(&mut self, bm: &mut crate::kernel::bookmarks::BookmarkCache) {
        AppManager::save_active_state(self, bm);
    }

    fn flush_deferred_persistence(
        &mut self,
        k: &mut KernelHandle<'_>,
        reason: DeferredPersistenceReason,
    ) -> crate::error::Result<()> {
        AppManager::flush_deferred_persistence(self, k, reason)
    }

    fn collect_session(&self, session: &mut crate::kernel::rtc_session::RtcSession) {
        AppManager::collect_session(self, session);
    }

    fn apply_session(
        &mut self,
        session: &crate::kernel::rtc_session::RtcSession,
        k: &mut KernelHandle<'_>,
    ) -> bool {
        AppManager::apply_session(self, session, k)
    }

    fn needs_special_mode(&self) -> bool {
        self.launcher.active() == AppId::Upload
    }

    async fn run_special_mode(
        &mut self,
        epd: &mut Epd,
        strip: &mut StripBuffer,
        delay: &mut Delay,
        sd: &SdStorage,
    ) {
        // Safety: WIFI is not owned by any other driver.  Upload mode
        // runs in isolation (the scheduler exits the main dispatch loop
        // first) and tears down the radio stack before returning.  The
        // peripheral is not accessed again until the next upload session.
        let wifi = unsafe { esp_hal::peripherals::WIFI::steal() };

        crate::apps::upload::run_upload_mode(
            wifi,
            epd,
            strip,
            delay,
            sd,
            self.settings.system_settings().ui_font_size_idx,
            &*self.bumps,
            self.settings.wifi_config(),
        )
        .await;
    }

    fn suppress_deferred_input(&self) -> bool {
        self.quick_menu.open
    }
}