//! The file-view workspace: everything the signed-in shell and the public
/// share page share around the full-page file view.
///
/// Both pages open files in the same topbar-headed view with the same
/// close/save/dirty plumbing, the same selection + dialog state, and the
/// same Escape semantics. [`FileWorkspace`] owns all of that; the pages
/// keep only what differs (sidebar + section routing vs. share resolution
/// + states) and pull the exposed handles into their browser.
use std::sync::Arc;

use leptos::ev::keydown;
use leptos::html::Header;
use leptos::prelude::*;
use web_sys::KeyboardEvent;

use crate::api::{Entry, Me};
use crate::components::logo::Logo;
use crate::components::toast::{ToastMsg, ToastView};
use crate::router::{self, Location, Section};
use crate::uploads;
use crate::util::owned_window_listener;
use crate::views::browser::SelectionActions;
use crate::views::dialogs::{Dialog, DialogView};
use crate::views::file_view::{FileView, FileViewActions, FileViewContent, FileViewTitle};
use crate::views::uploads::UploadPanel;

/// The shared state and behavior around the full-page file view.
///
/// Create one per page in the page component body, after `provide_toast`:
/// the signals, the navigation effect and the Escape listener are owned by
/// the page, so everything is cleaned up when the page unmounts.
pub struct FileWorkspace {
    pub file_view: ReadSignal<Option<FileView>>,
    /// Open a file in the full-page view (hand to the browser / search).
    pub open_file: WriteSignal<Option<FileView>>,
    pub selected: ReadSignal<Vec<Entry>>,
    pub set_selected: WriteSignal<Vec<Entry>>,
    pub dialog: ReadSignal<Option<Dialog>>,
    pub set_dialog: WriteSignal<Option<Dialog>>,
    /// The browser stores its fetch there so the editor can re-list after a
    /// save.
    pub set_browser_refresh: WriteSignal<Option<Callback<()>>>,
    pub topbar_ref: NodeRef<Header>,

    me: ReadSignal<Option<Me>>,
    loc: ReadSignal<Location>,
    toast: ToastMsg,
    owner: Owner,
    save_cb: ReadSignal<Option<Callback<()>>>,
    set_save_cb: WriteSignal<Option<Callback<()>>>,
    close_cb: ReadSignal<Option<Callback<()>>>,
    set_close_cb: WriteSignal<Option<Callback<()>>>,
    dirty: ReadSignal<bool>,
    set_dirty: WriteSignal<bool>,
    saving: ReadSignal<bool>,
    set_saving: WriteSignal<bool>,
    browser_refresh: ReadSignal<Option<Callback<()>>>,
    close_file: Callback<()>,
    /// What the file view becomes on close (see the parameter of the same
    /// name in [`FileWorkspace::new`]).
    close_target: Arc<dyn Fn() -> Option<FileView> + Send + Sync>,
    /// Whether the topbar shows the selection actions while no file is
    /// open (i.e. the page's browser is the visible content).
    show_actions: Arc<dyn Fn() -> bool + Send + Sync>,
}

impl FileWorkspace {
    /// `close_target` is what the file view becomes on close: `None` =
    /// back to the listing (signed-in app); `Some` = the same file is
    /// shown again (a file share has nothing to close back to). With a
    /// `Some` target the close button and Escape are disabled.
    ///
    /// `show_actions` decides whether the topbar shows the selection
    /// actions while no file is open (i.e. the page's browser is the
    /// visible content).
    pub fn new(
        me: ReadSignal<Option<Me>>,
        loc: ReadSignal<Location>,
        close_target: impl Fn() -> Option<FileView> + 'static + Send + Sync,
        show_actions: impl Fn() -> bool + 'static + Send + Sync,
    ) -> Self {
        let toast = use_context::<ToastMsg>().expect("toast context");
        let owner = Owner::current().unwrap();
        let close_target = Arc::new(close_target);
        let show_actions = Arc::new(show_actions);

        let (file_view, set_file_view) = signal(Option::<FileView>::None);
        // The open editor stores its save callback here for the top-bar button.
        let (save_cb, set_save_cb) = signal(Option::<Callback<()>>::None);
        // The open editor's guarded close request (unsaved-changes prompt).
        let (close_cb, set_close_cb) = signal(Option::<Callback<()>>::None);
        let (dirty, set_dirty) = signal(false);
        let (saving, set_saving) = signal(false);
        // The browser's fetch, exposed so the editor can re-list after a save.
        let (browser_refresh, set_browser_refresh) = signal(Option::<Callback<()>>::None);
        // The selected entries in the file browser; their action buttons
        // live in the top bar's top right.
        let (selected, set_selected) = signal(Vec::<Entry>::new());
        // Dialogs are rendered here, above everything.
        let (dialog, set_dialog) = signal(Option::<Dialog>::None);
        let topbar_ref = NodeRef::<Header>::new();

        // Navigating (new folder, root, section) invalidates the selection
        // and the dialog, which act on it. A page turn or an open file keeps
        // them. An upload's conflict question is not about the folder shown.
        let folder = Memo::new(move |_| loc.with(Location::folder_key));
        Effect::new(move |_| {
            folder.with(|_| ());
            set_selected.set(Vec::new());
            set_dialog.update(|d| {
                if !matches!(d, Some(Dialog::UploadConflict { .. })) {
                    *d = None;
                }
            });
        });

        // A finished upload re-lists the folder it went into, if that is
        // the one on screen.
        // The closure captures this page's signals: it must go when the
        // page does, or a job finishing later reads disposed signals.
        let hook = uploads::set_on_done(move |root_id, dir| {
            let here = loc.with_untracked(|l| {
                me.with_untracked(|m| {
                    m.as_ref()
                        .and_then(|m| crate::views::browser::effective_root(&m.roots, l))
                        .is_some_and(|r| r.id == root_id)
                        && l.path.join("/") == dir
                })
            });
            if here && let Some(f) = browser_refresh.get_untracked() {
                f.run(());
            }
        });
        on_cleanup(move || uploads::clear_on_done(hook));
        // Leaving the page kills every running upload: let the browser ask.
        owned_window_listener(
            leptos::ev::beforeunload,
            move |ev: web_sys::BeforeUnloadEvent| {
                if uploads::any_active() {
                    ev.prevent_default();
                    ev.set_return_value("");
                }
            },
        );

        let close_now = {
            let ct = close_target.clone();
            move || {
                set_save_cb.set(None);
                set_close_cb.set(None);
                set_dirty.set(false);
                set_saving.set(false);
                set_file_view.set(ct());
            }
        };
        // The URL holds the open file, so closing edits the URL. The effect
        // below then closes the view.
        let close_file = {
            let close_now = close_now.clone();
            Callback::new(move |_| {
                if loc.with_untracked(|l| l.open.is_none()) {
                    close_now();
                    return;
                }
                set_dirty.set(false);
                router::close_open();
            })
        };

        // A file shown here goes into the URL. Every file view shares one
        // history entry: a switch to the next file replaces it.
        {
            let ct = close_target.clone();
            Effect::new(move |_| {
                let param = file_view.with(|v| {
                    v.as_ref()
                        .and_then(|v| loc.with_untracked(|l| open_param(l, v)))
                });
                let Some(p) = param else {
                    return;
                };
                if ct().is_none() && loc.with_untracked(|l| l.open.as_ref() != Some(&p)) {
                    router::set_open(&p);
                }
            });
        }
        // A URL without a file (Back, a link, a new folder) closes the view.
        // Back cannot be cancelled, so with unsaved changes the file's entry
        // comes back and the editor asks first.
        {
            let ct = close_target.clone();
            let open_url = StoredValue::new(None::<String>);
            Effect::new(move |_| {
                if loc.with(|l| l.open.is_some()) {
                    open_url.set_value(Some(router::current_hash()));
                    return;
                }
                if ct().is_some() || file_view.with_untracked(Option::is_none) {
                    return;
                }
                if dirty.get_untracked()
                    && let (Some(url), Some(ask)) = (open_url.get_value(), close_cb.get_untracked())
                {
                    router::push_open_url(&url);
                    ask.run(());
                    return;
                }
                close_now();
                // Back lands on the page the first file was opened from. The
                // arrow keys may have moved on since: show the last file's page.
                let Some(was) = open_url.get_value().map(|u| router::parse_hash(&u)) else {
                    return;
                };
                let now = loc.get_untracked();
                if router::at_open_origin()
                    && was.folder_key() == now.folder_key()
                    && (was.page, was.size, was.sort) != (now.page, now.size, now.sort)
                {
                    router::replace(&Location { open: None, ..was });
                }
            });
        }

        // Escape closes previews and the "no preview" view — except when
        // there is nothing to close back to (file share). The editor handles
        // Escape itself (it asks first when there are unsaved changes).
        {
            let ct = close_target.clone();
            owned_window_listener(keydown, move |ev: KeyboardEvent| {
                if ev.key() != "Escape" || ct().is_some() {
                    return;
                }
                if file_view
                    .get()
                    .is_some_and(|v| v.kind != api_types::FileKind::Text)
                {
                    close_file.run(());
                }
            });
        }

        Self {
            file_view,
            open_file: set_file_view,
            selected,
            set_selected,
            dialog,
            set_dialog,
            set_browser_refresh,
            topbar_ref,
            me,
            loc,
            toast,
            owner,
            save_cb,
            set_save_cb,
            close_cb,
            set_close_cb,
            dirty,
            set_dirty,
            saving,
            set_saving,
            browser_refresh,
            close_file,
            close_target,
            show_actions,
        }
    }

    /// Topbar left: the brand. In file mode the brand shrinks to its icon
    /// (a link to `/`) and the file title takes its place.
    pub fn topbar_left(&self) -> impl IntoView + 'static + use<> {
        let file_view = self.file_view;
        let dirty = self.dirty;
        let me = self.me;
        // The home link opens the profile's default root, else the overview.
        // A share page's synthetic `me` has no default, so it stays `#/`.
        let home = move || {
            let root = me.with(|m| {
                m.as_ref()
                    .and_then(|m| m.user.as_ref())
                    .and_then(|u| u.default_root_id)
            });
            match root {
                Some(id) => {
                    crate::router::location_to_hash(&Location::folder(Some(id), None, vec![]))
                }
                None => "#/".to_string(),
            }
        };
        view! {
            {move || match file_view.get() {
                Some(ref v) => view! {
                    <a class="brand brand-icon" href=home>
                        <Logo />
                    </a>
                    <FileViewTitle view=v.clone() dirty=dirty />
                }
                .into_any(),
                None => view! {
                    <a class="brand" href=home>
                        <Logo />
                        <span class="brand-name">"filebrowser-ng"</span>
                    </a>
                }
                .into_any(),
            }}
        }
    }

    /// Topbar right: the open file's actions (download / save / close) or,
    /// while no file is open, the selected entry's actions.
    pub fn topbar_right(&self) -> impl IntoView + 'static + use<> {
        let file_view = self.file_view;
        let show_actions = self.show_actions.clone();
        let close_target = self.close_target.clone();
        let save_cb = self.save_cb;
        let dirty = self.dirty;
        let saving = self.saving;
        let close_cb = self.close_cb;
        let close_file = self.close_file;
        let me = self.me;
        let loc = self.loc;
        let selected = self.selected;
        let open_file = self.open_file;
        let browser_refresh = self.browser_refresh;
        let toast = self.toast;
        let dialog = self.dialog;
        let set_dialog = self.set_dialog;
        let owner = self.owner.clone();
        let topbar_ref = self.topbar_ref;
        view! {
            {move || {
                if let Some(v) = file_view.get() {
                    view! {
                        <FileViewActions
                            view=v
                            saving=saving
                            dirty=dirty
                            save_cb=save_cb
                            close_cb=close_cb
                            show_close=close_target().is_none()
                            on_close=close_file
                            toast=toast
                        />
                    }
                    .into_any()
                } else if show_actions() {
                    let refresh = browser_refresh
                        .get()
                        .unwrap_or_else(|| Callback::new(move |_| {}));
                    view! {
                        <SelectionActions
                            me=me
                            loc=loc
                            selected=selected
                            open_file=open_file
                            refresh=refresh
                            toast=toast
                            dialog=dialog
                            set_dialog=set_dialog
                            owner=owner.clone()
                            topbar_ref=topbar_ref
                        />
                    }
                    .into_any()
                } else {
                    view! {}.into_any()
                }
            }}
        }
    }

    /// The full-page content (preview / editor / "no preview"), rendered
    /// while a file is open.
    pub fn file_content(&self) -> impl IntoView + 'static + use<> {
        let file_view = self.file_view;
        let set_save_cb = self.set_save_cb;
        let set_close_cb = self.set_close_cb;
        let dirty = self.dirty;
        let set_dirty = self.set_dirty;
        let set_saving = self.set_saving;
        let close_file = self.close_file;
        let toast = self.toast;
        let browser_refresh = self.browser_refresh;
        view! {
            {move || file_view.get().map(|v| {
                    let refresh = browser_refresh
                        .get()
                        .unwrap_or_else(|| Callback::new(move |_| {}));
                    view! {
                        <FileViewContent
                            view=v
                            register_save=set_save_cb
                            register_close=set_close_cb
                            dirty=dirty
                            set_dirty=set_dirty
                            set_saving=set_saving
                            close=close_file
                            toast=toast
                            refresh=refresh
                        />
                    }
            })}
        }
    }

    /// The page-level overlays: toasts + dialogs, above everything.
    pub fn overlays(&self) -> impl IntoView + 'static + use<> {
        let toast = self.toast;
        let dialog = self.dialog;
        let set_dialog = self.set_dialog;
        view! {
            <ToastView toast=toast />
            <UploadPanel />
            <DialogView dialog=dialog set_dialog=set_dialog />
        }
    }
}

/// How the URL names the open file `v`: by name in the listed folder, or
/// on the search view by its path in the root. `None` for a file outside
/// the folder, which the URL cannot name.
fn open_param(loc: &Location, v: &FileView) -> Option<String> {
    let path = v.path.as_str();
    if loc.section == Section::Search {
        return Some(path.to_string());
    }
    let dir = loc.path.join("/");
    let name = if dir.is_empty() {
        path
    } else {
        path.strip_prefix(&dir)?.strip_prefix('/')?
    };
    (!name.contains('/')).then(|| name.to_string())
}