//! Quick capture: a system-wide hotkey that opens a small window to type into.
//!
//! The point is capture WITHOUT the app. Bringing the whole board forward to write
//! one line is the friction this removes, so the shortcut opens a small window of
//! its own rather than focusing `main` — and that window closes itself the moment
//! the note is saved.
//!
//! ## Why the shortcut is configurable, and why it starts unset
//!
//! A global shortcut is the one setting in this app that can collide with software
//! it knows nothing about. Whatever default is picked is a key combination taken
//! away from something on somebody's machine, silently, at install time. So there
//! is no default: the feature is off until someone chooses a combination, and
//! choosing one is how it turns on.
//!
//! The suggestion the settings screen offers (`CommandOrControl+Shift+N`) lives in
//! the frontend, not here. It is a UI affordance — a starting point put in front of
//! someone — and this side accepts any combination the OS will take, so a constant
//! here would be a second copy of a string only the UI ever reads.
//!
//! ## Failure has to be visible
//!
//! Registering can fail — the combination may already be held by the window
//! manager or another app, and on Wayland a compositor may refuse global grabs
//! outright. A hotkey that quietly does nothing is worse than one that was never
//! offered, because there is nothing to look at and nothing to fix. So the stored
//! shortcut and the LIVE registration are reported separately: see
//! [`CaptureShortcut`].

use serde::{Deserialize, Serialize};
use tauri::{AppHandle, Emitter, Manager, State, WebviewUrl, WebviewWindowBuilder};
use tauri_plugin_global_shortcut::{GlobalShortcutExt, Shortcut, ShortcutState};

use inkwell_core::local::{store, Db};

const SHORTCUT_PREF: &str = "capture_shortcut";

/// The window the hotkey opens. Also the label the capability file grants to.
pub const CAPTURE_WINDOW: &str = "capture";

/// Emitted to the main window after a capture is saved, so the board reloads.
///
/// The two windows hold separate copies of the frontend and therefore separate
/// Pinia stores; nothing in the capture window's store can reach the board's. The
/// note is already in SQLite by the time this fires — this only says "look again".
pub const CAPTURED_EVENT: &str = "inkwell://captured";

/// The stored shortcut and whether it is actually live.
///
/// Two fields rather than one because they genuinely disagree: a combination can
/// be saved and refuse to register, and the person needs to be told which of those
/// they are looking at. `registered: false` with a non-empty `shortcut` is the
/// "something else already has this" case.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct CaptureShortcut {
    /// The stored combination, or empty when quick capture is off.
    pub shortcut: String,
    /// Whether the OS accepted it. Always false when `shortcut` is empty.
    pub registered: bool,
}

fn stored(db: &Db) -> Result<String, String> {
    let conn = db.conn()?;
    Ok(store::pref(&conn, SHORTCUT_PREF)
        .map_err(|e| e.to_string())?
        .unwrap_or_default())
}

/// Open (or focus) the capture window.
///
/// Reused rather than recreated: holding one window and showing it is what makes
/// the second press feel instant, and it means a half-typed capture survives the
/// window being dismissed and reopened.
///
/// `always_on_top` and `center` because this is summoned over whatever you were
/// doing — a capture window that opens behind the app you called it from has
/// failed at the only thing it does.
fn open_capture_window(app: &AppHandle) {
    if let Some(window) = app.get_webview_window(CAPTURE_WINDOW) {
        let _ = window.show();
        let _ = window.unminimize();
        let _ = window.set_focus();
        return;
    }

    // `index.html?capture=1` rather than a `/capture` path: the bundled assets are
    // served as files, so a path with no file behind it is a 404 in the production
    // build even though it routes fine under the dev server. A query string is
    // carried through untouched and the router reads it on boot.
    let built = WebviewWindowBuilder::new(
        app,
        CAPTURE_WINDOW,
        WebviewUrl::App("index.html?capture=1".into()),
    )
    .title("Quick capture")
    .inner_size(520.0, 220.0)
    .min_inner_size(360.0, 160.0)
    .resizable(true)
    .always_on_top(true)
    .center()
    .skip_taskbar(true)
    .build();

    match built {
        Ok(window) => {
            let _ = window.set_focus();
        }
        // Never a panic and never fatal: failing to open a capture window must not
        // take down an app whose board is working fine.
        Err(e) => log::error!("could not open the capture window: {e}"),
    }
}

/// Register `shortcut`, replacing whatever was live.
///
/// Unregisters everything first rather than tracking the previous binding: this
/// app owns exactly one global shortcut, so "all of ours" and "the old one" are
/// the same set, and keeping a copy of it is one more thing to get out of step.
fn register(app: &AppHandle, shortcut: &str) -> Result<(), String> {
    let manager = app.global_shortcut();
    let _ = manager.unregister_all();
    if shortcut.is_empty() {
        return Ok(());
    }
    let parsed: Shortcut = shortcut
        .parse()
        .map_err(|_| format!("'{shortcut}' is not a shortcut this system understands."))?;
    manager
        .on_shortcut(parsed, |app, _shortcut, event| {
            // Pressed only. Without this the window is opened on the press AND on
            // the release, and the second one lands on the window the first opened.
            if event.state == ShortcutState::Pressed {
                open_capture_window(app);
            }
        })
        .map_err(|e| format!("Something else on this system is already using it ({e})."))
}

/// Restore the stored shortcut at startup.
///
/// Best-effort by construction: a combination that worked when it was chosen can
/// be taken by something installed later, and the app must still open. The failure
/// is logged and the UI will show it as not registered when the settings screen is
/// next opened.
pub fn restore(app: &AppHandle, db: &Db) {
    let shortcut = match stored(db) {
        Ok(s) if !s.is_empty() => s,
        Ok(_) => return,
        Err(e) => {
            log::warn!("could not read the capture shortcut: {e}");
            return;
        }
    };
    match register(app, &shortcut) {
        Ok(()) => log::info!("quick capture is on: {shortcut}"),
        Err(e) => log::warn!("quick capture shortcut '{shortcut}' did not register: {e}"),
    }
}

#[tauri::command]
pub fn capture_shortcut_get(app: AppHandle, db: State<'_, Db>) -> Result<CaptureShortcut, String> {
    let shortcut = stored(&db)?;
    // Asked of the manager rather than remembered from startup: the answer can
    // have changed since, and a settings screen that reports a stale success is
    // the exact thing this pair of fields exists to prevent.
    let registered = !shortcut.is_empty()
        && shortcut
            .parse::<Shortcut>()
            .map(|s| app.global_shortcut().is_registered(s))
            .unwrap_or(false);
    Ok(CaptureShortcut {
        shortcut,
        registered,
    })
}

/// Store a shortcut and make it live, or clear it with an empty string.
///
/// Registers BEFORE storing, so a combination the system refuses is not written
/// down as though it worked — the person would reopen the settings and find it
/// listed as their shortcut while nothing happened when they pressed it.
#[tauri::command]
pub fn capture_shortcut_set(
    shortcut: String,
    app: AppHandle,
    db: State<'_, Db>,
) -> Result<CaptureShortcut, String> {
    let wanted = shortcut.trim().to_string();
    register(&app, &wanted)?;
    let conn = db.conn()?;
    store::set_pref(&conn, SHORTCUT_PREF, &wanted).map_err(|e| e.to_string())?;
    log::info!(
        "quick capture shortcut {}",
        if wanted.is_empty() {
            "cleared".to_string()
        } else {
            format!("set to {wanted}")
        }
    );
    Ok(CaptureShortcut {
        shortcut: wanted.clone(),
        registered: !wanted.is_empty(),
    })
}

/// Hide the capture window and tell the board to reload.
///
/// Hidden rather than closed so the next press has a window to show instead of one
/// to build. Called after a save and on Escape alike; `saved` is what decides
/// whether the board is told to look again.
#[tauri::command]
pub fn capture_done(saved: bool, app: AppHandle) -> Result<(), String> {
    if let Some(window) = app.get_webview_window(CAPTURE_WINDOW) {
        window.hide().map_err(|e| e.to_string())?;
    }
    if saved {
        if let Some(main) = app.get_webview_window(crate::MAIN_WINDOW) {
            // Failure here is cosmetic — the note is saved either way and the board
            // will show it on its next load — so it is logged, not raised.
            if let Err(e) = main.emit(CAPTURED_EVENT, ()) {
                log::warn!("could not tell the board about a capture: {e}");
            }
        }
    }
    Ok(())
}