// Multi-window support is desktop-only. Android Tauri apps run as a
// single Activity, so `WebviewWindowBuilder` is not available there.
// All four commands below have an Android stub that returns a clear
// error so frontend invokes don't panic — the frontend itself is
// expected to detect Android via `isAndroid()` and route the previously-
// secondary content (preview overlay, transcript viewer, task float)
// into routes inside the main window instead.
#[cfg(not(target_os = "android"))]
use tauri::{Emitter, Manager, WebviewUrl, WebviewWindowBuilder};

#[cfg(not(target_os = "android"))]
use crate::PreferencesScript;

#[cfg(target_os = "android")]
const ANDROID_MULTIWINDOW_ERR: &str =
    "Multi-window is not supported on Android; this command is desktop-only";

#[cfg(target_os = "android")]
#[tauri::command]
pub async fn open_task_window(_app: tauri::AppHandle) -> Result<(), String> {
    Err(ANDROID_MULTIWINDOW_ERR.into())
}

#[cfg(target_os = "android")]
#[tauri::command]
pub async fn open_preview_window(_app: tauri::AppHandle) -> Result<(), String> {
    Err(ANDROID_MULTIWINDOW_ERR.into())
}

#[cfg(target_os = "android")]
#[tauri::command]
pub async fn open_viewer_window(_app: tauri::AppHandle) -> Result<(), String> {
    Err(ANDROID_MULTIWINDOW_ERR.into())
}

/// Open a floating always-on-top task window.
#[cfg(not(target_os = "android"))]
#[tauri::command]
pub async fn open_task_window(app: tauri::AppHandle) -> Result<(), String> {
    if let Some(window) = app.get_webview_window("tasks-float") {
        window.show().map_err(|e| e.to_string())?;
        window.set_focus().map_err(|e| e.to_string())?;
        app.emit("task-window-focus", ())
            .map_err(|e| e.to_string())?;
        return Ok(());
    }

    // On Linux we use native KWin/Mutter decorations so resize and drag
    // are handled by the compositor. Tauri's frameless path on Wayland
    // doesn't honour diagonal resize reliably and Tauri's own drag
    // region adds latency on webkit2gtk. macOS and Windows keep the
    // custom frameless chrome drawn by the Titlebar component.
    let use_native_decorations = cfg!(target_os = "linux");

    let mut builder =
        WebviewWindowBuilder::new(&app, "tasks-float", WebviewUrl::App("/float".into()))
            .title("Magnotia Tasks")
            .inner_size(480.0, 520.0)
            .min_inner_size(360.0, 480.0)
            .always_on_top(true)
            .decorations(use_native_decorations)
            .resizable(true);

    // Inject preferences before Svelte mounts
    if let Some(script) = app.try_state::<PreferencesScript>() {
        if !script.0.is_empty() {
            builder = builder.initialization_script(&script.0);
        }
    }

    builder.build().map_err(|e| e.to_string())?;

    Ok(())
}

/// Open the always-on-top transcription preview window. Idempotent — an
/// existing window is shown and focused; otherwise a new one is built.
/// The preview is passive: it subscribes to the `transcription-result`
/// event and the cross-window `preview-*` events that DictationPage fires
/// as it moves through the phases of a dictation run.
#[cfg(not(target_os = "android"))]
#[tauri::command]
pub async fn open_preview_window(app: tauri::AppHandle) -> Result<(), String> {
    if let Some(window) = app.get_webview_window("transcription-preview") {
        window.show().map_err(|e| e.to_string())?;
        // Intentionally NOT set_focus — the preview window is meant to
        // appear next to whatever the user is typing into; stealing focus
        // defeats the whole point.
        return Ok(());
    }

    let use_native_decorations = cfg!(target_os = "linux");

    // Preview is a transient helper overlay, not a primary surface. It
    // should (a) follow the user across virtual desktops — otherwise the
    // overlay vanishes the moment they switch workspace mid-dictation —
    // and (b) stay out of the Alt+Tab / taskbar lists. skip_taskbar covers
    // both on KWin (KWin's default Alt+Tab list reads _NET_WM_STATE_SKIP_TASKBAR);
    // visible_on_all_workspaces sets _NET_WM_STATE_STICKY via GTK on X11
    // / XWayland so the overlay is pinned. Matches the ergonomic OpenWhispr
    // PR #183 shipped for KDE Plasma Wayland.
    //
    // Built hidden so we can set the Linux WindowTypeHint before the
    // window maps — GTK3 only honours the hint pre-realize.
    let mut builder = WebviewWindowBuilder::new(
        &app,
        "transcription-preview",
        WebviewUrl::App("/preview".into()),
    )
    .title("Magnotia — Preview")
    .inner_size(420.0, 200.0)
    .min_inner_size(360.0, 140.0)
    .max_inner_size(520.0, 360.0)
    .always_on_top(true)
    .skip_taskbar(true)
    .visible_on_all_workspaces(true)
    .focused(false)
    .visible(false)
    .decorations(use_native_decorations)
    .resizable(true);

    if let Some(script) = app.try_state::<PreferencesScript>() {
        if !script.0.is_empty() {
            builder = builder.initialization_script(&script.0);
        }
    }

    let window = builder.build().map_err(|e| e.to_string())?;

    // Defence-in-depth for non-KDE compositors (Hyprland, Sway, GNOME
    // Mutter) where SKIP_TASKBAR alone may not hide a window from the
    // alt-tab switcher. Classifying as Utility signals to the compositor
    // that this is an assistive auxiliary window — switchers and tilers
    // treat it accordingly. Noop on KWin (already handled by skip_taskbar)
    // but harmless. Must happen before show() per GTK3 docs.
    #[cfg(target_os = "linux")]
    {
        use gdk::WindowTypeHint;
        use gtk::prelude::GtkWindowExt;
        if let Ok(gtk_window) = window.gtk_window() {
            gtk_window.set_type_hint(WindowTypeHint::Utility);
        }
    }

    window.show().map_err(|e| e.to_string())?;
    Ok(())
}

/// Open the transcript viewer window.
#[cfg(not(target_os = "android"))]
#[tauri::command]
pub async fn open_viewer_window(app: tauri::AppHandle) -> Result<(), String> {
    if let Some(window) = app.get_webview_window("transcript-viewer") {
        window.show().map_err(|e| e.to_string())?;
        window.set_focus().map_err(|e| e.to_string())?;
        return Ok(());
    }

    // See note in open_task_window for the Linux-vs-other platform split.
    let use_native_decorations = cfg!(target_os = "linux");

    let mut builder =
        WebviewWindowBuilder::new(&app, "transcript-viewer", WebviewUrl::App("/viewer".into()))
            .title("Magnotia - Transcription Editor")
            .inner_size(600.0, 700.0)
            .min_inner_size(560.0, 520.0)
            .decorations(use_native_decorations)
            .resizable(true);

    // Inject preferences before Svelte mounts
    if let Some(script) = app.try_state::<PreferencesScript>() {
        if !script.0.is_empty() {
            builder = builder.initialization_script(&script.0);
        }
    }

    builder.build().map_err(|e| e.to_string())?;

    Ok(())
}