/// What Android's create-document sheet answered: where the file went, and
/// the name it actually got (the sheet lets the user change it on the way
/// past). Both absent when the sheet was dismissed — a cancel is not an
/// error here, because the export it serves answers a cancel with None.
#[derive(Debug, Clone, Serialize, Deserialize, Default)]
#[serde(rename_all = "camelCase")]
pub struct CreatedDocument {
    pub uri: Option<String>,
    pub name: Option<String>,
}

/// What `createDocument` is handed, as the Kotlin `@InvokeArg` names it.
/// Borrowed: the file can be long and nothing here keeps a copy.
#[derive(Serialize)]
#[serde(rename_all = "camelCase")]
#[allow(dead_code)] // only the phone ever sends one; the desktop has a dialog
struct CreateDocumentArgs<'a> {
    name: &'a str,
    mime: &'a str,
    text: &'a str,
}

/// A text file written wherever the user points: Android's create-document
/// sheet (ACTION_CREATE_DOCUMENT), and the Kotlin side writing the bytes
/// through the ContentResolver. That last part is the whole reason this
/// exists — the sheet answers with a `content://` URI, and `std::fs` has
/// never been able to open one, which is why the playlist export had no
/// door on the phone at all.
///
/// Deliberately NOT a `#[tauri::command]`: the caller is Rust, so the file
/// is built where the desktop builds it and the bytes never pass through
/// the WebView. Nothing is added to the ACL, and there is no JS wrapper to
/// keep in step with.
///
/// A dismissed sheet is not an error — it answers with both fields empty.
pub fn create_document<R: Runtime>(
    app: &tauri::AppHandle<R>,
    name: &str,
    mime: &str,
    text: &str,
) -> Result<CreatedDocument, String> {
    #[cfg(mobile)]
    {
        use tauri::Manager;
        let storage = app.state::<Storage<R>>();
        storage
            .0
            .run_mobile_plugin::<CreatedDocument>(
                "createDocument",
                CreateDocumentArgs { name, mime, text },
            )
            .map_err(|e| e.to_string())
    }
    #[cfg(not(mobile))]
    {
        let _ = (app, name, mime, text);
        Err("the create-document sheet is the phone's; here a save dialog picks the path".into())
    }
}