// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.web;

using fuchsia.net.http;

/// Interface supplied by the embedder for receiving notifications about navigation events in a
/// [`fuchsia.web.Frame`].
protocol NavigationEventListener {
    /// Called when user-visible navigation state has changed since [`fuchsia.web.Frame`] creation
    /// or the last acknowledgement callback, whichever occurred last. `change` will contain all
    /// the differences in navigation state since the last acknowledgement. Any unchanged
    /// properties will be left unset in `change`.
    ///
    /// Implementer must call the acknowledgement callback to receive new navigation events.
    OnNavigationStateChanged(NavigationState change) -> ();
};

/// Represents the return status of a [`fuchsia.web.NavigationController`] method.
enum NavigationControllerError : int32 {
    /// The provided URL is invalid.
    INVALID_URL = 1;

    /// At least one of the provided headers was invalid.
    INVALID_HEADER = 2;
};

/// Provides methods for controlling and querying the navigation state of a [`fuchsia.web.Frame`].
protocol NavigationController {
    /// Tells the [`fuchsia.web.Frame`] to navigate to a `url`.
    ///
    /// - `url`:    The address to navigate to.
    /// - `params`: Additional parameters that affect how the resource will be
    ///   loaded (e.g. cookies, HTTP headers, etc.)
    ///
    /// If an error occured, the [`fuchsia.web.NavigationControllerError`] will be set to one of
    /// these values:
    /// - `INVALID_URL`: The `url` parameter is invalid.
    /// - `INVALID_HEADER`: At least one of the headers in [`fuchsia.web.LoadUrlParams/headers`]
    ///   is invalid.
    LoadUrl(Url url, LoadUrlParams params)
        -> () error NavigationControllerError;

    /// Tells the [`fuchsia.web.Frame`] to navigate to the previous page in its history, if any.
    GoBack();

    /// Tells the [`fuchsia.web.Frame`] to navigate to the next page in its history, if any.
    GoForward();

    /// Tells the [`fuchsia.web.Frame`] to stop the current navigation if a navigation is ongoing.
    Stop();

    /// Tells the [`fuchsia.web.Frame`] to reload the current page.
    Reload(ReloadType type);

    /// Returns information for the currently visible content regardless of loading state, or an
    /// empty entry if no content is being displayed.
    GetVisibleEntry() -> (NavigationState entry);
};

/// Additional parameters for modifying the behavior of
/// [`fuchsia.web.NavigationController/LoadUrl`].
table LoadUrlParams {
    /// Provides a hint to the browser UI about how [`fuchsia.web.NavigationController/LoadUrl`]
    /// was triggered.
    1: LoadUrlReason type;

    /// The URL that linked to the resource being requested.
    2: Url referrer_url;

    /// Should be set to true to propagate user activation to the frame. User activation implies
    /// that the user is interacting with the web frame. It enables some web features that are not
    /// available otherwise. For example, autoplay will work only when this flag is set to true.
    3: bool was_user_activated;

    /// Custom HTTP headers.
    4: vector<fuchsia.net.http.Header> headers;
};

/// Contains information about the [`fuchsia.web.Frame`]'s navigation state.
table NavigationState {
    /// The page's URL.
    1: Url url;

    /// The user-visible page title.
    2: string title;

    /// Indicates whether this was a navigation to an error page.
    3: PageType page_type;

    /// Indicates if there is a following navigation.
    4: bool can_go_forward;

    /// Indicates if there is a previous navigation.
    5: bool can_go_back;

    /// Indicates that the main document's statically declared resources have been loaded.
    6: bool is_main_document_loaded;
};

/// Characterizes the type of reload.
enum ReloadType : uint32 {
    /// Reloads the current entry, bypassing the cache for the main resource.
    PARTIAL_CACHE = 0;

    /// Reloads the current entry, bypassing the cache entirely.
    NO_CACHE = 1;
};

/// Characterizes the origin of a [`fuchsia.web.NavigationController/LoadUrl`] request.
enum LoadUrlReason : uint32 {
    /// Navigation was initiated by the user following a link.
    LINK = 0;

    /// Navigation was initiated by a user-provided URL.
    TYPED = 1;
};

/// Characterizes the page type in a [`fuchsia.web.NavigationState`].
enum PageType {
    /// Regular web page.
    NORMAL = 0;

    /// Error page.
    ERROR = 1;
};