ladybird/Userland/Libraries/LibWeb/HTML/TraversableNavigable.cpp

/*
 * Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibWeb/Bindings/MainThreadVM.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/HTML/BrowsingContextGroup.h>
#include <LibWeb/HTML/DocumentState.h>
#include <LibWeb/HTML/SessionHistoryEntry.h>
#include <LibWeb/HTML/TraversableNavigable.h>

namespace Web::HTML {

TraversableNavigable::TraversableNavigable() = default;

TraversableNavigable::~TraversableNavigable() = default;

void TraversableNavigable::visit_edges(Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    for (auto& entry : m_session_history_entries)
        visitor.visit(entry);
}

static OrderedHashTable<TraversableNavigable*>& user_agent_top_level_traversable_set()
{
    static OrderedHashTable<TraversableNavigable*> set;
    return set;
}

struct BrowsingContextAndDocument {
    JS::NonnullGCPtr<HTML::BrowsingContext> browsing_context;
    JS::NonnullGCPtr<DOM::Document> document;
};

// https://html.spec.whatwg.org/multipage/document-sequences.html#creating-a-new-top-level-browsing-context
static WebIDL::ExceptionOr<BrowsingContextAndDocument> create_a_new_top_level_browsing_context_and_document(Page& page)
{
    // 1. Let group and document be the result of creating a new browsing context group and document.
    auto [group, document] = TRY(BrowsingContextGroup::create_a_new_browsing_context_group_and_document(page));

    // 2. Return group's browsing context set[0] and document.
    return BrowsingContextAndDocument { **group->browsing_context_set().begin(), document };
}

// https://html.spec.whatwg.org/multipage/document-sequences.html#creating-a-new-top-level-traversable
WebIDL::ExceptionOr<JS::NonnullGCPtr<TraversableNavigable>> TraversableNavigable::create_a_new_top_level_traversable(Page& page, JS::GCPtr<HTML::BrowsingContext> opener, String target_name)
{
    auto& vm = Bindings::main_thread_vm();

    // 1. Let document be null.
    JS::GCPtr<DOM::Document> document = nullptr;

    // 2. If opener is null, then set document to the second return value of creating a new top-level browsing context and document.
    if (!opener) {
        document = TRY(create_a_new_top_level_browsing_context_and_document(page)).document;
    }

    // 3. Otherwise, set document to the second return value of creating a new auxiliary browsing context and document given opener.
    else {
        document = TRY(BrowsingContext::create_a_new_auxiliary_browsing_context_and_document(page, *opener)).document;
    }

    // 4. Let documentState be a new document state, with
    auto document_state = vm.heap().allocate_without_realm<DocumentState>();

    // document: document
    document_state->set_document(document);

    // navigable target name: targetName
    document_state->set_navigable_target_name(target_name);

    // 5. Let traversable be a new traversable navigable.
    auto traversable = vm.heap().allocate_without_realm<TraversableNavigable>();

    // 6. Initialize the navigable traversable given documentState.
    TRY_OR_THROW_OOM(vm, traversable->initialize_navigable(document_state, nullptr));

    // 7. Let initialHistoryEntry be traversable's active session history entry.
    auto initial_history_entry = traversable->active_session_history_entry();
    VERIFY(initial_history_entry);

    // 8. Set initialHistoryEntry's step to 0.
    initial_history_entry->step = 0;

    // 9. Append initialHistoryEntry to traversable's session history entries.
    traversable->m_session_history_entries.append(*initial_history_entry);

    // FIXME: 10. If opener is non-null, then legacy-clone a traversable storage shed given opener's top-level traversable and traversable. [STORAGE]

    // 11. Append traversable to the user agent's top-level traversable set.
    user_agent_top_level_traversable_set().set(traversable);

    // 12. Return traversable.
    return traversable;
}

// https://html.spec.whatwg.org/multipage/document-sequences.html#create-a-fresh-top-level-traversable
WebIDL::ExceptionOr<JS::NonnullGCPtr<TraversableNavigable>> TraversableNavigable::create_a_fresh_top_level_traversable(Page& page, AK::URL const& initial_navigation_url, Variant<Empty, String, POSTResource> initial_navigation_post_resource)
{
    // 1. Let traversable be the result of creating a new top-level traversable given null and the empty string.
    auto traversable = TRY(create_a_new_top_level_traversable(page, nullptr, {}));

    // 2. Navigate traversable to initialNavigationURL using traversable's active document, with documentResource set to initialNavigationPostResource.
    TRY(traversable->navigate(initial_navigation_url, *traversable->active_document(), initial_navigation_post_resource));

    // 3. Return traversable.
    return traversable;
}

// https://html.spec.whatwg.org/multipage/document-sequences.html#top-level-traversable
bool TraversableNavigable::is_top_level_traversable() const
{
    // A top-level traversable is a traversable navigable with a null parent.
    return parent() == nullptr;
}

// https://html.spec.whatwg.org/multipage/browsing-the-web.html#getting-all-used-history-steps
Vector<int> TraversableNavigable::get_all_used_history_steps() const
{
    // FIXME: 1. Assert: this is running within traversable's session history traversal queue.

    // 2. Let steps be an empty ordered set of non-negative integers.
    OrderedHashTable<int> steps;

    // 3. Let entryLists be the ordered set « traversable's session history entries ».
    Vector<Vector<JS::NonnullGCPtr<SessionHistoryEntry>>> entry_lists { session_history_entries() };

    // 4. For each entryList of entryLists:
    while (!entry_lists.is_empty()) {
        auto entry_list = entry_lists.take_first();

        // 1. For each entry of entryList:
        for (auto& entry : entry_list) {
            // 1. Append entry's step to steps.
            steps.set(entry->step.get<int>());

            // 2. For each nestedHistory of entry's document state's nested histories, append nestedHistory's entries list to entryLists.
            for (auto& nested_history : entry->document_state->nested_histories())
                entry_lists.append(nested_history.entries);
        }
    }

    // 5. Return steps, sorted.
    auto sorted_steps = steps.values();
    quick_sort(sorted_steps);
    return sorted_steps;
}

// https://html.spec.whatwg.org/multipage/browsing-the-web.html#getting-the-history-object-length-and-index
TraversableNavigable::HistoryObjectLengthAndIndex TraversableNavigable::get_the_history_object_length_and_index(int step) const
{
    // 1. Let steps be the result of getting all used history steps within traversable.
    auto steps = get_all_used_history_steps();

    // 2. Let scriptHistoryLength be the size of steps.
    auto script_history_length = steps.size();

    // 3. Assert: steps contains step.
    VERIFY(steps.contains_slow(step));

    // 4. Let scriptHistoryIndex be the index of step in steps.
    auto script_history_index = *steps.find_first_index(step);

    // 5. Return (scriptHistoryLength, scriptHistoryIndex).
    return HistoryObjectLengthAndIndex {
        .script_history_length = script_history_length,
        .script_history_index = script_history_index
    };
}

// https://html.spec.whatwg.org/multipage/browsing-the-web.html#getting-the-used-step
int TraversableNavigable::get_the_used_step(int step) const
{
    // 1. Let steps be the result of getting all used history steps within traversable.
    auto steps = get_all_used_history_steps();

    // 2. Return the greatest item in steps that is less than or equal to step.
    VERIFY(!steps.is_empty());
    Optional<int> result;
    for (size_t i = 0; i < steps.size(); i++) {
        if (steps[i] <= step) {
            if (!result.has_value() || (result.value() < steps[i])) {
                result = steps[i];
            }
        }
    }
    return result.value();
}

// https://html.spec.whatwg.org/multipage/browsing-the-web.html#get-all-navigables-whose-current-session-history-entry-will-change-or-reload
Vector<JS::Handle<Navigable>> TraversableNavigable::get_all_navigables_whose_current_session_history_entry_will_change_or_reload(int target_step) const
{
    // 1. Let results be an empty list.
    Vector<JS::Handle<Navigable>> results;

    // 2. Let navigablesToCheck be « traversable ».
    Vector<JS::Handle<Navigable>> navigables_to_check;
    navigables_to_check.append(const_cast<TraversableNavigable&>(*this));

    // 3. For each navigable of navigablesToCheck:
    while (!navigables_to_check.is_empty()) {
        auto navigable = navigables_to_check.take_first();

        // 1. Let targetEntry be the result of getting the target history entry given navigable and targetStep.
        auto target_entry = navigable->get_the_target_history_entry(target_step);

        // 2. If targetEntry is not navigable's current session history entry or targetEntry's document state's reload pending is true, then append navigable to results.
        if (target_entry != navigable->current_session_history_entry() || target_entry->document_state->reload_pending()) {
            results.append(*navigable);
        }

        // 3. If targetEntry's document is navigable's document, and targetEntry's document state's reload pending is false, then extend navigablesToCheck with the child navigables of navigable.
        if (target_entry->document_state->document() == navigable->active_document() && !target_entry->document_state->reload_pending()) {
            navigables_to_check.extend(navigable->child_navigables());
        }
    }

    // 4. Return results.
    return results;
}

// https://html.spec.whatwg.org/multipage/browsing-the-web.html#clear-the-forward-session-history
void TraversableNavigable::clear_the_forward_session_history()
{
    // FIXME: 1. Assert: this is running within navigable's session history traversal queue.

    // 2. Let step be the navigable's current session history step.
    auto step = current_session_history_step();

    // 3. Let entryLists be the ordered set « navigable's session history entries ».
    Vector<Vector<JS::NonnullGCPtr<SessionHistoryEntry>>&> entry_lists;
    entry_lists.append(session_history_entries());

    // 4. For each entryList of entryLists:
    while (!entry_lists.is_empty()) {
        auto& entry_list = entry_lists.take_first();

        // 1. Remove every session history entry from entryList that has a step greater than step.
        entry_list.remove_all_matching([step](auto& entry) {
            return entry->step.template get<int>() > step;
        });

        // 2. For each entry of entryList:
        for (auto& entry : entry_list) {
            // 1. For each nestedHistory of entry's document state's nested histories, append nestedHistory's entries list to entryLists.
            for (auto& nested_history : entry->document_state->nested_histories()) {
                entry_lists.append(nested_history.entries);
            }
        }
    }
}

}