/*
 * Copyright (c) 2018-2024, Andreas Kling <andreas@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/Array.h>
#include <AK/HashMap.h>
#include <LibWeb/CSS/Selector.h>
#include <LibWeb/DOM/Element.h>

namespace Web::SelectorEngine {

enum class SelectorKind {
    Normal,
    Relative,
};

enum class HasMatchResult : u8 {
    Matched,
    NotMatched,
};

struct HasResultCacheKey {
    CSS::Selector const* selector;
    GC::Ptr<DOM::Element const> element;

    void visit_edges(GC::Cell::Visitor& visitor)
    {
        visitor.visit(element);
    }

    bool operator==(HasResultCacheKey const&) const = default;
};

struct HasResultCacheKeyTraits : Traits<HasResultCacheKey> {
    static unsigned hash(HasResultCacheKey const& key)
    {
        return pair_int_hash(ptr_hash(key.selector), ptr_hash(key.element.ptr()));
    }
};

using HasResultCache = HashMap<HasResultCacheKey, HasMatchResult, HasResultCacheKeyTraits>;

enum class HasFastRejectFilterTraversalType : u8 {
    Children,
    Descendants,
};

struct HasFastRejectFilterKey {
    GC::Ptr<DOM::Element const> element;
    HasFastRejectFilterTraversalType traversal_type;

    void visit_edges(GC::Cell::Visitor& visitor)
    {
        visitor.visit(element);
    }

    bool operator==(HasFastRejectFilterKey const&) const = default;
};

struct HasFastRejectFilterKeyTraits : Traits<HasFastRejectFilterKey> {
    static unsigned hash(HasFastRejectFilterKey const& key)
    {
        return pair_int_hash(ptr_hash(key.element.ptr()), to_underlying(key.traversal_type));
    }
};

struct HasFastRejectFilter {
    static constexpr size_t bucket_count = 64;

    bool seen_once { false };
    bool populated { false };
    Array<u64, bucket_count> buckets {};

    void add(u32 hash);
    [[nodiscard]] bool may_contain(u32 hash) const;
};

using HasFastRejectFilterCache = HashMap<HasFastRejectFilterKey, HasFastRejectFilter, HasFastRejectFilterKeyTraits>;

struct MatchContext {
    GC::Ptr<CSS::CSSStyleSheet const> style_sheet_for_rule {};
    GC::Ptr<DOM::Element const> subject {};
    GC::Ptr<DOM::ShadowRoot const> rule_shadow_root {}; // Shadow root the matched rule belongs to
    bool collect_per_element_selector_involvement_metadata { false };
    // True while we are evaluating the argument of a :has() pseudo-class.
    // Elements visited by selector walks (descendants, siblings, etc.) while
    // this is set get marked as in_has_scope so the invalidation walker can
    // later terminate once it leaves the scope. Transparent to callers; set
    // by matches_has_pseudo_class with a ScopeGuard.
    bool inside_has_argument_match { false };
    HasResultCache* has_result_cache { nullptr };
    HasFastRejectFilterCache* has_fast_reject_filter_cache { nullptr };
};

bool matches(CSS::Selector const&, DOM::AbstractElement const&, GC::Ptr<DOM::Element const> shadow_host, MatchContext& context, GC::Ptr<DOM::ParentNode const> scope = {}, SelectorKind selector_kind = SelectorKind::Normal, GC::Ptr<DOM::Element const> anchor = nullptr);
bool matches_originating_element_for_pseudo_element(CSS::Selector const&, CSS::PseudoElement, DOM::AbstractElement const&, GC::Ptr<DOM::Element const> shadow_host, MatchContext&, GC::Ptr<DOM::ParentNode const> scope = {});

}