// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_CSS_MIXIN_MAP_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_CSS_MIXIN_MAP_H_

#include <optional>

#include "third_party/blink/renderer/core/css/resolver/media_query_result.h"
#include "third_party/blink/renderer/core/css/style_rule.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_hash_map.h"
#include "third_party/blink/renderer/platform/heap/collection_support/heap_vector.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"
#include "third_party/blink/renderer/platform/wtf/text/atomic_string_hash.h"

namespace blink {

class StyleRuleMixin;

// The set of mixins available when building a given RuleSet.
// Typically contains all mixins from a given TreeScope
// (and possibly non-overridden ones from parent TreeScopes,
// after we've done appropriate merging), plus information
// needed for invalidation.
struct MixinMap {
  DISALLOW_NEW();

 public:
  HeapHashMap<AtomicString, Member<StyleRuleMixin>> mixins;

  // Media queries that affected the contents of “mixins”.
  // We currently store only one set of flags, not specifically
  // which mixin would be invalidated by which media query.
  MediaQueryResultFlags media_query_result_flags;
  HeapVector<MediaQuerySetResult> media_query_set_results;

  // See AllocateMapIdentifier(). This identifier is only set for finalized
  // MixinMaps for an entire scope, not when extracting mixins from a
  // single stylesheet. IDs are unique across all tree scopes and Documents
  // on the renderer main thread.
  std::optional<uint64_t> map_identifier;

  static uint64_t AllocateMapIdentifier();

  bool HasMixins() const {
    return !mixins.empty() || !media_query_set_results.empty();
  }

  // Add everything from "other" to this map, overwriting any mixins that may
  // already exist. Does not touch "map_identifier"; the caller is responsible
  // for giving the combined map an appropriate identity.
  void Merge(const MixinMap& other);

  void Trace(Visitor* visitor) const {
    visitor->Trace(mixins);
    visitor->Trace(media_query_set_results);
  }
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_CSS_MIXIN_MAP_H_