// Copyright 2014 The Chromium Authors. All rights reserved.
// 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_PARSER_CSS_SELECTOR_PARSER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_CSS_PARSER_CSS_SELECTOR_PARSER_H_

#include <memory>
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/css/parser/css_parser_selector.h"
#include "third_party/blink/renderer/core/css/parser/css_parser_token_range.h"

namespace blink {

class CSSParserContext;
class CSSParserTokenStream;
class CSSParserObserver;
class CSSSelectorList;
class StyleSheetContents;

// FIXME: We should consider building CSSSelectors directly instead of using
// the intermediate CSSParserSelector.
class CORE_EXPORT CSSSelectorParser {
  STACK_ALLOCATED();

 public:
  static CSSSelectorList ParseSelector(CSSParserTokenRange,
                                       const CSSParserContext*,
                                       StyleSheetContents*);
  static CSSSelectorList ConsumeSelector(CSSParserTokenStream&,
                                         const CSSParserContext*,
                                         StyleSheetContents*,
                                         CSSParserObserver*);

  static bool ConsumeANPlusB(CSSParserTokenRange&, std::pair<int, int>&);

  static bool SupportsComplexSelector(CSSParserTokenRange,
                                      const CSSParserContext*);

 private:
  CSSSelectorParser(const CSSParserContext*, StyleSheetContents*);

  // These will all consume trailing comments if successful

  CSSSelectorList ConsumeComplexSelectorList(CSSParserTokenRange&);
  CSSSelectorList ConsumeComplexSelectorList(CSSParserTokenStream&,
                                             CSSParserObserver*);
  CSSSelectorList ConsumeCompoundSelectorList(CSSParserTokenRange&);
  // Consumes a complex selector list if inside_compound_pseudo_ is false,
  // otherwise consumes a compound selector list.
  CSSSelectorList ConsumeNestedSelectorList(CSSParserTokenRange&);
  CSSSelectorList ConsumeForgivingNestedSelectorList(CSSParserTokenRange&);
  // https://drafts.csswg.org/selectors/#typedef-forgiving-selector-list
  CSSSelectorList ConsumeForgivingComplexSelectorList(CSSParserTokenRange&);
  CSSSelectorList ConsumeForgivingCompoundSelectorList(CSSParserTokenRange&);

  std::unique_ptr<CSSParserSelector> ConsumeComplexSelector(
      CSSParserTokenRange&);
  std::unique_ptr<CSSParserSelector> ConsumeCompoundSelector(
      CSSParserTokenRange&);
  // This doesn't include element names, since they're handled specially
  std::unique_ptr<CSSParserSelector> ConsumeSimpleSelector(
      CSSParserTokenRange&);

  bool ConsumeName(CSSParserTokenRange&,
                   AtomicString& name,
                   AtomicString& namespace_prefix);

  // These will return nullptr when the selector is invalid
  std::unique_ptr<CSSParserSelector> ConsumeId(CSSParserTokenRange&);
  std::unique_ptr<CSSParserSelector> ConsumeClass(CSSParserTokenRange&);
  std::unique_ptr<CSSParserSelector> ConsumePseudo(CSSParserTokenRange&);
  std::unique_ptr<CSSParserSelector> ConsumeAttribute(CSSParserTokenRange&);

  CSSSelector::RelationType ConsumeCombinator(CSSParserTokenRange&);
  CSSSelector::MatchType ConsumeAttributeMatch(CSSParserTokenRange&);
  CSSSelector::AttributeMatchType ConsumeAttributeFlags(CSSParserTokenRange&);

  const AtomicString& DefaultNamespace() const;
  const AtomicString& DetermineNamespace(const AtomicString& prefix);
  void PrependTypeSelectorIfNeeded(const AtomicString& namespace_prefix,
                                   bool has_element_name,
                                   const AtomicString& element_name,
                                   CSSParserSelector*);
  static std::unique_ptr<CSSParserSelector> AddSimpleSelectorToCompound(
      std::unique_ptr<CSSParserSelector> compound_selector,
      std::unique_ptr<CSSParserSelector> simple_selector);
  static std::unique_ptr<CSSParserSelector>
  SplitCompoundAtImplicitShadowCrossingCombinator(
      std::unique_ptr<CSSParserSelector> compound_selector);
  void RecordUsageAndDeprecations(const CSSSelectorList&);
  static bool ContainsUnknownWebkitPseudoElements(
      const CSSSelector& complex_selector);

  const CSSParserContext* context_;
  const StyleSheetContents* style_sheet_;

  bool failed_parsing_ = false;
  bool disallow_pseudo_elements_ = false;
  // If we're inside a pseudo class that only accepts compound selectors,
  // for example :host, inner :is()/:where() pseudo classes are also only
  // allowed to contain compound selectors.
  bool inside_compound_pseudo_ = false;
  // When parsing a compound which includes a pseudo-element, the simple
  // selectors permitted to follow that pseudo-element may be restricted.
  // If this is the case, then restricting_pseudo_element_ will be set to the
  // PseudoType of the pseudo-element causing the restriction.
  CSSSelector::PseudoType restricting_pseudo_element_ =
      CSSSelector::kPseudoUnknown;
  // If we're _resisting_ the default namespace, it means that we are inside
  // a nested selector (:is(), :where(), etc) where we should _consider_
  // ignoring the default namespace (depending on circumstance). See the
  // relevant spec text [1] regarding default namespaces for information about
  // those circumstances.
  //
  // [1] https://drafts.csswg.org/selectors/#matches
  bool resist_default_namespace_ = false;
  // While this flag is true, the default namespace is ignored. In other words,
  // the default namespace is '*' while this flag is true.
  bool ignore_default_namespace_ = false;

  class DisallowPseudoElementsScope {
    STACK_ALLOCATED();

   public:
    DisallowPseudoElementsScope(CSSSelectorParser* parser)
        : parser_(parser), was_disallowed_(parser_->disallow_pseudo_elements_) {
      parser_->disallow_pseudo_elements_ = true;
    }
    DisallowPseudoElementsScope(const DisallowPseudoElementsScope&) = delete;
    DisallowPseudoElementsScope& operator=(const DisallowPseudoElementsScope&) =
        delete;

    ~DisallowPseudoElementsScope() {
      parser_->disallow_pseudo_elements_ = was_disallowed_;
    }

   private:
    CSSSelectorParser* parser_;
    bool was_disallowed_;
  };
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_CSS_PARSER_CSS_SELECTOR_PARSER_H_