/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

use crate::attr::CaseSensitivity;
use crate::bloom::BloomFilter;
use crate::nth_index_cache::NthIndexCache;
use crate::parser::SelectorImpl;
use crate::tree::{Element, OpaqueElement};

/// What kind of selector matching mode we should use.
///
/// There are two modes of selector matching. The difference is only noticeable
/// in presence of pseudo-elements.
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum MatchingMode {
  /// Don't ignore any pseudo-element selectors.
  Normal,

  /// Ignores any stateless pseudo-element selectors in the rightmost sequence
  /// of simple selectors.
  ///
  /// This is useful, for example, to match against ::before when you aren't a
  /// pseudo-element yourself.
  ///
  /// For example, in presence of `::before:hover`, it would never match, but
  /// `::before` would be ignored as in "matching".
  ///
  /// It's required for all the selectors you match using this mode to have a
  /// pseudo-element.
  ForStatelessPseudoElement,
}

/// The mode to use when matching unvisited and visited links.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum VisitedHandlingMode {
  /// All links are matched as if they are unvisted.
  AllLinksUnvisited,
  /// All links are matched as if they are visited and unvisited (both :link
  /// and :visited match).
  ///
  /// This is intended to be used from invalidation code, to be conservative
  /// about whether we need to restyle a link.
  AllLinksVisitedAndUnvisited,
  /// A element's "relevant link" is the element being matched if it is a link
  /// or the nearest ancestor link. The relevant link is matched as though it
  /// is visited, and all other links are matched as if they are unvisited.
  RelevantLinkVisited,
}

impl VisitedHandlingMode {
  #[inline]
  pub fn matches_visited(&self) -> bool {
    matches!(
      *self,
      VisitedHandlingMode::RelevantLinkVisited | VisitedHandlingMode::AllLinksVisitedAndUnvisited
    )
  }

  #[inline]
  pub fn matches_unvisited(&self) -> bool {
    matches!(
      *self,
      VisitedHandlingMode::AllLinksUnvisited | VisitedHandlingMode::AllLinksVisitedAndUnvisited
    )
  }
}

/// Which quirks mode is this document in.
///
/// See: https://quirks.spec.whatwg.org/
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum QuirksMode {
  /// Quirks mode.
  Quirks,
  /// Limited quirks mode.
  LimitedQuirks,
  /// No quirks mode.
  NoQuirks,
}

impl QuirksMode {
  #[inline]
  pub fn classes_and_ids_case_sensitivity(self) -> CaseSensitivity {
    match self {
      QuirksMode::NoQuirks | QuirksMode::LimitedQuirks => CaseSensitivity::CaseSensitive,
      QuirksMode::Quirks => CaseSensitivity::AsciiCaseInsensitive,
    }
  }
}

/// Data associated with the matching process for a element.  This context is
/// used across many selectors for an element, so it's not appropriate for
/// transient data that applies to only a single selector.
pub struct MatchingContext<'a, 'i, Impl>
where
  Impl: SelectorImpl<'i>,
{
  /// Input with the matching mode we should use when matching selectors.
  matching_mode: MatchingMode,
  /// Input with the bloom filter used to fast-reject selectors.
  pub bloom_filter: Option<&'a BloomFilter>,
  /// An optional cache to speed up nth-index-like selectors.
  pub nth_index_cache: Option<&'a mut NthIndexCache>,
  /// The element which is going to match :scope pseudo-class. It can be
  /// either one :scope element, or the scoping element.
  ///
  /// Note that, although in theory there can be multiple :scope elements,
  /// in current specs, at most one is specified, and when there is one,
  /// scoping element is not relevant anymore, so we use a single field for
  /// them.
  ///
  /// When this is None, :scope will match the root element.
  ///
  /// See https://drafts.csswg.org/selectors-4/#scope-pseudo
  pub scope_element: Option<OpaqueElement>,

  /// The current shadow host we're collecting :host rules for.
  pub current_host: Option<OpaqueElement>,

  /// Controls how matching for links is handled.
  visited_handling: VisitedHandlingMode,

  /// The current nesting level of selectors that we're matching.
  ///
  /// FIXME(emilio): Consider putting the mutable stuff in a Cell, then make
  /// MatchingContext immutable again.
  nesting_level: usize,

  /// Whether we're inside a negation or not.
  in_negation: bool,

  /// An optional hook function for checking whether a pseudo-element
  /// should match when matching_mode is ForStatelessPseudoElement.
  pub pseudo_element_matching_fn: Option<&'a dyn Fn(&Impl::PseudoElement) -> bool>,

  /// Extra implementation-dependent matching data.
  pub extra_data: Impl::ExtraMatchingData,

  quirks_mode: QuirksMode,
  classes_and_ids_case_sensitivity: CaseSensitivity,
  _impl: ::std::marker::PhantomData<Impl>,
}

impl<'a, 'i, Impl> MatchingContext<'a, 'i, Impl>
where
  Impl: SelectorImpl<'i>,
{
  /// Constructs a new `MatchingContext`.
  pub fn new(
    matching_mode: MatchingMode,
    bloom_filter: Option<&'a BloomFilter>,
    nth_index_cache: Option<&'a mut NthIndexCache>,
    quirks_mode: QuirksMode,
  ) -> Self {
    Self::new_for_visited(
      matching_mode,
      bloom_filter,
      nth_index_cache,
      VisitedHandlingMode::AllLinksUnvisited,
      quirks_mode,
    )
  }

  /// Constructs a new `MatchingContext` for use in visited matching.
  pub fn new_for_visited(
    matching_mode: MatchingMode,
    bloom_filter: Option<&'a BloomFilter>,
    nth_index_cache: Option<&'a mut NthIndexCache>,
    visited_handling: VisitedHandlingMode,
    quirks_mode: QuirksMode,
  ) -> Self {
    Self {
      matching_mode,
      bloom_filter,
      visited_handling,
      nth_index_cache,
      quirks_mode,
      classes_and_ids_case_sensitivity: quirks_mode.classes_and_ids_case_sensitivity(),
      scope_element: None,
      current_host: None,
      nesting_level: 0,
      in_negation: false,
      pseudo_element_matching_fn: None,
      extra_data: Default::default(),
      _impl: ::std::marker::PhantomData,
    }
  }

  /// Whether we're matching a nested selector.
  #[inline]
  pub fn is_nested(&self) -> bool {
    self.nesting_level != 0
  }

  /// Whether we're matching inside a :not(..) selector.
  #[inline]
  pub fn in_negation(&self) -> bool {
    self.in_negation
  }

  /// The quirks mode of the document.
  #[inline]
  pub fn quirks_mode(&self) -> QuirksMode {
    self.quirks_mode
  }

  /// The matching-mode for this selector-matching operation.
  #[inline]
  pub fn matching_mode(&self) -> MatchingMode {
    self.matching_mode
  }

  /// The case-sensitivity for class and ID selectors
  #[inline]
  pub fn classes_and_ids_case_sensitivity(&self) -> CaseSensitivity {
    self.classes_and_ids_case_sensitivity
  }

  /// Runs F with a deeper nesting level.
  #[inline]
  pub fn nest<F, R>(&mut self, f: F) -> R
  where
    F: FnOnce(&mut Self) -> R,
  {
    self.nesting_level += 1;
    let result = f(self);
    self.nesting_level -= 1;
    result
  }

  /// Runs F with a deeper nesting level, and marking ourselves in a negation,
  /// for a :not(..) selector, for example.
  #[inline]
  pub fn nest_for_negation<F, R>(&mut self, f: F) -> R
  where
    F: FnOnce(&mut Self) -> R,
  {
    let old_in_negation = self.in_negation;
    self.in_negation = true;
    let result = self.nest(f);
    self.in_negation = old_in_negation;
    result
  }

  #[inline]
  pub fn visited_handling(&self) -> VisitedHandlingMode {
    self.visited_handling
  }

  /// Runs F with a different VisitedHandlingMode.
  #[inline]
  pub fn with_visited_handling_mode<F, R>(&mut self, handling_mode: VisitedHandlingMode, f: F) -> R
  where
    F: FnOnce(&mut Self) -> R,
  {
    let original_handling_mode = self.visited_handling;
    self.visited_handling = handling_mode;
    let result = f(self);
    self.visited_handling = original_handling_mode;
    result
  }

  /// Runs F with a given shadow host which is the root of the tree whose
  /// rules we're matching.
  #[inline]
  pub fn with_shadow_host<F, E, R>(&mut self, host: Option<E>, f: F) -> R
  where
    E: Element<'i>,
    F: FnOnce(&mut Self) -> R,
  {
    let original_host = self.current_host.take();
    self.current_host = host.map(|h| h.opaque());
    let result = f(self);
    self.current_host = original_host;
    result
  }

  /// Returns the current shadow host whose shadow root we're matching rules
  /// against.
  #[inline]
  pub fn shadow_host(&self) -> Option<OpaqueElement> {
    self.current_host
  }
}
