/* 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 http://mozilla.org/MPL/2.0/. */

//! Gecko-specific bits for selector-parsing.

use cssparser::{BasicParseError, Parser, ToCss, Token, CowRcStr};
use element_state::ElementState;
use gecko_bindings::structs::CSSPseudoClassType;
use selector_parser::{SelectorParser, PseudoElementCascadeType};
use selectors::parser::{Selector, SelectorMethods, SelectorParseError};
use selectors::visitor::SelectorVisitor;
use std::fmt;
use string_cache::{Atom, Namespace, WeakAtom, WeakNamespace};
use style_traits::{ParseError, StyleParseError};

pub use gecko::pseudo_element::{PseudoElement, EAGER_PSEUDOS, EAGER_PSEUDO_COUNT, SIMPLE_PSEUDO_COUNT};
pub use gecko::snapshot::SnapshotMap;

bitflags! {
    // See NonTSPseudoClass::is_enabled_in()
    flags NonTSPseudoClassFlag: u8 {
        const PSEUDO_CLASS_ENABLED_IN_UA_SHEETS = 1 << 0,
        const PSEUDO_CLASS_ENABLED_IN_CHROME = 1 << 1,
        const PSEUDO_CLASS_ENABLED_IN_UA_SHEETS_AND_CHROME =
            PSEUDO_CLASS_ENABLED_IN_UA_SHEETS.bits | PSEUDO_CLASS_ENABLED_IN_CHROME.bits,
    }
}

/// The type used for storing pseudo-class string arguments.
pub type PseudoClassStringArg = Box<[u16]>;

macro_rules! pseudo_class_name {
    (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
     string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*],
     keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
        #[doc = "Our representation of a non tree-structural pseudo-class."]
        #[derive(Clone, Debug, Eq, PartialEq)]
        pub enum NonTSPseudoClass {
            $(
                #[doc = $css]
                $name,
            )*
            $(
                #[doc = $s_css]
                $s_name(PseudoClassStringArg),
            )*
            $(
                #[doc = $k_css]
                $k_name(Box<[u16]>),
            )*
            /// The non-standard `:-moz-any` pseudo-class.
            ///
            /// TODO(emilio): We disallow combinators and pseudos here, so we
            /// should use SimpleSelector instead
            MozAny(Box<[Selector<SelectorImpl>]>),
        }
    }
}
apply_non_ts_list!(pseudo_class_name);

impl ToCss for NonTSPseudoClass {
    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
        use cssparser::CssStringWriter;
        use fmt::Write;
        macro_rules! pseudo_class_serialize {
            (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
             string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*],
             keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
                match *self {
                    $(NonTSPseudoClass::$name => concat!(":", $css),)*
                    $(NonTSPseudoClass::$s_name(ref s) => {
                        dest.write_str(concat!(":", $s_css, "("))?;
                        {
                            // FIXME(emilio): Avoid the extra allocation!
                            let mut css = CssStringWriter::new(dest);

                            // Discount the null char in the end from the
                            // string.
                            css.write_str(&String::from_utf16(&s[..s.len() - 1]).unwrap())?;
                        }
                        return dest.write_str(")")
                    }, )*
                    $(NonTSPseudoClass::$k_name(ref s) => {
                        // Don't include the terminating nul.
                        let value = String::from_utf16(&s[..s.len() - 1]).unwrap();
                        dest.write_str(concat!(":", $k_css, "("))?;
                        dest.write_str(&value)?;
                        return dest.write_char(')')
                    }, )*
                    NonTSPseudoClass::MozAny(ref selectors) => {
                        dest.write_str(":-moz-any(")?;
                        let mut iter = selectors.iter();
                        let first = iter.next().expect(":-moz-any must have at least 1 selector");
                        first.to_css(dest)?;
                        for selector in iter {
                            dest.write_str(", ")?;
                            selector.to_css(dest)?;
                        }
                        return dest.write_str(")")
                    }
                }
            }
        }
        let ser = apply_non_ts_list!(pseudo_class_serialize);
        dest.write_str(ser)
    }
}

impl SelectorMethods for NonTSPseudoClass {
    type Impl = SelectorImpl;

    fn visit<V>(&self, visitor: &mut V) -> bool
        where V: SelectorVisitor<Impl = Self::Impl>,
    {
        if let NonTSPseudoClass::MozAny(ref selectors) = *self {
            for selector in selectors.iter() {
                if !selector.visit(visitor) {
                    return false;
                }
            }
        }

        true
    }
}


impl NonTSPseudoClass {
    /// Returns true if this pseudo-class has any of the given flags set.
    fn has_any_flag(&self, flags: NonTSPseudoClassFlag) -> bool {
        macro_rules! check_flag {
            (_) => (false);
            ($flags:expr) => ($flags.intersects(flags));
        }
        macro_rules! pseudo_class_check_is_enabled_in {
            (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
            string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*],
            keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
                match *self {
                    $(NonTSPseudoClass::$name => check_flag!($flags),)*
                    $(NonTSPseudoClass::$s_name(..) => check_flag!($s_flags),)*
                    $(NonTSPseudoClass::$k_name(..) => check_flag!($k_flags),)*
                    NonTSPseudoClass::MozAny(_) => false,
                }
            }
        }
        apply_non_ts_list!(pseudo_class_check_is_enabled_in)
    }

    /// Returns whether the pseudo-class is enabled in content sheets.
    fn is_enabled_in_content(&self) -> bool {
        use gecko_bindings::structs::mozilla;
        match self {
            // For pseudo-classes with pref, the availability in content
            // depends on the pref.
            &NonTSPseudoClass::Fullscreen =>
                unsafe { mozilla::StylePrefs_sUnprefixedFullscreenApiEnabled },
            // Otherwise, a pseudo-class is enabled in content when it
            // doesn't have any enabled flag.
            _ => !self.has_any_flag(PSEUDO_CLASS_ENABLED_IN_UA_SHEETS_AND_CHROME),
        }
    }

    /// https://drafts.csswg.org/selectors-4/#useraction-pseudos
    ///
    /// We intentionally skip the link-related ones.
    pub fn is_safe_user_action_state(&self) -> bool {
        matches!(*self, NonTSPseudoClass::Hover |
                        NonTSPseudoClass::Active |
                        NonTSPseudoClass::Focus)
    }

    /// Get the state flag associated with a pseudo-class, if any.
    pub fn state_flag(&self) -> ElementState {
        macro_rules! flag {
            (_) => (ElementState::empty());
            ($state:ident) => (::element_state::$state);
        }
        macro_rules! pseudo_class_state {
            (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
             string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*],
             keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
                match *self {
                    $(NonTSPseudoClass::$name => flag!($state),)*
                    $(NonTSPseudoClass::$s_name(..) => flag!($s_state),)*
                    $(NonTSPseudoClass::$k_name(..) => flag!($k_state),)*
                    NonTSPseudoClass::MozAny(..) => ElementState::empty(),
                }
            }
        }
        apply_non_ts_list!(pseudo_class_state)
    }

    /// Returns true if the given pseudoclass should trigger style sharing cache
    /// revalidation.
    pub fn needs_cache_revalidation(&self) -> bool {
        self.state_flag().is_empty() &&
        !matches!(*self,
                  // :-moz-any is handled by the revalidation visitor walking
                  // the things inside it; it does not need to cause
                  // revalidation on its own.
                  NonTSPseudoClass::MozAny(_) |
                  // :dir() depends on state only, but doesn't use state_flag
                  // because its semantics don't quite match.  Nevertheless, it
                  // doesn't need cache revalidation, because we already compare
                  // states for elements and candidates.
                  NonTSPseudoClass::Dir(_) |
                  // :-moz-is-html only depends on the state of the document and
                  // the namespace of the element; the former is invariant
                  // across all the elements involved and the latter is already
                  // checked for by our caching precondtions.
                  NonTSPseudoClass::MozIsHTML |
                  // :-moz-placeholder is parsed but never matches.
                  NonTSPseudoClass::MozPlaceholder |
                  // :-moz-locale-dir and :-moz-window-inactive depend only on
                  // the state of the document, which is invariant across all
                  // the elements involved in a given style cache.
                  NonTSPseudoClass::MozLocaleDir(_) |
                  NonTSPseudoClass::MozWindowInactive |
                  // Similar for the document themes.
                  NonTSPseudoClass::MozLWTheme |
                  NonTSPseudoClass::MozLWThemeBrightText |
                  NonTSPseudoClass::MozLWThemeDarkText
        )
    }

    /// Convert NonTSPseudoClass to Gecko's CSSPseudoClassType.
    pub fn to_gecko_pseudoclasstype(&self) -> Option<CSSPseudoClassType> {
        macro_rules! gecko_type {
            (_) => (None);
            ($gecko_type:ident) =>
                (Some(::gecko_bindings::structs::CSSPseudoClassType::$gecko_type));
        }
        macro_rules! pseudo_class_geckotype {
            (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
             string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*],
             keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
                match *self {
                    $(NonTSPseudoClass::$name => gecko_type!($gecko_type),)*
                    $(NonTSPseudoClass::$s_name(..) => gecko_type!($s_gecko_type),)*
                    $(NonTSPseudoClass::$k_name(..) => gecko_type!($k_gecko_type),)*
                    NonTSPseudoClass::MozAny(_) => gecko_type!(any),
                }
            }
        }
        apply_non_ts_list!(pseudo_class_geckotype)
    }

    /// Returns true if the evaluation of the pseudo-class depends on the
    /// element's attributes.
    pub fn is_attr_based(&self) -> bool {
        matches!(*self,
                 NonTSPseudoClass::MozTableBorderNonzero |
                 NonTSPseudoClass::MozBrowserFrame |
                 NonTSPseudoClass::Lang(..))
    }
}

/// The dummy struct we use to implement our selector parsing.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SelectorImpl;

impl ::selectors::SelectorImpl for SelectorImpl {
    type AttrValue = Atom;
    type Identifier = Atom;
    type ClassName = Atom;
    type LocalName = Atom;
    type NamespacePrefix = Atom;
    type NamespaceUrl = Namespace;
    type BorrowedNamespaceUrl = WeakNamespace;
    type BorrowedLocalName = WeakAtom;

    type PseudoElement = PseudoElement;
    type NonTSPseudoClass = NonTSPseudoClass;

    #[inline]
    fn is_active_or_hover(pseudo_class: &Self::NonTSPseudoClass) -> bool {
        matches!(*pseudo_class, NonTSPseudoClass::Active |
                                NonTSPseudoClass::Hover)
    }
}

impl<'a> SelectorParser<'a> {
    fn is_pseudo_class_enabled(&self,
                               pseudo_class: &NonTSPseudoClass)
                               -> bool {
        pseudo_class.is_enabled_in_content() ||
            (self.in_user_agent_stylesheet() &&
             pseudo_class.has_any_flag(PSEUDO_CLASS_ENABLED_IN_UA_SHEETS)) ||
            (self.in_chrome_stylesheet() &&
             pseudo_class.has_any_flag(PSEUDO_CLASS_ENABLED_IN_CHROME))
    }
}

impl<'a, 'i> ::selectors::Parser<'i> for SelectorParser<'a> {
    type Impl = SelectorImpl;
    type Error = StyleParseError<'i>;

    fn is_pseudo_element_allows_single_colon(name: &CowRcStr<'i>) -> bool {
        ::selectors::parser::is_css2_pseudo_element(name) ||
            name.starts_with("-moz-tree-") // tree pseudo-elements
    }

    fn parse_non_ts_pseudo_class(&self, name: CowRcStr<'i>)
                                 -> Result<NonTSPseudoClass, ParseError<'i>> {
        macro_rules! pseudo_class_parse {
            (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
             string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*],
             keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
                match_ignore_ascii_case! { &name,
                    $($css => NonTSPseudoClass::$name,)*
                    _ => return Err(::selectors::parser::SelectorParseError::UnsupportedPseudoClassOrElement(
                        name.clone()).into())
                }
            }
        }
        let pseudo_class = apply_non_ts_list!(pseudo_class_parse);
        if self.is_pseudo_class_enabled(&pseudo_class) {
            Ok(pseudo_class)
        } else {
            Err(SelectorParseError::UnsupportedPseudoClassOrElement(name).into())
        }
    }

    fn parse_non_ts_functional_pseudo_class<'t>(&self,
                                                name: CowRcStr<'i>,
                                                parser: &mut Parser<'i, 't>)
                                                -> Result<NonTSPseudoClass, ParseError<'i>> {
        macro_rules! pseudo_class_string_parse {
            (bare: [$(($css:expr, $name:ident, $gecko_type:tt, $state:tt, $flags:tt),)*],
             string: [$(($s_css:expr, $s_name:ident, $s_gecko_type:tt, $s_state:tt, $s_flags:tt),)*],
             keyword: [$(($k_css:expr, $k_name:ident, $k_gecko_type:tt, $k_state:tt, $k_flags:tt),)*]) => {
                match_ignore_ascii_case! { &name,
                    $($s_css => {
                        let name = parser.expect_ident_or_string()?;
                        // convert to null terminated utf16 string
                        // since that's what Gecko deals with
                        let utf16: Vec<u16> = name.encode_utf16().chain(Some(0u16)).collect();
                        NonTSPseudoClass::$s_name(utf16.into_boxed_slice())
                    }, )*
                    $($k_css => {
                        let name = parser.expect_ident()?;
                        // Convert to ASCII-lowercase nul-terminated UTF-16 string.
                        let utf16: Vec<u16> = name.encode_utf16().map(utf16_to_ascii_lowercase)
                            .chain(Some(0u16)).collect();
                        NonTSPseudoClass::$k_name(utf16.into_boxed_slice())
                    }, )*
                    "-moz-any" => {
                        let selectors = parser.parse_comma_separated(|input| {
                            Selector::parse(self, input)
                        })?;
                        // Selectors inside `:-moz-any` may not include combinators.
                        if selectors.iter().flat_map(|x| x.iter_raw_match_order()).any(|s| s.is_combinator()) {
                            return Err(SelectorParseError::UnexpectedIdent("-moz-any".into()).into())
                        }
                        NonTSPseudoClass::MozAny(selectors.into_boxed_slice())
                    }
                    _ => return Err(SelectorParseError::UnsupportedPseudoClassOrElement(name.clone()).into())
                }
            }
        }
        let pseudo_class = apply_non_ts_list!(pseudo_class_string_parse);
        if self.is_pseudo_class_enabled(&pseudo_class) {
            Ok(pseudo_class)
        } else {
            Err(SelectorParseError::UnsupportedPseudoClassOrElement(name).into())
        }
    }

    fn parse_pseudo_element(&self, name: CowRcStr<'i>) -> Result<PseudoElement, ParseError<'i>> {
        PseudoElement::from_slice(&name, self.in_user_agent_stylesheet())
            .ok_or(SelectorParseError::UnsupportedPseudoClassOrElement(name.clone()).into())
    }

    fn parse_functional_pseudo_element<'t>(&self, name: CowRcStr<'i>,
                                           parser: &mut Parser<'i, 't>)
                                           -> Result<PseudoElement, ParseError<'i>> {
        if name.starts_with("-moz-tree-") {
            // Tree pseudo-elements can have zero or more arguments,
            // separated by either comma or space.
            let mut args = Vec::new();
            loop {
                match parser.next() {
                    Ok(&Token::Ident(ref ident)) => args.push(ident.as_ref().to_owned()),
                    Ok(&Token::Comma) => {},
                    Ok(t) => return Err(BasicParseError::UnexpectedToken(t.clone()).into()),
                    Err(BasicParseError::EndOfInput) => break,
                    _ => unreachable!("Parser::next() shouldn't return any other error"),
                }
            }
            let args = args.into_boxed_slice();
            if let Some(pseudo) = PseudoElement::tree_pseudo_element(&name, args) {
                return Ok(pseudo);
            }
        }
        Err(SelectorParseError::UnsupportedPseudoClassOrElement(name.clone()).into())
    }

    fn default_namespace(&self) -> Option<Namespace> {
        self.namespaces.default.clone().as_ref().map(|&(ref ns, _)| ns.clone())
    }

    fn namespace_for_prefix(&self, prefix: &Atom) -> Option<Namespace> {
        self.namespaces.prefixes.get(prefix).map(|&(ref ns, _)| ns.clone())
    }
}

impl SelectorImpl {
    #[inline]
    /// Legacy alias for PseudoElement::cascade_type.
    pub fn pseudo_element_cascade_type(pseudo: &PseudoElement) -> PseudoElementCascadeType {
        pseudo.cascade_type()
    }

    /// A helper to traverse each eagerly cascaded pseudo-element, executing
    /// `fun` on it.
    #[inline]
    pub fn each_eagerly_cascaded_pseudo_element<F>(mut fun: F)
        where F: FnMut(PseudoElement),
    {
        for pseudo in &EAGER_PSEUDOS {
            fun(pseudo.clone())
        }
    }


    /// Returns the relevant state flag for a given non-tree-structural
    /// pseudo-class.
    pub fn pseudo_class_state_flag(pc: &NonTSPseudoClass) -> ElementState {
        pc.state_flag()
    }
}

fn utf16_to_ascii_lowercase(unit: u16) -> u16 {
    match unit {
        65...90 => unit + 32, // A-Z => a-z
        _ => unit
    }
}