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//! Generic values for four sided properties.

use crate::error::{ParserError, PrinterError};
use crate::printer::Printer;
use crate::traits::{Parse, ToCss};
use cssparser::*;

/// A generic value that represents a value for four sides of a box,
/// e.g. border-width, margin, padding, etc.
///
/// When serialized, as few components as possible are written when
/// there are duplicate values.
#[derive(Clone, Debug, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Rect<T>(
  /// The top component.
  pub T,
  /// The right component.
  pub T,
  /// The bottom component.
  pub T,
  /// The left component.
  pub T,
);

impl<T> Rect<T> {
  /// Returns a new `Rect<T>` value.
  pub fn new(first: T, second: T, third: T, fourth: T) -> Self {
    Rect(first, second, third, fourth)
  }
}

impl<T: Default + Clone> Default for Rect<T> {
  fn default() -> Rect<T> {
    Rect::all(T::default())
  }
}

impl<T> Rect<T>
where
  T: Clone,
{
  /// Returns a rect with all the values equal to `v`.
  pub fn all(v: T) -> Self {
    Rect::new(v.clone(), v.clone(), v.clone(), v)
  }

  /// Parses a new `Rect<T>` value with the given parse function.
  pub fn parse_with<'i, 't, Parse>(
    input: &mut Parser<'i, 't>,
    parse: Parse,
  ) -> Result<Self, ParseError<'i, ParserError<'i>>>
  where
    Parse: Fn(&mut Parser<'i, 't>) -> Result<T, ParseError<'i, ParserError<'i>>>,
  {
    let first = parse(input)?;
    let second = if let Ok(second) = input.try_parse(|i| parse(i)) {
      second
    } else {
      // <first>
      return Ok(Self::new(first.clone(), first.clone(), first.clone(), first));
    };
    let third = if let Ok(third) = input.try_parse(|i| parse(i)) {
      third
    } else {
      // <first> <second>
      return Ok(Self::new(first.clone(), second.clone(), first, second));
    };
    let fourth = if let Ok(fourth) = input.try_parse(|i| parse(i)) {
      fourth
    } else {
      // <first> <second> <third>
      return Ok(Self::new(first, second.clone(), third, second));
    };
    // <first> <second> <third> <fourth>
    Ok(Self::new(first, second, third, fourth))
  }
}

impl<'i, T> Parse<'i> for Rect<T>
where
  T: Clone + PartialEq + Parse<'i>,
{
  fn parse<'t>(input: &mut Parser<'i, 't>) -> Result<Self, ParseError<'i, ParserError<'i>>> {
    Self::parse_with(input, T::parse)
  }
}

impl<T> ToCss for Rect<T>
where
  T: PartialEq + ToCss,
{
  fn to_css<W>(&self, dest: &mut Printer<W>) -> Result<(), PrinterError>
  where
    W: std::fmt::Write,
  {
    self.0.to_css(dest)?;
    let same_vertical = self.0 == self.2;
    let same_horizontal = self.1 == self.3;
    if same_vertical && same_horizontal && self.0 == self.1 {
      return Ok(());
    }
    dest.write_str(" ")?;
    self.1.to_css(dest)?;
    if same_vertical && same_horizontal {
      return Ok(());
    }
    dest.write_str(" ")?;
    self.2.to_css(dest)?;
    if same_horizontal {
      return Ok(());
    }
    dest.write_str(" ")?;
    self.3.to_css(dest)
  }
}