/* 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/. */

//! Specified types for CSS values that are related to motion path.

use crate::parser::{Parse, ParserContext};
use crate::values::computed::motion::OffsetRotate as ComputedOffsetRotate;
use crate::values::computed::{Context, ToComputedValue};
use crate::values::generics::motion as generics;
use crate::values::specified::basic_shape::BasicShape;
use crate::values::specified::position::{HorizontalPosition, VerticalPosition};
use crate::values::specified::url::SpecifiedUrl;
use crate::values::specified::{Angle, Position};
use crate::Zero;
use cssparser::Parser;
use style_traits::{ParseError, StyleParseErrorKind};

/// The specified value of ray() function.
pub type RayFunction = generics::GenericRayFunction<Angle, Position>;

/// The specified value of <offset-path>.
pub type OffsetPathFunction =
    generics::GenericOffsetPathFunction<BasicShape, RayFunction, SpecifiedUrl>;

/// The specified value of `offset-path`.
pub type OffsetPath = generics::GenericOffsetPath<OffsetPathFunction>;

/// The specified value of `offset-position`.
pub type OffsetPosition = generics::GenericOffsetPosition<HorizontalPosition, VerticalPosition>;

/// The <coord-box> value, which defines the box that the <offset-path> sizes into.
/// https://drafts.fxtf.org/motion-1/#valdef-offset-path-coord-box
///
/// <coord-box> = content-box | padding-box | border-box | fill-box | stroke-box | view-box
/// https://drafts.csswg.org/css-box-4/#typedef-coord-box
#[allow(missing_docs)]
#[derive(
    Animate,
    Clone,
    ComputeSquaredDistance,
    Copy,
    Debug,
    Deserialize,
    MallocSizeOf,
    Parse,
    PartialEq,
    Serialize,
    SpecifiedValueInfo,
    ToAnimatedValue,
    ToComputedValue,
    ToCss,
    ToResolvedValue,
    ToShmem,
)]
#[repr(u8)]
pub enum CoordBox {
    ContentBox,
    PaddingBox,
    BorderBox,
    FillBox,
    StrokeBox,
    ViewBox,
}

impl CoordBox {
    /// Returns true if it is default value, border-box.
    #[inline]
    pub fn is_default(&self) -> bool {
        matches!(*self, Self::BorderBox)
    }
}

impl Parse for RayFunction {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        if !static_prefs::pref!("layout.css.motion-path-ray.enabled") {
            return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
        }

        input.expect_function_matching("ray")?;
        input.parse_nested_block(|i| Self::parse_function_arguments(context, i))
    }
}

impl RayFunction {
    /// Parse the inner arguments of a `ray` function.
    fn parse_function_arguments<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        use crate::values::specified::PositionOrAuto;

        let mut angle = None;
        let mut size = None;
        let mut contain = false;
        let mut position = None;
        loop {
            if angle.is_none() {
                angle = input.try_parse(|i| Angle::parse(context, i)).ok();
            }

            if size.is_none() {
                size = input.try_parse(generics::RaySize::parse).ok();
                if size.is_some() {
                    continue;
                }
            }

            if !contain {
                contain = input
                    .try_parse(|i| i.expect_ident_matching("contain"))
                    .is_ok();
                if contain {
                    continue;
                }
            }

            if position.is_none() {
                if input.try_parse(|i| i.expect_ident_matching("at")).is_ok() {
                    let pos = Position::parse(context, input)?;
                    position = Some(PositionOrAuto::Position(pos));
                }

                if position.is_some() {
                    continue;
                }
            }
            break;
        }

        if angle.is_none() {
            return Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError));
        }

        Ok(RayFunction {
            angle: angle.unwrap(),
            // If no <ray-size> is specified it defaults to closest-side.
            size: size.unwrap_or(generics::RaySize::ClosestSide),
            contain,
            position: position.unwrap_or(PositionOrAuto::auto()),
        })
    }
}

impl Parse for OffsetPathFunction {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        use crate::values::specified::basic_shape::{AllowedBasicShapes, ShapeType};

        // <offset-path> = <ray()> | <url> | <basic-shape>
        // https://drafts.fxtf.org/motion-1/#typedef-offset-path

        if static_prefs::pref!("layout.css.motion-path-ray.enabled") {
            if let Ok(ray) = input.try_parse(|i| RayFunction::parse(context, i)) {
                return Ok(OffsetPathFunction::Ray(ray));
            }
        }

        if static_prefs::pref!("layout.css.motion-path-url.enabled") {
            if let Ok(url) = input.try_parse(|i| SpecifiedUrl::parse(context, i)) {
                return Ok(OffsetPathFunction::Url(url));
            }
        }

        let allowed_shapes = if static_prefs::pref!("layout.css.motion-path-basic-shapes.enabled") {
            AllowedBasicShapes::ALL
        } else {
            AllowedBasicShapes::PATH
        };

        BasicShape::parse(context, input, allowed_shapes, ShapeType::Outline)
            .map(OffsetPathFunction::Shape)
    }
}

impl Parse for OffsetPath {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        // Parse none.
        if input.try_parse(|i| i.expect_ident_matching("none")).is_ok() {
            return Ok(OffsetPath::none());
        }

        let mut path = None;
        let mut coord_box = None;
        loop {
            if path.is_none() {
                path = input
                    .try_parse(|i| OffsetPathFunction::parse(context, i))
                    .ok();
            }

            if static_prefs::pref!("layout.css.motion-path-coord-box.enabled") &&
                coord_box.is_none()
            {
                coord_box = input.try_parse(CoordBox::parse).ok();
                if coord_box.is_some() {
                    continue;
                }
            }
            break;
        }

        if let Some(p) = path {
            return Ok(OffsetPath::OffsetPath {
                path: Box::new(p),
                coord_box: coord_box.unwrap_or(CoordBox::BorderBox),
            });
        }

        match coord_box {
            Some(c) => Ok(OffsetPath::CoordBox(c)),
            None => Err(input.new_custom_error(StyleParseErrorKind::UnspecifiedError)),
        }
    }
}

/// The direction of offset-rotate.
#[derive(
    Clone, Copy, Debug, MallocSizeOf, Parse, PartialEq, SpecifiedValueInfo, ToCss, ToShmem,
)]
#[repr(u8)]
pub enum OffsetRotateDirection {
    /// Unspecified direction keyword.
    #[css(skip)]
    None,
    /// 0deg offset (face forward).
    Auto,
    /// 180deg offset (face backward).
    Reverse,
}

impl OffsetRotateDirection {
    /// Returns true if it is none (i.e. the keyword is not specified).
    #[inline]
    fn is_none(&self) -> bool {
        *self == OffsetRotateDirection::None
    }
}

#[inline]
fn direction_specified_and_angle_is_zero(direction: &OffsetRotateDirection, angle: &Angle) -> bool {
    !direction.is_none() && angle.is_zero()
}

/// The specified offset-rotate.
/// The syntax is: "[ auto | reverse ] || <angle>"
///
/// https://drafts.fxtf.org/motion-1/#offset-rotate-property
#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, SpecifiedValueInfo, ToCss, ToShmem)]
pub struct OffsetRotate {
    /// [auto | reverse].
    #[css(skip_if = "OffsetRotateDirection::is_none")]
    direction: OffsetRotateDirection,
    /// <angle>.
    /// If direction is None, this is a fixed angle which indicates a
    /// constant clockwise rotation transformation applied to it by this
    /// specified rotation angle. Otherwise, the angle will be added to
    /// the angle of the direction in layout.
    #[css(contextual_skip_if = "direction_specified_and_angle_is_zero")]
    angle: Angle,
}

impl OffsetRotate {
    /// Returns the initial value, auto.
    #[inline]
    pub fn auto() -> Self {
        OffsetRotate {
            direction: OffsetRotateDirection::Auto,
            angle: Angle::zero(),
        }
    }

    /// Returns true if self is auto 0deg.
    #[inline]
    pub fn is_auto(&self) -> bool {
        self.direction == OffsetRotateDirection::Auto && self.angle.is_zero()
    }
}

impl Parse for OffsetRotate {
    fn parse<'i, 't>(
        context: &ParserContext,
        input: &mut Parser<'i, 't>,
    ) -> Result<Self, ParseError<'i>> {
        let location = input.current_source_location();
        let mut direction = input.try_parse(OffsetRotateDirection::parse);
        let angle = input.try_parse(|i| Angle::parse(context, i));
        if direction.is_err() {
            // The direction and angle could be any order, so give it a change to parse
            // direction again.
            direction = input.try_parse(OffsetRotateDirection::parse);
        }

        if direction.is_err() && angle.is_err() {
            return Err(location.new_custom_error(StyleParseErrorKind::UnspecifiedError));
        }

        Ok(OffsetRotate {
            direction: direction.unwrap_or(OffsetRotateDirection::None),
            angle: angle.unwrap_or(Zero::zero()),
        })
    }
}

impl ToComputedValue for OffsetRotate {
    type ComputedValue = ComputedOffsetRotate;

    #[inline]
    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
        use crate::values::computed::Angle as ComputedAngle;

        ComputedOffsetRotate {
            auto: !self.direction.is_none(),
            angle: if self.direction == OffsetRotateDirection::Reverse {
                // The computed value should always convert "reverse" into "auto".
                // e.g. "reverse calc(20deg + 10deg)" => "auto 210deg"
                self.angle.to_computed_value(context) + ComputedAngle::from_degrees(180.0)
            } else {
                self.angle.to_computed_value(context)
            },
        }
    }

    #[inline]
    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
        OffsetRotate {
            direction: if computed.auto {
                OffsetRotateDirection::Auto
            } else {
                OffsetRotateDirection::None
            },
            angle: ToComputedValue::from_computed_value(&computed.angle),
        }
    }
}