use strum_macros::{Display, EnumString, IntoStaticStr};

/// https://oreillymedia.github.io/Using_SVG/guide/units.html
#[derive(Clone, Copy, PartialEq, Eq, Debug, Display, EnumString, IntoStaticStr)]
pub enum SVGUnit {
    /// Pixel units, directly equivalent to SVG user units.
    #[strum(serialize = "px")]
    Pixel,
    /// Inches.
    #[strum(serialize = "in")]
    Inch,
    /// Centimeters.
    #[strum(serialize = "cm")]
    Centimeter,
    /// Millimeters.
    #[strum(serialize = "mm")]
    Millimeter,
    /// Points.
    #[strum(serialize = "pt")]
    Point,
    // Picas.
    #[strum(serialize = "pc")]
    Pica,
}

impl SVGUnit {
    pub const fn to_user_units(&self) -> f64 {
        use SVGUnit::*;
        match self {
            Pixel => 1.0,
            Inch => 96.0,
            Centimeter => 37.795,
            Millimeter => 3.7795,
            Point => 1.3333,
            Pica => 16.0,
        }
    }
}