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    #![warn(missing_docs)]
    //! Calculate [Delta E](http://www.colorwiki.com/wiki/Delta_E:_The_Color_Difference)
    //! (color difference) between two colors in CIE Lab space.
    //!
    //! # Examples
    //!
    //! ```
    //! use std::error::Error;
    //! use deltae::*;
    //!
    //! fn main() -> Result<(), Box<dyn Error>>{
    //!     // Lab from a string
    //!     let lab0: LabValue = "89.73, 1.88, -6.96".parse()?;
    //!     // Lab directly from values
    //!     let lab1 = LabValue {
    //!         l: 95.08,
    //!         a: -0.17,
    //!         b: -10.81,
    //!     }.validate()?; // Validate that the values are in range
    //!
    //!     // Create your own Lab type
    //!     #[derive(Clone, Copy)]
    //!     struct MyLab(f32, f32, f32);
    //!
    //!     // Types that implement Into<LabValue> also implement the Delta trait
    //!     impl From<MyLab> for LabValue {
    //!         fn from(mylab: MyLab) -> Self {
    //!             LabValue { l: mylab.0, a: mylab.1, b: mylab.2 }
    //!         }
    //!     }
    //!     let mylab = MyLab(95.08, -0.17, -10.81);
    //!
    //!     // Implement DeltaEq for your own types
    //!     impl<D: Delta + Copy> DeltaEq<D> for MyLab {}
    //!
    //!     // Assert that colors are equivalent within a tolerance
    //!     assert_delta_eq!(mylab, lab1, DE2000, 0.0, "mylab is not equal to lab1!");
    //!
    //!     // Calculate DeltaE between two lab values
    //!     let de0 = DeltaE::new(&lab0, &lab1, DE2000);
    //!     // Use the Delta trait
    //!     let de1 = lab0.delta(lab1, DE2000);
    //!     assert_eq!(de0, de1);
    //!
    //!     // Convert to other color types
    //!     let lch0 = LchValue::from(lab0);
    //!     let xyz0 = XyzValue::from(lab1);
    //!     // If DE2000 is less than 1.0, the colors are considered equivalent
    //!     assert!(lch0.delta_eq(&lab0, DE2000, 1.0));
    //!     assert!(xyz0.delta_eq(&lab1, DE2000, 1.0));
    //!
    //!     // Calculate DeltaE between different color types
    //!     let de2 = lch0.delta(xyz0, DE2000);
    //!     assert_eq!(de2.round_to(4), de0.round_to(4));
    //!     // There is some loss of accuracy in the conversion.
    //!     // Usually rounding to 4 decimal places is more than enough.
    //!
    //!     // Recalculate DeltaE with different method
    //!     let de3 = de2.with_method(DE1976);
    //!
    //!     println!("{}\n{}\n{}\n{}\n{}\n{}\n{}\n{}\n",
    //!         lab0, // [L:89.73, a:1.88, b:-6.96]
    //!         lab1, // [L:95.08, a:-0.17, b:-10.81]
    //!         lch0, // [L:89.73, c:7.2094383, h:285.11572]
    //!         xyz0, // [X:0.84574246, Y:0.8780792, Z:0.8542397]
    //!         de0,  // 5.316941
    //!         de1,  // 5.316941
    //!         de2,  // 5.316937
    //!         de3,  // 6.902717
    //!     );
    //!
    //!     Ok(())
    //! }
    //! ```

    pub mod color;
    mod convert;
    mod delta;
    pub mod eq;
    mod round;
    mod validate;

    #[cfg(test)]
    mod tests;

    pub use DEMethod::*;
    pub use color::*;
    pub use delta::*;
    pub use eq::*;
    pub use round::*;
    pub use validate::*;

    use std::fmt;
    use std::io;

    pub(crate) type ValueResult<T> = Result<T, color::ValueError>;

    /// ## The measured difference between two colors
    ///
    /// There are many different methods of calculating color difference. Different methods have a
    /// specific purpose, mainly in determining the level of tolerance for describing the difference
    /// between two colors. Regardless of the [`DEMethod`] used, [`DeltaE`] is always calculated based on the
    /// [`LabValue`]s of the two colors.
    #[derive(Debug, Clone, Copy)]
    pub struct DeltaE {
        /// The mathematical method used for calculating color difference
        method: DEMethod,
        /// The calculated Delta E value
        value: f32,
        /// The reference color
        reference: LabValue,
        /// The sample color
        sample: LabValue,
    }

    impl DeltaE {
        /// New [`DeltaE`] from two colors and a [`DEMethod`].
        /// ```
        /// use deltae::{LabValue, DeltaE, DEMethod::DE2000};
        ///
        /// let lab0 = LabValue::new(89.73, 1.88, -6.96).unwrap();
        /// let lab1 = LabValue::new(95.08, -0.17, -10.81).unwrap();
        /// let de0 = DeltaE::new(&lab0, &lab1, DE2000);
        /// assert_eq!(de0, 5.316941);
        /// ```
        #[inline]
        pub fn new<A, B>(a: A, b: B, method: DEMethod) -> DeltaE
        where A: Delta, B: Delta {
            a.delta(b, method)
        }

        /// Recalculate [`DeltaE`] with another [`DEMethod`]
        /// ```
        /// use deltae::{Delta, DeltaE, LabValue, DEMethod};
        ///
        /// let lab0 = LabValue::new(89.73, 1.88, -6.96).unwrap();
        /// let lab1 = LabValue::new(95.08, -0.17, -10.81).unwrap();
        /// let de2000 = lab0.delta(lab1, DEMethod::DE2000);
        /// let de1976 = de2000.with_method(DEMethod::DE1976);
        /// assert_eq!(de1976, 6.902716);
        /// ```
        #[inline]
        pub fn with_method(self, method: DEMethod) -> Self {
            self.reference.delta(self.sample, method)
        }

        /// Return a reference to the [`DeltaE`] method used in the calculation
        pub fn method(&self) -> &DEMethod {
            &self.method
        }

        /// Return a reference to the [`DeltaE`] value
        pub fn value(&self) -> &f32 {
            &self.value
        }

        /// Return a reference to the reference [`LabValue`] used in the calculation. A reference color
        /// is the base color to which the sample color is being compared.
        pub fn reference(&self) -> &LabValue {
            &self.reference
        }

        /// Return a reference to the sample [`LabValue`] used in the calculation. A sample color is
        /// the color being compared to the reference color.
        pub fn sample(&self) -> &LabValue {
            &self.sample
        }
    }

    impl fmt::Display for DeltaE {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            write!(f, "{}", &self.value)
        }
    }

    impl PartialEq<f32> for DeltaE {
        fn eq(&self, f: &f32) -> bool {
            &self.value == f
        }
    }

    impl PartialEq for DeltaE {
        fn eq(&self, other: &Self) -> bool {
            self.value == other.value
        }
    }

    /// One should be careful when ordering DeltaE. A `DE2000:1.0` value is not
    /// necessarily the same amount of color difference as a amount of color
    /// difference `DE1976:1.0` value.
    impl PartialOrd for DeltaE {
        fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
            self.value.partial_cmp(&other.value)
        }
    }

    /// The most common DeltaE methods
    #[derive(Debug, PartialEq, Clone, Copy)]
    pub enum DEMethod{
        /// The default DeltaE method
        DE2000,
        /// An implementation of DeltaE with separate tolerances for Lightness and Chroma
        DECMC(
            /// Lightness tolerance
            f32,
            /// Chroma tolerance
            f32,
        ),
        /// CIE94 DeltaE implementation, weighted with a tolerance for graphics
        DE1994G,
        /// CIE94 DeltaE implementation, weighted with a tolerance for textiles
        DE1994T,
        /// The original DeltaE implementation, a basic euclidian distance formula
        DE1976,
    }

    /// DeltaE CMC (1:1)
    pub const DECMC1: DEMethod = DECMC(1.0, 1.0);
    /// DeltaE CMC (2:1)
    pub const DECMC2: DEMethod = DECMC(2.0, 1.0);

    impl Eq for DEMethod {}

    impl Default for DEMethod {
        fn default() -> DEMethod {
            DEMethod::DE2000
        }
    }

    impl fmt::Display for DEMethod {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            match self {
                DECMC(tl, tc) => {
                    if (tl, tc) == (&1.0, &1.0) {
                        write!(f, "DECMC1")
                    } else if (tl, tc) == (&2.0, &1.0) {
                        write!(f, "DECMC2")
                    } else {
                        write!(f, "DECMC({:0.2}:{:0.2})", tl, tc)
                    }
                }
                _ => write!(f, "{:?}", self)
            }
        }
    }