sbrd-gen 0.1.0

//! Module for value boundary

use rand::distributions::uniform::{SampleRange, SampleUniform, UniformSampler};
use rand::distributions::{Distribution, Standard};
use rand::{Rng, RngCore};
use serde::{Deserialize, Serialize};
use std::ops::RangeBounds;

/// Value boundary option
#[derive(Deserialize, Serialize, Debug, PartialEq, Eq, Clone, Copy)]
pub struct ValueBound<T> {
    #[serde(skip_serializing_if = "Option::is_none")]
    start: Option<T>,
    #[serde(
        skip_serializing_if = "skip_serialize_include_end",
        default = "default_include_end"
    )]
    include_end: bool,
    #[serde(skip_serializing_if = "Option::is_none")]
    end: Option<T>,
}

fn skip_serialize_include_end(b: &bool) -> bool {
    b == &default_include_end()
}

fn default_include_end() -> bool {
    true
}

impl<T> Default for ValueBound<T> {
    fn default() -> Self {
        ValueBound::<T>::new_full()
    }
}

impl<T> ValueBound<T> {
    /// Create as [`RangeFull`]
    ///
    /// [`RangeFull`]: https://doc.rust-lang.org/nightly/core/ops/struct.RangeFull.html
    pub fn new_full() -> Self {
        Self::new(None, None)
    }

    /// Create value boundary from start to end.
    /// If end is `Some((true, _))`, then include end.
    pub fn new(start: Option<T>, end: Option<(bool, T)>) -> Self {
        let (_include_end, _end): (bool, Option<T>) = match end {
            None => (false, None),
            Some((_include_end, _end)) => (_include_end, Some(_end)),
        };

        Self {
            start,
            end: _end,
            include_end: _include_end,
        }
    }

    /// Get start value
    pub fn get_start(&self) -> &Option<T> {
        &self.start
    }

    /// Get end value
    pub fn get_end(&self) -> &Option<T> {
        &self.end
    }

    /// Check include end
    pub fn is_include_end(&self) -> bool {
        self.include_end
    }

    /// Convert into other with into-method
    pub fn convert_into<U>(self) -> ValueBound<U>
    where
        T: Into<U>,
    {
        self.convert_with(|v| v.into())
    }

    /// Convert into other with custom-method
    pub fn convert_with<F, U>(self, mut convert: F) -> ValueBound<U>
    where
        F: FnMut(T) -> U,
    {
        let Self {
            start,
            include_end,
            end,
        } = self;

        ValueBound {
            start: start.map(|s| {
                #[allow(clippy::redundant_closure)]
                convert(s)
            }),
            include_end,
            end: end.map(|e| {
                #[allow(clippy::redundant_closure)]
                convert(e)
            }),
        }
    }

    /// Try convert into other with custom-method
    pub fn try_convert_with<F, U, E>(self, mut convert: F) -> Result<ValueBound<U>, E>
    where
        F: FnMut(T) -> Result<U, E>,
    {
        let Self {
            start,
            include_end,
            end,
        } = self;

        let _start = match start {
            None => None,
            Some(s) => Some(convert(s)?),
        };

        let _end = match end {
            None => None,
            Some(e) => Some(convert(e)?),
        };

        Ok(ValueBound {
            start: _start,
            include_end,
            end: _end,
        })
    }

    /// Replace from no bound with other's bound each start and end
    pub fn without_no_bound_from_other(self, other: ValueBound<T>) -> ValueBound<T> {
        let Self {
            start,
            include_end,
            end,
        } = self;
        let Self {
            start: other_start,
            include_end: other_include_end,
            end: other_end,
        } = other;

        ValueBound {
            start: start.or(other_start),
            include_end: if end.is_some() {
                include_end
            } else {
                other_include_end
            },
            end: end.or(other_end),
        }
    }
}

impl<T: std::cmp::PartialOrd> ValueBound<T> {
    /// Check contains value
    pub fn contains(&self, v: &T) -> bool {
        let Self {
            start,
            include_end,
            end,
        } = &self;

        match (start, include_end, end) {
            (None, _, None) => (..).contains(&v),
            (None, true, Some(e)) => (..=e).contains(&v),
            (None, false, Some(e)) => (..e).contains(&v),
            (Some(s), _, None) => (s..).contains(&v),
            (Some(s), true, Some(e)) => (s..=e).contains(&v),
            (Some(s), false, Some(e)) => (s..e).contains(&v),
        }
    }

    /// Check range is empty.
    pub fn is_empty(&self) -> bool {
        let Self {
            start,
            include_end,
            end,
        } = &self;
        match (start, include_end, end) {
            (None, _, None) => false,
            (None, true, Some(_)) => false,
            // endのとる値で範囲が空か決まるが、最少を指定することはめったにないのであきらめて最小以外を指定していることにする
            (None, false, Some(_)) => true,
            // include start
            (Some(_), _, None) => false,
            (Some(s), true, Some(e)) => (s..=e).is_empty(),
            (Some(s), false, Some(e)) => (s..e).is_empty(),
        }
    }
}

impl<T: std::fmt::Display> std::fmt::Display for ValueBound<T> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let Self {
            start,
            include_end,
            end,
        } = &self;

        match (start, end, include_end) {
            (Some(s), Some(e), true) => write!(f, "{}..={}", s, e),
            (Some(s), Some(e), false) => write!(f, "{}..{}", s, e),
            (Some(s), None, _) => write!(f, "{}..", s),
            (None, Some(e), true) => write!(f, "..={}", e),
            (None, Some(e), false) => write!(f, "..{}", e),
            (None, None, _) => write!(f, "..",),
        }
    }
}

impl<T: PartialOrd> From<std::ops::RangeFull> for ValueBound<T> {
    fn from(_range: std::ops::RangeFull) -> Self {
        ValueBound::new(None, None)
    }
}

impl<T: PartialOrd> From<std::ops::Range<T>> for ValueBound<T> {
    fn from(range: std::ops::Range<T>) -> Self {
        let std::ops::Range { start, end } = range;
        ValueBound::new(Some(start), Some((false, end)))
    }
}

impl<T: PartialOrd> From<std::ops::RangeFrom<T>> for ValueBound<T> {
    fn from(range: std::ops::RangeFrom<T>) -> Self {
        let std::ops::RangeFrom { start } = range;
        ValueBound::new(Some(start), None)
    }
}

impl<T: PartialOrd> From<std::ops::RangeInclusive<T>> for ValueBound<T> {
    fn from(range: std::ops::RangeInclusive<T>) -> Self {
        let (start, end) = range.into_inner();
        ValueBound::new(Some(start), Some((true, end)))
    }
}

impl<T: PartialOrd> From<std::ops::RangeTo<T>> for ValueBound<T> {
    fn from(range: std::ops::RangeTo<T>) -> Self {
        let std::ops::RangeTo { end } = range;
        ValueBound::new(None, Some((false, end)))
    }
}

impl<T: PartialOrd> From<std::ops::RangeToInclusive<T>> for ValueBound<T> {
    fn from(range: std::ops::RangeToInclusive<T>) -> Self {
        let std::ops::RangeToInclusive { end } = range;
        ValueBound::new(None, Some((true, end)))
    }
}

impl<T: SampleUniform + PartialOrd> SampleRange<T> for ValueBound<T>
where
    Standard: Distribution<T>,
{
    #[inline]
    fn sample_single<R: RngCore + ?Sized>(self, rng: &mut R) -> T {
        if self.start.is_none() || self.end.is_none() {
            loop {
                let s = rng.gen::<T>();
                if self.contains(&s) {
                    return s;
                }
            }
        }

        match (self.start, self.end) {
            (Some(s), Some(e)) => {
                if self.include_end {
                    T::Sampler::sample_single_inclusive(s, e, rng)
                } else {
                    T::Sampler::sample_single(s, e, rng)
                }
            }
            (_, _) => unreachable!(),
        }
    }

    #[inline]
    fn is_empty(&self) -> bool {
        self.is_empty()
    }
}