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//! Totalistic rules with von Neumann neighborhood.

use super::Gen;
use crate::ParseRuleError;

rule_struct!(Neumann);

impl Neumann {
    parse_bs!(4);
    parse_rule!('V');
}

/// A trait for parsing totalistic rules with
/// [von Neumann neighborhood](http://www.conwaylife.com/wiki/Von_Neumann_neighbourhood).
///
/// The `b` / `s` data of this type of rules consists of numbers of live neighbors
/// that cause a cell to be born / survive.
///
/// # Examples
///
/// ```
/// use ca_rules::ParseNeumann;
///
/// #[derive(Debug, Eq, PartialEq)]
/// struct Rule {
///     b: Vec<u8>,
///     s: Vec<u8>,
/// }
///
/// impl ParseNeumann for Rule {
///     fn from_bs(b: Vec<u8>, s: Vec<u8>) -> Self {
///         Rule { b, s }
///     }
/// }
///
/// let life = Rule::parse_rule("B2/S013V").unwrap();
///
/// assert_eq!(
///     life,
///     Rule {
///         b: vec![2],
///         s: vec![0, 1, 3],
///     }
/// )
/// ```
pub trait ParseNeumann {
    /// Construct the rule from `b` / `s` data.
    fn from_bs(b: Vec<u8>, s: Vec<u8>) -> Self;

    /// The parser.
    fn parse_rule(input: &str) -> Result<Self, ParseRuleError>
    where
        Self: Sized,
    {
        let Neumann { b, s } = Neumann::parse_rule(input)?;
        Ok(Self::from_bs(b, s))
    }
}

/// A trait for parsing totalistic [Generations](http://www.conwaylife.com/wiki/Generations) rules
/// with [von Neumann neighborhood](http://www.conwaylife.com/wiki/Von_Neumann_neighbourhood).
///
/// The `b` / `s` data of this type of rules consists of numbers of live neighbors
/// that cause a cell to be born / survive.
///
/// # Examples
///
/// ```
/// use ca_rules::ParseNeumannGen;
///
/// #[derive(Debug, Eq, PartialEq)]
/// struct Rule {
///     b: Vec<u8>,
///     s: Vec<u8>,
///     gen: usize,
/// }
///
/// impl ParseNeumannGen for Rule {
///     fn from_bsg(b: Vec<u8>, s: Vec<u8>, gen: usize) -> Self {
///         Rule { b, s, gen }
///     }
/// }
///
/// let life = Rule::parse_rule("B2/S013/3V").unwrap();
///
/// assert_eq!(
///     life,
///     Rule {
///         b: vec![2],
///         s: vec![0, 1, 3],
///         gen: 3,
///     }
/// )
/// ```
pub trait ParseNeumannGen {
    /// Construct the rule from `b` / `s` data and the number of states.
    fn from_bsg(b: Vec<u8>, s: Vec<u8>, gen: usize) -> Self;

    /// The parser.
    fn parse_rule(input: &str) -> Result<Self, ParseRuleError>
    where
        Self: Sized,
    {
        let Gen {
            rule: Neumann { b, s },
            gen,
        } = Neumann::parse_rule_gen(input)?;
        Ok(Self::from_bsg(b, s, gen))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    struct Rule;

    impl ParseNeumann for Rule {
        fn from_bs(_b: Vec<u8>, _s: Vec<u8>) -> Self {
            Rule
        }
    }

    #[test]
    fn valid_rules() -> Result<(), ParseRuleError> {
        Rule::parse_rule("B3/S23V")?;
        Rule::parse_rule("B3S23V")?;
        Rule::parse_rule("b3s23v")?;
        Rule::parse_rule("23/3V")?;
        Rule::parse_rule("23/v")?;
        Ok(())
    }

    #[test]
    fn invalid_rules() {
        assert_eq!(
            Rule::parse_rule("B3/S23va").err(),
            Some(ParseRuleError::ExtraJunk)
        );
        assert_eq!(
            Rule::parse_rule("B3V/S23").err(),
            Some(ParseRuleError::Missing('S'))
        );
        assert_eq!(
            Rule::parse_rule("B3/S23").err(),
            Some(ParseRuleError::Missing('V'))
        );
        assert_eq!(
            Rule::parse_rule("B3/S25V").err(),
            Some(ParseRuleError::Missing('V'))
        );
        assert_eq!(
            Rule::parse_rule("233v").err(),
            Some(ParseRuleError::Missing('/'))
        );
    }
}