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//! VCF record genotype value.

pub mod allele;

pub use self::allele::Allele;

use std::{error, fmt, str::FromStr};

/// A VCF record genotype value.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Genotype(Vec<Allele>);

/// An error returned when a raw VCF record genotype value fails to parse.
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum ParseError {
    /// The input is empty.
    Empty,
    /// An allele is invalid.
    InvalidAllele(allele::ParseError),
}

impl error::Error for ParseError {}

impl fmt::Display for ParseError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Empty => f.write_str("empty input"),
            Self::InvalidAllele(e) => write!(f, "invalid allele: {}", e),
        }
    }
}

impl FromStr for Genotype {
    type Err = ParseError;

    fn from_str(mut s: &str) -> Result<Self, Self::Err> {
        if s.is_empty() {
            return Err(ParseError::Empty);
        }

        let mut alleles = Vec::new();

        while let Some(i) = s.chars().skip(1).position(|c| matches!(c, '/' | '|')) {
            let allele = s[..i + 1].parse().map_err(ParseError::InvalidAllele)?;
            alleles.push(allele);
            s = &s[i + 1..];
        }

        let allele = s.parse().map_err(ParseError::InvalidAllele)?;
        alleles.push(allele);

        Ok(Self(alleles))
    }
}

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

    #[test]
    fn test_from_str() {
        use allele::Phasing;

        assert_eq!(
            "0/1".parse(),
            Ok(Genotype(vec![
                Allele::new(Some(0), None),
                Allele::new(Some(1), Some(Phasing::Unphased)),
            ]))
        );

        assert_eq!(
            "0|1".parse(),
            Ok(Genotype(vec![
                Allele::new(Some(0), None),
                Allele::new(Some(1), Some(Phasing::Phased)),
            ]))
        );

        assert_eq!(
            "./.".parse(),
            Ok(Genotype(vec![
                Allele::new(None, None),
                Allele::new(None, Some(Phasing::Unphased)),
            ]))
        );

        assert_eq!("0".parse(), Ok(Genotype(vec![Allele::new(Some(0), None)])));

        assert_eq!(
            "0/1/2".parse(),
            Ok(Genotype(vec![
                Allele::new(Some(0), None),
                Allele::new(Some(1), Some(Phasing::Unphased)),
                Allele::new(Some(2), Some(Phasing::Unphased)),
            ]))
        );

        assert_eq!(
            "0/1|2".parse(),
            Ok(Genotype(vec![
                Allele::new(Some(0), None),
                Allele::new(Some(1), Some(Phasing::Unphased)),
                Allele::new(Some(2), Some(Phasing::Phased)),
            ]))
        );

        assert!(matches!(
            "0:1".parse::<Genotype>(),
            Err(ParseError::InvalidAllele(_))
        ));
    }
}