use super::*;
use smallmap::Map;

#[derive(Debug)]
pub struct Bytes;

const KB: u64 = 1024;

lazy_static! {
    static ref SUFFIX: Map<char, u64> = smallmap::smallmap! {
	{'k' => KB},
	{'m' => KB * KB},
	{'g' => KB * KB * KB},
	{'p' => KB * KB * KB * KB},
    };
}

impl Conversion for Bytes
{
    const UNIT: &'static str = "bytes";

    type Output = u64;

    fn convert(&self, input: &str) -> Result<Self::Output, Self::Error>
    {
	#[macro_export] macro_rules! parse {
	    ($non:expr) => (($non).parse::<u64>().map_err(|e| ConversionError(format!("Failed to parse u64: {}", e)))?)
	}

	match input.char_indices().last().map(|(idx, chr)| (chr.to_lowercase().next().unwrap(), &input[..idx])) {
	    Some((chr, _)) if chr.is_numeric() => Ok(parse!(input)),
	    
	    Some((ref chr, non)) if SUFFIX.contains_key(chr) => Ok(*SUFFIX.get(chr).unwrap() * parse!(non)),
	    
	    Some((chr, _)) => Err(ConversionError(format!("Unknown suffix {}", chr))),
	    None => Ok(0),
	}
    }
}