use nom::
{
	IResult,
	branch::alt,
	bytes::complete::tag,
	character::complete::digit1,
	combinator::{map, map_res, opt, recognize},
	sequence::pair,
};

pub fn integer(i: &str) -> IResult<&str, crate::Term>
{
	map
	(
		map_res
		(
			recognize
			(
				pair
				(
					opt
					(
						alt
						((
							tag("-"),
							tag("+"),
						))
					),
					digit1,
				)
			),
			std::str::FromStr::from_str,
		),
		crate::Term::integer,
	)(i)
}

fn infimum(i: &str) -> IResult<&str, crate::Term>
{
	map
	(
		tag("#inf"),
		|_| crate::Term::infimum(),
	)(i)
}

fn supremum(i: &str) -> IResult<&str, crate::Term>
{
	map
	(
		tag("#sup"),
		|_| crate::Term::supremum(),
	)(i)
}

pub fn special_integer(i: &str) -> IResult<&str, crate::Term>
{
	alt
	((
		infimum,
		supremum,
	))(i)
}

/*
fn string<'a>(i: &'a str, declarations: &Declarations) -> IResult<&'a str, crate::Term>
{
	map
	(
		delimited
		(
			multispace0,
			delimited
			(
				tag("\""),
				is_not("\""),
				tag("\""),
			),
			multispace0
		),
		|s: &str| crate::Term::String(s.to_string())
	)(i)
}


fn function<'a>(i: &'a str, declarations: &Declarations) -> IResult<&'a str, crate::Formula>
{
	alt
	((
		function_n_ary,
		function_0_ary
	))(i)
}

fn function_0_ary<'a>(i: &'a str, declarations: &Declarations) -> IResult<&'a str, crate::Term>
{
	map
	(
		delimited(multispace0, function_identifier, multispace0),
		|name| crate::Formula::function(
			crate::FunctionDeclaration
			{
				name: name,
				arity: 0,
			},
			vec![])
	)(i)
}

fn function_n_ary<'a>(i: &'a str, declarations: &Declarations) -> IResult<&'a str, crate::Term>
{
	map
	(
		pair
		(
			delimited(multispace0, function_identifier, multispace0),
			delimited
			(
				multispace0,
				delimited
				(
					tag("("),
					separated_list(tag(","), term),
					tag(")")
				),
				multispace0
			)
		),
		|(name, arguments)| crate::Formula::function(
			crate::PredicateDeclaration
			{
				name: name,
				arity: arguments.len(),
			},
			arguments)
	)(i)
}

*/

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

	#[test]
	fn parse_integer()
	{
		assert_eq!(integer("0"), Ok(("", crate::Term::integer(0))));
		assert_eq!(integer("10000"), Ok(("", crate::Term::integer(10000))));
		assert_eq!(integer("-10000"), Ok(("", crate::Term::integer(-10000))));
		assert_eq!(integer("1.5"), Ok((".5", crate::Term::integer(1))));
		assert!(integer("a").is_err());
		assert!(integer("-").is_err());
		assert!(integer(" ").is_err());
	}

	#[test]
	fn parse_special_integer()
	{
		assert_eq!(special_integer("#inf"), Ok(("", crate::Term::infimum())));
		assert_eq!(special_integer("#sup"), Ok(("", crate::Term::supremum())));
		assert!(special_integer("inf").is_err());
		assert!(special_integer("sup").is_err());
		assert!(special_integer("0").is_err());
		assert!(special_integer("10000").is_err());
		assert!(special_integer("-10000").is_err());
		assert!(special_integer(" ").is_err());
	}
}