use crate::sql::comment::comment;
use crate::sql::comment::{mightbespace, shouldbespace};
use crate::sql::error::IResult;
use crate::sql::operator::{assigner, binary};
use nom::branch::alt;
use nom::bytes::complete::tag;
use nom::bytes::complete::tag_no_case;
use nom::character::complete::char;
use nom::character::complete::multispace1;
use nom::combinator::peek;
use nom::combinator::{eof, value};
use nom::sequence::preceded;

pub fn number(i: &str) -> IResult<&str, ()> {
	peek(alt((
		value((), multispace1), // 1 + 1
		value((), binary),      // 1+1
		value((), assigner),    // 1=1
		value((), comment),     // 1/*comment*/
		value((), char(')')),   // (1)
		value((), char(']')),   // a[1]
		value((), char('}')),   // {k: 1}
		value((), char('"')),
		value((), char('\'')),
		value((), char(';')), // SET a = 1;
		value((), char(',')), // [1, 2]
		value((), tag("..")), // thing:1..2
		value((), eof),       // SET a = 1
	)))(i)
}

pub fn ident(i: &str) -> IResult<&str, ()> {
	peek(alt((
		value((), multispace1), // a + 1
		value((), binary),      // a+1
		value((), assigner),    // a+=1
		value((), comment),     // a/*comment*/
		value((), char(')')),   // (a)
		value((), char(']')),   // foo[a]
		value((), char('}')),   // {k: a}
		value((), char(';')),   // SET k = a;
		value((), char(',')),   // [a, b]
		value((), char('.')),   // a.k
		value((), char('…')),   // a…
		value((), char('[')),   // a[0]
		value((), eof),         // SET k = a
	)))(i)
}

/// none, false, etc.
pub fn keyword(i: &str) -> IResult<&str, ()> {
	peek(alt((
		value((), multispace1), // false || true
		value((), binary),      // false||true
		value((), comment),     // false/*comment*/
		value((), char(')')),   // (false)
		value((), char(']')),   // [WHERE k = false]
		value((), char('}')),   // {k: false}
		value((), char(';')),   // SET a = false;
		value((), char(',')),   // [false, true]
		value((), eof),         // SET a = false
	)))(i)
}

pub fn duration(i: &str) -> IResult<&str, ()> {
	peek(alt((
		value((), multispace1),
		value((), binary),
		value((), assigner),
		value((), comment),
		value((), char(')')),
		value((), char(']')),
		value((), char('}')),
		value((), char(';')),
		value((), char(',')),
		value((), char('.')),
		value((), eof),
	)))(i)
}

pub fn field(i: &str) -> IResult<&str, ()> {
	peek(alt((
		value((), preceded(shouldbespace, tag_no_case("FROM"))),
		value((), char(';')),
		value((), eof),
	)))(i)
}

pub fn subquery(i: &str) -> IResult<&str, ()> {
	alt((
		|i| {
			let (i, _) = mightbespace(i)?;
			let (i, _) = char(';')(i)?;
			let (i, _) = peek(alt((
				preceded(shouldbespace, tag_no_case("THEN")),
				preceded(shouldbespace, tag_no_case("ELSE")),
				preceded(shouldbespace, tag_no_case("END")),
			)))(i)?;
			Ok((i, ()))
		},
		peek(alt((
			value((), preceded(shouldbespace, tag_no_case("THEN"))),
			value((), preceded(shouldbespace, tag_no_case("ELSE"))),
			value((), preceded(shouldbespace, tag_no_case("END"))),
			value((), comment),
			value((), char(']')),
			value((), char('}')),
			value((), char(';')),
			value((), char(',')),
			value((), eof),
		))),
	))(i)
}