use crate::tokenizer::{LexicalToken, LexicalTokenType};
use nom::branch::alt;
use nom::bytes::complete::{tag, take_until};
use nom::character::complete::{
    alpha1, alphanumeric1, digit0, digit1, hex_digit0, multispace1, oct_digit0, one_of,
};
use nom::combinator::{map, not, peek, recognize, value};
use nom::multi::many0_count;
use nom::sequence::{delimited, pair, tuple};
use nom::IResult;
use std::str::FromStr;

fn keyword_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(
        recognize(tuple((
            alt((
                tag("break"),
                tag("const"),
                tag("continue"),
                tag("else"),
                tag("float"),
                tag("if"),
                tag("int"),
                tag("return"),
                tag("void"),
                tag("while"),
            )),
            not(alt((peek(alphanumeric1), tag("_")))),
        ))),
        |x| LexicalToken {
            token_type: LexicalTokenType::Keyword,
            literal_value: x,
        },
    )(input)
}

fn delimiter_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(
        alt((
            tag(","),
            tag(";"),
            tag("("),
            tag(")"),
            tag("["),
            tag("]"),
            tag("{"),
            tag("}"),
        )),
        |x| LexicalToken {
            token_type: LexicalTokenType::Delimiter,
            literal_value: x,
        },
    )(input)
}

fn operator_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(
        alt((
            tag(">="),
            tag("<="),
            tag("=="),
            tag("!="),
            tag("&&"),
            tag("||"),
            tag("="),
            tag("+"),
            tag("-"),
            tag("!"),
            tag("*"),
            tag("/"),
            tag("%"),
            tag(">"),
            tag("<"),
        )),
        |x| LexicalToken {
            token_type: LexicalTokenType::Operator,
            literal_value: x,
        },
    )(input)
}

fn identifier_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(
        recognize(pair(
            alt((alpha1, tag("_"))),
            many0_count(alt((alphanumeric1, tag("_")))),
        )),
        |s| LexicalToken {
            token_type: LexicalTokenType::Identifier,
            literal_value: s,
        },
    )(input)
}

fn decimal_integer_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(recognize(pair(one_of("123456789"), digit0)), |x| {
        let number = u32::from_str_radix(x, 10).unwrap();

        LexicalToken {
            token_type: LexicalTokenType::ConstInteger(number),
            literal_value: x,
        }
    })(input)
}

fn octal_integer_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(recognize(pair(tag("0"), oct_digit0)), |x| {
        let number = u32::from_str_radix(x, 8).unwrap();

        LexicalToken {
            token_type: LexicalTokenType::ConstInteger(number),
            literal_value: x,
        }
    })(input)
}

fn hexadecimal_integer_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(
        recognize(pair(alt((tag("0x"), tag("0X"))), hex_digit0)),
        |x: &str| {
            let number = u32::from_str_radix(&x[2..], 16).unwrap();

            LexicalToken {
                token_type: LexicalTokenType::ConstInteger(number),
                literal_value: x,
            }
        },
    )(input)
}

fn integer_parser(input: &str) -> IResult<&str, LexicalToken> {
    alt((
        hexadecimal_integer_parser,
        octal_integer_parser,
        decimal_integer_parser,
    ))(input)
}

fn float_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(recognize(tuple((digit1, tag("."), digit1))), |x| {
        let number = f32::from_str(x).unwrap();

        LexicalToken {
            token_type: LexicalTokenType::ConstFloat(number),
            literal_value: x,
        }
    })(input)
}

fn literal_string_parser(input: &str) -> IResult<&str, LexicalToken> {
    map(delimited(tag("\""), take_until("\""), tag("\"")), |s| {
        LexicalToken {
            token_type: LexicalTokenType::LiteralString,
            literal_value: s,
        }
    })(input)
}

fn comments_parser(input: &str) -> IResult<&str, ()> {
    alt((
        value((), tuple((tag("//"), take_until("\n"), tag("\n")))),
        value((), tuple((tag("/*"), take_until("*/"), tag("*/")))),
    ))(input)
}

pub fn junk_parser(input: &str) -> IResult<&str, ()> {
    alt((value((), multispace1), comments_parser))(input)
}

pub fn combine_parser(input: &str) -> IResult<&str, LexicalToken> {
    alt((
        float_parser,
        integer_parser,
        literal_string_parser,
        keyword_parser,
        identifier_parser,
        delimiter_parser,
        operator_parser,
    ))(input)
}