use minisql::type_system::Value;
use nom::{
    branch::alt,
    character::complete::{char, digit1, none_of, u64},
    combinator::opt,
    error::make_error,
    multi::many0,
    sequence::{delimited, pair, preceded},
    IResult,
};

pub fn parse_db_value(input: &str) -> IResult<&str, Value> {
    alt((parse_string, parse_number, parse_int, parse_uuid))(input)
}

pub fn parse_number(input: &str) -> IResult<&str, Value> {
    // Parse the integer part
    let (input, (sign, digits)) = pair(opt(char('-')), digit1)(input)?;

    // Parse the fractional part
    let (input, frac_part) = opt(pair(char('.'), digit1))(input)?;

    match frac_part {
        Some((_fsign, fdigits)) => {
            // Combine integer and fractional parts
            let combined_parts = format!("{}{}.{}", sign.unwrap_or('+'), digits, fdigits);
            // Parse the combined parts as a floating-point number
            let value = combined_parts
                .parse::<f64>()
                .map_err(|_| nom::Err::Failure(make_error(input, nom::error::ErrorKind::Fail)))?;
            Ok((input, Value::Number(value)))
        }
        None => {
            let value = format!("{}{}", sign.unwrap_or('+'), digits)
                .parse::<u64>()
                .map_err(|_| nom::Err::Failure(make_error(input, nom::error::ErrorKind::Fail)))?;
            Ok((input, Value::Int(value)))
        }
    }
}

pub fn parse_int(input: &str) -> IResult<&str, Value> {
    u64(input).map(|(input, v)| (input, Value::Int(v)))
}

fn escape_tab(input: &str) -> IResult<&str, char> {
    let (input, _) = preceded(char('\\'), char('t'))(input)?;
    Ok((input, '\t'))
}

fn escape_backslash(input: &str) -> IResult<&str, char> {
    let (input, _) = preceded(char('\\'), char('\\'))(input)?;
    Ok((input, '\\'))
}

fn escape_newline(input: &str) -> IResult<&str, char> {
    let (input, _) = preceded(char('\\'), char('n'))(input)?;
    Ok((input, '\n'))
}

fn escape_carriegereturn(input: &str) -> IResult<&str, char> {
    let (input, _) = preceded(char('\\'), char('r'))(input)?;
    Ok((input, '\r'))
}

fn escape_doublequote(input: &str) -> IResult<&str, char> {
    preceded(char('\\'), char('"'))(input)
}

pub fn parse_string(input: &str) -> IResult<&str, Value> {
    // Parse the content inside the double quotes
    let (input, content) = delimited(
        char('"'),
        many0(alt((
            escape_backslash,
            escape_carriegereturn,
            escape_newline,
            escape_doublequote,
            escape_tab,
            none_of(r#"\""#),
        ))),
        char('"'),
    )(input)?;

    // Combine the characters into a string
    let value: String = content.into_iter().collect();

    Ok((input, Value::String(value)))
}

pub fn parse_uuid(input: &str) -> IResult<&str, Value> {
    let (input, value) = pair(char('u'), u64)(input)
        .map(|(input, (_, v))| (input, Value::Uuid(v)))?;
    Ok((input, value))
}

#[cfg(test)]
mod tests {
    use crate::parsing::literal::{parse_db_value, parse_string, parse_uuid};
    use minisql::type_system::Value;

    #[test]
    fn test_string_parser() {
        assert_eq!(
            parse_string(r#""simple""#),
            Ok((
                "",
                Value::String(String::from("simple"))
            ))
        );
        assert_eq!(
            parse_string(r#""\"\t\r\n\\""#),
            Ok((
                "",
                Value::String(String::from("\"\t\r\n\\"))
            ))
        );
        assert_eq!(
            parse_string(r#""name is \"John\".""#),
            Ok((
                "",
                Value::String(String::from("name is \"John\"."))
            ))
        );
    }

    #[test]
    fn test_parse_db_value() {
        let (input, value) = parse_db_value("5").expect("should parse");
        assert_eq!(input, "");
        assert_eq!(value, Value::Int(5));

        let (input, value) = parse_db_value("5.5").expect("should parse");
        assert_eq!(input, "");
        assert_eq!(value, Value::Number(5.5));

        let (_, _) = parse_db_value("\"STRING\"").expect("should parse");
        let (input, value) =
            parse_db_value("\"abcdefghkjklmnopqrstuvwxyz!@#$%^&*()_+ \"").expect("should parse");
        assert_eq!(input, "");
        assert_eq!(
            value,
            Value::String(
                "abcdefghkjklmnopqrstuvwxyz!@#$%^&*()_+ ".to_string()
            )
        );
    }

    #[test]
    fn test_parse_positive_float() {
        assert_eq!(
            parse_db_value("23.213313"),
            Ok(("", Value::Number(23.213313)))
        );
        assert_eq!(
            parse_db_value("2241.9734"),
            Ok(("", Value::Number(2241.9734)))
        );
    }

    #[test]
    fn test_parse_negative_float() {
        assert_eq!(
            parse_db_value("-9241.873654"),
            Ok(("", Value::Number(-9241.873654)))
        );
        assert_eq!(
            parse_db_value("-62625.0"),
            Ok(("", Value::Number(-62625.0)))
        );
    }

    #[test]
    fn test_parse_float_between_0_and_1() {
        assert_eq!(
            parse_db_value("0.873654"),
            Ok(("", Value::Number(0.873654)))
        );
        assert_eq!(parse_db_value("0.62625"), Ok(("", Value::Number(0.62625))));
    }

    #[test]
    fn test_parse_int() {
        assert_eq!(
            parse_db_value("5134616"),
            Ok(("", Value::Int(5134616)))
        );
    }

    #[test]
    fn test_parse_uuid() {
        assert_eq!(
            parse_uuid("u131515"),
            Ok(("", Value::Uuid(131515)))
        )
    }
}