wal-css 0.1.1

use std::{cell::RefCell, rc::Rc};

use regex::Regex;

thread_local! {
    static COMMENTS_REGEX: Rc<RefCell<Regex>> =
        Rc::new(RefCell::new(Regex::new(r"/\*([^*]|[\r\n]|(\*+([^*/]|[\r\n])))*\*+/").unwrap()));
    static MULTIPLE_NEWLINES_REGEX: Rc<RefCell<Regex>> =
        Rc::new(RefCell::new(Regex::new(r"[ \t\r\n]+").unwrap()));
}

/// removes comments and insetrs space in their position
pub fn remove_comments(input: &str) -> String {
    COMMENTS_REGEX.with(|rgx| {
        rgx.as_ref()
            .borrow_mut()
            .replace_all(input, " ")
            .into_owned()
    })
}

/// removes leading and trailing whitespaces and colappses each inner whitespace into single space.
pub fn collapse_whitespaces(input: &str) -> String {
    MULTIPLE_NEWLINES_REGEX.with(|rgx| {
        rgx.as_ref()
            .borrow_mut()
            .replace_all(input, " ")
            .trim()
            .to_owned()
    })
}
/// prepares css string to be parsed by removing comments, collapsin inner whitespaces and removing leading and trailing whitespaces
pub fn clear_css(input: &str) -> String {
    collapse_whitespaces(&remove_comments(input))
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn collapses_multiple_spaces() {
        assert_eq!("ab ba", collapse_whitespaces("  ab  ba  "))
    }
    #[test]
    fn collapses_multiple_newlines() {
        assert_eq!("ab ba", collapse_whitespaces("\n\nab\n\nba\n\n\n"))
    }
    #[test]
    fn collapses_multiple_tabs() {
        assert_eq!("ab ba", collapse_whitespaces("\t\tab\t\tba\t"))
    }
    #[test]
    fn collapses_multiple_returns() {
        assert_eq!("ab ba", collapse_whitespaces("\r\rab\r\rba\r"))
    }
    #[test]
    fn collapses_mixed_whitespaces() {
        assert_eq!(
            "ab ba",
            collapse_whitespaces(" \t \n\rab \t    \n\n\rba \t    \n\n\r \r")
        )
    }

    #[test]
    fn removes_single_line_comments() {
        assert_eq!(" \nabba", remove_comments("/*this is a comment*/\nabba"))
    }
    #[test]
    fn removes_muti_line_comments() {
        assert_eq!(
            " \nabba",
            remove_comments("/*this \n is \n a \n comment*/\nabba")
        )
    }
    #[test]
    fn removes_intext_comments() {
        assert_eq!("ab ba", remove_comments("ab/*this is a comment*/ba"))
    }
    #[test]
    fn removes_comments_with_stars_and_slashes() {
        assert_eq!(
            "ab ba",
            remove_comments("ab/***this // is ///* / ** ** / a comment***/ba")
        )
    }

    #[test]
    fn clears_css_properly() {
        assert_eq!(
            ".container { background: yellow; }",
            clear_css(
                "
            /* this is a comment */
            .container  {
                background: yellow;
                
            }
            "
            )
        )
    }
}