#[derive(Debug, Default, Clone)]
pub struct KWIndex<'a> {
    word: Vec<&'a str>,
}

impl<'a> KWIndex<'a> {
    // Make a new empty target words list.
    pub fn new() -> Self {
        let word = Vec::new();
        Self { word }
    }

    // Parse the `target` text and add the sequence of
    // valid words contained in it to this `KWIndex`
    // index.
    pub fn extend_from_text(mut self, target: &'a str) -> Self {
        for i in target.split_whitespace() {
            let mut temp = i;

            for j in i.chars() {
                if !j.is_alphabetic() {
                    // check if j is the last char in word
                    if j == i.chars().next().unwrap() || j == i.chars().last().unwrap() {
                        println!("[{}] is removed from [{}]", j, temp);
                        // temp = i.trim_matches(|c: char| c == ',' || c == '.' || c == '!' || c == '?');
                        temp = temp.trim_matches(|c: char| c == j);
                    } else {
                        println!("[{}] is removed because {} is no alphabetic", temp, j);
                        temp = "";
                        break;
                    }
                }
            }
            if !temp.is_empty() {
                println!("[{}] is add to KWIndex index", temp);
                self.word.push(temp);
            }
        }
        self
    }

    // Count the number of occurrences of the given `keyword`
    // that are indexed by this `KWIndex`.
    pub fn count_matches(&self, keyword: &str) -> usize {
        if self.is_empty() {
            return 0;
        }

        let mut counter = 0;
        for i in &self.word {
            if i == &keyword {
                counter += 1;
            }
        }
        counter
    }

    // Count the number of words that are indexed by this
    // `KWIndex`.
    pub fn len(&self) -> usize {
        self.word.len()
    }

    // Is this index empty?
    pub fn is_empty(&self) -> bool {
        self.word.len() == 0
    }
}