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    //#![warn(missing_docs)]
    #![doc(html_playground_url = "https://playground.example.com/")] // TODO add playground if possible

    //! This crate implements Fuzzy Searching with trigrams
    //!
    //!
    //! Fuzzy searching allows to compare strings by similarity rather then by equality:\
    //! Similar strings will get a high score (close to `1.0f32`) while dissimilar strings will get a lower score (closer to `0.0f32`).
    //!
    //! Fuzzy searching tolerates changes in word order:\
    //! ex. `"John Dep"` and `"Dep John"` will get a high score.
    //!
    //!
    //! The crate exposes 4 main functions:
    //!  - [fuzzy_compare] will take 2 strings and return a score representing how similar those strings are.
    //!  - [fuzzy_search] applies [fuzzy_compare] to a list of strings and returns a list of tuples: (word, score).
    //!  - [fuzzy_search_sorted] is similar to [fuzzy_search] but orders the output in descending order.
    //!  - [fuzzy_search_threshold] will take an additional `f32` as input and returns only tuples with score greater than the threshold.
    //!  - [fuzzy_search_best_n] will take an additional `usize` arguments and returns the first `n` tuples.
    //!
    //! The Algorithm used is taken from : <https://dev.to/kaleman15/fuzzy-searching-with-postgresql-97o>
    //!
    //! Basic idea:
    //!
    //! 1. From both strings extracts all groups of 3 adjacent letters.\
    //! (`"House"` becomes `['  H', ' Ho', 'Hou', 'ous', 'use', 'se ']`).\
    //! Note the 2 spaces added to the head of the string and the one on the tail, used to make the algorithm work on zero length words.
    //!
    //! 1. Then counts the number of trigrams of the first words that are also present on the second word and divide by the number of trigrams of the first word.\
    //!
    //!
    //! Example: Comparing 2 strings
    //! ```rust
    //! fn test () {
    //!    use rust_fuzzy_search::fuzzy_compare;
    //!    let score : f32 = fuzzy_compare("kolbasobulko", "kolbasobulko");
    //!    println!("score = {:?}", score);
    //! }
    //! ```
    //!
    //! Example: Comparing a string with a list of strings and retrieving only the best matches
    //! ```
    //! fn test() {
    //!     use rust_fuzzy_search::fuzzy_search_best_n;
    //!     let s = "bulko";
    //!     let list : Vec<&str> = vec![
    //!         "kolbasobulko",
    //!         "sandviĉo",
    //!         "ŝatas",
    //!         "domo",
    //!         "emuo",
    //!         "fabo",
    //!         "fazano"
    //!     ];
    //!     let n : usize = 3;
    //!     let res : Vec<(&str, f32)> = fuzzy_search_best_n(s,&list, n);
    //!     for (_word, score) in res {
    //!         println!("{:?}",score)
    //!     }
    //! }
    //! ```
    //!
    //!

    use std::iter;

    #[inline]
    fn trigrams(s : &str) -> Vec<(char,char,char)> {

        let mut it_1 = iter::once(' ').chain(iter::once(' ')).chain(s.chars());
        let mut it_2 = iter::once(' ').chain(s.chars());
        let mut it_3 = s.chars().chain(iter::once(' '));
        let string_len = s.chars().count();
        let mut trigrams : Vec<(char,char,char)> = Vec::with_capacity(string_len);
        for _  in 0..string_len {
            let tup : (char, char, char) = (it_1.next().unwrap(), it_2.next().unwrap(), it_3.next().unwrap());
            trigrams.push(tup);
        }
        trigrams
    }

    /// Use this function to compare 2 strings.
    ///
    /// The output is a score (between `0.0f32 and 1.0f32`) representing how similar the 2 strings are.
    ///
    /// Arguments:
    ///  * `a` : the first string to compare.
    ///  * `b` : the second string to compare.
    ///
    ///
    /// example:
    /// ```rust
    /// fn test () {
    ///     use rust_fuzzy_search::fuzzy_compare;
    ///     let score : f32 = fuzzy_compare("kolbasobulko", "kolbasobulko");
    ///     println!("score = {:?}", score);
    /// }
    /// ```
    pub fn fuzzy_compare (a : &str, b : &str) -> f32 {
        /*
        //let chars_a: Vec<char> = ["1", "2", &a, "3"].join("").chars().collect();
        //let chars_b: Vec<char> = [" ", " ", &b, " "].join("").chars().collect();
        //let mut a1 = chars_a.iter();
        //let mut a2 = chars_a.iter();
        //a2.next();
        //let mut a3 = chars_a.iter();
        //a3.next();
        //a3.next();
        */

        let string_len = a.chars().count();

        let trigrams_a = trigrams(a);
        let trigrams_b = trigrams(b);

        let mut acc : f32 = 0.0f32;
        for t_a in &trigrams_a {
            for t_b in &trigrams_b {
                if t_a == t_b {
                    acc += 1.0f32;
                    break
                }
            }
        }
        let res = acc / (string_len as f32);
        if (0.0f32..=1.0f32).contains(&res) {
            res
        }else{
            0.0f32
        }
    /*
        //for (a,b,c) in &res3 {
        //    print!("{}{}{} ",a,b,c);
        //};
        //println!("-----------------");

     */
    }

    /// Use this function to compare a string (`&str`) with all elements of a list.
    ///
    ///
    /// The result is a list whose elements are tuples of the form `(string, score)`, the first element being the word of the list and the second element the score.
    ///
    /// Arguments:
    ///  * `s` : the string to compare.
    ///  * `list` : the list of strings to compare with `s`.
    ///
    /// example:
    /// ```rust
    /// fn test() {
    ///     use rust_fuzzy_search::fuzzy_search;
    ///     let s = "bulko";
    ///     let list : Vec<&str> = vec!["kolbasobulko", "sandviĉo"];
    ///     let res : Vec<(&str, f32)> = fuzzy_search(s,&list);
    ///     for (_word, score) in res {
    ///         println!("{:?}",score)
    ///     }
    /// }
    /// ```
    ///
    ///
    pub fn fuzzy_search<'a> (s : &'a str, list : &'a [&str]) -> Vec<(&'a str, f32)> {
        list.iter().map(| &value |{
            let res = fuzzy_compare(s,value);
            (value, res)
        }).collect()
    }

    /// This function is similar to [fuzzy_search] but sorts the result in descending order (the best matches are placed at the beginning).
    ///
    /// Arguments:
    ///  * `s` : the string to compare.
    ///  * `list` : the list of strings to compare with `s`.
    ///
    /// example:
    /// ```rust
    /// fn test() {
    ///     use rust_fuzzy_search::fuzzy_search_sorted;
    ///     let s = "bulko";
    ///     let list : Vec<&str> = vec!["kolbasobulko", "sandviĉo"];
    ///     let res : Vec<(&str, f32)> = fuzzy_search_sorted(s,&list);
    ///     for (_word, score) in res {
    ///         println!("{:?}",score)
    ///     }
    /// }
    /// ```
    ///
    pub fn fuzzy_search_sorted<'a> (s : &'a str, list : &'a [&str]) -> Vec<(&'a str, f32)> {
        let mut res = fuzzy_search(s, list);
        res.sort_by(|(_, d1), (_, d2)| { d2.partial_cmp(d1).unwrap()}); // TODO to fix the unwrap call
        res
    }

    /// This function is similar to [fuzzy_search] but filters out element with a score lower than the specified one.
    ///
    /// Arguments:
    ///  * `s` : the string to compare.
    ///  * `list` : the list of strings to compare with `s`.
    ///  * `threshold` : the minimum allowed score for the elements in the result: elements with lower score will be removed.
    ///
    /// ```rust
    /// fn test() {
    ///     use rust_fuzzy_search::fuzzy_search_threshold;
    ///     let s = "bulko";
    ///     let list : Vec<&str> = vec!["kolbasobulko", "sandviĉo"];
    ///     let threshold : f32 = 0.4f32;
    ///     let res : Vec<(&str, f32)> = fuzzy_search_threshold(s,&list, threshold);
    ///     for (_word, score) in res {
    ///         println!("{:?}",score)
    ///     }
    /// }
    /// ```
    pub fn fuzzy_search_threshold<'a> (s : &'a str, list : &'a [&str], threshold: f32) -> Vec<(&'a str, f32)>{
        fuzzy_search(s, list).into_iter().filter(|&(_,score)| {score >= threshold}).collect()
    }

    /// This function is similar to [fuzzy_search_sorted] but keeps only the `n` best items, those with a better match.
    ///
    /// Arguments :
    ///  * `s` : the string to compare.
    ///  * `list` : the list of strings to compare with `s`.
    ///  * `n` : the number of element to retrieve.
    ///
    /// example:
    /// ```
    /// fn test() {
    ///     use rust_fuzzy_search::fuzzy_search_best_n;
    ///     let s = "bulko";
    ///     let list : Vec<&str> = vec!["kolbasobulko", "sandviĉo"];
    ///     let n : usize = 1;
    ///     let res : Vec<(&str, f32)> = fuzzy_search_best_n(s,&list, n);
    ///     for (_word, score) in res {
    ///         println!("{:?}",score)
    ///     }
    /// }
    /// ```
    ///
    pub fn fuzzy_search_best_n<'a> (s : &'a str, list : &'a [&str], n: usize) -> Vec<(&'a str, f32)>{
        fuzzy_search_sorted(s,list).into_iter().take(n).collect()
    }

    #[cfg(test)]
    mod tests {
        use crate::{fuzzy_compare, fuzzy_search, fuzzy_search_sorted, fuzzy_search_threshold, fuzzy_search_best_n};

        //use std::fs::File;
        #[test]
        fn perfect_match_1(){
            assert_eq!(fuzzy_compare("kolbasobulko", "kolbasobulko"),1.0f32)
        }
        #[test]
        fn perfect_match_2(){
            assert_eq!(fuzzy_compare("sandviĉo", "sandviĉo"),1.0f32)
        }
        #[test]
        fn perfect_match_3(){
            assert_eq!(fuzzy_compare("domo", "domo"),1.0f32)
        }
        #[test]
        fn perfect_match_4(){
            assert_eq!(fuzzy_compare("ŝatas", "ŝatas"),1.0f32)
        }
        #[test]
        fn perfect_match_5(){
            assert_eq!(fuzzy_compare("mirinda estonto", "mirinda estonto"),1.0f32)
        }
        #[test]
        fn no_match(){
            assert_eq!(fuzzy_compare("abc", "def"),0.0f32)
        }
        #[test]
        fn empty_word(){
            assert_eq!(fuzzy_compare("", ""),0.0f32)
        }
        #[test]
        fn one_letter(){
            assert_eq!(fuzzy_compare("a", "a"),1.0f32)
        }
        #[test]
        fn utf8_one_letter_1(){
            assert_eq!(fuzzy_compare("ĉ", "ĉ"),1.0f32)
        }
        #[test]
        fn utf8_one_letter_2(){
            assert_eq!(fuzzy_compare("ł", "ł"),1.0f32)
        }
        #[test]
        fn utf8_no_match(){
            assert_eq!(fuzzy_compare("cgs", "ĉĝŝ"),0.0f32)
        }
        #[test]
        fn test_fuzzy_search_1(){
            let s : &str = "bulko";
            let list : Vec<&str> = vec!{"kolbasobulko", "sandviĉo", "kolbasobulkejo"};
            let res: Vec<(&str, f32)> = fuzzy_search(s, &list);
            assert_eq!(res.into_iter().count(), 3);
        }
        #[test]
        fn test_fuzzy_search_sorted(){
            let s : &str = "bulko";
            let list : Vec<&str> = vec!{"kolbasobulko", "sandviĉo", "kolbasobulkejo"};
            let res: Vec<(&str, f32)> = fuzzy_search_sorted(s, &list);
            assert_eq!(res.into_iter().count(), 3);
        }
        #[test]
        fn no_lowers(){
            let threshold = 0.5f32;
            let s : &str = "bulko";
            let list : Vec<&str> = vec!{"kolbasobulko", "sandviĉo", "kolbasobulkejo"};
            for (_word, score) in fuzzy_search_threshold(s, &list, threshold) {
                assert!(score > threshold)
            }
        }
        #[test]
        fn test_fuzzy_search_best_n(){
            let s : &str = "bulko";
            let list : Vec<&str> = vec!{"kolbasobulko", "sandviĉo", "kolbasobulkejo"};
            let res: Vec<(&str, f32)> = fuzzy_search_best_n(s, &list, 2);
            assert_eq!(res.into_iter().count(), 2);
        }

    }

    // (<a href="https://www.codecogs.com/eqnedit.php?latex=\frac{number&space;_&space;of&space;_&space;trigrams&space;_&space;of&space;_&space;the&space;f_&space;irst&space;_&space;words&space;_&space;that&space;_&space;are&space;_&space;also&space;_&space;present&space;_&space;on&space;_&space;the&space;_&space;second&space;_&space;word}{number&space;_&space;of&space;_&space;trigrams&space;_&space;of&space;_&space;the&space;_&space;first&space;_&space;word}" target="_blank"><img src="https://latex.codecogs.com/gif.latex?\frac{number&space;_&space;of&space;_&space;trigrams&space;_&space;of&space;_&space;the&space;f_&space;irst&space;_&space;words&space;_&space;that&space;_&space;are&space;_&space;also&space;_&space;present&space;_&space;on&space;_&space;the&space;_&space;second&space;_&space;word}{number&space;_&space;of&space;_&space;trigrams&space;_&space;of&space;_&space;the&space;_&space;first&space;_&space;word}" title="\frac{number _ of _ trigrams _ of _ the f_ irst _ words _ that _ are _ also _ present _ on _ the _ second _ word}{number _ of _ trigrams _ of _ the _ first _ word}" /></a>)