/*!
 * Provides traits and helpers for generating and manipulating written lanuage constructs
 */

/// A type that can be compiled into a sentence.
pub trait ToSentence {
    /// Sentencifies self. The result should be suitable to be placed within a sentence.
    fn to_sentence(&self) -> String;

    /// Sentencifies self, upper-casing the first letter and adding a period to the end. Using this is discouraged due to its lack of flexibility (i.e. needing alternate punctuation or a lowercase first letter).
    fn to_sentence_finalize(&self) -> String {
        let s = self.to_sentence();
        let mut c = s.chars();
        match s.len() {
            0 => format!(""),
            1 => format!("{}.", s.to_uppercase()),
            _ => format!("{}{}.", c.nth(0).unwrap().to_uppercase(), c.as_str()),
        }
    }
}

impl<'a, T> ToSentence for T where T: AsRef<[&'a str]> {
    fn to_sentence(&self) -> String {
        let s = self.as_ref();
        let len = s.len();
        let mut str = String::new();
        for (i, seg) in s.iter().map(|s| s.as_ref()).enumerate() {
            if i == 0 {
                str.push_str(seg);
            } else if i == len-1 {
                if len == 2 {
                    str.push_str(&format!(" and {}", seg));
                } else {
                    str.push_str(&format!(", and {}", seg));
                }
            } else {
                str.push_str(&format!(", {}", seg));
            }
        }
        str
    }
}

// impl<T> ToSentence for T where T: AsRef<[String]> {
//     fn to_sentence(&self) -> String {
//         let s = self.as_ref();
//         let len = s.len();
//         let mut str = String::new();
//         for (i, seg) in s.iter().map(|s| s.as_ref()).enumerate() {
//             if i == 0 {
//                 str.push_str(seg);
//             } else if i == len {
//                 if len == 2 {
//                     str.push_str(&format!(" and {}", seg));
//                 } else {
//                     str.push_str(&format!(", and {}", seg));
//                 }
//             } else {
//                 str.push_str(&format!(", {}", seg));
//             }
//         }
//         str
//     }
// }

#[cfg(test)]
mod test {
    use super::ToSentence;

    const STRING_SLICE_A: &'static [&'static str] = &[
        "a",
    ];

    const STRING_SLICE_B: &'static [&'static str] = &[
        "a",
        "b",
    ];

    const STRING_SLICE_C: &'static [&'static str] = &[
        "a",
        "b",
        "c",
        "d",
        "e",
        "f",
        "g",
    ];

    #[test]
    fn str_slice_to_sentence() {
        assert_eq!(STRING_SLICE_A.to_sentence(), "a");
        assert_eq!(STRING_SLICE_B.to_sentence(), "a and b");
        assert_eq!(STRING_SLICE_C.to_sentence(), "a, b, c, d, e, f, and g");
    }

    #[test]
    fn str_slice_to_sentence_finalize() {
        assert_eq!(STRING_SLICE_A.to_sentence_finalize(), "A.");
        assert_eq!(STRING_SLICE_B.to_sentence_finalize(), "A and b.");
        assert_eq!(STRING_SLICE_C.to_sentence_finalize(), "A, b, c, d, e, f, and g.");
    }

    #[test]
    fn string_vec_to_sentence() {
        let vec: Vec<String> = vec!{
            "a".to_owned(),
        };

        assert_eq!(vec.iter().map(|e| e.as_ref()).collect::<Vec<&str>>().to_sentence(), "a");

        let vec: Vec<String> = vec!{
            "a".to_owned(),
            "b".to_owned(),
        };

        assert_eq!(vec.iter().map(|e| e.as_ref()).collect::<Vec<&str>>().to_sentence(), "a and b");

        let vec: Vec<String> = vec!{
            "a".to_owned(),
            "b".to_owned(),
            "c".to_owned(),
            "d".to_owned(),
            "e".to_owned(),
            "f".to_owned(),
            "g".to_owned(),
        };

        assert_eq!(vec.iter().map(|e| e.as_ref()).collect::<Vec<&str>>().to_sentence(), "a, b, c, d, e, f, and g");
    }

    #[test]
    fn string_vec_to_sentence_finalize() {
        let vec: Vec<String> = vec!{
            "a".to_owned(),
        };

        assert_eq!(vec.iter().map(|e| e.as_ref()).collect::<Vec<&str>>().to_sentence_finalize(), "A.");

        let vec: Vec<String> = vec!{
            "a".to_owned(),
            "b".to_owned(),
        };

        assert_eq!(vec.iter().map(|e| e.as_ref()).collect::<Vec<&str>>().to_sentence_finalize(), "A and b.");

        let vec: Vec<String> = vec!{
            "a".to_owned(),
            "b".to_owned(),
            "c".to_owned(),
            "d".to_owned(),
            "e".to_owned(),
            "f".to_owned(),
            "g".to_owned(),
        };

        assert_eq!(vec.iter().map(|e| e.as_ref()).collect::<Vec<&str>>().to_sentence_finalize(), "A, b, c, d, e, f, and g.");
    }
}