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use crate::Result;
use crate::{has_hardened_diacritic, has_softened_diacritic};

/// Defines a type as being able to convert to half-width katakana.
///
/// # Example
///
/// ```
/// use to_kana::{ToKana, HalfWidth};
///
/// assert_eq!("ﾜｰﾙﾄﾞ", "wa-rudo".kata().half_width().unwrap());
/// ```
pub trait HalfWidth {
    fn half_width(self) -> Result;
}

impl HalfWidth for &str {
    fn half_width(self) -> Result {
        let mut s = String::new();
        for c in self.chars() {
            let has_softened_diacritic = has_softened_diacritic(c);
            let has_hardened_diacritic = has_hardened_diacritic(c);
            let c = match c {
                'ー' => 'ｰ',
                'ア' => 'ｱ',
                'イ' => 'ｲ',
                'ウ' | 'ヴ' => 'ｳ',
                'エ' => 'ｴ',
                'オ' => 'ｵ',
                'カ' | 'ガ' => 'ｶ',
                'キ' | 'ギ' => 'ｷ',
                'ク' | 'グ' => 'ｸ',
                'ケ' | 'ゲ' => 'ｹ',
                'コ' | 'ゴ' => 'ｺ',
                'サ' | 'ザ' => 'ｻ',
                'シ' | 'ジ' => 'ｼ',
                'ス' | 'ズ' => 'ｽ',
                'セ' | 'ゼ' => 'ｾ',
                'ソ' | 'ゾ' => 'ｿ',
                'タ' | 'ダ' => 'ﾀ',
                'チ' | 'ヂ' => 'ﾁ',
                'ツ' | 'ヅ' => 'ﾂ',
                'ッ' => 'ｯ',
                'テ' | 'デ' => 'ﾃ',
                'ト' | 'ド' => 'ﾄ',
                'ナ' => 'ﾅ',
                'ニ' => 'ﾆ',
                'ヌ' => 'ﾇ',
                'ネ' => 'ﾈ',
                'ノ' => 'ﾉ',
                'ハ' | 'バ' | 'パ' => 'ﾊ',
                'ヒ' | 'ビ' | 'ピ' => 'ﾋ',
                'フ' | 'ブ' | 'プ' => 'ﾌ',
                'ヘ' | 'ベ' | 'ペ' => 'ﾍ',
                'ホ' | 'ボ' | 'ポ' => 'ﾎ',
                'マ' => 'ﾏ',
                'ミ' => 'ﾐ',
                'ム' => 'ﾑ',
                'メ' => 'ﾒ',
                'モ' => 'ﾓ',
                'ヤ' => 'ﾔ',
                'ユ' => 'ﾕ',
                'ヨ' => 'ﾖ',
                'ャ' => 'ｬ',
                'ュ' => 'ｭ',
                'ョ' => 'ｮ',
                'ラ' => 'ﾗ',
                'リ' => 'ﾘ',
                'ル' => 'ﾙ',
                'レ' => 'ﾚ',
                'ロ' => 'ﾛ',
                'ワ' => 'ﾜ',
                'ヲ' => 'ｦ',
                'ン' => 'ﾝ',
                _ => c,
            };
            s.push(c);
            if has_softened_diacritic {
                s.push('ﾞ');
            } else if has_hardened_diacritic {
                s.push('ﾟ');
            }
        }
        Ok(s)
    }
}
impl HalfWidth for String {
    fn half_width(self) -> Result {
        let s: &str = &self;
        s.half_width()
    }
}
impl HalfWidth for Result {
    fn half_width(self) -> Result {
        self?.half_width()
    }
}

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

    #[test]
    fn half_width_aiueo() {
        assert_eq!("ｱｲｳｴｵ", "アイウエオ".half_width().unwrap());
    }

    #[test]
    fn half_width_kakikukeko() {
        assert_eq!(
            "ｶﾞｷﾞｸﾞｹﾞｺﾞ",
            "ガギグゲゴ".half_width().unwrap()
        );
    }
}