import addCircumflex from './utils/add_circumflex';

type ReplacerFn = (_match: any, p1: string) => string;
type Replacer = string | ReplacerFn;

// Rules based on D.A. Black's "Learn to Read New Testament Greek" (3rd ed, 133-134)

// distinguish between genuine and spurious dipthongs

const substitutions: [pattern: string, replacement: Replacer][] = [
  ['α(α|ε|η)', 'α'],
  // ["αι", "αι"],
  // ["αυ", "αυ"],
  ['αο', 'ω'],
  ['αω', 'ω'],

  ['εα', 'η'],
  ['εε', '[ει]'],
  ['εη', 'η'],
  // ["ει", "ει"],
  // ["ευ", "ευ"]
  ['εο', '[ου]'],
  ['εω', 'ω'],

  ['η(α|ε|η)', 'η'],
  ['ηι', 'ῃ'],
  // ["ηυ", "ηυ"],
  ['η(ο|ω)', 'ω'],

  ['οα', 'ω'],
  ['οε', '[ου]'],
  ['οη', 'ω'],
  // ["οι", "οι"],
  // ["ου", "ου"],
  ['οο', '[ου]'],
  ['οω', 'ω'],

  ['ω(α|ε|η)', 'ω'],
  ['ωι', 'ῳ'],
  // ["ωυ", "ωυ"],
  ['ωο', 'ω'],
  ['ωω', 'ω'],

  //   ᾳαι ει 1 ει 2 ῃ οι ου 3 ῳ
  // α ᾳ ᾳ α ᾳ ῳ ω ῳ
  // ε ῃ ει ει ῃ οι ου ῳ
  // η ῃ ῃ η ῃ ῳ ῳ
  // ο ῳ οι ου οι οι ου ῳ

  ['αᾳαι', 'ᾳ'],
  ['αει', 'ᾳ'],
  ['α[ει]', 'α'],
  ['αῃ', 'ᾳ'],
  ['αοι', 'ῳ'],
  ['α[ου]', 'ω'],
  ['αῳ', 'ῳ'],

  ['εᾳαι', 'ῃ'],
  ['εει', '[ει]'],
  ['ε[ει]', '[ει]'],
  ['εῃ', 'ῃ'],
  ['εοι', 'οι'],
  ['ε[ου]', 'ου'],
  ['εῳ', 'ῳ'],

  ['ηᾳαι', 'ῃ'],
  ['ηει', 'ῃ'],
  ['η[ει]', 'η'],
  ['ηῃ', 'ῃ'],
  ['ηοι', 'ῳ'],
  ['η[ου]', ''],
  ['ηῳ', 'ῳ'],

  ['οᾳαι', 'ῳ'],
  ['οει', 'οι'],
  ['ο[ει]', 'ου'],
  ['οῃ', 'οι'],
  ['οοι', 'οι'],
  ['ο[ου]', 'ου'],
  ['οῳ', 'ῳ'],
];

const oldSubstitutions: [pattern: string, replacement: Replacer][] = [
  // "ε + ο = ου"
  ['εο', 'οῦ'],

  ['οει', 'οῖ'],
  ['οου', 'οῦ'],

  //
  // ["εα", "η"],

  // "ε before any long vowel or diphthong drops out"
  [
    'ε([ηω]|ει|ου|ευ|αι|υι|αυ|οι)',
    (_match: any, p1: string) => {
      p1 = p1.normalize('NFC');
      const upToLastCharacter = p1.substr(0, p1.length - 1);
      const lastCharacter = addCircumflex(p1.substr(-1));
      return upToLastCharacter + lastCharacter;
    },
  ],

  // "ε + ε = ει"
  ['εε', 'εῖ'],

  // "α + any combination with ι = ᾳ"
  ['α[αειουηω]ι', 'ᾷ'],

  // "α + E-sound (ε or η) = α"
  ['α[εη]', 'ᾶ'],

  // "α + O sound (ο, ω, or ου) = ω"
  ['α[οω]', 'ῶ'],
  ['αου', 'ῶ'],

  // "ο + long vowel = ω"
  ['ο[ηω]', 'ῶ'],

  // "ο + short vowel or ου = ου"
  ['ο[αειου]', 'οῦ'],

  // "ο + any combination with ι = οι"
  ['ο[αεου]ι', 'οῖ'],
];

export default function (characters: string) {
  for (const [pattern, replacement] of substitutions) {
    if (characters.match(new RegExp(pattern, 'g'))) {
      console.log({ pattern });
      // https://github.com/microsoft/TypeScript/issues/22378#issuecomment-419983692
      if (typeof replacement === 'string') {
        return characters.replace(new RegExp(pattern, 'g'), replacement);
      } else {
        return characters.replace(new RegExp(pattern, 'g'), replacement);
      }
    }
  }
  return characters;
}

// See also: http://www.biblicalgreek.org/grammar/images/pcontracts.pdf