import ImmutablePrioritySet from "../util/ImmutablePrioritySet";
import Predicate from "../util/Predicate";
import Accidental from "./Accidental";
import Key from "./Key";
import KeySignature from "./KeySignature";
import Letter from "./Letter";

interface Policy extends Predicate<Key> {
}

module Policy {
  export function prioritize(...policies: Policy[]): ImmutablePrioritySet<Policy> {
    return ImmutablePrioritySet.of(policies);
  }

  export function matchLetter(letter: Letter): Policy {
    return k => k.getLetter() === letter;
  }

  export function matchAccidental(accidental: Accidental): Policy {
    return k => k.getAccidental().orElse(null) === accidental;
  }

  export function matchKeySignature(keySignature: KeySignature): Policy {
    const keys = Letter
      .values()
      .map(l => new Key(l))
      .map(k => k.apply(keySignature))
    return k => keys[k.getLetter().ordinal()].equals(k);
  }

  export const NONE = matchAccidental(null);
  export const NATURAL = matchAccidental(Accidental.NATURAL);
  export const NONE_OR_NATURAL = k => NONE(k) || NATURAL(k);
  export const SHARP = matchAccidental(Accidental.SHARP);
  export const DOUBLE_SHARP = matchAccidental(Accidental.DOUBLE_SHARP);
  export const TRIPLE_SHARP = matchAccidental(Accidental.TRIPLE_SHARP);
  export const SHARPS = k => SHARP(k) || DOUBLE_SHARP(k) || TRIPLE_SHARP(k);
  export const FLAT = matchAccidental(Accidental.FLAT);
  export const DOUBLE_FLAT = matchAccidental(Accidental.DOUBLE_FLAT);
  export const TRIPLE_FLAT = matchAccidental(Accidental.TRIPLE_FLAT);
  export const FLATS = k => FLAT(k) || DOUBLE_FLAT(k) || TRIPLE_FLAT(k);

  export const DEFAULT_PRIORITY = prioritize(
    NONE_OR_NATURAL,
    SHARP,
    FLAT
  );
}

export default Policy;