import { JOHTO, RAM, WRAM } from "../rom/profile";
import { magikarpLength } from "../battle/battle";
import type { Gen, SpecialContext } from "./special-context";

const MAGIKARP = 129;

/** MAGIKARPLENGTH_* (constants/script_constants.asm). */
export const MAGIKARP_LENGTH = {
  notMagikarp: 0,
  refused: 1,
  tooShort: 2,
  beatRecord: 3,
} as const;

/** wBestMagikarpLengthFeet/Inches and wMagikarpRecordHoldersName;
 * InitializeMagikarpHouse starts a new game at 3′6″ by RALPH. */
export interface MagikarpRecord {
  feet: number;
  inches: number;
  holder: string;
}
export const initialMagikarpRecord = (): MagikarpRecord => ({
  feet: 3,
  inches: 6,
  holder: "RALPH",
});

/** PrintMagikarpLength: feet and inches, each a left-aligned number, with
 * the feet and inches marks it loads into tiles $6e and $6f. */
const lengthString = (feet: number, inches: number) => `${feet}′${inches}″`;

/** FindThatSpecies: wPartySpecies holds EGG for an Egg, so an Egg never
 * matches. */
export const findPartyMonThatSpecies = (c: SpecialContext, species: number) =>
  c.state.party.some((mon) => !mon.egg && mon.species === species) ? 1 : 0;

/** CheckMagikarpLength (engine/events/magikarp.asm): pick a party
 * Pokémon; a Magikarp is measured from its DVs and its own OT ID, and a
 * longer one (both bytes compared, feet first) becomes the record, with
 * its OT's name as the holder. */
export function* checkMagikarpLength(
  c: SpecialContext,
  record: MagikarpRecord,
): Gen<number> {
  const slot = yield* c.selectMon();
  if (slot < 0) return MAGIKARP_LENGTH.refused;
  const mon = c.state.party[slot];
  // wCurPartySpecies comes from wPartySpecies, EGG for an Egg.
  if (mon.egg || mon.species !== MAGIKARP) return MAGIKARP_LENGTH.notMagikarp;
  const { feet, inches } = magikarpLength(c.reader, mon.dvs, mon.otId);
  c.strings[RAM.stringBuffer1] = lengthString(feet, inches);
  c.write(JOHTO["CheckMagikarpLength.MagikarpGuruMeasureText"]);
  // CompareBytes over wMagikarpLength and the record: carry when the new
  // length is greater.
  if (feet * 256 + inches <= record.feet * 256 + record.inches)
    return MAGIKARP_LENGTH.tooShort;
  record.feet = feet;
  record.inches = inches;
  record.holder = mon.ot;
  return MAGIKARP_LENGTH.beatRecord;
}

/** MagikarpHouseSign: the record and its holder. */
export function magikarpHouseSign(c: SpecialContext, record: MagikarpRecord) {
  c.strings[RAM.stringBuffer1] = lengthString(record.feet, record.inches);
  c.strings[WRAM.wMagikarpRecordHoldersName] = record.holder;
  c.write(JOHTO["MagikarpHouseSign.KarpGuruRecordText"]);
}