import { writeFileSync } from "node:fs";
import players from "../data/players.json" with { type: "json" };

const POSITIONS = ["GK", "DEF", "MID", "WING", "ST"];
const DIFFICULTIES = ["easy", "medium", "hard"];
const positionLabels = {
  GK: "goalkeeper",
  DEF: "defender",
  MID: "midfielder",
  WING: "winger",
  ST: "striker",
};
const START_DATE_KEY = process.env.PUZZLE_START_DATE ?? "2026-05-05";
const DAYS = 365;
const byPosition = POSITIONS.map((position) => players.filter((player) => player.position === position));
const totalCombinations = byPosition.reduce((product, group) => product * group.length, 1);
const permutationA = 1103;
const permutationB = 7919;

const puzzles = [];
for (let day = 0; day < DAYS; day += 1) {
  const dateKey = addDays(START_DATE_KEY, day);
  for (let difficultyIndex = 0; difficultyIndex < DIFFICULTIES.length; difficultyIndex += 1) {
    const ordinal = day * DIFFICULTIES.length + difficultyIndex;
    const index = permuteIndex(ordinal, totalCombinations);
    const lineup = lineupFromIndex(index);
    const difficulty = DIFFICULTIES[difficultyIndex];
    const fixedPosition = POSITIONS[(ordinal + 2) % POSITIONS.length];
    puzzles.push({
      id: `${dateKey}-${difficulty}`,
      date: dateKey,
      difficulty,
      solution: Object.fromEntries(POSITIONS.map((position) => [position, lineup[position].id])),
      fixedPosition,
      clues: buildClues(lineup, difficulty, fixedPosition),
    });
  }
}

writeFileSync(new URL("../data/puzzles.json", import.meta.url), `${JSON.stringify(puzzles, null, 2)}\n`);

function permuteIndex(value, modulo) {
  return (permutationA * value + permutationB) % modulo;
}

function lineupFromIndex(index) {
  const [gks, defs, mids, wings, sts] = byPosition;
  const divisorGk = defs.length * mids.length * wings.length * sts.length;
  const divisorDef = mids.length * wings.length * sts.length;
  const divisorMid = wings.length * sts.length;
  let remaining = index;

  const gkIndex = Math.floor(remaining / divisorGk);
  remaining %= divisorGk;

  const defIndex = Math.floor(remaining / divisorDef);
  remaining %= divisorDef;

  const midIndex = Math.floor(remaining / divisorMid);
  remaining %= divisorMid;

  const wingIndex = Math.floor(remaining / sts.length);
  const stIndex = remaining % sts.length;

  return {
    GK: gks[gkIndex],
    DEF: defs[defIndex],
    MID: mids[midIndex],
    WING: wings[wingIndex],
    ST: sts[stIndex],
  };
}

function buildClues(lineup, difficulty, fixedPosition) {
  const hiddenPositions = POSITIONS.filter((position) => position !== fixedPosition);

  if (difficulty === "easy") {
    return hiddenPositions.flatMap((position) => [
      buildNationalityClue(position, lineup[position]),
      buildCurrentLeagueClue(position, lineup[position]),
    ]);
  }

  if (difficulty === "medium") {
    return dedupeClues([
      ...hiddenPositions.map((position) => buildTitleCountryClue(lineup[position], subjectFor(position))),
      ...buildHiddenPairClues(lineup, hiddenPositions).slice(0, 2),
    ]);
  }

  return dedupeClues([
    ...hiddenPositions.map((position) => buildTitleCountryPairClue(lineup[position], subjectFor(position))),
    ...hiddenPositions.map((position) => buildChampionsLeagueCountClue(lineup[position], subjectFor(position))),
    ...buildHiddenPairClues(lineup, hiddenPositions).slice(0, 3),
  ]);
}

function subjectFor(position) {
  return `The ${positionLabels[position]}`;
}

function buildNationalityClue(position, player) {
  return `${subjectFor(position)} is from ${player.nationality}.`;
}

function buildCurrentLeagueClue(position, player) {
  return `${subjectFor(position)} plays in ${player.league}.`;
}

function buildTitleCountryClue(player, subject) {
  const country = player.leagueTitleCountries?.[0];
  if (country) {
    return `${subject} has won league titles in ${country}.`;
  }
  return `${subject} has won ${player.leagueTitles} league titles.`;
}

function buildChampionsLeagueCountClue(player, subject) {
  return `${subject} has won ${player.championsLeagueTitles} Champions League title${player.championsLeagueTitles === 1 ? "" : "s"}.`;
}

function buildNumericLeagueClue(player, subject) {
  return buildLeagueTitleCountClue(player, subject);
}

function buildFormerClubClue(playerA, playerB, subject) {
  const common = (playerA.formerClubs ?? []).find((club) => (playerB.formerClubs ?? []).includes(club));
  if (common) {
    return `${subject} were once teammates at ${common}.`;
  }
  if ((playerA.championsLeagueTitles ?? 0) === (playerB.championsLeagueTitles ?? 0)) {
    return `${subject} have won the same number of Champions League titles.`;
  }
  if ((playerA.leagueTitles ?? 0) === (playerB.leagueTitles ?? 0)) {
    return `${subject} have won the same number of league titles.`;
  }
  const firstCountry = playerA.leagueTitleCountries?.[0] ?? null;
  if (firstCountry) {
    return `${subject.split(" and ")[0]} has won league titles in ${firstCountry}.`;
  }
  return buildLeagueTitleCountClue(playerA, subject.split(" and ")[0]);
}

function buildHiddenPairClues(lineup, hiddenPositions) {
  const clues = [];
  for (let leftIndex = 0; leftIndex < hiddenPositions.length; leftIndex += 1) {
    for (let rightIndex = leftIndex + 1; rightIndex < hiddenPositions.length; rightIndex += 1) {
      const left = hiddenPositions[leftIndex];
      const right = hiddenPositions[rightIndex];
      clues.push(buildFormerClubClue(lineup[left], lineup[right], `${subjectFor(left)} and ${positionLabels[right]}`));
      clues.push(buildLeagueTitleComparisonClue(left, lineup[left], right, lineup[right]));
      clues.push(buildChampionsLeagueComparisonClue(left, lineup[left], right, lineup[right]));
    }
  }
  return dedupeClues(clues);
}

function buildTitleCountryPairClue(player, subject) {
  const countries = player.leagueTitleCountries ?? [];
  if (countries.length >= 2) {
    return `${subject} has won league titles in ${countries.slice(0, 2).join(" and ")}.`;
  }
  if (countries.length === 1) {
    return `${subject} has won league titles in ${countries[0]}.`;
  }
  return buildLeagueTitleCountClue(player, subject);
}

function buildLeagueTitleCountClue(player, subject) {
  return `${subject} has won ${player.leagueTitles} league title${player.leagueTitles === 1 ? "" : "s"}.`;
}

function buildLeagueTitleComparisonClue(positionA, playerA, positionB, playerB) {
  const subjectA = subjectFor(positionA);
  const subjectB = `the ${positionLabels[positionB]}`;
  if (playerA.leagueTitles > playerB.leagueTitles) {
    return `${subjectA} has more league titles than ${subjectB}.`;
  }
  if (playerB.leagueTitles > playerA.leagueTitles) {
    return `${subjectFor(positionB)} has more league titles than the ${positionLabels[positionA]}.`;
  }
  return `${subjectA} and ${positionLabels[positionB]} have won the same number of league titles.`;
}

function buildChampionsLeagueComparisonClue(positionA, playerA, positionB, playerB) {
  const subjectA = subjectFor(positionA);
  const subjectB = `the ${positionLabels[positionB]}`;
  if (playerA.championsLeagueTitles > playerB.championsLeagueTitles) {
    return `${subjectA} has more Champions League titles than ${subjectB}.`;
  }
  if (playerB.championsLeagueTitles > playerA.championsLeagueTitles) {
    return `${subjectFor(positionB)} has more Champions League titles than the ${positionLabels[positionA]}.`;
  }
  return `${subjectA} and ${positionLabels[positionB]} have won the same number of Champions League titles.`;
}

function dedupeClues(clues) {
  return [...new Set(clues)];
}

function addDays(dateKey, daysToAdd) {
  const date = new Date(`${dateKey}T00:00:00.000Z`);
  date.setUTCDate(date.getUTCDate() + daysToAdd);
  return date.toISOString().slice(0, 10);
}

function getTodayKeyInTimeZone(date, timeZone) {
  const formatter = new Intl.DateTimeFormat("en-CA", {
    timeZone,
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
  });

  const parts = formatter.formatToParts(date);
  const year = parts.find((part) => part.type === "year")?.value;
  const month = parts.find((part) => part.type === "month")?.value;
  const day = parts.find((part) => part.type === "day")?.value;
  return `${year}-${month}-${day}`;
}