import { effectiveCooldownSeconds } from './timeline.ts';
import { passiveScoreSupportAt } from './passive-support.ts';
import type {
  CooldownReduction,
  ExactScoreOptions,
  ExactScoreResult,
  ExactSongChart,
  OptimizerCard
} from './types.ts';

type ActiveCandidate = {
  memberIndex: number;
  probability: number;
  boost: number;
};

// QUEEN 및 Our Promise Expert의 인게임 실측값으로 보정한 전역 환산 상수다.
export const CHART_SCORE_WEIGHT_COEFFICIENT = 0.3713416563352296;

export function scoreRatioFromNotes(notes: ExactSongChart['notes']): number {
  let weight = 0;

  for (const note of notes) {
    if (note.type === 'mid') {
      weight += 0.1;
      continue;
    }
    weight += note.isFlick ? 1.05 : 1;
  }

  return weight * CHART_SCORE_WEIGHT_COEFFICIENT;
}

function comboBonus(combo: number): number {
  if (combo >= 1_000) return 0.1;
  if (combo >= 100) return Math.floor(combo / 100) * 0.01;
  return 0;
}

function activeAttempt(card: OptimizerCard, reduction: CooldownReduction, timeSeconds: number): number {
  const interval = effectiveCooldownSeconds(card.active.cooldownSeconds, reduction);
  return Math.floor((timeSeconds + 1e-9) / interval);
}

function specialIsActive(
  card: OptimizerCard,
  startSeconds: number | null | undefined,
  timeSeconds: number
): boolean {
  return startSeconds !== null && startSeconds !== undefined &&
    startSeconds <= timeSeconds && timeSeconds < startSeconds + card.special.durationSeconds;
}

function specialSupportAt(
  cardsInOrder: readonly OptimizerCard[],
  chart: ExactSongChart,
  timeSeconds: number
): number {
  return cardsInOrder.reduce((sum, card, slot) =>
    sum + (specialIsActive(card, chart.specialStartSeconds[slot], timeSeconds) ? card.special.scoreUpPercent : 0), 0);
}

function activationRateBonusAt(
  cardsInOrder: readonly OptimizerCard[],
  chart: ExactSongChart,
  timeSeconds: number
): number {
  return cardsInOrder.reduce((sum, card, slot) =>
    sum + (specialIsActive(card, chart.specialStartSeconds[slot], timeSeconds)
      ? card.special.activationRateUpPercent ?? 0
      : 0), 0);
}

function activeCandidates(
  cardsInOrder: readonly OptimizerCard[],
  reductions: Readonly<Record<string, CooldownReduction>>,
  chart: ExactSongChart,
  timeSeconds: number
): ActiveCandidate[] {
  const specialSupport = specialSupportAt(cardsInOrder, chart, timeSeconds);
  const candidates = cardsInOrder.flatMap((card, memberIndex) => {
    const reduction = reductions[card.id] ?? 0;
    const attempt = activeAttempt(card, reduction, timeSeconds);
    if (attempt <= 0) return [];
    const interval = effectiveCooldownSeconds(card.active.cooldownSeconds, reduction);
    const activationTime = attempt * interval;
    if (timeSeconds >= activationTime + card.active.durationSeconds) return [];
    const activationRateBonus = activationRateBonusAt(cardsInOrder, chart, activationTime);
    const probability = Math.min(1, ((card.active.probabilityPercent ?? 100) / 100) * (1 + activationRateBonus / 100));
    const support = specialSupport + (card.scoreSupportPercent ?? 0) + passiveScoreSupportAt(cardsInOrder, memberIndex);
    return [{
      memberIndex,
      probability,
      boost: card.active.scoreUpPercent / 100 * (1 + support / 100)
    }];
  });
  return candidates.sort((left, right) => right.boost - left.boost || left.memberIndex - right.memberIndex);
}

function expectedStrongestBoost(candidates: readonly ActiveCandidate[]): number {
  let expectedBoost = 0;
  let previousFailed = 1;
  for (const candidate of candidates) {
    expectedBoost += previousFailed * candidate.probability * candidate.boost;
    previousFailed *= 1 - candidate.probability;
  }
  return expectedBoost;
}

function finalNoteScore(score: number, percent: number): number {
  const scaled = score * (1 + percent / 100);
  return Math.ceil(scaled - Number.EPSILON * Math.max(1, scaled) * 4);
}

export function perfectNoteScoreFromPower(overallPower: number, scoreRatio: number | null, fallback = 600): number {
  if (overallPower > 0 && scoreRatio !== null && scoreRatio > 0) {
    return Math.max(1, overallPower / scoreRatio);
  }
  return fallback;
}

export function calculateExactScore(
  cardsInOrder: readonly OptimizerCard[],
  reductions: Readonly<Record<string, CooldownReduction>>,
  chart: ExactSongChart,
  options: ExactScoreOptions
): ExactScoreResult {
  const directBonus = options.directSongScoreBonusPercent ?? 0;
  const scoreNotes = chart.notes;
  const notePoints = scoreNotes.map((note, index) => {
    const combo = index + 1;
    const baseNoteScore = note.type === 'mid'
      ? Math.ceil(options.perfectNoteScore * 0.1)
      : options.perfectNoteScore * (note.isFlick ? 1.05 : 1);
    const rawBaselineScore = baseNoteScore * (1 + comboBonus(combo));
    const candidates = activeCandidates(cardsInOrder, reductions, chart, note.timeSeconds);
    const baselineScore = finalNoteScore(rawBaselineScore, directBonus);
    const expectedScore = finalNoteScore(rawBaselineScore * (1 + expectedStrongestBoost(candidates)), directBonus);
    const theoreticalMaxScore = finalNoteScore(rawBaselineScore * (1 + (candidates[0]?.boost ?? 0)), directBonus);
    return { timeSeconds: note.timeSeconds, combo, expectedScore, theoreticalMaxScore, baselineScore };
  });

  const rawExpected = notePoints.reduce((sum, note) => sum + note.expectedScore, 0);
  const rawMaximum = notePoints.reduce((sum, note) => sum + note.theoreticalMaxScore, 0);
  const rawBaseline = notePoints.reduce((sum, note) => sum + note.baselineScore, 0);
  const scoreBySecond = Array.from({ length: Math.ceil(chart.durationSeconds) }, () => 0);
  notePoints.forEach((note) => {
    const second = Math.floor(note.timeSeconds);
    if (second >= 0 && second < scoreBySecond.length) scoreBySecond[second] += note.expectedScore;
  });

  return {
    expectedScore: rawExpected,
    theoreticalMaxScore: rawMaximum,
    baselineScore: rawBaseline,
    perfectNoteScore: options.perfectNoteScore,
    scoreBySecond,
    notes: notePoints
  };
}