import type { PlayerStatsInput } from "@/lib/types";

type StatValue = number | null | undefined;

function stat(value: StatValue) {
  return value ?? 0;
}

function hasValue(value: StatValue) {
  return value !== null && value !== undefined;
}

function formatRate(value: number | null, digits = 3) {
  if (value === null || Number.isNaN(value)) {
    return null;
  }

  return value.toFixed(digits).replace(/^0(?=\.)/, "");
}

function formatDecimal(value: number | null, digits = 2) {
  if (value === null || Number.isNaN(value)) {
    return null;
  }

  return value.toFixed(digits);
}

export function formatInningsPitched(outs: StatValue) {
  const totalOuts = stat(outs);
  if (totalOuts <= 0) {
    return null;
  }

  const wholeInnings = Math.floor(totalOuts / 3);
  const remainder = totalOuts % 3;
  return `${wholeInnings}.${remainder}`;
}

export function hasBattingStats(stats?: PlayerStatsInput | null) {
  if (!stats) return false;

  return [
    stats.atBats,
    stats.runs,
    stats.hits,
    stats.doubles,
    stats.triples,
    stats.homeRuns,
    stats.runsBattedIn,
    stats.walks,
    stats.strikeouts,
    stats.stolenBases
  ].some(hasValue);
}

export function hasPitchingStats(stats?: PlayerStatsInput | null) {
  if (!stats) return false;

  return [
    stats.inningsPitchedOuts,
    stats.earnedRunsAllowed,
    stats.hitsAllowed,
    stats.walksAllowed,
    stats.strikeoutsPitched
  ].some(hasValue);
}

export function getBattingSummary(stats?: PlayerStatsInput | null) {
  if (!hasBattingStats(stats)) {
    return [];
  }

  const atBats = stat(stats?.atBats);
  const hits = stat(stats?.hits);
  const walks = stat(stats?.walks);
  const doubles = stat(stats?.doubles);
  const triples = stat(stats?.triples);
  const homeRuns = stat(stats?.homeRuns);
  const singles = Math.max(hits - doubles - triples - homeRuns, 0);
  const totalBases = singles + doubles * 2 + triples * 3 + homeRuns * 4;

  const average = atBats > 0 ? hits / atBats : null;
  const onBase = atBats + walks > 0 ? (hits + walks) / (atBats + walks) : null;
  const slugging = atBats > 0 ? totalBases / atBats : null;
  const ops = onBase !== null || slugging !== null ? (onBase ?? 0) + (slugging ?? 0) : null;

  return [
    ["AVG", formatRate(average)],
    ["OBP", formatRate(onBase)],
    ["SLG", formatRate(slugging)],
    ["OPS", formatRate(ops)]
  ] as const;
}

export function getPitchingSummary(stats?: PlayerStatsInput | null) {
  if (!hasPitchingStats(stats)) {
    return [];
  }

  const outs = stat(stats?.inningsPitchedOuts);
  const innings = outs / 3;
  const earnedRuns = stat(stats?.earnedRunsAllowed);
  const hitsAllowed = stat(stats?.hitsAllowed);
  const walksAllowed = stat(stats?.walksAllowed);
  const strikeoutsPitched = stat(stats?.strikeoutsPitched);

  const era = outs > 0 ? (earnedRuns * 27) / outs : null;
  const whip = innings > 0 ? (hitsAllowed + walksAllowed) / innings : null;

  return [
    ["IP", formatInningsPitched(outs)],
    ["ERA", formatDecimal(era)],
    ["WHIP", formatDecimal(whip)],
    ["K", strikeoutsPitched > 0 || hasValue(stats?.strikeoutsPitched) ? String(strikeoutsPitched) : null]
  ] as const;
}