import {
  GROUP_IDS, GroupId, Match, Team,
  StandingRow, GroupTable, ThirdPlaceRow,
} from "./types";

// Berechnet eine leere Tabellenzeile.
function emptyRow(teamId: string): StandingRow {
  return {
    teamId, played: 0, won: 0, drawn: 0, lost: 0,
    goalsFor: 0, goalsAgainst: 0, goalDiff: 0, points: 0, rank: 0,
  };
}

// Trägt ein abgeschlossenes Spiel in zwei Tabellenzeilen ein.
function applyMatch(rows: Map<string, StandingRow>, m: Match) {
  if (m.status !== "FINISHED") return;
  if (m.homeTeamId == null || m.awayTeamId == null) return;
  if (m.homeScore == null || m.awayScore == null) return;
  const h = rows.get(m.homeTeamId);
  const a = rows.get(m.awayTeamId);
  if (!h || !a) return;
  h.played++; a.played++;
  h.goalsFor += m.homeScore; h.goalsAgainst += m.awayScore;
  a.goalsFor += m.awayScore; a.goalsAgainst += m.homeScore;
  if (m.homeScore > m.awayScore) { h.won++; a.lost++; h.points += 3; }
  else if (m.homeScore < m.awayScore) { a.won++; h.lost++; a.points += 3; }
  else { h.drawn++; a.drawn++; h.points += 1; a.points += 1; }
}

function finalizeRow(r: StandingRow) {
  r.goalDiff = r.goalsFor - r.goalsAgainst;
}

// Vergleicht zwei Teams nach FIFA-Kriterien innerhalb derselben Gruppe.
// Reihenfolge: Punkte, dann Direktvergleich (Punkte/TD/Tore in den Spielen
// der punktgleichen Teams), dann Gesamt-TD, Gesamt-Tore. Fair-Play/Ranking
// werden hier nicht abgebildet (kein Feed dafür) -> bleibt bei Gleichstand stabil.
function compareInGroup(
  a: StandingRow, b: StandingRow,
  matches: Match[], tiedIds: Set<string>,
): number {
  if (b.points !== a.points) return b.points - a.points;

  // Direktvergleich nur unter den punktgleichen Teams
  if (tiedIds.size >= 2 && tiedIds.has(a.teamId) && tiedIds.has(b.teamId)) {
    const mini = miniTable(matches, tiedIds);
    const ma = mini.get(a.teamId);
    const mb = mini.get(b.teamId);
    if (ma && mb) {
      if (mb.points !== ma.points) return mb.points - ma.points;
      const mdA = ma.goalsFor - ma.goalsAgainst;
      const mdB = mb.goalsFor - mb.goalsAgainst;
      if (mdB !== mdA) return mdB - mdA;
      if (mb.goalsFor !== ma.goalsFor) return mb.goalsFor - ma.goalsFor;
    }
  }

  if (b.goalDiff !== a.goalDiff) return b.goalDiff - a.goalDiff;
  if (b.goalsFor !== a.goalsFor) return b.goalsFor - a.goalsFor;
  return 0;
}

// Baut eine Minitabelle aus den Spielen, in denen NUR die tiedIds gegeneinander spielten.
function miniTable(matches: Match[], tiedIds: Set<string>): Map<string, StandingRow> {
  const rows = new Map<string, StandingRow>();
  tiedIds.forEach((id) => rows.set(id, emptyRow(id)));
  for (const m of matches) {
    if (m.status !== "FINISHED") continue;
    if (m.homeTeamId == null || m.awayTeamId == null) continue;
    if (!tiedIds.has(m.homeTeamId) || !tiedIds.has(m.awayTeamId)) continue;
    applyMatch(rows, m);
  }
  rows.forEach(finalizeRow);
  return rows;
}

// Berechnet alle 12 Gruppentabellen aus Teams + Spielen.
export function computeGroupTables(teams: Team[], matches: Match[]): GroupTable[] {
  const tables: GroupTable[] = [];
  for (const g of GROUP_IDS) {
    const groupTeams = teams.filter((t) => t.group === g);
    const rows = new Map<string, StandingRow>();
    groupTeams.forEach((t) => rows.set(t.id, emptyRow(t.id)));
    const groupMatches = matches.filter((m) => m.group === g);
    for (const m of groupMatches) applyMatch(rows, m);
    rows.forEach(finalizeRow);

    const arr = [...rows.values()];
    // Gruppen punktgleicher Teams für den Direktvergleich bestimmen
    const byPoints = new Map<number, string[]>();
    arr.forEach((r) => {
      const list = byPoints.get(r.points) ?? [];
      list.push(r.teamId);
      byPoints.set(r.points, list);
    });

    arr.sort((a, b) => {
      const tied = byPoints.get(a.points) ?? [];
      const tiedIds = new Set(a.points === b.points && tied.length >= 2 ? tied : []);
      return compareInGroup(a, b, groupMatches, tiedIds);
    });
    arr.forEach((r, i) => (r.rank = i + 1));
    tables.push({ group: g, rows: arr });
  }
  return tables;
}

// Rankt die 12 Gruppendritten gruppenübergreifend (ohne Direktvergleich).
// Kriterien: Punkte, TD, Tore. Beste 8 -> qualifies = true.
export function computeThirdPlaceTable(tables: GroupTable[]): ThirdPlaceRow[] {
  const thirds: ThirdPlaceRow[] = tables
    .map((t) => {
      const r = t.rows.find((x) => x.rank === 3);
      if (!r) return null;
      return { ...r, group: t.group, qualifies: false, overallRank: 0 };
    })
    .filter((x): x is ThirdPlaceRow => x !== null);

  thirds.sort((a, b) => {
    if (b.points !== a.points) return b.points - a.points;
    if (b.goalDiff !== a.goalDiff) return b.goalDiff - a.goalDiff;
    if (b.goalsFor !== a.goalsFor) return b.goalsFor - a.goalsFor;
    return a.group.localeCompare(b.group); // stabil
  });

  thirds.forEach((r, i) => {
    r.overallRank = i + 1;
    r.qualifies = i < 8;
  });
  return thirds;
}