import { Score, Team, TeamResult, Criterion, CriterionStats } from '../shared/types.js';

/**
 * Calculate the aggregated result for a single team.
 *
 * - total = sum of all score.value where score.teamId matches
 * - jurorCount = count of distinct jurorIds that have submitted ALL criteria (criteriaCount scores)
 * - average = total / jurorCount (or 0 if jurorCount is 0)
 * - stddev = standard deviation of per-juror totals
 * - complete = jurorCount equals total number of jurors who have at least one score for this team
 *             AND all have all criteria
 */
export function calculateTeamResult(
  teamId: string,
  teamName: string,
  scores: Score[],
  criteriaCount: number,
  criteria?: Criterion[]
): TeamResult {
  const teamScores = scores.filter((s) => s.teamId === teamId);
  const total = teamScores.reduce((sum, s) => sum + s.value, 0);

  // Group scores by jurorId
  const scoresByJuror = new Map<string, Score[]>();
  for (const score of teamScores) {
    const existing = scoresByJuror.get(score.jurorId) || [];
    existing.push(score);
    scoresByJuror.set(score.jurorId, existing);
  }

  // Count jurors who have submitted ALL criteria
  const jurorCount = Array.from(scoresByJuror.values()).filter(
    (jurorScores) => jurorScores.length >= criteriaCount
  ).length;

  const average = jurorCount > 0 ? total / jurorCount : 0;

  // Calculate stddev of per-juror totals
  const jurorTotals = Array.from(scoresByJuror.values())
    .filter((jurorScores) => jurorScores.length >= criteriaCount)
    .map((jurorScores) => jurorScores.reduce((sum, s) => sum + s.value, 0));

  let stddev = 0;
  if (jurorTotals.length > 1) {
    const mean = jurorTotals.reduce((a, b) => a + b, 0) / jurorTotals.length;
    const variance = jurorTotals.reduce((sum, v) => sum + (v - mean) ** 2, 0) / jurorTotals.length;
    stddev = Math.sqrt(variance);
  }

  // Complete = all jurors who have at least one score have submitted all criteria
  const totalJurorsWithScores = scoresByJuror.size;
  const complete = totalJurorsWithScores > 0 && jurorCount === totalJurorsWithScores;

  // Per-criterion stats
  let criteriaStats: CriterionStats[] | undefined;
  if (criteria) {
    criteriaStats = criteria.map((criterion) => {
      const criterionScores = teamScores
        .filter((s) => s.criterionId === criterion.id)
        .map((s) => s.value);
      const cMean = criterionScores.length > 0
        ? criterionScores.reduce((a, b) => a + b, 0) / criterionScores.length
        : 0;
      let cStddev = 0;
      if (criterionScores.length > 1) {
        const cVariance = criterionScores.reduce((sum, v) => sum + (v - cMean) ** 2, 0) / criterionScores.length;
        cStddev = Math.sqrt(cVariance);
      }
      return {
        criterionId: criterion.id,
        criterionName: criterion.nameDE,
        mean: cMean,
        stddev: cStddev,
        scores: criterionScores,
      };
    });
  }

  return {
    teamId,
    teamName,
    total,
    average,
    stddev,
    rank: 0, // Will be assigned by calculateRankings
    jurorCount,
    complete,
    criteriaStats,
  };
}

/**
 * Sort team results by total descending and assign dense ranking.
 * Ties get the same rank.
 * Example: totals [250, 240, 240, 230] → ranks [1, 2, 2, 4]
 */
export function calculateRankings(teamResults: TeamResult[]): TeamResult[] {
  // Sort by total descending
  const sorted = [...teamResults].sort((a, b) => b.total - a.total);

  // Assign dense ranking with ties
  let currentRank = 1;
  for (let i = 0; i < sorted.length; i++) {
    if (i > 0 && sorted[i].total < sorted[i - 1].total) {
      currentRank = i + 1;
    }
    sorted[i] = { ...sorted[i], rank: currentRank };
  }

  return sorted;
}

/**
 * Get the completion status for a specific juror-team pair.
 *
 * - 0 scores → 'pending'
 * - 1 to criteriaCount-1 → 'partial'
 * - criteriaCount → 'complete'
 */
export function getCompletionStatus(
  jurorId: string,
  teamId: string,
  scores: Score[],
  criteriaCount: number
): 'complete' | 'partial' | 'pending' {
  const count = scores.filter(
    (s) => s.jurorId === jurorId && s.teamId === teamId
  ).length;

  if (count === 0) return 'pending';
  if (count >= criteriaCount) return 'complete';
  return 'partial';
}

/**
 * Calculate results for all teams and apply rankings.
 * Convenience function combining calculateTeamResult + calculateRankings.
 */
export function calculateAllResults(
  scores: Score[],
  teams: Team[],
  criteriaCount: number,
  criteria?: Criterion[]
): TeamResult[] {
  const teamResults = teams.map((team) =>
    calculateTeamResult(team.id, team.name, scores, criteriaCount, criteria)
  );
  return calculateRankings(teamResults);
}