import type { CellResult, ScoreInput, ScoringMode } from "./types";

/**
 * SCORING.md §1: the value of one team × criterion cell.
 * `cellScores` are all score rows for that cell; `activeJudgeIds` are the game's non-revoked judges.
 */
export function computeCell(
  mode: ScoringMode,
  cellScores: ScoreInput[],
  activeJudgeIds: ReadonlySet<string>,
): CellResult {
  const adminRow = cellScores.find((score) => score.judgeId === null);

  if (mode === "direct") {
    // Judge rows are ignored in direct games (e.g. left over from a mode switch).
    return adminRow
      ? { value: adminRow.value, source: "admin", judgeAverage: null, judgeCount: 0 }
      : { value: null, source: "none", judgeAverage: null, judgeCount: 0 };
  }

  // Missing judges are ignored, not counted as zero.
  const judgeValues = cellScores
    .filter((score) => score.judgeId !== null && activeJudgeIds.has(score.judgeId))
    .map((score) => score.value);
  const judgeCount = judgeValues.length;
  const judgeAverage =
    judgeCount > 0 ? judgeValues.reduce((sum, value) => sum + value, 0) / judgeCount : null;

  if (adminRow) {
    return { value: adminRow.value, source: "override", judgeAverage, judgeCount };
  }
  return {
    value: judgeAverage,
    source: judgeAverage === null ? "none" : "judges",
    judgeAverage,
    judgeCount,
  };
}