const HITTING_STATS = [
  'hits', 'total_bases', 'home_runs', 'rbis', 'runs_scored',
  'strikeouts_batter', 'walks', 'stolen_bases',
];

const PITCHING_STATS = [
  'strikeouts', 'earned_runs', 'outs_recorded', 'walks_allowed',
  'hits_allowed', 'pitches_thrown',
];

const ALL_MLB_STATS = [...HITTING_STATS, ...PITCHING_STATS];

function isMlbStatType(statType) {
  return ALL_MLB_STATS.includes(statType);
}

function calculateMlbEdge(playerAvg, line, direction) {
  if (playerAvg == null || line == null) return 0;
  if (direction === 'over') {
    return ((playerAvg - line) / line) * 100;
  }
  // under
  return ((line - playerAvg) / line) * 100;
}

function gradeMlbProp({ player, stat_type, line, direction, seasonAvg, recentAvg, killConditions = [] }) {
  if (!isMlbStatType(stat_type)) {
    return { grade: 'D', confidence: 30, edge_pct: 0, composite: 0 };
  }

  const seasonEdge = calculateMlbEdge(seasonAvg, line, direction);
  const recentEdge = calculateMlbEdge(recentAvg, line, direction);

  // Weighted composite: 60% season, 40% recent
  const edge_pct = Math.round((seasonEdge * 0.6 + recentEdge * 0.4) * 100) / 100;

  // Grade thresholds based on edge
  let grade;
  if (edge_pct >= 5) {
    grade = 'A';
  } else if (edge_pct >= 3) {
    grade = 'B';
  } else if (edge_pct >= 1) {
    grade = 'C';
  } else {
    grade = 'D';
  }

  // Confidence based on edge magnitude
  let confidence;
  if (grade === 'A') {
    confidence = Math.min(95, 80 + Math.floor(edge_pct));
  } else if (grade === 'B') {
    confidence = Math.min(79, 65 + Math.floor(edge_pct));
  } else if (grade === 'C') {
    confidence = Math.min(64, 50 + Math.floor(edge_pct * 2));
  } else {
    confidence = Math.max(30, 45 + Math.floor(edge_pct));
  }

  // Kill condition penalty: cap at C and reduce confidence by 15 per condition
  if (killConditions.length > 0) {
    if (grade === 'A' || grade === 'B') {
      grade = 'C';
    }
    confidence -= killConditions.length * 15;
  }

  confidence = Math.max(30, Math.min(95, confidence));

  const composite = Math.round(edge_pct * 100) / 100;

  return { grade, confidence, edge_pct, composite };
}

module.exports = { gradeMlbProp, calculateMlbEdge, isMlbStatType, HITTING_STATS, PITCHING_STATS, ALL_MLB_STATS };