Sessions 5-7a: 955 tests, deployment ready

src/services/processing/LineShoppingEngine.js

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+/**
+ * Line shopping — for each unique prop (game/player/stat), find the best
+ * line per side across books.
+ *
+ * Best Over = lowest line + best odds at that line.
+ * Best Under = highest line + best odds at that line.
+ *
+ * We also flag "outlier" books — a book that's 1+ points off the median.
+ */
+
+function propKey(p) {
+  return `${p.game_id}|${p.player_id ?? p.player_name}|${p.stat_type}`;
+}
+
+function americanToImplied(odds) {
+  if (typeof odds !== 'number' || !Number.isFinite(odds)) return null;
+  return odds > 0 ? 100 / (odds + 100) : -odds / (-odds + 100);
+}
+
+function median(values) {
+  if (!values.length) return null;
+  const sorted = [...values].sort((a, b) => a - b);
+  const mid = Math.floor(sorted.length / 2);
+  return sorted.length % 2 ? sorted[mid] : (sorted[mid - 1] + sorted[mid]) / 2;
+}
+
+function process(props) {
+  const grouped = new Map();
+  for (const p of props || []) {
+    const key = propKey(p);
+    if (!grouped.has(key)) grouped.set(key, []);
+    grouped.get(key).push(p);
+  }
+
+  const out = [];
+  for (const [key, rows] of grouped.entries()) {
+    if (rows.length === 1) {
+      out.push({ ...rows[0], best_over: rows[0], best_under: rows[0], line_outliers: [] });
+      continue;
+    }
+    const lines = rows.map((r) => r.line).filter((n) => typeof n === 'number');
+    const med = median(lines);
+
+    const overs = rows.filter((r) => r.odds_over != null);
+    const unders = rows.filter((r) => r.odds_under != null);
+
+    // Best Over = lowest line, then best (highest implied prob) odds at that line.
+    let bestOver = null;
+    for (const r of overs) {
+      if (!bestOver) { bestOver = r; continue; }
+      if (r.line < bestOver.line) bestOver = r;
+      else if (r.line === bestOver.line) {
+        const a = americanToImplied(r.odds_over);
+        const b = americanToImplied(bestOver.odds_over);
+        if (a != null && b != null && a < b) bestOver = r;
+      }
+    }
+    let bestUnder = null;
+    for (const r of unders) {
+      if (!bestUnder) { bestUnder = r; continue; }
+      if (r.line > bestUnder.line) bestUnder = r;
+      else if (r.line === bestUnder.line) {
+        const a = americanToImplied(r.odds_under);
+        const b = americanToImplied(bestUnder.odds_under);
+        if (a != null && b != null && a < b) bestUnder = r;
+      }
+    }
+
+    const outliers = (med != null)
+      ? rows.filter((r) => Math.abs(r.line - med) >= 1).map((r) => ({ book: r.book, line: r.line, delta: r.line - med }))
+      : [];
+
+    out.push({
+      key,
+      median_line: med,
+      books: rows,
+      best_over: bestOver,
+      best_under: bestUnder,
+      line_outliers: outliers,
+    });
+  }
+  return out;
+}
+
+module.exports = { process, americanToImplied };