feat: add Amazon seller and buy box share metrics to product analysis

- Introduced `amazonIsSeller` and `amazonBuyboxSharePct90d` fields in KeepaData type.
- Updated database schema and queries to store Amazon seller status and buy box share percentage.
- Enhanced product analysis results with new metrics from Keepa API.
- Modified frontend components to display Amazon seller status and buy box share percentage.
- Implemented reanalysis functionality for products to refresh Amazon-related metrics.

src/keepa.ts

@@ -3,6 +3,8 @@ import type { KeepaData } from "./types.ts";
 
 const KEEPA_BASE = "https://api.keepa.com";
 const MAX_ASINS_PER_REQUEST = 100;
+const AMAZON_US_SELLER_ID = "ATVPDKIKX0DER";
+const KEEPA_MINUTES_OFFSET = 21_564_000;
 
 // Token-based rate limiting: Keepa Pro = 1 token/min regeneration.
 // Each product request costs 1 token regardless of ASIN count (up to 100).
@@ -44,7 +46,7 @@ export async function fetchKeepaDataBatch(
     await waitForToken();
 
     const asinParam = chunk.join(",");
-    const url = `${KEEPA_BASE}/product?key=${config.keepaApiKey}&domain=1&asin=${asinParam}&stats=90`;
+    const url = `${KEEPA_BASE}/product?key=${config.keepaApiKey}&domain=1&asin=${asinParam}&stats=90&buybox=1&days=90`;
 
     console.log(
       `Keepa: fetching ${chunk.length} ASINs (tokens left: ${tokensLeft})...`,
@@ -97,6 +99,14 @@ function parseKeepaProduct(product: Record<string, any>): KeepaData {
   const monthlySold =
     pickKeepaNumber(product.monthlySold, stats?.monthlySold) ??
     salesRankDrops30;
+  const amazonIsSeller = resolveAmazonIsSeller(product, stats, csv);
+  const amazonBuyboxSharePct90d =
+    extractAmazonBuyboxSharePct90d(product, stats) ??
+    computeAmazonBuyBoxSharePctFromHistory(
+      product.buyBoxSellerIdHistory,
+      90,
+      new Set([AMAZON_US_SELLER_ID]),
+    );
 
   return {
     currentPrice: extractCurrentPrice(csv),
@@ -108,6 +118,8 @@ function parseKeepaProduct(product: Record<string, any>): KeepaData {
     salesRankDrops30,
     salesRankDrops90,
     sellerCount: stats?.current?.[11] ?? null,
+    amazonIsSeller,
+    amazonBuyboxSharePct90d,
     buyBoxSeller: product.buyBoxSellerId ?? null,
     buyBoxPrice: stats?.current?.[18] != null ? stats.current[18] / 100 : null,
     monthlySold,
@@ -116,6 +128,111 @@ function parseKeepaProduct(product: Record<string, any>): KeepaData {
   };
 }
 
+function resolveAmazonIsSeller(
+  product: Record<string, any>,
+  stats: Record<string, any> | undefined,
+  csv: number[][] | undefined,
+): boolean | null {
+  if (typeof product.isAmazonSeller === "boolean") {
+    return product.isAmazonSeller;
+  }
+
+  if (typeof product.availabilityAmazon === "number") {
+    if (product.availabilityAmazon >= 0) return true;
+    if (
+      product.availabilityAmazon === -1 ||
+      product.availabilityAmazon === -2
+    ) {
+      return false;
+    }
+  }
+
+  if (stats?.buyBoxIsAmazon === true) {
+    return true;
+  }
+
+  if (typeof stats?.current?.[0] === "number") {
+    if (stats.current[0] > 0) return true;
+    if (stats.current[0] === -1 || stats.current[0] === -2) return false;
+  }
+
+  const latestAmazonPrice = extractLatestPositivePrice(csv?.[0]);
+  if (latestAmazonPrice != null) return true;
+
+  return null;
+}
+
+function extractAmazonBuyboxSharePct90d(
+  product: Record<string, any>,
+  stats: Record<string, any> | undefined,
+): number | null {
+  const candidates: unknown[] = [
+    product.buyBoxStatsAmazon90,
+    stats?.buyBoxStatsAmazon90,
+    product.buyBoxStats?.amazon90,
+    product.buyBoxStats?.amazon?.[90],
+    product.buyBoxStats?.amazon?.["90"],
+    product.buyBoxStats?.[AMAZON_US_SELLER_ID]?.[90],
+    product.buyBoxStats?.[AMAZON_US_SELLER_ID]?.["90"],
+  ];
+
+  for (const value of candidates) {
+    if (typeof value !== "number" || !Number.isFinite(value)) continue;
+    if (value < 0 || value > 100) continue;
+    return Math.round(value * 100) / 100;
+  }
+
+  return null;
+}
+
+function computeAmazonBuyBoxSharePctFromHistory(
+  history: unknown,
+  windowDays: number,
+  amazonSellerIds: Set<string>,
+): number | null {
+  if (!Array.isArray(history) || history.length < 2) return null;
+
+  const nowKeepaMinutes =
+    Math.floor(Date.now() / 60_000) - KEEPA_MINUTES_OFFSET;
+  const windowStart = nowKeepaMinutes - windowDays * 24 * 60;
+  let qualifiedMinutes = 0;
+  let amazonMinutes = 0;
+
+  for (let i = 0; i < history.length - 1; i += 2) {
+    const startMinute = Number.parseInt(String(history[i]), 10);
+    const sellerId = String(history[i + 1] ?? "").toUpperCase();
+    const nextRaw = i + 2 < history.length ? history[i + 2] : nowKeepaMinutes;
+    const endMinute = Number.parseInt(String(nextRaw), 10);
+
+    if (!Number.isFinite(startMinute) || !Number.isFinite(endMinute)) continue;
+    if (endMinute <= startMinute) continue;
+
+    const intervalStart = Math.max(startMinute, windowStart);
+    const intervalEnd = Math.min(endMinute, nowKeepaMinutes);
+    if (intervalEnd <= intervalStart) continue;
+
+    if (sellerId === "-1" || sellerId === "-2") continue;
+
+    const minutes = intervalEnd - intervalStart;
+    qualifiedMinutes += minutes;
+    if (amazonSellerIds.has(sellerId)) {
+      amazonMinutes += minutes;
+    }
+  }
+
+  if (qualifiedMinutes === 0) return null;
+  return Math.round((amazonMinutes / qualifiedMinutes) * 10_000) / 100;
+}
+
+function extractLatestPositivePrice(series: unknown): number | null {
+  if (!Array.isArray(series) || series.length < 2) return null;
+  const last = series[series.length - 1];
+  if (typeof last !== "number" || !Number.isFinite(last) || last <= 0) {
+    return null;
+  }
+  return last / 100;
+}
+
 function pickKeepaNumber(...values: unknown[]): number | null {
   for (const value of values) {
     if (typeof value !== "number" || !Number.isFinite(value)) continue;