feat: implement SQLite persistent storage for analysis results

- Implemented database initialization and connection management in `database.ts` using Bun's SQLite.
- Created `runs` and `results` tables to track historical analysis metadata and detailed product performance.
- Updated `writer.ts` to persist analysis results to the database within a transaction, replacing the previous CSV output logic.
- Updated README and `.gitignore` to reflect the new persistent storage capability.

src/writer.ts

@@ -1,4 +1,4 @@
-import * as XLSX from "xlsx";
+import { getDb } from "./database.ts";
 import type { AnalysisResult } from "./types.ts";
 
 function buildRow(r: AnalysisResult) {
@@ -7,6 +7,12 @@ function buildRow(r: AnalysisResult) {
     r.product.record.sellingPriceFromSheet ??
     r.product.spApi.estimatedSalePrice;
   const rank = r.product.keepa?.salesRank ?? r.product.record.amazonRank;
+  const canSellStatus =
+    r.product.spApi.canSell == null
+      ? "unknown"
+      : r.product.spApi.canSell
+        ? "yes"
+        : "no";
 
   return {
     ASIN: r.product.record.asin,
@@ -44,12 +50,7 @@ function buildRow(r: AnalysisResult) {
     "FBA Fee": r.product.spApi.fbaFee,
     "FBM Fee": r.product.spApi.fbmFee,
     "Referral %": r.product.spApi.referralFeePercent,
-    "Can Sell":
-      r.product.spApi.canSell == null
-        ? "unknown"
-        : r.product.spApi.canSell
-          ? "yes"
-          : "no",
+    "Can Sell": canSellStatus,
     Sellability: r.product.spApi.sellabilityStatus,
     "Sellability Reason": r.product.spApi.sellabilityReason ?? "",
     Verdict: r.verdict.verdict,
@@ -58,6 +59,113 @@ function buildRow(r: AnalysisResult) {
   };
 }
 
+export function writeResultsToDb(
+  results: AnalysisResult[],
+  dbPath: string,
+  inputFile: string,
+  outputFile: string | undefined,
+): void {
+  const database = getDb(dbPath);
+
+  const timestamp = new Date().toISOString();
+  const fbaCount = results.filter((r) => r.verdict.verdict === "FBA").length;
+  const fbmCount = results.filter((r) => r.verdict.verdict === "FBM").length;
+  const skipCount = results.filter((r) => r.verdict.verdict === "SKIP").length;
+
+  const insertRun = database.prepare(
+    `INSERT INTO runs (
+      timestamp,
+      input_file,
+      output_file,
+      total_products,
+      fba_count,
+      fbm_count,
+      skip_count
+    ) VALUES (?, ?, ?, ?, ?, ?, ?)`,
+  );
+  const runInfo = insertRun.run(
+    timestamp,
+    inputFile,
+    outputFile ?? null,
+    results.length,
+    fbaCount,
+    fbmCount,
+    skipCount,
+  );
+  const runId =
+    (runInfo.changes as number) > 0
+      ? (runInfo.lastInsertRowid as number)
+      : null;
+
+  if (runId === null) {
+    console.error("Failed to insert run record into SQLite.");
+    return;
+  }
+
+  const insertResult = database.prepare(
+    `INSERT INTO results (
+      run_id, asin, product_name, brand, category, unit_cost, current_price,
+      avg_price_90d, avg_price_90d_sheet, selling_price_sheet, sales_rank, rank_avg_90d,
+      sellers, monthly_sold, rank_drops_30d, rank_drops_90d, fba_net_sheet,
+      gross_profit_dollar, gross_profit_pct, net_profit_sheet, roi_sheet, moq, moq_cost,
+      qty_available, supplier, source_url, asin_link, promo_coupon_code, notes, lead_date,
+      fba_fee, fbm_fee, referral_percent, can_sell, sellability_status, sellability_reason,
+      verdict, confidence, reasoning, fetched_at
+    ) VALUES (
+      ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?,
+      ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?
+    )`,
+  );
+
+  database.transaction(() => {
+    for (const r of results) {
+      const row = buildRow(r);
+      insertResult.run(
+        runId,
+        row.ASIN,
+        row.Name,
+        row.Brand,
+        row.Category,
+        row["Unit Cost"] ?? null,
+        row["Current Price"] ?? null,
+        row["Avg Price 90d"] ?? null,
+        row["Avg Price 90d (sheet)"] ?? null,
+        row["Selling Price (sheet)"] ?? null,
+        row["Sales Rank"] ?? null,
+        row["Rank Avg 90d"] ?? null,
+        row.Sellers ?? null,
+        row["Monthly Sold"] ?? null,
+        row["Rank Drops 30d"] ?? null,
+        row["Rank Drops 90d"] ?? null,
+        row["FBA Net (sheet)"] ?? null,
+        row["Gross Profit $"] ?? null,
+        row["Gross Profit %"] ?? null,
+        row["Net Profit (sheet)"] ?? null,
+        row["ROI (sheet)"] ?? null,
+        row.MOQ ?? null,
+        row["MOQ Cost"] ?? null,
+        row["Qty Available"] ?? null,
+        row.Supplier ?? null,
+        row["Source URL"] ?? null,
+        row["ASIN Link"] ?? null,
+        row["Promo/Coupon Code"] ?? null,
+        row.Notes ?? null,
+        row["Lead Date"] ?? null,
+        row["FBA Fee"] ?? null,
+        row["FBM Fee"] ?? null,
+        row["Referral %"] ?? null,
+        row["Can Sell"],
+        row.Sellability,
+        row["Sellability Reason"] ?? null,
+        row.Verdict,
+        row.Confidence ?? null,
+        row.Reasoning,
+        r.product.fetchedAt,
+      );
+    }
+  })();
+  console.log(`Results written to SQLite database for run_id: ${runId}`);
+}
 export function printResults(results: AnalysisResult[]): void {
   const rows = results
     .filter((r) => r.verdict.verdict === "FBA" || r.verdict.verdict === "FBM")
@@ -144,16 +252,3 @@ export function printResults(results: AnalysisResult[]): void {
     `Sellability: ${summary.Available} available | ${summary.Restricted} restricted | ${summary.NotAvailable} not_available | ${summary.Unknown} unknown\n`,
   );
 }
-
-export function writeResultsCsv(
-  results: AnalysisResult[],
-  outputPath: string,
-): void {
-  const rows = results.map(buildRow);
-
-  const ws = XLSX.utils.json_to_sheet(rows);
-  const wb = XLSX.utils.book_new();
-  XLSX.utils.book_append_sheet(wb, ws, "Results");
-  XLSX.writeFile(wb, outputPath);
-  console.log(`Results written to ${outputPath}`);
-}