feat(analysis): rolling 12-month table with external API fallback

- monthly-last endpoint now returns last 12 months (rolling)
- For months without DB data, fetches from ArgentinaDatos API
- Casa mapping: BELO=cripto, BLUE=blue, BNA=oficial
- DB data takes priority over external API data

apps/backend/src/modules/quotes/handlers/getMonthlyLast.ts

@@ -2,12 +2,56 @@ import type { Context } from "hono";
 import { cache } from "../../../lib/cache";
 import { prisma } from "../../../lib/prisma";
 
+type MonthlyLastRow = {
+  month: string;
+  type: string;
+  buy: number;
+};
+
+type ExternalQuote = {
+  casa: string;
+  fecha: string;
+  compra: number;
+  venta: number;
+};
+
+const CASA_MAP: Record<string, string> = {
+  BELO: "cripto",
+  BLUE: "blue",
+  BNA: "oficial",
+};
+
+const TYPES = ["BELO", "BLUE", "BNA"] as const;
+
+function getMonthKey(date: Date): string {
+  const y = date.getFullYear();
+  const m = String(date.getMonth() + 1).padStart(2, "0");
+  return `${y}-${m}`;
+}
+
+function subtractMonths(date: Date, months: number): Date {
+  const result = new Date(date);
+  result.setMonth(result.getMonth() - months);
+  return result;
+}
+
 export async function getMonthlyLast(c: Context) {
-  const cacheKey = "quotes:monthly-last";
+  const cacheKey = "quotes:monthly-last-v2";
   const cached = cache.get(cacheKey);
   if (cached) return c.json(cached);
 
-  const rows = await prisma.$queryRaw<
+  const today = new Date();
+  const currentMonthKey = getMonthKey(today);
+  const startMonth = subtractMonths(today, 11);
+
+  const startDate = new Date(
+    startMonth.getFullYear(),
+    startMonth.getMonth(),
+    1,
+  );
+  const endDate = new Date(today.getFullYear(), today.getMonth() + 1, 1);
+
+  const dbRows = await prisma.$queryRaw<
     Array<{
       month: string;
       type: string;
@@ -19,10 +63,106 @@ export async function getMonthlyLast(c: Context) {
       "type"::text,
       (ARRAY_AGG(buy ORDER BY "timeStamp" DESC))[1]::numeric::float8 AS buy
     FROM "quotes_history"
+    WHERE "timeStamp" >= ${startDate}::timestamptz
+      AND "timeStamp" < ${endDate}::timestamptz
     GROUP BY DATE_TRUNC('month', "timeStamp"), "type"
     ORDER BY month ASC
   `;
 
-  cache.set(cacheKey, rows, 300);
-  return c.json(rows);
+  const dbMap = new Map<string, Map<string, number>>();
+  for (const row of dbRows) {
+    if (!dbMap.has(row.month)) dbMap.set(row.month, new Map());
+    dbMap.get(row.month)?.set(row.type, row.buy);
+  }
+
+  const expectedMonths: string[] = [];
+  let cursor = new Date(startMonth.getFullYear(), startMonth.getMonth(), 1);
+  while (getMonthKey(cursor) <= currentMonthKey) {
+    expectedMonths.push(getMonthKey(cursor));
+    cursor = new Date(cursor.getFullYear(), cursor.getMonth() + 1, 1);
+  }
+
+  const missingByType = new Map<string, string[]>();
+  for (const type of TYPES) {
+    const missing = expectedMonths.filter((m) => !dbMap.get(m)?.has(type));
+    if (missing.length > 0) missingByType.set(type, missing);
+  }
+
+  if (missingByType.size === 0) {
+    const result: MonthlyLastRow[] = [];
+    for (const month of expectedMonths) {
+      for (const type of TYPES) {
+        const buy = dbMap.get(month)?.get(type);
+        if (buy !== undefined) {
+          result.push({ month, type, buy });
+        }
+      }
+    }
+    cache.set(cacheKey, result, 300);
+    return c.json(result);
+  }
+
+  const neededMonths = new Set<string>();
+  for (const months of missingByType.values()) {
+    for (const m of months) neededMonths.add(m);
+  }
+  const sortedNeeded = [...neededMonths].sort();
+  const minNeeded = sortedNeeded[0];
+  const maxNeeded = sortedNeeded[sortedNeeded.length - 1];
+
+  const externalData = new Map<string, Map<string, number>>();
+
+  for (const [type, casa] of Object.entries(CASA_MAP)) {
+    if (!missingByType.has(type)) continue;
+
+    try {
+      const res = await fetch(
+        `https://api.argentinadatos.com/v1/cotizaciones/dolares/${casa}`,
+      );
+      if (!res.ok) continue;
+
+      const quotes: ExternalQuote[] = await res.json();
+      const monthLast = new Map<string, { fecha: string; compra: number }>();
+
+      for (const q of quotes) {
+        const fecha = q.fecha.slice(0, 10);
+        if (fecha < minNeeded || fecha > maxNeeded) continue;
+
+        const monthKey = fecha.slice(0, 7);
+        if (!neededMonths.has(monthKey)) continue;
+
+        const existing = monthLast.get(monthKey);
+        if (!existing || fecha > existing.fecha) {
+          monthLast.set(monthKey, { fecha, compra: q.compra });
+        }
+      }
+
+      const typeMap = new Map<string, number>();
+      for (const [month, data] of monthLast) {
+        typeMap.set(month, data.compra);
+      }
+      externalData.set(type, typeMap);
+    } catch {
+      // If external API fails, continue without those values
+    }
+  }
+
+  const result: MonthlyLastRow[] = [];
+  for (const month of expectedMonths) {
+    for (const type of TYPES) {
+      const dbBuy = dbMap.get(month)?.get(type);
+      if (dbBuy !== undefined) {
+        result.push({ month, type, buy: dbBuy });
+        continue;
+      }
+
+      const extBuy = externalData.get(type)?.get(month);
+      if (extBuy !== undefined) {
+        result.push({ month, type, buy: extBuy });
+      }
+    }
+  }
+
+  cache.set(cacheKey, result, 300);
+  return c.json(result);
 }