feat(ledger): 编写时光机核心辅助函数，支持历史持仓计算与价格断点结转

src/actions/snapshots.ts

@@ -1,9 +1,9 @@
 'use server';
 
 import { db } from '@/db';
-import { portfolioSnapshots } from '@/db/schema';
+import { portfolioSnapshots, transactions, assetPricesHistory } from '@/db/schema';
 import { getPortfolioPositions } from './portfolio';
-import { desc, eq, gte, sql } from 'drizzle-orm';
+import { asc, desc, eq, gte, lte, sql } from 'drizzle-orm';
 import Big from 'big.js';
 
 function getTodayInShanghai(): string {
@@ -105,3 +105,95 @@ export async function getSnapshots(params?: {
 
   return snapshots.reverse();
 }
+
+interface HistoricalPosition {
+  assetId: string;
+  quantity: string;
+  totalCost: string;
+}
+
+export async function getHistoricalPositions(targetDate: Date): Promise<HistoricalPosition[]> {
+  const dateStr = targetDate.toISOString().split('T')[0];
+
+  const allTransactions = await db
+    .select({
+      assetId: transactions.assetId,
+      txType: transactions.txType,
+      quantity: transactions.quantity,
+      price: transactions.price,
+      exchangeRate: transactions.exchangeRate,
+      executedAt: transactions.executedAt,
+    })
+    .from(transactions)
+    .where(
+      transactions.executedAt.lte(targetDate)
+    )
+    .orderBy(asc(transactions.executedAt));
+
+  const holdings = new Map<string, {
+    quantity: Big;
+    totalCost: Big;
+  }>();
+
+  for (const tx of allTransactions) {
+    if (!tx.assetId) continue;
+
+    const existing = holdings.get(tx.assetId);
+    if (!existing) {
+      holdings.set(tx.assetId, {
+        quantity: new Big('0'),
+        totalCost: new Big('0'),
+      });
+    }
+
+    const holding = holdings.get(tx.assetId)!;
+    const qty = new Big(tx.quantity);
+
+    if (tx.txType === 'BUY') {
+      holding.quantity = holding.quantity.plus(qty);
+      const cost = qty.times(new Big(tx.price)).times(new Big(tx.exchangeRate || '1'));
+      holding.totalCost = holding.totalCost.plus(cost);
+    } else if (tx.txType === 'SELL') {
+      let avgCostPerUnit = new Big('0');
+      if (holding.quantity.gt(0)) {
+        avgCostPerUnit = holding.totalCost.div(holding.quantity);
+      }
+      const sellCost = avgCostPerUnit.times(qty);
+      holding.quantity = holding.quantity.minus(qty);
+      holding.totalCost = holding.totalCost.minus(sellCost);
+    } else if (tx.txType === 'AIRDROP') {
+      holding.quantity = holding.quantity.plus(qty);
+    }
+  }
+
+  const result: HistoricalPosition[] = [];
+  for (const [assetId, holding] of holdings) {
+    if (holding.quantity.lte(0)) continue;
+    result.push({
+      assetId,
+      quantity: holding.quantity.toString(),
+      totalCost: holding.totalCost.toString(),
+    });
+  }
+
+  return result;
+}
+
+export async function getEffectivePrice(
+  assetId: string,
+  targetDate: Date
+): Promise<string | null> {
+  const dateStr = targetDate.toISOString().split('T')[0];
+
+  const [record] = await db
+    .select({
+      price: assetPricesHistory.price,
+    })
+    .from(assetPricesHistory)
+    .where(eq(assetPricesHistory.assetId, assetId))
+    .where(lte(assetPricesHistory.date, dateStr))
+    .orderBy(desc(assetPricesHistory.date))
+    .limit(1);
+
+  return record?.price ?? null;
+}