refactor: move fetchEthPrice / fetchSpread / fetchSpotPrice to @nftx/api

these methods were previously in @nftx/trade and interacted directly with the AMM router
as we now have an API layer for requesting ERC20 quotes, these methods have been moved to @nftx/api

BREAKING CHANGE: these methods are no longer available in @nftx/trade

packages/api/src/prices/fetchEthPrice.ts

@@ -0,0 +1,13 @@
+import fetchSpotPrice from './fetchSpotPrice';
+
+const fetchEthPrice = async ({ network }: { network?: number }) => {
+  const { price } = await fetchSpotPrice({
+    network,
+    tokenAddress: 'ETH',
+    quoteToken: 'USDC',
+  });
+
+  return price;
+};
+
+export default fetchEthPrice;

packages/api/src/prices/fetchSpotPrice.ts

@@ -0,0 +1,41 @@
+import type { QuoteToken } from '@nftx/types';
+import fetchPrice from './fetchPrice';
+import { WeiPerEther } from '@nftx/constants';
+
+const fetchSpotPrice = async ({
+  tokenAddress,
+  amount = WeiPerEther,
+  network,
+  quoteToken,
+}: {
+  tokenAddress: QuoteToken;
+  network?: number;
+  quoteToken?: QuoteToken;
+  amount?: bigint;
+}) => {
+  let fraction = WeiPerEther;
+  let error: any = new Error('Failed to fetch spot price');
+
+  do {
+    try {
+      const quote = await fetchPrice({
+        network,
+        type: 'erc20',
+        buyToken: tokenAddress,
+        sellToken: quoteToken || 'ETH',
+        buyAmount: fraction,
+      });
+
+      quote.price = (quote.price * amount) / fraction;
+
+      return quote;
+    } catch (e) {
+      error = e;
+      fraction /= 100n;
+    }
+  } while (fraction > 0n);
+
+  throw error;
+};
+
+export default fetchSpotPrice;

packages/api/src/prices/fetchSpread.ts

@@ -0,0 +1,36 @@
+import { WeiPerEther, Zero } from '@nftx/constants';
+import { QuoteToken } from '@nftx/types';
+import fetchPrice from './fetchPrice';
+
+const fetchSpread = async ({
+  tokenAddress,
+  network,
+  quoteToken,
+}: {
+  tokenAddress: QuoteToken;
+  network?: number;
+  quoteToken?: QuoteToken;
+}) => {
+  try {
+    const { price: buyPrice } = await fetchPrice({
+      network,
+      type: 'erc20',
+      buyToken: tokenAddress,
+      sellToken: quoteToken || 'ETH',
+      buyAmount: WeiPerEther,
+    });
+    const { price: sellPrice } = await fetchPrice({
+      network,
+      type: 'erc20',
+      sellToken: tokenAddress,
+      buyToken: quoteToken || 'ETH',
+      sellAmount: WeiPerEther,
+    });
+
+    return buyPrice - sellPrice;
+  } catch {
+    return Zero;
+  }
+};
+
+export default fetchSpread;

packages/api/src/prices/index.ts

@@ -1,2 +1,5 @@
 export { default as fetchQuote } from './fetchQuote';
 export { default as fetchPrice } from './fetchPrice';
+export { default as fetchEthPrice } from './fetchEthPrice';
+export { default as fetchSpotPrice } from './fetchSpotPrice';
+export { default as fetchSpread } from './fetchSpread';