Add usageEngine and usage routes

src/index.js

@@ -13,6 +13,7 @@ const createEventsApi = require('./lib/eventsApi');
 const createSynchronizer = require('./lib/synchronizer');
 
 const capacityRouter = require('./routes/capacity');
+const usageRouter = require('./routes/usage');
 const quoteRouter = require('./routes/quote');
 
 const main = async () => {
@@ -48,6 +49,7 @@ const main = async () => {
 
   // initiate routes
   app.use('/v2', capacityRouter);
+  app.use('/v2', usageRouter);
   app.use('/v2', quoteRouter);
 
   const port = config.get('port');

src/lib/usageEngine.js

@@ -0,0 +1,35 @@
+const { ethers } = require('ethers');
+
+const { selectPoolProducts } = require('../store/selectors');
+const { NXM_PER_ALLOCATION_UNIT } = require('./constants');
+
+const { WeiPerEther, Zero } = ethers.constants;
+
+function usageEngine(store, poolIds) {
+  const { assets, assetRates } = store.getState();
+  const usage = [];
+  const ids = poolIds.length === 0 ? Object.keys(store.getState().poolProductIds) : [...poolIds];
+
+  for (const poolId of ids) {
+    const poolProducts = selectPoolProducts(store, poolId);
+
+    const poolCapacities = poolProducts.map(pool => {
+      const { productId, allocations } = pool;
+      const used = allocations.reduce((total, allocation) => total.add(allocation), Zero);
+      const capacityUsedNXM = used.mul(NXM_PER_ALLOCATION_UNIT);
+      return {
+        productId,
+        capacityUsed: Object.values(assets).map(assetId => ({
+          assetId,
+          amount: capacityUsedNXM.mul(assetRates[assetId]).div(WeiPerEther),
+        })),
+      };
+    });
+
+    usage.push({ poolId, products: poolCapacities });
+  }
+
+  return usage;
+}
+
+module.exports = usageEngine;

src/routes/usage.js

@@ -0,0 +1,41 @@
+const express = require('express');
+const usageEngine = require('../lib/usageEngine');
+const { asyncRoute } = require('../lib/helpers');
+
+const router = express.Router();
+
+const formatUsageResult = ({ poolId, products }) => ({
+  poolId: poolId.toString(),
+  products: products.map(({ productId, capacityUsed }) => ({
+    productId,
+    capacityUsed: capacityUsed.map(({ assetId, amount }) => ({ assetId, amount: amount.toString() })),
+  })),
+});
+
+router.get(
+  '/usage',
+  asyncRoute(async (req, res) => {
+    const store = req.app.get('store');
+
+    const response = usageEngine(store, []);
+    res.json(response.map(usage => formatUsageResult(usage)));
+  }),
+);
+
+router.get(
+  '/usage/:poolId',
+  asyncRoute(async (req, res) => {
+    const poolId = Number(req.params.poolId);
+    const store = req.app.get('store');
+
+    const [usage] = usageEngine(store, [poolId]);
+
+    if (!usage) {
+      return res.status(400).send({ error: 'Invalid Pool Id', response: null });
+    }
+
+    res.json(formatUsageResult(usage));
+  }),
+);
+
+module.exports = router;

src/store/reducer.js

@@ -12,6 +12,7 @@ const initialState = {
   globalCapacityRatio: 0,
   poolProducts: {}, // {productId}_{poolId} -> { allocations, trancheCapacities }
   productPoolIds: {}, // productId -> [ poolIds ]
+  poolProductIds: {}, // productId -> [ poolIds ]
   products: {}, // productId -> { product }
   trancheId: 0,
 };
@@ -29,10 +30,16 @@ function reducer(state = initialState, { type, payload }) {
     const key = `${productId}_${poolId}`;
     const newPoolProduct = { productId, poolId, ...poolProduct };
     const poolProducts = { ...state.poolProducts, [key]: newPoolProduct };
-    const previousIds = state.productPoolIds[productId] || [];
-    const newIds = [...new Set([...previousIds, poolId])];
-    const productPoolIds = { ...state.productPoolIds, [productId]: newIds };
-    return { ...state, poolProducts, productPoolIds };
+
+    const previousPoolIds = state.productPoolIds[productId] || [];
+    const newPoolIds = [...new Set([...previousPoolIds, poolId])];
+    const productPoolIds = { ...state.productPoolIds, [productId]: newPoolIds };
+
+    const previousProductIds = state.poolProductIds[poolId] || [];
+    const newProductIds = [...new Set([...previousProductIds, productId])];
+    const poolProductIds = { ...state.poolProductIds, [poolId]: newProductIds };
+
+    return { ...state, poolProducts, productPoolIds, poolProductIds };
   }
 
   if (type === SET_ASSET_RATE) {

src/store/selectors.js

@@ -17,6 +17,15 @@ const selectProductPools = (store, productId) => {
   });
 };
 
+const selectPoolProducts = (store, poolId) => {
+  const { poolProducts, poolProductIds } = store.getState();
+  const productIds = poolProductIds[poolId] || [];
+  return productIds.map(productId => {
+    const key = `${productId}_${poolId}`;
+    return poolProducts[key];
+  });
+};
+
 const selectAssetSymbol = (store, assetId) => {
   const { assets } = store.getState();
   return Object.keys(assets).find(key => assets[key] === assetId);
@@ -27,4 +36,5 @@ module.exports = {
   selectAssetSymbol,
   selectProduct,
   selectProductPools,
+  selectPoolProducts,
 };