price subscriptions

src/blockchain/prices.js

@@ -0,0 +1,84 @@
+import {socket} from "@/socket.js";
+import {useStore} from "@/store/store.js";
+import {Exchange} from "@/blockchain/orderlib.js";
+import {uniswapV3PoolAddress} from "@/blockchain/uniswap.js";
+import {ethers, FixedNumber} from "ethers";
+import {erc20Abi, uniswapV3PoolAbi} from "@/blockchain/abi.js";
+
+const subs = {} // key is route and value is a subscription counter
+
+
+export function subPrices( routes ) {
+    const subRoutes = []
+    let chainId = null
+    for( const route of routes ) {
+        if( !(route in subRoutes) || subRoutes[route] === 0 ) {
+            subRoutes[route] = 1
+            console.log('subscribing to pool', route.pool)
+            subRoutes.push(route)
+        }
+        else {
+            subRoutes[route]++
+            if( chainId !== null && route.chainId !== chainId )
+                throw Error('cannot mix chainIds in a subscription list')
+            chainId = route.chainId
+        }
+    }
+    if( subRoutes.length ) {
+        socket.emit('subPools', chainId, routes.map((r)=>r.address) )
+        // perform a local query if necessary
+        for( const route of subRoutes ) {
+            const s = useStore()
+            if( !(route.address in s.poolPrices) ) {
+                getPriceForRoute(route).then((price)=>s.poolPrices[route.address]=price)
+            }
+        }
+    }
+}
+
+export function unsubPrices( routes ) {
+    let chainId = null
+    const unsubAddrs = []
+    for( const route of routes ) {
+        if( !(route in subs) ) {
+            console.error('unsubscribed to a nonexistent route', route)
+        }
+        else {
+            subs[route]--
+            if( subs[route] === 0 ) {
+                unsubAddrs.push(route.pool)
+                if( chainId !== null && route.chainId !== chainId )
+                    throw Error('cannot mix chainIds in a subscription list')
+                console.log('unsubscribing from pool', route.pool)
+                chainId = route.chainId
+            }
+            else if( subs[route] < 0 ) {
+                console.error('unsubscribed to an already unsubbed route', route)
+                subs[route] = 0 // fix
+            }
+        }
+    }
+    if( unsubAddrs.length )
+        socket.emit('unsubPool', chainId, unsubAddrs )
+}
+
+
+async function getPriceForRoute(route) {
+    console.log('route is',route)
+    if( route.exchange === Exchange.UniswapV3 ) {
+        const addr = uniswapV3PoolAddress(route.chainId, route.token0.address, route.token1.address, route.fee)
+        const provider = useStore().provider;
+        if( provider === null ) {
+            console.error('provider was null during getPriceForRoute')
+            return null
+        }
+        const pool = new ethers.Contract(addr, uniswapV3PoolAbi, provider)
+        const got = await pool.slot0()
+        const [sqrtPrice,,,,,,] = got
+        const spn = Number(sqrtPrice)
+        const price = spn*spn/2**(96*2) * 10**(route.token0.decimals-route.token1.decimals)
+        console.log(`price for ${route.token0.symbol}/${route.token1.symbol}`,price)
+    }
+    else
+        throw Error(`Unsupported exchange ${route.exchange}`)
+}