Add demo for using oracle

https://oracle-demo.vercel.app/docs

src/contracts/priceBet2.ts

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+import {
+    SmartContract,
+    prop,
+    ByteString,
+    method,
+    assert,
+    Utils,
+    Sig,
+    PubKey,
+    slice,
+    byteString2Int,
+} from 'scrypt-ts'
+import { RabinSig, RabinPubKey, RabinVerifier } from 'scrypt-ts-lib'
+
+export type Message = {
+    marker: bigint // 1 byte
+    timestamp: bigint // 4 bytes LE
+    price: bigint // 8 bytes LE
+    decimal: bigint // 1 byte
+    tradingPair: ByteString
+}
+
+/*
+ * A betting contract that lets Alice and Bob bet on the price of the BSV-USDC pair
+ * in the future. The price is obtained from a trusted oracle.
+ * https://oracle-demo.vercel.app/docs#/v1/V1Controller_getPrice
+ */
+export class PriceBet2 extends SmartContract {
+    // Price target that needs to be reached.
+    @prop()
+    targetPrice: bigint
+    @prop()
+    decimal: bigint
+
+    // Trading pair, e.g. "BSV-USDC"
+    @prop()
+    tradingPair: ByteString
+
+    // Timestamp window in which the price target needs to be reached.
+    @prop()
+    timestampFrom: bigint
+    @prop()
+    timestampTo: bigint
+
+    // Oracles Rabin public key.
+    @prop()
+    oraclePubKey: RabinPubKey
+
+    // Public keys of both players.
+    @prop()
+    alicePubKey: PubKey
+    @prop()
+    bobPubKey: PubKey
+
+    constructor(
+        targetPrice: bigint,
+        decimal: bigint,
+        tradingPair: ByteString,
+        timestampFrom: bigint,
+        timestampTo: bigint,
+        oraclePubKey: RabinPubKey,
+        alicePubKey: PubKey,
+        bobPubKey: PubKey
+    ) {
+        super(...arguments)
+        this.targetPrice = targetPrice
+        this.decimal = decimal
+        this.tradingPair = tradingPair
+        this.timestampFrom = timestampFrom
+        this.timestampTo = timestampTo
+        this.oraclePubKey = oraclePubKey
+        this.alicePubKey = alicePubKey
+        this.bobPubKey = bobPubKey
+    }
+
+    // Parses signed message from the oracle.
+    @method()
+    static parseMessage(msg: ByteString): Message {
+        return {
+            marker: Utils.fromLEUnsigned(slice(msg, 0n, 1n)),
+            timestamp: Utils.fromLEUnsigned(slice(msg, 1n, 5n)),
+            price: Utils.fromLEUnsigned(slice(msg, 5n, 13n)),
+            decimal: Utils.fromLEUnsigned(slice(msg, 13n, 14n)),
+            tradingPair: slice(msg, 14n),
+        }
+    }
+
+    @method()
+    public unlock(msg: ByteString, sig: RabinSig, winnerSig: Sig) {
+        // Verify oracle signature.
+        assert(
+            RabinVerifier.verifySig(msg, sig, this.oraclePubKey),
+            'Oracle sig verify failed.'
+        )
+
+        // Decode data.
+        const message = PriceBet2.parseMessage(msg)
+
+        // Validate data.
+        assert(message.marker == 2n, 'incorrect oracle message type.')
+        assert(message.decimal == this.decimal, 'incorrect decimal.')
+        assert(message.timestamp >= this.timestampFrom, 'Timestamp too early.')
+        assert(message.timestamp <= this.timestampTo, 'Timestamp too late.')
+        assert(
+            message.tradingPair == this.tradingPair,
+            'incorrect trading pair.'
+        )
+
+        // Decide winner and check their signature.
+        const winner =
+            message.price >= this.targetPrice
+                ? this.alicePubKey
+                : this.bobPubKey
+        assert(this.checkSig(winnerSig, winner), 'Winner checkSig failed.')
+    }
+
+    static parseSig(sig: { s: ByteString; padding: ByteString }): RabinSig {
+        return {
+            s: byteString2Int(sig.s + '00'),
+            padding: sig.padding,
+        }
+    }
+}

tests/priceBet2.test.ts

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+import { PriceBet2 } from '../src/contracts/priceBet2'
+import {
+    ByteString,
+    bsv,
+    PubKey,
+    byteString2Int,
+    toByteString,
+    MethodCallOptions,
+    findSig,
+} from 'scrypt-ts'
+import { RabinPubKey, RabinSig } from 'scrypt-ts-lib'
+import { expect, use } from 'chai'
+import { getDefaultSigner } from './utils/helper'
+import chaiAsPromised from 'chai-as-promised'
+use(chaiAsPromised)
+
+// All data was pre-fetched from https://oracle-demo.vercel.app/docs
+
+// https://oracle-demo.vercel.app/info
+const PUBKEY =
+    '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'
+const RESP = {
+    timestamp: 1700428685,
+    tradingPair: 'BSV-USDC',
+    price: 478400,
+    decimal: 4,
+    data: '028d7b5a65c04c070000000000044253562d55534443',
+    signature: {
+        s: '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',
+        padding: '0000000000',
+    },
+}
+
+describe('Test SmartContract `PriceBet2`', () => {
+    let alicePrivKey: bsv.PrivateKey
+    let bobPrivKey: bsv.PrivateKey
+
+    let priceBet: PriceBet2
+
+    const decimal = 4
+    const currentPrice = Math.round(RESP.price * 10 ** decimal)
+
+    before(() => {
+        // Prepare inital data.
+        alicePrivKey = bsv.PrivateKey.fromRandom(bsv.Networks.testnet)
+        bobPrivKey = bsv.PrivateKey.fromRandom(bsv.Networks.testnet)
+        const rabinPubKey: bigint = byteString2Int(PUBKEY + '00')
+
+        const targetPriceFloat = 36.3 // USDC
+        const targetPrice = Math.round(targetPriceFloat * 10 ** decimal)
+        const timestampFrom = 1700352000n // Sun Nov 19 2023 00:00:00 GMT
+        const timestampTo = 1700438400n // Mon Nov 20 2023 00:00:00 GMT
+        const tradingPair = toByteString('BSV-USDC', true)
+
+        PriceBet2.loadArtifact()
+        priceBet = new PriceBet2(
+            BigInt(targetPrice),
+            BigInt(decimal),
+            tradingPair,
+            timestampFrom,
+            timestampTo,
+            rabinPubKey as RabinPubKey,
+            PubKey(alicePrivKey.publicKey.toByteString()),
+            PubKey(bobPrivKey.publicKey.toByteString())
+        )
+    })
+
+    it('should pass w correct sig and data.', async () => {
+        // Pick winner.
+        const winner =
+            currentPrice >= priceBet.targetPrice ? alicePrivKey : bobPrivKey
+        const winnerPubKey = winner.publicKey
+
+        // Connect signer.
+        await priceBet.connect(getDefaultSigner(winner))
+        await priceBet.deploy(1)
+
+        const oracleSig: RabinSig = PriceBet2.parseSig(RESP.signature)
+
+        const callContract = async () =>
+            priceBet.methods.unlock(
+                RESP.data as ByteString,
+                oracleSig,
+                (sigResps) => findSig(sigResps, winnerPubKey),
+                // Method call options:
+                {
+                    pubKeyOrAddrToSign: winnerPubKey,
+                } as MethodCallOptions<PriceBet2>
+            )
+        return expect(callContract()).not.rejected
+    })
+
+    it('should fail paying wrong player.', async () => {
+        // Pick loser.
+        const loser =
+            currentPrice >= priceBet.targetPrice ? bobPrivKey : alicePrivKey
+        const loserPubKey = loser.publicKey
+
+        // Connect signer.
+        await priceBet.connect(getDefaultSigner(loser))
+        await priceBet.deploy(1)
+
+        const oracleSig: RabinSig = PriceBet2.parseSig(RESP.signature)
+
+        const callContract = async () =>
+            priceBet.methods.unlock(
+                RESP.data as ByteString,
+                oracleSig,
+                (sigResps) => findSig(sigResps, loserPubKey),
+                // Method call options:
+                {
+                    pubKeyOrAddrToSign: loserPubKey,
+                } as MethodCallOptions<PriceBet2>
+            )
+
+        return expect(callContract()).to.be.rejectedWith(
+            /signature check failed/
+        )
+    })
+})