WIP: feat(price_feeds/starknet): add send_usd example

price_feeds/starknet/send_usd/contract/.gitignore

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+target

price_feeds/starknet/send_usd/contract/.tool-versions

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+scarb 2.5.4
+starknet-foundry 0.21.0
+dojo 0.6.0
+starkli 0.2.8

price_feeds/starknet/send_usd/contract/Scarb.lock

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+# Code generated by scarb DO NOT EDIT.
+version = 1
+
+[[package]]
+name = "openzeppelin"
+version = "0.10.0"
+source = "git+https://github.com/OpenZeppelin/cairo-contracts.git?tag=v0.10.0#d77082732daab2690ba50742ea41080eb23299d3"
+
+[[package]]
+name = "pyth"
+version = "0.1.0"
+source = "git+https://github.com/pyth-network/pyth-crosschain.git?rev=ecc3a2f1#ecc3a2f17d470c8d59586ecd4897c4a63ece282a"
+dependencies = [
+ "openzeppelin",
+ "snforge_std",
+]
+
+[[package]]
+name = "send_usd"
+version = "0.1.0"
+dependencies = [
+ "openzeppelin",
+ "pyth",
+]
+
+[[package]]
+name = "snforge_std"
+version = "0.21.0"
+source = "git+https://github.com/foundry-rs/starknet-foundry?tag=v0.21.0#2996b8c1dd66b2715fc67e69578089f278a46790"

price_feeds/starknet/send_usd/contract/Scarb.toml

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+[package]
+name = "send_usd"
+version = "0.1.0"
+edition = "2023_11"
+
+[dependencies]
+starknet = ">=2.5.4"
+openzeppelin = { git = "https://github.com/OpenZeppelin/cairo-contracts.git", tag = "v0.10.0" }
+
+# TODO: replace with tag after release
+pyth = { git = "https://github.com/pyth-network/pyth-crosschain.git", rev = "ecc3a2f1" }
+
+[[target.starknet-contract]]

price_feeds/starknet/send_usd/contract/deploy/local_deploy

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+#!/bin/bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+set -x
+
+starkli --version
+scarb --version
+
+export STARKNET_ACCOUNT=katana-0
+export STARKNET_RPC=http://0.0.0.0:5050
+sleep="sleep 0.3"
+
+cd "$(dirname "$0")/.."
+scarb build
+
+# predeployed fee token contract in katana
+fee_token_address=0x49d36570d4e46f48e99674bd3fcc84644ddd6b96f7c741b1562b82f9e004dc7
+
+if [ -z ${PYTH_ADDRESS+x} ]; then
+    echo "Missing PYTH_ADDRESS env var"
+    exit 1
+fi
+
+send_usd_hash=$(starkli declare --watch target/dev/send_usd_send_usd.contract_class.json)
+${sleep}
+
+# ETH/USD
+price_feed_id=0xff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace
+
+price_feed_u128_low=$(
+    python3 -c "print(${price_feed_id} % (1<<128))"
+)
+price_feed_u128_high=$(
+    python3 -c "print(${price_feed_id} // (1<<128))"
+)
+
+send_usd_address=$(starkli deploy --watch "${send_usd_hash}" \
+    "${PYTH_ADDRESS}" \
+    "${fee_token_address}" \
+    "${price_feed_u128_low}" "${price_feed_u128_high}" \
+)
+${sleep}
+
+update_data=$(
+    curl --request "GET" \
+        "https://hermes.pyth.network/v2/updates/price/latest?ids%5B%5D=${price_feed_id}" \
+        --header "accept: application/json" \
+    | jq --raw-output '.binary.data[0]' \
+    | cargo run --manifest-path "../../../../../pyth-crosschain/target_chains/starknet/tools/test_vaas/Cargo.toml" --bin hex_to_cairo_calldata
+)
+
+starkli invoke --watch "${fee_token_address}" approve "${send_usd_address}" 1000000000000000000000 0
+${sleep}
+
+destination=0x1001
+
+echo "Old destination balance:"
+starkli balance "${destination}"
+
+starkli invoke --watch --log-traffic "${send_usd_address}" send_usd \
+    "${destination}" \
+    10 0 `# amount_in_usd` \
+    ${update_data} \
+
+${sleep}
+
+echo "New destination balance:"
+starkli balance "${destination}"
+
+echo send_usd contract has been successfully deployed at "${send_usd_address}"

price_feeds/starknet/send_usd/contract/src/lib.cairo

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+use starknet::ContractAddress;
+use pyth::ByteArray;
+
+#[starknet::interface]
+pub trait ISendUsd<T> {
+    /// Sends ETH from the caller to the destination. The amount of ETH will be equivalent
+    /// to the specified amount of USD, converted using the last available ETH/USD price from Pyth.
+    /// `price_update` should be the latest available price update for the ETH/USD price feed.
+    /// The caller needs to set up sufficient allowance for this contract.
+    fn send_usd(
+        ref self: T, destination: ContractAddress, amount_in_usd: u256, price_update: ByteArray
+    );
+}
+
+#[starknet::contract]
+mod send_usd {
+    use core::panic_with_felt252;
+    use starknet::{ContractAddress, get_caller_address, get_contract_address};
+    use pyth::{ByteArray, IPythDispatcher, IPythDispatcherTrait, exp10, UnwrapWithFelt252};
+    use openzeppelin::token::erc20::interface::{IERC20CamelDispatcherTrait, IERC20CamelDispatcher};
+
+    const MAX_PRICE_AGE: u64 = 3600; // 1 hour
+    const WEI_PER_ETH: u256 = 1000000000000000000;
+
+    #[storage]
+    struct Storage {
+        pyth_address: ContractAddress,
+        eth_erc20_address: ContractAddress,
+        eth_usd_price_id: u256,
+    }
+
+    /// Initializes the contract.
+    /// `pyth_address` is the address of the deployed Pyth account.
+    /// `eth_erc20_address` is the address of the ERC20 token account for the ETH token.
+    /// `eth_usd_price_id` is the ID of Pyth's price feed for ETH/USD.
+    #[constructor]
+    fn constructor(
+        ref self: ContractState,
+        pyth_address: ContractAddress,
+        eth_erc20_address: ContractAddress,
+        eth_usd_price_id: u256,
+    ) {
+        self.pyth_address.write(pyth_address);
+        self.eth_erc20_address.write(eth_erc20_address);
+        self.eth_usd_price_id.write(eth_usd_price_id);
+    }
+
+    #[abi(embed_v0)]
+    impl SendUsd of super::ISendUsd<ContractState> {
+        fn send_usd(
+            ref self: ContractState,
+            destination: ContractAddress,
+            amount_in_usd: u256,
+            price_update: ByteArray
+        ) {
+            let pyth = IPythDispatcher { contract_address: self.pyth_address.read() };
+            let eth_erc20 = IERC20CamelDispatcher {
+                contract_address: self.eth_erc20_address.read()
+            };
+            let caller = get_caller_address();
+            let contract = get_contract_address();
+
+            let pyth_fee = pyth.get_update_fee(price_update.clone());
+            if !eth_erc20.transferFrom(caller, contract, pyth_fee) {
+                panic_with_felt252('insufficient allowance for fee');
+            }
+            if !eth_erc20.approve(pyth.contract_address, pyth_fee) {
+                panic_with_felt252('approve failed');
+            }
+
+            pyth.update_price_feeds(price_update);
+
+            let price = pyth
+                .get_price_no_older_than(self.eth_usd_price_id.read(), MAX_PRICE_AGE)
+                .unwrap_with_felt252();
+
+            let price_u64: u64 = price.price.try_into().unwrap();
+            let amount_in_wei = WEI_PER_ETH
+                * exp10((-price.expo).try_into().unwrap())
+                * amount_in_usd
+                / price_u64.into();
+
+            let transfer_ok = eth_erc20
+                .transferFrom(caller, destination, amount_in_wei);
+            if !transfer_ok {
+                panic_with_felt252('insufficient allowance');
+            }
+        }
+    }
+}