Gateway localnet examples (#189)

Co-authored-by: skosito <[email protected]>

universal/hello/.eslintignore

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+.yarn
+artifacts
+cache
+coverage
+node_modules
+typechain-types

universal/hello/.eslintrc.js

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+const path = require("path");
+
+/**
+ * @type {import("eslint").Linter.Config}
+ */
+module.exports = {
+  env: {
+    browser: false,
+    es2021: true,
+    mocha: true,
+    node: true,
+  },
+  extends: ["plugin:prettier/recommended"],
+  parser: "@typescript-eslint/parser",
+  parserOptions: {
+    ecmaVersion: 12,
+  },
+  plugins: [
+    "@typescript-eslint",
+    "prettier",
+    "simple-import-sort",
+    "sort-keys-fix",
+    "typescript-sort-keys",
+  ],
+  rules: {
+    "@typescript-eslint/sort-type-union-intersection-members": "error",
+    camelcase: "off",
+    "simple-import-sort/exports": "error",
+    "simple-import-sort/imports": "error",
+    "sort-keys-fix/sort-keys-fix": "error",
+    "typescript-sort-keys/interface": "error",
+    "typescript-sort-keys/string-enum": "error",
+  },
+  settings: {
+    "import/parsers": {
+      "@typescript-eslint/parser": [".js", ".jsx", ".ts", ".tsx", ".d.ts"],
+    },
+    "import/resolver": {
+      node: {
+        extensions: [".js", ".jsx", ".ts", ".tsx", ".d.ts"],
+      },
+      typescript: {
+        project: path.join(__dirname, "tsconfig.json"),
+      },
+    },
+  },
+};

universal/hello/.gitignore

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+node_modules
+.env
+coverage
+coverage.json
+typechain
+typechain-types
+dependencies
+
+# Hardhat files
+cache
+artifacts
+
+# Foundry files
+out
+cache_forge
+
+access_token

universal/hello/LICENSE

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+MIT License
+
+Copyright (c) 2023 ZetaChain
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

universal/hello/README.md

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+# ZetaChain Contracts Template
+
+## Getting Started
+
+Install dependencies:
+
+```
+yarn
+```
+
+## Next Steps
+
+Ready to dive in? Follow our [**🚀 smart contract
+tutorials**](https://www.zetachain.com/docs/developers/tutorials/intro/) to
+start building universal app contracts.

universal/hello/contracts/Hello.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.26;
+
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+
+import {RevertContext, RevertOptions} from "@zetachain/protocol-contracts/contracts/Revert.sol";
+import "@zetachain/protocol-contracts/contracts/zevm/interfaces/UniversalContract.sol";
+import "@zetachain/protocol-contracts/contracts/zevm/interfaces/IGatewayZEVM.sol";
+import "@zetachain/protocol-contracts/contracts/zevm/interfaces/IZRC20.sol";
+
+contract Hello is UniversalContract {
+    event HelloEvent(string, string);
+    event ContextDataRevert(RevertContext);
+
+    address constant gatewayAddress =
+        0x610178dA211FEF7D417bC0e6FeD39F05609AD788;
+
+    function onCrossChainCall(
+        zContext calldata context,
+        address zrc20,
+        uint256 amount,
+        bytes calldata message
+    ) external override {
+        string memory decodedMessage;
+        if (message.length > 0) {
+            decodedMessage = abi.decode(message, (string));
+        }
+        emit HelloEvent("Hello from a universal app", decodedMessage);
+    }
+
+    function callFromZetaChain(
+        bytes memory receiver,
+        address zrc20,
+        bytes calldata message,
+        uint256 gasLimit,
+        RevertOptions memory revertOptions
+    ) external {
+        IZRC20(zrc20).approve(gatewayAddress, 1_000_000_000);
+        IGatewayZEVM(gatewayAddress).call(
+            receiver,
+            zrc20,
+            message,
+            gasLimit,
+            revertOptions
+        );
+    }
+
+    function onRevert(RevertContext calldata revertContext) external override {
+        emit ContextDataRevert(revertContext);
+    }
+}

universal/hello/contracts/ReceiverContract.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.26;
+
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+
+import {RevertContext} from "@zetachain/protocol-contracts/contracts/Revert.sol";
+import "@zetachain/protocol-contracts/contracts/zevm/interfaces/UniversalContract.sol";
+
+contract ReceiverContract {
+    event RevertEvent(string);
+    event HelloEvent(string);
+
+    function hello(string memory message) external {
+        emit HelloEvent(message);
+    }
+
+    function onRevert(RevertContext calldata revertContext) external {
+        emit RevertEvent("Event from RevertContract!");
+    }
+
+    receive() external payable {}
+
+    fallback() external payable {}
+}