feat: add example of an LND TypeScript app

Author: murtyjones

examples/typescript/lnd/.env.example

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+# These values can come from any `lnd` node in the polar app:
+ALICE_LND_MACAROON_PATH=/Users/satoshi/.polar/networks/1/volumes/lnd/alice/data/chain/bitcoin/regtest/admin.macaroon
+ALICE_LND_HOST=127.0.0.1:10001
+ALICE_TLS_CERT_PATH=/Users/satoshi/.polar/networks/1/volumes/lnd/alice/tls.cert

examples/typescript/lnd/.gitignore

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+dist
+.env

examples/typescript/lnd/README.md

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+# TypeScript LND app
+
+This is an example app that shows how Polar can be used in your development workflow while working on Lightning Network applications.
+
+This example is a simple app, designed for LND nodes, that allows the user to:
+
+1. Open a channel
+1. List peers
+1. List pending channels
+1. List open channels
+
+# Getting Started
+
+1. Start the Polar app using `yarn dev` or opening the app itself
+1. In Polar, run an environment with at least one `lnd` node and has at least two nodes (the default environment, which has one of each node type, is good)
+1. Run `cp .env.example .env` in this directory
+1. Under the `Connect` tab for the `lnd` node in your Polar environment, copy the following values to `.env`:
+   - Copy the `Admin Macaroon` path to `ALICE_LND_MACAROON_PATH`
+   - Copy the `GRPC Host` path to `ALICE_LND_HOST`
+   - Copy the `TLS Cert` path to `ALICE_TLS_CERT_PATH`
+1. Install this app's dependencies by running `yarn`
+1. Run the app by running `yarn start`

examples/typescript/lnd/package.json

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+{
+  "name": "example-ts-lnd-app",
+  "version": "1.0.0",
+  "description": "An example TypeScript app developed using Polar",
+  "main": "src/index.js",
+  "license": "MIT",
+  "scripts": {
+    "start": "ts-node --transpile-only src/index.ts"
+  },
+  "dependencies": {
+    "@radar/lnrpc": "^0.11.1-beta.0",
+    "dotenv": "^8.2.0",
+    "inquirer": "^7.3.3",
+    "prompts": "^2.4.0"
+  },
+  "devDependencies": {
+    "@types/inquirer": "^7.3.1",
+    "@types/prompts": "^2.0.9",
+    "ts-node": "^9.1.1",
+    "typescript": "^4.1.2"
+  }
+}

examples/typescript/lnd/src/config.ts

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+import { LnRpcClientConfig } from '@radar/lnrpc';
+import dotenv from 'dotenv';
+
+dotenv.config();
+
+export const ALICE_LND: LnRpcClientConfig = {
+  server: String(process.env.ALICE_LND_HOST),
+  tls: String(process.env.ALICE_TLS_CERT_PATH),
+  macaroonPath: String(process.env.ALICE_LND_MACAROON_PATH),
+};

examples/typescript/lnd/src/index.ts

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+import createLnrpc from '@radar/lnrpc';
+import { ALICE_LND } from './config';
+import NodeHandler from './nodeHandler';
+
+(async () => {
+  const lnrpc = await createLnrpc(ALICE_LND);
+  const nodeHandler = new NodeHandler(lnrpc);
+  nodeHandler.whatWouldYouLikeToDo();
+})();

examples/typescript/lnd/src/nodeHandler.ts

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+import { LnRpc, Peer, WalletUnlockerRpc } from '@radar/lnrpc';
+import inquirer from 'inquirer';
+import { cropStringMiddle } from './utils';
+
+enum BaseAnswers {
+  OpenChannel = 'Open a channel',
+  ListPeers = 'List peers',
+  ListPendingChannels = 'List pending channels',
+  ListOpenChannels = 'List open channels',
+}
+
+export default class NodeHandler {
+  constructor(private lnrpc: LnRpc & WalletUnlockerRpc) {}
+
+  whatWouldYouLikeToDo = async () => {
+    try {
+      const info = await this.lnrpc.getInfo();
+      const { action } = await inquirer.prompt<{ action: BaseAnswers }>({
+        type: 'list',
+        name: 'action',
+        message: `Hi ${info.alias}, what would you like to do?`,
+        choices: Object.values(BaseAnswers),
+      });
+      let answerOrNextQuestion = await this.getAnswer(action);
+      while (typeof answerOrNextQuestion !== 'string') {
+        answerOrNextQuestion = await answerOrNextQuestion();
+      }
+      console.log(answerOrNextQuestion);
+      await this.whatWouldYouLikeToDo();
+    } catch (err) {
+      console.error('Sorry, something went wrong trying to connect with your LND node');
+    }
+  };
+
+  getAnswer = async (
+    question: BaseAnswers,
+  ): Promise<string | (() => Promise<string>)> => {
+    switch (question) {
+      case 'Open a channel': {
+        return this.specifyChannelOpeningParameters;
+      }
+      case 'List peers': {
+        const { peersWithAliases } = await this.getPeers();
+        return `Your peers:\n\n`.concat(
+          peersWithAliases.map(p => p.alias || cropStringMiddle(p.pubKey, 4)).join('\n'),
+        );
+      }
+      case 'List pending channels': {
+        const info = await this.lnrpc.pendingChannels();
+        return `Pending channels:\n${JSON.stringify(info)}`;
+      }
+      case 'List open channels': {
+        const info = await this.lnrpc.listChannels();
+        return `Open channels:\n${JSON.stringify(info)}`;
+      }
+      default:
+        throw new Error('Question not recognized');
+    }
+  };
+
+  specifyChannelOpeningParameters = async () => {
+    const { peersWithAliases } = await this.getPeers();
+    const { pubKey } = await inquirer.prompt<{ pubKey: string }>({
+      type: 'list',
+      name: 'pubKey',
+      message: 'Which peer would you like to open a channel with?',
+      choices: peersWithAliases.map(p => p.alias || cropStringMiddle(p.pubKey, 4)),
+    });
+    const { amount } = await inquirer.prompt<{ amount: number }>({
+      type: 'number',
+      name: 'amount',
+      message: 'How much (in Satoshis) would you like to open with (e.g. 100000)?',
+      validate: answer => {
+        if (!answer || answer < 100000) {
+          return 'You must choose an amount greater than 100,000 satoshis.';
+        }
+        return true;
+      },
+    });
+    await this.lnrpc.openChannelSync({
+      nodePubkeyString: pubKey,
+      localFundingAmount: amount.toString(),
+    });
+    return 'Success!';
+  };
+
+  getPeers = async () => {
+    const { peers } = await this.lnrpc.listPeers();
+    const { nodes } = await this.lnrpc.describeGraph();
+    const peersWithAliases = peers.map((peer, i) => {
+      const peerWithAlias: Peer & { alias?: string } = { ...peer };
+      const maybeNode = nodes.filter(e => e.pubKey === peerWithAlias.pubKey)[0];
+      if (maybeNode?.alias) {
+        peerWithAlias.alias = maybeNode.alias;
+      }
+      return peerWithAlias;
+    });
+    return { peersWithAliases };
+  };
+}

examples/typescript/lnd/src/utils.ts

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+/**
+ * Replaces the middle of a string with ellipses.
+ *
+ * @example
+ * // returns '03f1...7472'
+ * cropStringMiddle('03f101adfdb17bcca537b46c8bed691f88f9949865f448479a9245646f2b5c7472', 4);
+ * @param str
+ * @param around
+ */
+export const cropStringMiddle = (str: string, around: number) => {
+  if (around * 2 >= str.length) {
+    return str;
+  }
+  return str.substr(0, around) + '...' + str.substr(str.length - around, str.length);
+};

examples/typescript/lnd/tsconfig.json

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+{
+  "compilerOptions": {
+    /* Visit https://aka.ms/tsconfig.json to read more about this file */
+
+    /* Basic Options */
+    // "incremental": true,                   /* Enable incremental compilation */
+    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
+    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
+    // "lib": [],                             /* Specify library files to be included in the compilation. */
+    // "allowJs": true,                       /* Allow javascript files to be compiled. */
+    // "checkJs": true,                       /* Report errors in .js files. */
+    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
+    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
+    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
+    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
+    // "outFile": "./",                       /* Concatenate and emit output to single file. */
+    "outDir": "./dist",                        /* Redirect output structure to the directory. */
+    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
+    // "composite": true,                     /* Enable project compilation */
+    // "tsBuildInfoFile": "./",               /* Specify file to store incremental compilation information */
+    // "removeComments": true,                /* Do not emit comments to output. */
+    // "noEmit": true,                        /* Do not emit outputs. */
+    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
+    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
+    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
+
+    /* Strict Type-Checking Options */
+    "strict": true,                           /* Enable all strict type-checking options. */
+    // "noImplicitAny": true,                 /* Raise error on expressions and declarations with an implied 'any' type. */
+    // "strictNullChecks": true,              /* Enable strict null checks. */
+    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
+    // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
+    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
+    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
+    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
+
+    /* Additional Checks */
+    // "noUnusedLocals": true,                /* Report errors on unused locals. */
+    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
+    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
+    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
+    // "noUncheckedIndexedAccess": true,      /* Include 'undefined' in index signature results */
+
+    /* Module Resolution Options */
+    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
+    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
+    // "typeRoots": [],                       /* List of folders to include type definitions from. */
+    // "types": [],                           /* Type declaration files to be included in compilation. */
+    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
+    "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
+    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "allowUmdGlobalAccess": true,          /* Allow accessing UMD globals from modules. */
+
+    /* Source Map Options */
+    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
+    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
+    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
+    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
+
+    /* Experimental Options */
+    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
+    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
+
+    /* Advanced Options */
+    "skipLibCheck": true,                     /* Skip type checking of declaration files. */
+    "forceConsistentCasingInFileNames": true  /* Disallow inconsistently-cased references to the same file. */
+  }
+}