feat: class administrators and also number of students

Author: jeffreymeng

.firebaserc

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+{
+  "projects": {
+    "default": "usaco-guide"
+  }
+}

firebase.json

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+{
+  "functions": {
+    "predeploy": [
+      "npm --prefix \"$RESOURCE_DIR\" run lint",
+      "npm --prefix \"$RESOURCE_DIR\" run build"
+    ]
+  }
+}

functions/.eslintrc.js

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+module.exports = {
+  env: {
+    browser: true,
+    es6: true,
+    node: true,
+  },
+  extends: [
+    'plugin:import/errors',
+    'plugin:import/warnings',
+    'plugin:import/typescript',
+  ],
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    project: 'tsconfig.json',
+    sourceType: 'module',
+  },
+  plugins: ['@typescript-eslint', 'import'],
+  rules: {
+    '@typescript-eslint/adjacent-overload-signatures': 'error',
+    '@typescript-eslint/no-empty-function': 'error',
+    '@typescript-eslint/no-empty-interface': 'warn',
+    '@typescript-eslint/no-floating-promises': 'error',
+    '@typescript-eslint/no-namespace': 'error',
+    '@typescript-eslint/no-unnecessary-type-assertion': 'error',
+    '@typescript-eslint/prefer-for-of': 'warn',
+    '@typescript-eslint/triple-slash-reference': 'error',
+    '@typescript-eslint/unified-signatures': 'warn',
+    'comma-dangle': 'warn',
+    'constructor-super': 'error',
+    eqeqeq: ['warn', 'always'],
+    'import/no-deprecated': 'warn',
+    'import/no-extraneous-dependencies': 'error',
+    'import/no-unassigned-import': 'warn',
+    'no-cond-assign': 'error',
+    'no-duplicate-case': 'error',
+    'no-duplicate-imports': 'error',
+    'no-empty': [
+      'error',
+      {
+        allowEmptyCatch: true,
+      },
+    ],
+    'no-invalid-this': 'error',
+    'no-new-wrappers': 'error',
+    'no-param-reassign': 'error',
+    'no-redeclare': 'error',
+    'no-sequences': 'error',
+    'no-shadow': [
+      'error',
+      {
+        hoist: 'all',
+      },
+    ],
+    'no-throw-literal': 'error',
+    'no-unsafe-finally': 'error',
+    'no-unused-labels': 'error',
+    'no-var': 'warn',
+    'no-void': 'error',
+    'prefer-const': 'warn',
+  },
+  settings: {
+    jsdoc: {
+      tagNamePreference: {
+        returns: 'return',
+      },
+    },
+  },
+};

functions/.gitignore

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+# Compiled JavaScript files
+**/*.js
+**/*.js.map
+
+# Except the ESLint config file
+!.eslintrc.js
+
+# TypeScript v1 declaration files
+typings/
+
+# Node.js dependency directory
+node_modules/

functions/package.json

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+{
+  "name": "functions",
+  "scripts": {
+    "lint": "eslint \"src/**/*\"",
+    "build": "tsc",
+    "serve": "npm run build && firebase emulators:start --only functions",
+    "shell": "npm run build && firebase functions:shell",
+    "start": "npm run shell",
+    "deploy": "firebase deploy --only functions",
+    "logs": "firebase functions:log"
+  },
+  "engines": {
+    "node": "12"
+  },
+  "main": "lib/index.js",
+  "dependencies": {
+    "@types/vfile-message": "^2.0.0",
+    "firebase-admin": "^9.2.0",
+    "firebase-functions": "^3.11.0"
+  },
+  "devDependencies": {
+    "@typescript-eslint/eslint-plugin": "^3.9.1",
+    "@typescript-eslint/parser": "^3.8.0",
+    "eslint": "^7.6.0",
+    "eslint-plugin-import": "^2.22.0",
+    "firebase-functions-test": "^0.2.0",
+    "typescript": "^3.8.0"
+  },
+  "private": true
+}

functions/src/index.ts

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+import * as functions from 'firebase-functions';
+import admin from 'firebase-admin';
+admin.initializeApp();
+
+export const getUsers = functions.https.onCall(
+  (
+    data: {
+      users: ({ uid: string } | { email: string })[];
+    },
+    context
+  ) => {
+    const { users } = data;
+    const callerUid = context.auth?.uid;
+
+    if (!callerUid || !users || users.length === 0) {
+      throw new functions.https.HttpsError(
+        'invalid-argument',
+        'The function was not called with the correct data, or the caller is not logged in.'
+      );
+    }
+    return admin
+      .firestore()
+      .collection('classes')
+      .doc('permissions')
+      .get()
+      .then(snapshot => snapshot.data())
+      .then(permissions => {
+        if (
+          !permissions?.admins?.includes(callerUid) &&
+          !permissions?.instructors?.includes(callerUid)
+        ) {
+          throw new functions.https.HttpsError(
+            'permission-denied',
+            'Caller is not an admin or instructor.'
+          );
+        } else {
+          return admin.auth().getUsers(users);
+        }
+      });
+  }
+);

functions/tsconfig.json

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+{
+  "compilerOptions": {
+    "module": "commonjs",
+    "noImplicitReturns": true,
+    "noUnusedLocals": true,
+    "outDir": "lib",
+    "sourceMap": true,
+    "target": "es2017",
+
+    "esModuleInterop": true
+  },
+  "compileOnSave": true,
+  "include": ["src"]
+}