Add eslint to project

eslint.config.mjs

@@ -0,0 +1,91 @@
+import typescriptEslint from "@typescript-eslint/eslint-plugin";
+import globals from "globals";
+import tsParser from "@typescript-eslint/parser";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import js from "@eslint/js";
+import { FlatCompat } from "@eslint/eslintrc";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const compat = new FlatCompat({
+    baseDirectory: __dirname,
+    recommendedConfig: js.configs.recommended,
+    allConfig: js.configs.all
+});
+
+export default [{
+    ignores: [
+        "src/templates",
+        "**/node_modules",
+        "**/dist",
+        "**/hack",
+        "**/pepr-test-module",
+        "**/build.mjs",
+        "**/journey",
+        "**/__mocks__",
+        "integration/testroot",
+    ],
+}, ...compat.extends("eslint:recommended", "plugin:@typescript-eslint/recommended"), {
+    plugins: {
+        "@typescript-eslint": typescriptEslint,
+    },
+
+    languageOptions: {
+        parser: tsParser,
+        parserOptions: {
+            projectService: {
+                allowDefaultProject: ["eslint.config.mjs"],
+            },
+            tsconfigRootDir: __dirname,
+            sourceType: "module",
+        },
+    },
+
+    rules: {
+        "@typescript-eslint/no-floating-promises": "warn",
+        "class-methods-use-this": "warn",
+
+        complexity: ["warn", {
+            max: 10,
+        }],
+
+        "consistent-this": "warn",
+        eqeqeq: "error",
+
+        "max-depth": ["warn", {
+            max: 3,
+        }],
+
+        "max-nested-callbacks": ["warn", {
+            max: 4,
+        }],
+
+        "max-params": ["error", {
+            max: 4,
+        }],
+
+        "max-statements": ["warn", {
+            max: 20,
+        }, {
+            ignoreTopLevelFunctions: true,
+        }],
+
+        "no-invalid-this": "warn",
+    },
+}, {
+    files: ["**/*.test.ts"],
+
+    rules: {
+        "max-nested-callbacks": ["warn", {
+            max: 8,
+        }],
+    },
+}, {
+    files: ["**/*.ts"],
+    ignores: ["**/*.test.ts"],
+
+    rules: {
+        "@typescript-eslint/explicit-function-return-type": "error",
+    },
+}];