/**
 * @license
 * Copyright 2025 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import eslint from '@eslint/js';
import tseslint from 'typescript-eslint';
import reactPlugin from 'eslint-plugin-react';
import reactHooks from 'eslint-plugin-react-hooks';
import prettierConfig from 'eslint-config-prettier';
import importPlugin from 'eslint-plugin-import';
import vitest from '@vitest/eslint-plugin';
import globals from 'globals';
import headers from 'eslint-plugin-headers';
import path from 'node:path';
import url from 'node:url';

// --- ESM way to get __dirname ---
const __filename = url.fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
// --- ---

// Determine the monorepo root (assuming eslint.config.js is at the root)
const projectRoot = __dirname;
const currentYear = new Date().getFullYear();

const commonRestrictedSyntaxRules = [
  {
    selector: 'CallExpression[callee.name="require"]',
    message: 'Avoid using require(). Use ES6 imports instead.',
  },
  {
    selector: 'ThrowStatement > Literal:not([value=/^\\w+Error:/])',
    message:
      'Do not throw string literals or non-Error objects. Throw new Error("...") instead.',
  },
  {
    selector:
      'UnaryExpression[operator="typeof"] > MemberExpression[computed=true][property.type="Literal"]',
    message:
      'Do not use typeof to check object properties. Define a TypeScript interface and a type guard function instead.',
  },
  {
    selector: 'CatchClause > Identifier[name=/^_/]',
    message:
      'Do not use underscored identifiers in catch blocks. If the error is unused, use "catch {}". If it is used, remove the underscore.',
  },
];

export default tseslint.config(
  {
    // Global ignores
    ignores: [
      '**/node_modules/**',
      'eslint.config.js',
      '**/coverage/**',
      'packages/**/dist/**',
      'bundle/**',
      'package/bundle/**',
      '.integration-tests/**',
      'dist/**',
      'evals/**',
      'packages/test-utils/**',
      '.gemini/**',
      '**/*.d.ts',
    ],
  },
  eslint.configs.recommended,
  ...tseslint.configs.recommended,
  reactHooks.configs['recommended-latest'],
  reactPlugin.configs.flat.recommended,
  reactPlugin.configs.flat['jsx-runtime'], // Add this if you are using React 17+
  {
    // Settings for eslint-plugin-react
    settings: {
      react: {
        version: 'detect',
      },
    },
  },
  {
    // Rules for packages/*/src (TS/TSX)
    files: ['packages/*/src/**/*.{ts,tsx}'],
    plugins: {
      import: importPlugin,
    },
    settings: {
      'import/resolver': {
        node: true,
      },
    },
    languageOptions: {
      parser: tseslint.parser,
      parserOptions: {
        projectService: true,
        tsconfigRootDir: projectRoot,
      },
      globals: {
        ...globals.node,
        ...globals.es2021,
      },
    },
    rules: {
      ...importPlugin.configs.recommended.rules,
      ...importPlugin.configs.typescript.rules,
      'import/no-default-export': 'warn',
      'import/no-unresolved': 'off',
      'import/no-duplicates': 'error',
      // General Best Practice Rules (subset adapted for flat config)
      '@typescript-eslint/array-type': ['error', { default: 'array-simple' }],
      'arrow-body-style': ['error', 'as-needed'],
      curly: ['error', 'multi-line'],
      eqeqeq: ['error', 'always', { null: 'ignore' }],
      '@typescript-eslint/consistent-type-assertions': [
        'error',
        { assertionStyle: 'as' },
      ],
      '@typescript-eslint/explicit-member-accessibility': [
        'error',
        { accessibility: 'no-public' },
      ],
      '@typescript-eslint/no-explicit-any': 'error',
      '@typescript-eslint/no-inferrable-types': [
        'error',
        { ignoreParameters: true, ignoreProperties: true },
      ],
      '@typescript-eslint/consistent-type-imports': [
        'error',
        { disallowTypeAnnotations: false },
      ],
      '@typescript-eslint/no-namespace': ['error', { allowDeclarations: true }],
      '@typescript-eslint/no-unused-vars': [
        'error',
        {
          argsIgnorePattern: '^_',
          varsIgnorePattern: '^_',
          caughtErrors: 'all',
        },
      ],
      // Prevent async errors from bypassing catch handlers
      '@typescript-eslint/return-await': ['error', 'in-try-catch'],
      'import/no-internal-modules': 'off',
      'import/no-relative-packages': 'error',
      'no-cond-assign': 'error',
      'no-debugger': 'error',
      'no-duplicate-case': 'error',
      'no-restricted-syntax': ['error', ...commonRestrictedSyntaxRules],
      'no-unsafe-finally': 'error',
      'no-unused-expressions': 'off', // Disable base rule
      '@typescript-eslint/no-unused-expressions': [
        // Enable TS version
        'error',
        { allowShortCircuit: true, allowTernary: true },
      ],
      'no-var': 'error',
      'object-shorthand': 'error',
      'one-var': ['error', 'never'],
      'prefer-arrow-callback': 'error',
      'prefer-const': ['error', { destructuring: 'all' }],
      radix: 'error',
      'no-console': 'error',
      'default-case': 'error',
      '@typescript-eslint/await-thenable': ['error'],
      '@typescript-eslint/no-floating-promises': ['error'],
      '@typescript-eslint/no-unnecessary-type-assertion': ['error'],
      '@typescript-eslint/no-misused-spread': ['error'],
      'no-restricted-imports': [
        'error',
        {
          paths: [
            {
              name: 'node:os',
              importNames: ['homedir', 'tmpdir'],
              message:
                'Please use the helpers from @google/gemini-cli-core instead of node:os homedir()/tmpdir() to ensure strict environment isolation.',
            },
            {
              name: 'os',
              importNames: ['homedir', 'tmpdir'],
              message:
                'Please use the helpers from @google/gemini-cli-core instead of os homedir()/tmpdir() to ensure strict environment isolation.',
            },
          ],
        },
      ],
    },
  },
  {
    // API Response Optionality enforcement for Code Assist
    files: ['packages/core/src/code_assist/**/*.{ts,tsx}'],
    rules: {
      'no-restricted-syntax': [
        'error',
        ...commonRestrictedSyntaxRules,
        {
          selector:
            'TSInterfaceDeclaration[id.name=/.+Response$/] TSPropertySignature:not([optional=true])',
          message:
            'All fields in API response interfaces (*Response) must be marked as optional (?) to prevent developers from accidentally assuming a field will always be present based on current backend behavior.',
        },
        {
          selector:
            'TSTypeAliasDeclaration[id.name=/.+Response$/] TSPropertySignature:not([optional=true])',
          message:
            'All fields in API response types (*Response) must be marked as optional (?) to prevent developers from accidentally assuming a field will always be present based on current backend behavior.',
        },
      ],
    },
  },
  {
    // Rules that only apply to product code
    files: ['packages/*/src/**/*.{ts,tsx}'],
    ignores: ['**/*.test.ts', '**/*.test.tsx', 'packages/*/src/test-utils/**'],
    rules: {
      '@typescript-eslint/no-unsafe-type-assertion': 'error',
      '@typescript-eslint/no-unsafe-assignment': 'error',
      '@typescript-eslint/no-unsafe-return': 'error',
      'no-restricted-syntax': [
        'error',
        ...commonRestrictedSyntaxRules,
        {
          selector:
            'CallExpression[callee.object.name="Object"][callee.property.name="create"]',
          message:
            'Avoid using Object.create() in product code. Use object spread {...obj}, explicit class instantiation, structuredClone(), or copy constructors instead.',
        },
        {
          selector: 'Identifier[name="Reflect"]',
          message:
            'Avoid using Reflect namespace in product code. Do not use reflection to make copies. Instead, use explicit object copying or cloning (structuredClone() for values, new instance/clone function for classes).',
        },
      ],
    },
  },
  {
    // Allow os.homedir() in tests and paths.ts where it is used to implement the helper
    files: [
      '**/*.test.ts',
      '**/*.test.tsx',
      'packages/core/src/utils/paths.ts',
      'packages/test-utils/src/**/*.ts',
      'scripts/**/*.js',
    ],
    rules: {
      'no-restricted-imports': 'off',
    },
  },
  {
    // Prevent self-imports in packages
    files: ['packages/core/src/**/*.{ts,tsx}'],
    rules: {
      'no-restricted-imports': [
        'error',
        {
          name: '@google/gemini-cli-core',
          message: 'Please use relative imports within the @google/gemini-cli-core package.',
        },
      ],
    },
  },
  {
    files: ['packages/cli/src/**/*.{ts,tsx}'],
    rules: {
      'no-restricted-imports': [
        'error',
        {
          name: '@google/gemini-cli',
          message: 'Please use relative imports within the @google/gemini-cli package.',
        },
      ],
    },
  },
  {
    files: ['packages/sdk/src/**/*.{ts,tsx}'],
    rules: {
      'no-restricted-imports': [
        'error',
        {
          name: '@google/gemini-cli-sdk',
          message: 'Please use relative imports within the @google/gemini-cli-sdk package.',
        },
      ],
    },
  },
  {
    files: ['packages/*/src/**/*.test.{ts,tsx}'],
    plugins: {
      vitest,
    },
    rules: {
      ...vitest.configs.recommended.rules,
      'vitest/expect-expect': 'off',
      'vitest/no-commented-out-tests': 'off',
      'no-restricted-syntax': ['error', ...commonRestrictedSyntaxRules],
    },
  },
  {
    files: ['./**/*.{tsx,ts,js,cjs}'],
    plugins: {
      headers,
      import: importPlugin,
    },
    rules: {
      'headers/header-format': [
        'error',
        {
          source: 'string',
          content: [
            '@license',
            'Copyright (year) Google LLC',
            'SPDX-License-Identifier: Apache-2.0',
          ].join('\n'),
          patterns: {
            year: {
              pattern: `202[5-${currentYear.toString().slice(-1)}]`,
              defaultValue: currentYear.toString(),
            },
          },
        },
      ],
      'import/enforce-node-protocol-usage': ['error', 'always'],
    },
  },
  {
    files: [
      './scripts/**/*.js',
      'packages/*/scripts/**/*.js',
      'esbuild.config.js',
      'packages/core/scripts/**/*.{js,mjs}',
    ],
    languageOptions: {
      globals: {
        ...globals.node,
        process: 'readonly',
        console: 'readonly',
      },
    },
    rules: {
      '@typescript-eslint/no-unused-vars': [
        'error',
        {
          argsIgnorePattern: '^_',
          varsIgnorePattern: '^_',
          caughtErrors: 'all',
        },
      ],
    },
  },
  {
    files: ['**/*.cjs'],
    languageOptions: {
      sourceType: 'commonjs',
      globals: {
        ...globals.node,
      },
    },
    rules: {
      'no-restricted-syntax': 'off',
      'no-console': 'off',
      'no-empty': 'off',
      'no-redeclare': 'off',
      '@typescript-eslint/no-require-imports': 'off',
      '@typescript-eslint/no-unused-vars': [
        'error',
        {
          argsIgnorePattern: '^_',
          varsIgnorePattern: '^_',
          caughtErrors: 'all',
        },
      ],
    },
  },
  {
    files: ['packages/vscode-ide-companion/esbuild.js'],
    languageOptions: {
      globals: {
        ...globals.node,
        process: 'readonly',
        console: 'readonly',
      },
    },
    rules: {
      'no-restricted-syntax': 'off',
      '@typescript-eslint/no-require-imports': 'off',
    },
  },
  // Examples should have access to standard globals like fetch
  {
    files: ['packages/cli/src/commands/extensions/examples/**/*.js'],
    languageOptions: {
      globals: {
        ...globals.node,
        fetch: 'readonly',
      },
    },
  },
  // extra settings for scripts that we run directly with node
  {
    files: ['packages/vscode-ide-companion/scripts/**/*.js'],
    languageOptions: {
      globals: {
        ...globals.node,
        process: 'readonly',
        console: 'readonly',
      },
    },
    rules: {
      'no-restricted-syntax': 'off',
      '@typescript-eslint/no-require-imports': 'off',
    },
  },
  // Prettier config must be last
  prettierConfig,
  // extra settings for scripts that we run directly with node
  {
    files: ['./integration-tests/**/*.js'],
    languageOptions: {
      globals: {
        ...globals.node,
        process: 'readonly',
        console: 'readonly',
      },
    },
    rules: {
      '@typescript-eslint/no-unused-vars': [
        'error',
        {
          argsIgnorePattern: '^_',
          varsIgnorePattern: '^_',
          caughtErrors: 'all',
        },
      ],
    },
  },
);
