const { withDangerousMod } = require('@expo/config-plugins');
const fs = require('fs');
const path = require('path');

const MAX_JOBS = '8';

// React Native's hermes-engine build hardcodes
//   Runtime.getRuntime().availableProcessors()
// for cmake --build -j, ignoring all env vars.
// On high-core CI runners this exhausts memory.
// This plugin patches hermes-engine/build.gradle.kts
// during prebuild to cap parallel jobs.
const withCmakeJobLimit = (config) =>
  withDangerousMod(config, [
    'android',
    async (config) => {
      const root = config.modRequest.projectRoot;

      // 1. Patch hermes-engine: availableProcessors() -> "8"
      const hermesPath = path.join(
        root,
        'node_modules',
        'react-native',
        'ReactAndroid',
        'hermes-engine',
        'build.gradle.kts',
      );
      if (fs.existsSync(hermesPath)) {
        let content = fs.readFileSync(hermesPath, 'utf-8');
        content = content.replace(
          /Runtime\.getRuntime\(\)\.availableProcessors\(\)\.toString\(\)/,
          `"${MAX_JOBS}"`,
        );
        fs.writeFileSync(hermesPath, content);
      }

      // 2. Patch app/build.gradle: add cmake -j argument to externalNativeBuild
      const appGradlePath = path.join(
        config.modRequest.platformProjectRoot,
        'app',
        'build.gradle',
      );
      if (fs.existsSync(appGradlePath)) {
        let content = fs.readFileSync(appGradlePath, 'utf-8');
        // Insert externalNativeBuild cmake arguments block inside the android { } block
        // We add it right after "ndkVersion rootProject.ext.ndkVersion"
        if (!content.includes('CMAKE_BUILD_PARALLEL_LEVEL')) {
          content = content.replace(
            /(\s*ndkVersion rootProject\.ext\.ndkVersion)/,
            `$1\n    externalNativeBuild {\n        cmake {\n            arguments "-j${MAX_JOBS}"\n        }\n    }`,
          );
        }
        fs.writeFileSync(appGradlePath, content);
      }

      return config;
    },
  ]);

module.exports = withCmakeJobLimit;