import crypto from 'node:crypto';
import os from 'node:os';
import { env } from 'node:process';
import v8 from 'node:v8';
import { minimatch } from 'minimatch';
import type { JestConfigWithTsJest } from 'ts-jest';

const ci = !!process.env.CI;

type JestConfig = JestConfigWithTsJest & {
  // https://github.com/renovatebot/renovate/issues/17034
  workerIdleMemoryLimit?: string;
};

const cpus = os.cpus();
const mem = os.totalmem();
const stats = v8.getHeapStatistics();

/**
 * https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources
 * Currently it seems the runner only have 4GB
 */
function jestGithubRunnerSpecs(): JestConfig {
  // if (os.platform() === 'darwin') {
  //   return {
  //     maxWorkers: 2,
  //     workerIdleMemoryLimit: '4GB',
  //   };
  // }

  return {
    maxWorkers: cpus.length,
    workerIdleMemoryLimit: '1500MB', // '2GB',
  };
}

/**
 * Configuration for single test shard.
 */
interface ShardConfig {
  /**
   * Path patterns to match against the test file paths, of two types:
   *
   * 1. Particular file, e.g. `lib/util/git/index.spec.ts`
   *
   *    - File pattern MUST end with `.spec.ts`
   *    - This will only search for the particular test file
   *    - It enables coverage for the `*.ts` file with the same name,
   *      e.g. `lib/util/git/index.ts`
   *    - You probably want to use directory pattern instead
   *
   * 2. Whole directory, e.g. `lib/modules/datasource`
   *
   *    - This will search for all `*.spec.ts` files under the directory
   *    - It enables coverage all `*.ts` files under the directory,
   *      e.g. `lib/modules/datasource/foo/bar/baz.ts`
   */
  matchPaths: string[];
}

/**
 * Configuration for test shards that can be run with `TEST_SHARD` environment variable.
 *
 * For each shard, we specify a subset of tests to run.
 * The tests from previous shards are excluded from the next shard.
 *
 * Storing shards config in the separate file helps to form CI matrix
 * using pre-installed `jq` utility.
 */
const testShards: Record<string, ShardConfig> = {
  'datasources-1': {
    matchPaths: ['lib/modules/datasource/[a-g]*'],
  },
  'datasources-2': {
    matchPaths: ['lib/modules/datasource'],
  },
  'managers-1': {
    matchPaths: ['lib/modules/manager/[a-c]*'],
  },
  'managers-2': {
    matchPaths: ['lib/modules/manager/[d-h]*'],
  },
  'managers-3': {
    matchPaths: ['lib/modules/manager/[i-n]*'],
  },
  'managers-4': {
    matchPaths: ['lib/modules/manager'],
  },
  platform: {
    matchPaths: ['lib/modules/platform'],
  },
  versioning: {
    matchPaths: ['lib/modules/versioning'],
  },
  'workers-1': {
    matchPaths: [
      'lib/workers/repository/changelog',
      'lib/workers/repository/config-migration',
      'lib/workers/repository/extract',
      'lib/workers/repository/finalize',
      'lib/workers/repository/init',
      'lib/workers/repository/model',
    ],
  },
  'workers-2': {
    matchPaths: [
      'lib/workers/repository/onboarding',
      'lib/workers/repository/process',
    ],
  },
  'workers-3': {
    matchPaths: [
      'lib/workers/repository/update',
      'lib/workers/repository/updates',
    ],
  },
  'workers-4': {
    matchPaths: ['lib/workers'],
  },
  'git-1': {
    matchPaths: ['lib/util/git/index.spec.ts'],
  },
  'git-2': {
    matchPaths: ['lib/util/git'],
  },
  util: {
    matchPaths: ['lib/util'],
  },
  other: {
    matchPaths: ['lib'],
  },
};

/**
 * Subset of Jest config that is relevant for sharded test run.
 */
type JestShardedSubconfig = Pick<JestConfig, 'testMatch' | 'coverageDirectory'>;

/**
 * Convert match pattern to a form that matches on file with `.ts` or `.spec.ts` extension.
 */
function normalizePattern(pattern: string, suffix: '.ts' | '.spec.ts'): string {
  return pattern.endsWith('.spec.ts')
    ? pattern.replace(/\.spec\.ts$/, suffix)
    : `${pattern}/**/*${suffix}`;
}

/**
 * Generates Jest config for sharded test run.
 *
 * If `TEST_SHARD` environment variable is not set,
 * it falls back to the provided config.
 *
 * Otherwise, `fallback` value is used to determine some defaults.
 */
function configureShardingOrFallbackTo(
  fallback: JestShardedSubconfig,
): JestShardedSubconfig {
  const shardKey = process.env.TEST_SHARD;
  if (!shardKey) {
    return fallback;
  }

  if (!testShards[shardKey]) {
    const keys = Object.keys(testShards).join(', ');
    throw new Error(
      `Unknown value for TEST_SHARD: ${shardKey} (possible values: ${keys})`,
    );
  }

  const testMatch: string[] = [];

  for (const [key, { matchPaths: patterns }] of Object.entries(testShards)) {
    if (key === shardKey) {
      const testMatchPatterns = patterns.map((pattern) => {
        const filePattern = normalizePattern(pattern, '.spec.ts');
        return `<rootDir>/${filePattern}`;
      });
      testMatch.push(...testMatchPatterns);
      break;
    }

    const testMatchPatterns = patterns.map((pattern) => {
      const filePattern = normalizePattern(pattern, '.spec.ts');
      return `!**/${filePattern}`;
    });
    testMatch.push(...testMatchPatterns);
  }

  testMatch.reverse();

  const coverageDirectory = `./coverage/shard/${shardKey}`;
  return {
    testMatch,
    coverageDirectory,
  };
}

const config: JestConfig = {
  ...configureShardingOrFallbackTo({
    coverageDirectory: './coverage',
  }),
  collectCoverageFrom: [
    'lib/**/*.{js,ts}',
    '!lib/**/*.{d,spec}.ts',
    '!lib/**/{__fixtures__,__mocks__,__testutil__,test}/**/*.{js,ts}',
    '!lib/**/types.ts',
  ],
  coveragePathIgnorePatterns: getCoverageIgnorePatterns(),
  cacheDirectory: '.cache/jest',
  collectCoverage: true,
  coverageReporters: ci
    ? ['lcovonly', 'json']
    : ['html', 'text-summary', 'json'],
  transform: {
    '\\.ts$': [
      'ts-jest',
      {
        tsconfig: '<rootDir>/tsconfig.spec.json',
        diagnostics: false,
        isolatedModules: true,
      },
    ],
  },
  modulePathIgnorePatterns: [
    '<rootDir>/dist/',
    '/__fixtures__/',
    '/__mocks__/',
  ],
  reporters: ci ? ['default', 'github-actions'] : ['default'],
  resetMocks: true,
  setupFilesAfterEnv: [
    'jest-extended/all',
    'expect-more-jest',
    '<rootDir>/test/setup.ts',
    '<rootDir>/test/to-migrate.ts',
  ],
  snapshotSerializers: ['<rootDir>/test/newline-snapshot-serializer.ts'],
  testEnvironment: 'node',
  testRunner: 'jest-circus/runner',
  watchPathIgnorePatterns: ['<rootDir>/.cache/', '<rootDir>/coverage/'],
  // We can play with that value later for best dev experience
  workerIdleMemoryLimit: '500MB',
  // add github runner specific limits
  ...(ci && jestGithubRunnerSpecs()),
};

export default config;

type RunsOn = 'ubuntu-latest' | 'windows-latest' | 'macos-latest';

interface ShardGroup {
  /**
   * Input for `runs-on` field.
   */
  os: RunsOn;

  /**
   * Controls whether coverage is collected for this shard group.
   */
  coverage: boolean;

  /**
   * Input for `name` field.
   */
  name: string;

  /**
   * Space-separated list of shard keys, it's
   * meant to be inserted into bash for-loop.
   */
  shards: string;

  /**
   * It's meant to be used for Jest caching.
   */
  'cache-key': string;

  /**
   * It's used to set test runner timeout.
   */
  'runner-timeout-minutes': number;

  /**
   * It's used to set `--test-timeout` Jest CLI flag.
   */
  'test-timeout-milliseconds': number;

  /**
   * It's used as the name for coverage artifact.
   */
  'upload-artifact-name': string;
}

/**
 * Given the file list affected by commit, return the list
 * of shards that  test these changes.
 */
function getMatchingShards(files: string[]): string[] {
  const matchingShards = new Set<string>();
  for (const file of files) {
    for (const [key, { matchPaths }] of Object.entries(testShards)) {
      const patterns = matchPaths.map((path) =>
        path.endsWith('.spec.ts')
          ? path.replace(/\.spec\.ts$/, '{.ts,.spec.ts}')
          : `${path}/**/*`,
      );

      if (patterns.some((pattern) => minimatch(file, pattern))) {
        matchingShards.add(key);
        break;
      }
    }
  }

  return Object.keys(testShards).filter((shard) => matchingShards.has(shard));
}

/**
 * Distribute items evenly across runner instances.
 */
function scheduleItems<T>(items: T[], availableInstances: number): T[][] {
  const numInstances = Math.min(items.length, availableInstances);
  const maxPerInstance = Math.ceil(items.length / numInstances);
  const lighterInstancesIdx =
    items.length % numInstances === 0
      ? numInstances
      : items.length % numInstances;

  const partitionSizes = Array.from({ length: numInstances }, (_, idx) =>
    idx < lighterInstancesIdx ? maxPerInstance : maxPerInstance - 1,
  );

  const result: T[][] = Array.from({ length: numInstances }, () => []);
  let rest = items.slice();
  for (let idx = 0; idx < numInstances; idx += 1) {
    const partitionSize = partitionSizes[idx];
    const partition = rest.slice(0, partitionSize);
    result[idx] = partition;
    rest = rest.slice(partitionSize);
  }

  return result;
}

/**
 * If `SCHEDULE_TEST_SHARDS` env variable is set, it means we're in `setup` CI job.
 * We don't want to see anything except key-value pairs in the output.
 * Otherwise, we're printing useful stats.
 */
if (process.env.SCHEDULE_TEST_SHARDS) {
  let shardKeys = Object.keys(testShards);

  if (process.env.FILTER_SHARDS === 'true' && process.env.CHANGED_FILES) {
    try {
      const changedFiles: string[] = JSON.parse(process.env.CHANGED_FILES);
      const matchingShards = getMatchingShards(changedFiles);
      if (matchingShards.length === 0) {
        // eslint-disable-next-line no-console
        console.log(`test-matrix-empty=true`);
        process.exit(0);
      }
      shardKeys = shardKeys.filter((key) => matchingShards.includes(key));
    } catch (err) {
      // eslint-disable-next-line no-console
      console.error(err);
      process.exit(1);
    }
  }

  /**
   * Not all runners are created equal.
   * Minutes cost proportion is 1:2:10 for Ubuntu:Windows:MacOS.
   *
   * Although it's free in our case,
   * we can't run as many Windows and MacOS runners as we want.
   *
   * Because of this, we partition shards into groups, given that:
   * - There are 16 shards in total
   * - We can't run more than 10 Windows runners
   * - We can't run more than 5 MacOS runners
   */
  const shardGrouping: Record<string, string[][]> = {
    'ubuntu-latest': scheduleItems(shardKeys, 16),
  };

  if (process.env.ALL_PLATFORMS === 'true') {
    // shardGrouping['windows-latest'] = scheduleItems(shardKeys, 8);
    shardGrouping['macos-latest'] = scheduleItems(shardKeys, 4);
  }

  const shardGroups: ShardGroup[] = [];
  for (const [os, groups] of Object.entries(shardGrouping)) {
    const coverage = os === 'ubuntu-latest';

    const total = groups.length;
    for (let idx = 0; idx < groups.length; idx += 1) {
      const number = idx + 1;
      const platform = os.replace(/-latest$/, '');
      const name =
        platform === 'ubuntu'
          ? `test (${number}/${total})`
          : `test-${platform} (${number}/${total})`;

      const shards = groups[idx];
      const cacheKey = crypto
        .createHash('md5')
        .update(shards.join(':'))
        .digest('hex');

      const runnerTimeoutMinutes =
        {
          ubuntu: 10,
          windows: 20,
          macos: 20,
        }[platform] ?? 20;

      const testTimeoutMilliseconds =
        {
          windows: 240000,
        }[platform] ?? 120000;

      shardGroups.push({
        os: os as RunsOn,
        coverage,
        name,
        shards: shards.join(' '),
        'cache-key': cacheKey,
        'runner-timeout-minutes': runnerTimeoutMinutes,
        'test-timeout-milliseconds': testTimeoutMilliseconds,
        'upload-artifact-name': `coverage-${shards.sort().join('_')}`,
      });
    }
  }

  /**
   * Output will be consumed by `setup` CI job.
   */
  // eslint-disable-next-line no-console
  console.log(`test-shard-matrix=${JSON.stringify(shardGroups)}`);

  process.exit(0);
}

process.stderr.write(`Host stats:
    Cpus:      ${cpus.length}
    Memory:    ${(mem / 1024 / 1024 / 1024).toFixed(2)} GB
    HeapLimit: ${(stats.heap_size_limit / 1024 / 1024 / 1024).toFixed(2)} GB
  `);
function getCoverageIgnorePatterns(): string[] | undefined {
  const patterns = ['/node_modules/', '<rootDir>/test/', '<rootDir>/tools/'];

  if (env.TEST_LEGACY_DECRYPTION !== 'true') {
    patterns.push('<rootDir>/lib/config/decrypt/legacy.ts');
  }

  return patterns;
}