import { promises as fs } from 'fs';
import path from 'path';
import lockfile from 'proper-lockfile';

import type { HardhatRuntimeEnvironment } from 'hardhat/types/hre';
import {
  ValidationDataCurrent,
  ValidationRunData,
  concatRunData,
  isCurrentValidationData,
} from '@openzeppelin/upgrades-core';

async function lock(file: string) {
  await fs.mkdir(path.dirname(file), { recursive: true });
  return lockfile.lock(file, { retries: { minTimeout: 50, factor: 1.3 }, realpath: false });
}

export async function writeValidations(hre: HardhatRuntimeEnvironment, newRunData: ValidationRunData): Promise<void> {
  const cachePath = getValidationsCachePath(hre);
  let releaseLock;
  try {
    releaseLock = await lock(cachePath);
    const storedData = await readValidations(hre, false).catch(e => {
      // No prior data to append to: either the cache file is absent, or it was
      // outdated and readValidations has already removed it. In both cases,
      // write from scratch.
      if (e instanceof ValidationsCacheNotFound || e instanceof ValidationsCacheOutdated) {
        return undefined;
      } else {
        throw e;
      }
    });
    const validations = concatRunData(newRunData, storedData);
    await fs.writeFile(cachePath, JSON.stringify(validations, null, 2));
  } finally {
    await releaseLock?.();
  }
}

export async function readValidations(
  hre: HardhatRuntimeEnvironment,
  acquireLock = true,
): Promise<ValidationDataCurrent> {
  const cachePath = getValidationsCachePath(hre);
  let releaseLock;
  try {
    if (acquireLock) {
      releaseLock = await lock(cachePath);
    }
    const data = JSON.parse(await fs.readFile(cachePath, 'utf8'));
    if (!isCurrentValidationData(data)) {
      await fs.unlink(cachePath);
      throw new ValidationsCacheOutdated();
    }
    return data;
  } catch (e: any) {
    if (e.code === 'ENOENT') {
      throw new ValidationsCacheNotFound();
    } else {
      throw e;
    }
  } finally {
    await releaseLock?.();
  }
}

export class ValidationsCacheNotFound extends Error {
  constructor() {
    super('Validations cache not found. Recompile with `hardhat compile --force`');
  }
}

export class ValidationsCacheOutdated extends Error {
  constructor() {
    super('Validations cache is outdated. Recompile with `hardhat compile --force`');
  }
}

function getValidationsCachePath(hre: HardhatRuntimeEnvironment): string {
  return path.join(hre.config.paths.cache, 'validations.json');
}