import chalk from 'chalk';
import * as fs from 'fs';
import * as os from 'os';
import * as path from 'path';
import * as semver from 'semver';
import { ManifestDefinition } from 'oo-cli/dist/types/manifest';
import { TerminalOutput } from './TerminalOutput';
import { TerminalConfirm } from './TerminalConfirm';
import { TerminalPassthru } from './TeminalPassthru';

interface LastCheck {
  date: Date;
  upToDate: boolean;
}

const LAST_VERSION_CHECK_FILE = '.lastcheck';
const _24hours = 24 * 60 * 60 * 1000;

export async function checkForUpdate(manifest: ManifestDefinition): Promise<void> {
  const lastCheck = getLastCheck();
  if (lastCheck) {
    const now = new Date();
    if (now.getTime() - lastCheck.date.getTime() < _24hours && lastCheck.upToDate) {
      return;
    }
  }

  try {
    let upToDate = true;
    const latest = await fetchLatest();
    if (latest) {
      const installed = manifest.package?.version!;
      if (semver.gt(latest, installed)) {
        upToDate = false;
        if (await TerminalConfirm.ask(chalk.yellow('A new version of Opti CLI is available. Update now?'))) {
          TerminalPassthru.exec('yarn global upgrade @optimizely/opti-cli --latest');
        }
      }
    }
    setLastCheck(upToDate);
  } catch (e) {
    return;
  }
}

async function fetchLatest() {
  return TerminalOutput.exec('yarn info -s @optimizely/opti-cli dist-tags.latest').stdout.trim();
}

function getLastCheck(): LastCheck | undefined {
  const file = path.join(os.homedir(), `.opti/${LAST_VERSION_CHECK_FILE}`);
  if (fs.existsSync(file)) {
    const stat = fs.statSync(file);
    const upToDate = fs.readFileSync(file, {encoding: 'utf-8'}) === 'true';
    return {date: stat.mtime, upToDate};
  }
  return undefined;
}

function setLastCheck(upToDate: boolean) {
  const file = path.join(os.homedir(), `.opti/${LAST_VERSION_CHECK_FILE}`);
  fs.writeFileSync(file, upToDate.toString());
}