/*
 * Copyright Elasticsearch B.V. and other contributors where applicable.
 * Licensed under the BSD 2-Clause License; you may not use this file except in
 * compliance with the BSD 2-Clause License.
 */

'use strict';
const URL = require('url').URL;
const { httpRequest } = require('../http-request');
const DEFAULT_BASE_URL = new URL('/', 'http://metadata.google.internal:80');
/**
 * Checks for metadata server then fetches data
 *
 * The getMetadataGcp function will fetch cloud metadata information
 * from Amazon's IMDSv1 endpoint and return (via callback)
 * the formatted metadata.
 *
 * Before fetching data, the server will be "pinged" by attempting
 * to connect via TCP with a short timeout. (`connectTimeoutMs`)
 *
 * https://cloud.google.com/compute/docs/storing-retrieving-metadata
 */
function getMetadataGcp(
  connectTimeoutMs,
  resTimeoutMs,
  logger,
  baseUrlOverride,
  cb,
) {
  const baseUrl = baseUrlOverride || DEFAULT_BASE_URL;
  const options = {
    method: 'GET',
    timeout: resTimeoutMs,
    connectTimeout: connectTimeoutMs,
    headers: {
      'Metadata-Flavor': 'Google',
    },
  };
  const url = baseUrl + 'computeMetadata/v1/?recursive=true';
  const req = httpRequest(url, options, function (res) {
    const finalData = [];
    res.on('data', function (data) {
      finalData.push(data);
    });

    res.on('end', function (data) {
      let result;
      try {
        result = formatMetadataStringIntoObject(finalData.join(''));
      } catch (err) {
        logger.trace(
          'gcp metadata server responded, but there was an ' +
            'error parsing the result: %o',
          err,
        );
        cb(err);
        return;
      }
      cb(null, result);
    });
  });

  req.on('timeout', function () {
    req.destroy(new Error('request to metadata server timed out'));
  });

  req.on('connectTimeout', function () {
    req.destroy(new Error('could not ping metadata server'));
  });

  req.on('error', function (err) {
    cb(err);
  });

  req.end();
}

/**
 * Builds metadata object
 *
 * Takes the response from a /computeMetadata/v1/?recursive=true
 * service request and formats it into the cloud metadata object
 */
function formatMetadataStringIntoObject(string) {
  const data = JSON.parse(string);
  // cast string manipulation fields as strings "just in case"
  if (data.instance) {
    data.instance.machineType = String(data.instance.machineType);
    data.instance.zone = String(data.instance.zone);
  }

  const metadata = {
    availability_zone: null,
    region: null,
    instance: {
      id: null,
    },
    machine: {
      type: null,
    },
    provider: null,
    project: {
      id: null,
      name: null,
    },
  };

  metadata.availability_zone = null;
  metadata.region = null;
  if (data.instance && data.instance.zone) {
    // `projects/513326162531/zones/us-west1-b` manipuated into
    // `us-west1-b`, and then `us-west1`
    const regionWithZone = data.instance.zone.split('/').pop();
    const parts = regionWithZone.split('-');
    parts.pop();
    metadata.region = parts.join('-');
    metadata.availability_zone = regionWithZone;
  }

  if (data.instance) {
    metadata.instance = {
      id: String(data.instance.id),
    };

    metadata.machine = {
      type: String(data.instance.machineType.split('/').pop()),
    };
  } else {
    metadata.instance = {
      id: null,
    };

    metadata.machine = {
      type: null,
    };
  }

  metadata.provider = 'gcp';

  if (data.project) {
    metadata.project = {
      id: String(data.project.numericProjectId),
      name: String(data.project.projectId),
    };
  } else {
    metadata.project = {
      id: null,
      name: null,
    };
  }
  return metadata;
}

module.exports = { getMetadataGcp };