'use strict';

const _ = require('lodash');
const BbPromise = require('bluebird');
const path = require('path');
const resolveModulePath = require('ncjsm/resolve');
const memoizee = require('memoizee');
const spawn = require('child-process-ext/spawn');
const readFile = require('./fs/readFile');
const ServerlessError = require('../serverless-error');

const resolveTsNode = (serviceDir) => {
  const resolveModuleRealPath = (...args) =>
    resolveModulePath(...args).then(({ realPath }) => realPath);

  const ifNotFoundContinueWith = (cb) => (error) => {
    if (error.code !== 'MODULE_NOT_FOUND') throw error;
    return cb();
  };

  const resolveAsServerlessPeerDependency = () => resolveModuleRealPath(__dirname, 'ts-node');
  const resolveAsServiceDependency = () => resolveModuleRealPath(serviceDir, 'ts-node');
  const resolveAsGlobalInstallation = () =>
    spawn('npm', ['root', '-g']).then(
      ({ stdoutBuffer }) => require.resolve(`${String(stdoutBuffer).trim()}/ts-node`),
      (error) => {
        if (error.code !== 'ENOENT') throw error;
        throw Object.assign(new Error('npm not installed', { code: 'MODULE_NOT_FOUND' }));
      }
    );
  const throwTsNodeError = () => {
    throw new ServerlessError(
      'Ensure "ts-node" dependency when working with TypeScript configuration files',
      'TS_NODE_NOT_FOUND'
    );
  };

  return resolveAsServerlessPeerDependency()
    .catch(ifNotFoundContinueWith(resolveAsServiceDependency))
    .catch(ifNotFoundContinueWith(resolveAsGlobalInstallation))
    .catch(ifNotFoundContinueWith(throwTsNodeError));
};

const handleJsOrTsConfigFile = (configFile) =>
  BbPromise.try(() => {
    if (!configFile.endsWith('.ts')) return null;
    return resolveTsNode(path.dirname(configFile)).then((tsNodePath) => {
      try {
        require(tsNodePath).register();
      } catch (error) {
        throw new ServerlessError(
          `Registering "ts-node" failed with: ${error && error.stack ? error.stack : error}`
        );
      }
    });
  }).then(() => {
    try {
      return require(configFile);
    } catch (error) {
      throw new ServerlessError(
        `Loading ${configFile} failed with: ${error && error.stack ? error.stack : error}`
      );
    }
  });

const getServerlessConfigFile = memoizee(
  async (serverless) => {
    const configFilePath = serverless.configurationPath;
    if (!configFilePath) return null;
    const fileExtension = path.extname(configFilePath);
    const isJSOrTsConfigFile = fileExtension === '.js' || fileExtension === '.ts';

    const config = isJSOrTsConfigFile
      ? await handleJsOrTsConfigFile(configFilePath)
      : await readFile(configFilePath);

    if (_.isPlainObject(config)) return config;
    throw new ServerlessError(
      `${path.basename(configFilePath)} must export plain object`,
      'INVALID_CONFIG_OBJECT_TYPE'
    );
  },
  { promise: true }
);

module.exports = { getServerlessConfigFile };