'use strict';

const _ = require('lodash');
const assert = require('assert');
const moment = require('moment');
const SAPPassport = require('@sap/e2e-trace').Passport;
const consts = require('../constants');

const Logger = require('../logging-tools/Logger');
const NetworkLogger = require('../logging-tools/NetworkLogger');
const Tracer = require('../logging-tools/Tracer');

class LogContext {
  constructor(appContext, options) {
    this._timeCreated = moment();
    this._appContext = appContext;
    this._options = processOptions(options);
    this._sapPassport = parseSAPPassport(this);
  }

  getAppContext() {
    return this._appContext;
  }

  getLogger(category) {
    return new Logger(this, category);
  }

  getTracer(location) {
    return new Tracer(this, location);
  }

  get id() {
    return get(this, 'id', resolveId);
  }

  get correlationId() {
    return get(this, 'correlationId', resolveCorrelationId);
  }

  enableNetworkLog(res) {
    assert(_.isObject(res), 'Provided response should be an object');
    assert(this._options.hasOwnProperty('req'), 'The "req" property should be set to context in advance in order to enable network log');
    this._options.res = res;

    if (this._appContext._env.loggingOff) {
      return;
    }

    res.on('finish', () => {
      const networkLogger = new NetworkLogger(this);
      networkLogger.info();
    });
  }
}

function processOptions(options) {
  assert(options === undefined || _.isObject(options), 'Expected an object for log context options (if provided)');
  options = _.extend({}, options);
  assert(options.id === undefined || _.isString(options.id), '"id" (if provided) should be a string');
  assert(options.correlationId === undefined || _.isString(options.correlationId), '"correlationId" (if provided) should be a string');
  assert(options.req === undefined || _.isObject(options.req), '"req" (if provided) should be an object');
  return options;
}

function get(ctx, prop, fnResolve) {
  const options = ctx._options;
  if (!options.hasOwnProperty(prop)) {
    options[prop] = fnResolve(ctx);
  }
  return options[prop];
}

function resolveId(ctx) {
  const req = ctx._options.req;
  return (req && (req.headers['x-request-id'] || req.headers['x-vcap-request-id']))
    || ctx._appContext._idGen.nextId();
}

function resolveCorrelationId(ctx) {
  const req = ctx._options.req;
  return (req && req.headers['x-correlationid']) || ctx.id;
}

function parseSAPPassport(ctx) {
  const req = ctx._options.req;
  if (!req || !req.headers[SAPPassport.HEADER_NAME]) {
    return;
  }

  try {
    return new SAPPassport(req.headers[SAPPassport.HEADER_NAME]).readUniqueIdentifiers();
  } catch (err) {
    ctx.getLogger(consts.LIB_CATEGORY).error(err, 'Could not parse SAP Passport');
  }
}

module.exports = LogContext;