/* eslint-env mocha */
const testDb = 'workspace/test.db'
const { promises: fs } = require('fs')
const assert = require('assert').strict
const Datastore = require('../lib/datastore')
const Persistence = require('../lib/persistence')
const { exists } = require('./utils.test.js')

// Test that operations are executed in the right order
// We prevent Mocha from catching the exception we throw on purpose by remembering all current handlers, remove them and register them back after test ends
const testRightOrder = async d => {
  const docs = await d.findAsync({})
  assert.equal(docs.length, 0)

  await d.insertAsync({ a: 1 })
  await d.updateAsync({ a: 1 }, { a: 2 }, {})
  const docs2 = await d.findAsync({})
  assert.equal(docs2[0].a, 2)
  d.updateAsync({ a: 2 }, { a: 3 }, {}) // not awaiting
  d.executor.pushAsync(async () => { throw new Error('Some error') }) // not awaiting
  const docs3 = await d.findAsync({})
  assert.equal(docs3[0].a, 3)
}

// Note:  The following test does not have any assertion because it
// is meant to address the deprecation warning:
// (node) warning: Recursive process.nextTick detected. This will break in the next version of node. Please use setImmediate for recursive deferral.
// see
const testEventLoopStarvation = async d => {
  const times = 1001
  let i = 0
  while (i < times) {
    i++
    d.findAsync({ bogus: 'search' })
  }
  await d.findAsync({ bogus: 'search' })
}

// Test that operations are executed in the right order even with no callback
const testExecutorWorksWithoutCallback = async d => {
  d.insertAsync({ a: 1 })
  d.insertAsync({ a: 2 })
  const docs = await d.findAsync({})
  assert.equal(docs.length, 2)
}

describe('Executor async', function () {
  describe('With persistent database', async () => {
    let d

    beforeEach(async () => {
      d = new Datastore({ filename: testDb })
      assert.equal(d.filename, testDb)
      assert.equal(d.inMemoryOnly, false)
      await Persistence.ensureParentDirectoryExistsAsync(testDb)
      if (await exists(testDb)) await fs.unlink(testDb)
      await d.loadDatabaseAsync()
      assert.equal(d.getAllData().length, 0)
    })

    it('Operations are executed in the right order', () => testRightOrder(d))

    it('Does not starve event loop and raise warning when more than 1000 callbacks are in queue', () => testEventLoopStarvation(d))

    it('Works in the right order even with no supplied callback', () => testExecutorWorksWithoutCallback(d))
  })
}) // ==== End of 'With persistent database' ====

describe('With non persistent database', function () {
  let d

  beforeEach(async () => {
    d = new Datastore({ inMemoryOnly: true })
    assert.equal(d.inMemoryOnly, true)
    await d.loadDatabaseAsync()
    assert.equal(d.getAllData().length, 0)
  })

  it('Operations are executed in the right order', () => testRightOrder(d))

  it('Works in the right order even with no supplied callback', () => testExecutorWorksWithoutCallback(d))
}) // ==== End of 'With non persistent database' ====