const DOMElementPool = require ('../src/dom-element-pool')

describe('DOMElementPool', function () {
  let domElementPool

  beforeEach(() => {
    domElementPool = new DOMElementPool()
    spyOn(atom, 'isReleasedVersion').andReturn(true)
  })

  it('builds DOM nodes, recycling them when they are freed', function () {
    let elements
    const [div, span1, span2, span3, span4, span5, textNode] = Array.from(elements = [
      domElementPool.buildElement('div', 'foo'),
      domElementPool.buildElement('span'),
      domElementPool.buildElement('span'),
      domElementPool.buildElement('span'),
      domElementPool.buildElement('span'),
      domElementPool.buildElement('span'),
      domElementPool.buildText('Hello world!')
    ])

    expect(div.className).toBe('foo')
    div.textContent = 'testing'
    div.style.backgroundColor = 'red'
    div.dataset.foo = 'bar'

    expect(textNode.textContent).toBe('Hello world!')

    div.appendChild(span1)
    span1.appendChild(span2)
    div.appendChild(span3)
    span3.appendChild(span4)
    span4.appendChild(textNode)

    domElementPool.freeElementAndDescendants(div)
    domElementPool.freeElementAndDescendants(span5)

    expect(elements.includes(domElementPool.buildElement('div'))).toBe(true)
    expect(elements.includes(domElementPool.buildElement('span'))).toBe(true)
    expect(elements.includes(domElementPool.buildElement('span'))).toBe(true)
    expect(elements.includes(domElementPool.buildElement('span'))).toBe(true)
    expect(elements.includes(domElementPool.buildElement('span'))).toBe(true)
    expect(elements.includes(domElementPool.buildElement('span'))).toBe(true)
    expect(elements.includes(domElementPool.buildText('another text'))).toBe(true)

    expect(elements.includes(domElementPool.buildElement('div'))).toBe(false)
    expect(elements.includes(domElementPool.buildElement('span'))).toBe(false)
    expect(elements.includes(domElementPool.buildText('unexisting'))).toBe(false)

    expect(div.className).toBe('')
    expect(div.textContent).toBe('')
    expect(div.style.backgroundColor).toBe('')
    expect(div.dataset.foo).toBeUndefined()

    expect(textNode.textContent).toBe('another text')
  })

  it('forgets free nodes after being cleared', function () {
    const span = domElementPool.buildElement('span')
    const div = domElementPool.buildElement('div')
    domElementPool.freeElementAndDescendants(span)
    domElementPool.freeElementAndDescendants(div)

    domElementPool.clear()

    expect(domElementPool.buildElement('span')).not.toBe(span)
    expect(domElementPool.buildElement('div')).not.toBe(div)
  })

  it('does not attempt to free nodes that were not created by the pool', () => {
    let assertionFailure
    atom.onDidFailAssertion((error) => assertionFailure = error)

    const foreignDiv = document.createElement('div')
    const div = domElementPool.buildElement('div')
    div.appendChild(foreignDiv)
    domElementPool.freeElementAndDescendants(div)
    const span = domElementPool.buildElement('span')
    span.appendChild(foreignDiv)
    domElementPool.freeElementAndDescendants(span)

    expect(assertionFailure).toBeUndefined()
  })

  it('fails an assertion when freeing the same element twice', function () {
    let assertionFailure
    atom.onDidFailAssertion((error) => assertionFailure = error)

    const div = domElementPool.buildElement('div')
    div.textContent = 'testing'
    domElementPool.freeElementAndDescendants(div)
    expect(assertionFailure).toBeUndefined()
    domElementPool.freeElementAndDescendants(div)
    expect(assertionFailure.message).toBe('Assertion failed: The element has already been freed!')
    expect(assertionFailure.metadata.content).toBe('<div>testing</div>')
  })

  it('fails an assertion when freeing the same text node twice', function () {
    let assertionFailure
    atom.onDidFailAssertion((error) => assertionFailure = error)

    const node = domElementPool.buildText('testing')
    domElementPool.freeElementAndDescendants(node)
    expect(assertionFailure).toBeUndefined()
    domElementPool.freeElementAndDescendants(node)
    expect(assertionFailure.message).toBe('Assertion failed: The element has already been freed!')
    expect(assertionFailure.metadata.content).toBe('testing')
  })

  it('throws an error when trying to free an invalid element', function () {
    expect(() => domElementPool.freeElementAndDescendants(null)).toThrow()
    expect(() => domElementPool.freeElementAndDescendants(undefined)).toThrow()
  })
})