import {
  queueJob,
  nextTick,
  queuePostFlushCb,
  invalidateJob
} from '../src/scheduler'

describe('scheduler', () => {
  it('nextTick', async () => {
    const calls: string[] = []
    const dummyThen = Promise.resolve().then()
    const job1 = () => {
      calls.push('job1')
    }
    const job2 = () => {
      calls.push('job2')
    }
    nextTick(job1)
    job2()

    expect(calls.length).toBe(1)
    await dummyThen
    // job1 will be pushed in nextTick
    expect(calls.length).toBe(2)
    expect(calls).toMatchObject(['job2', 'job1'])
  })

  describe('queueJob', () => {
    it('basic usage', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')
      }
      const job2 = () => {
        calls.push('job2')
      }
      queueJob(job1)
      queueJob(job2)
      expect(calls).toEqual([])
      await nextTick()
      expect(calls).toEqual(['job1', 'job2'])
    })

    it('should dedupe queued jobs', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')
      }
      const job2 = () => {
        calls.push('job2')
      }
      queueJob(job1)
      queueJob(job2)
      queueJob(job1)
      queueJob(job2)
      expect(calls).toEqual([])
      await nextTick()
      expect(calls).toEqual(['job1', 'job2'])
    })

    it('queueJob while flushing', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')
        // job2 will be excuted after job1 at the same tick
        queueJob(job2)
      }
      const job2 = () => {
        calls.push('job2')
      }
      queueJob(job1)

      await nextTick()
      expect(calls).toEqual(['job1', 'job2'])
    })
  })

  describe('queuePostFlushCb', () => {
    it('basic usage', async () => {
      const calls: string[] = []
      const cb1 = () => {
        calls.push('cb1')
      }
      const cb2 = () => {
        calls.push('cb2')
      }
      const cb3 = () => {
        calls.push('cb3')
      }

      queuePostFlushCb([cb1, cb2])
      queuePostFlushCb(cb3)

      expect(calls).toEqual([])
      await nextTick()
      expect(calls).toEqual(['cb1', 'cb2', 'cb3'])
    })

    it('should dedupe queued postFlushCb', async () => {
      const calls: string[] = []
      const cb1 = () => {
        calls.push('cb1')
      }
      const cb2 = () => {
        calls.push('cb2')
      }
      const cb3 = () => {
        calls.push('cb3')
      }

      queuePostFlushCb([cb1, cb2])
      queuePostFlushCb(cb3)

      queuePostFlushCb([cb1, cb3])
      queuePostFlushCb(cb2)

      expect(calls).toEqual([])
      await nextTick()
      expect(calls).toEqual(['cb1', 'cb2', 'cb3'])
    })

    it('queuePostFlushCb while flushing', async () => {
      const calls: string[] = []
      const cb1 = () => {
        calls.push('cb1')
        // cb2 will be excuted after cb1 at the same tick
        queuePostFlushCb(cb2)
      }
      const cb2 = () => {
        calls.push('cb2')
      }
      queuePostFlushCb(cb1)

      await nextTick()
      expect(calls).toEqual(['cb1', 'cb2'])
    })
  })

  describe('queueJob w/ queuePostFlushCb', () => {
    it('queueJob inside postFlushCb', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')
      }
      const cb1 = () => {
        // queueJob in postFlushCb
        calls.push('cb1')
        queueJob(job1)
      }

      queuePostFlushCb(cb1)
      await nextTick()
      expect(calls).toEqual(['cb1', 'job1'])
    })

    it('queueJob & postFlushCb inside postFlushCb', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')
      }
      const cb1 = () => {
        calls.push('cb1')
        queuePostFlushCb(cb2)
        // job1 will executed before cb2
        // Job has higher priority than postFlushCb
        queueJob(job1)
      }
      const cb2 = () => {
        calls.push('cb2')
      }

      queuePostFlushCb(cb1)
      await nextTick()
      expect(calls).toEqual(['cb1', 'job1', 'cb2'])
    })

    it('postFlushCb inside queueJob', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')
        // postFlushCb in queueJob
        queuePostFlushCb(cb1)
      }
      const cb1 = () => {
        calls.push('cb1')
      }

      queueJob(job1)
      await nextTick()
      expect(calls).toEqual(['job1', 'cb1'])
    })

    it('queueJob & postFlushCb inside queueJob', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')
        // cb1 will executed after job2
        // Job has higher priority than postFlushCb
        queuePostFlushCb(cb1)
        queueJob(job2)
      }
      const job2 = () => {
        calls.push('job2')
      }
      const cb1 = () => {
        calls.push('cb1')
      }

      queueJob(job1)
      await nextTick()
      expect(calls).toEqual(['job1', 'job2', 'cb1'])
    })

    it('nested queueJob w/ postFlushCb', async () => {
      const calls: string[] = []
      const job1 = () => {
        calls.push('job1')

        queuePostFlushCb(cb1)
        queueJob(job2)
      }
      const job2 = () => {
        calls.push('job2')
        queuePostFlushCb(cb2)
      }
      const cb1 = () => {
        calls.push('cb1')
      }
      const cb2 = () => {
        calls.push('cb2')
      }

      queueJob(job1)
      await nextTick()
      expect(calls).toEqual(['job1', 'job2', 'cb1', 'cb2'])
    })
  })

  test('invalidateJob', async () => {
    const calls: string[] = []
    const job1 = () => {
      calls.push('job1')
      invalidateJob(job2)
      job2()
    }
    const job2 = () => {
      calls.push('job2')
    }
    const job3 = () => {
      calls.push('job3')
    }
    const job4 = () => {
      calls.push('job4')
    }
    // queue all jobs
    queueJob(job1)
    queueJob(job2)
    queueJob(job3)
    queuePostFlushCb(job4)
    expect(calls).toEqual([])
    await nextTick()
    // job2 should be called only once
    expect(calls).toEqual(['job1', 'job2', 'job3', 'job4'])
  })

  test('sort job based on id', async () => {
    const calls: string[] = []
    const job1 = () => calls.push('job1')
    // job1 has no id
    const job2 = () => calls.push('job2')
    job2.id = 2
    const job3 = () => calls.push('job3')
    job3.id = 1

    queueJob(job1)
    queueJob(job2)
    queueJob(job3)
    await nextTick()
    expect(calls).toEqual(['job3', 'job2', 'job1'])
  })
})