import { Stream } from '../src/iterator.js'
import { describe, it } from 'node:test'
import assert from 'node:assert/strict'

describe('Stream class', () => {
  it('should iterate a range', () => {
    const stream = new Stream([1, 2, 3])

    assert.equal(stream.index, 0)

    assert.deepStrictEqual(stream.next(), { value: 1, done: false })
    assert.equal(stream.index, 1)

    assert.deepStrictEqual(stream.next(), { value: 2, done: false })
    assert.equal(stream.index, 2)

    assert.deepStrictEqual(stream.next(), { value: 3, done: false })
    assert.equal(stream.index, 3)

    assert.deepStrictEqual(stream.next(), { value: undefined, done: true })
    assert.equal(stream.index, 3)
  })

  it('should handle an empty stream', () => {
    const stream = new Stream([])

    assert.deepStrictEqual(stream.next(), { value: undefined, done: true })
    assert.equal(stream.index, 0)
  })

  it('should handle a single item', () => {
    const stream = new Stream([1])

    assert.equal(stream.index, 0)

    assert.deepStrictEqual(stream.next(), { value: 1, done: false })
    assert.equal(stream.index, 1)

    assert.deepStrictEqual(stream.next(), { value: undefined, done: true })
    assert.equal(stream.index, 1)
  })

  it('should should an independent stream', () => {
    const stream = new Stream([1, 2, 3])

    assert.deepStrictEqual(stream.next(), { value: 1, done: false })
    assert.equal(stream.index, 1)

    const clone = stream.clone()
    assert.equal(clone.index, 1)

    assert.deepStrictEqual(clone.next(), { value: 2, done: false })
    assert.equal(clone.index, 2)

    assert.deepStrictEqual(clone.next(), { value: 3, done: false })
    assert.equal(clone.index, 3)

    assert.deepStrictEqual(stream.next(), { value: 2, done: false })
    assert.equal(stream.index, 2)
  })

  it('should support multiple clones', () => {
    const stream = new Stream('abcdefg')
    stream.next()
    stream.next()

    assert.deepStrictEqual(stream.index, 2)

    const clone1 = stream.clone()
    assert.deepStrictEqual(clone1.index, 2)

    stream.next()
    stream.next()
    assert.deepStrictEqual(stream.index, 4)

    const clone2 = stream.clone()
    assert.deepStrictEqual(clone2.index, 4)

    assert.deepStrictEqual(clone1.next(), { value: 'c', done: false })
    assert.deepStrictEqual(clone1.next(), { value: 'd', done: false })
    assert.deepStrictEqual(clone1.next(), { value: 'e', done: false })
    assert.deepStrictEqual(clone1.index, 5)

    assert.deepStrictEqual(clone2.next(), { value: 'e', done: false })
    assert.deepStrictEqual(clone2.next(), { value: 'f', done: false })
    assert.deepStrictEqual(clone2.index, 6)

    assert.deepStrictEqual(stream.next(), { value: 'e', done: false })
    assert.deepStrictEqual(stream.index, 5)
  })

  it('should yield a value on consume', () => {
    const stream = new Stream('abc')
    assert.deepStrictEqual(stream.consume().unwrap(), 'a')
    assert.deepStrictEqual(stream.consume().unwrap(), 'b')
    assert.deepStrictEqual(stream.consume().unwrap(), 'c')
    assert(stream.consume().isNone())
  })

  it('should take from a stream', () => {
    const stream5 = new Stream([1, 2, 3, 4, 5])
    const take3 = stream5.take(3)
    assert.deepStrictEqual(Array.from(take3), [1, 2, 3])

    assert.deepStrictEqual(stream5.index, 3)
    assert.deepStrictEqual(Array.from(stream5), [4, 5])

    const emptyStream = new Stream([])
    const take0 = emptyStream.take(3)
    assert.deepStrictEqual(Array.from(take0), [])
    assert.deepStrictEqual(emptyStream.index, 0)
    assert.deepStrictEqual(Array.from(emptyStream), [])

    const streamDefault = new Stream('abc')
    const genDefault = streamDefault.take()
    assert.deepStrictEqual(Array.from(genDefault), ['a'])
    assert.deepStrictEqual(streamDefault.index, 1)
    assert.deepStrictEqual(Array.from(streamDefault), ['b', 'c'])

    const stream3 = new Stream([10, 20, 30])
    const genZero = streamDefault.take(0)
    assert.deepStrictEqual(Array.from(genZero), [])
    assert.deepStrictEqual(stream3.index, 0)
    assert.deepStrictEqual(Array.from(stream3), [10, 20, 30])
  })
})