import { afterEach, describe, expect, it } from 'vitest'
import type { KVChangeEvent } from '../../src/kv-storage/base-kv-storage.js'
import { StorageUnavailableError } from '../../src/utils/errors.js'
import { TestNetwork } from './sync-helpers.js'

let network: TestNetwork
afterEach(() => network?.close())

describe('KVStorageHttp.subscribe (SSE)', () => {
  it('receives changes made by other clients as remote change events', async () => {
    network = new TestNetwork()
    const watcher = network.client()
    await watcher.subscribe('')
    const received = watcher.waitFor('change', (e) => e.origin === 'remote')
    await network.client().child('users').set('1', { name: 'Ada', n: 1n })
    const event = await received
    expect(event.changes).toEqual([{ key: 'users/1', value: { name: 'Ada', n: 1n } }])
    expect(event.id).toMatch(/^\w+-1$/)
    expect(watcher.lastEventId).toBe(event.id)
  })

  it('resumes from lastEventId and replays missed changes', async () => {
    network = new TestNetwork()
    const writer = network.client()
    const watcher = network.client()
    await watcher.subscribe('')
    const first = watcher.waitFor('change', (e) => e.origin === 'remote')
    await writer.writeMany([['a', 1]])
    await first
    await watcher.unsubscribe('')
    await writer.writeMany([['b', 2]])
    await writer.writeMany([['c', 3]])
    const replayed: KVChangeEvent[] = []
    watcher.on('change', (e) => replayed.push(e))
    await watcher.subscribe('') // resolves once caught up, so the missed changes have been emitted
    expect(replayed.map((e) => e.changes)).toEqual([[{ key: 'b', value: 2 }], [{ key: 'c', value: 3 }]])
  })

  it('asks for a resync when the missed changes are no longer in the history', async () => {
    network = new TestNetwork({ historySize: 1 })
    const writer = network.client()
    const watcher = network.client()
    await watcher.subscribe('')
    const seen = watcher.waitFor('change', () => true)
    await writer.writeMany([['a', 1]])
    await seen
    await watcher.unsubscribe('')
    await writer.writeMany([['b', 2]])
    await writer.writeMany([['c', 3]])
    const resync = watcher.waitFor('resync', () => true)
    await watcher.subscribe('')
    expect(await resync).toEqual({ id: expect.stringMatching(/-3$/) })
  })

  it('reports an unreachable server as StorageUnavailableError', async () => {
    network = new TestNetwork()
    const client = network.client()
    network.online = false
    await expect(client.readMany(['x'])).rejects.toBeInstanceOf(StorageUnavailableError)
  })
})