import { describe, expect, it } from 'vitest'
import fc from 'fast-check'
import { EventStorageKV } from '../../src/event-storage/event-storage-kv.js'
import type { BaseKVStorage } from '../../src/kv-storage/base-kv-storage.js'
import { KVStorageInMemory } from '../../src/kv-storage/kv-storage-in-memory.js'
import { collect, KVStorageCounting } from '../helpers.js'

function setup(kv: BaseKVStorage = new KVStorageCounting(), start = 1000) {
  let t = start
  return { kv, events: new EventStorageKV(kv, { now: () => t++ }) }
}

describe('EventStorageKV', () => {
  it('appends and reads in self and child forms', async () => {
    const orders = setup().events.child('orders')
    const [created] = await orders.append('o1', [{ type: 'created' }])
    const ids = await orders.child('o1').append([{ type: 'paid' }, { type: 'shipped' }])
    expect(await collect(orders.read('o1'))).toEqual([
      { id: created, at: 1000, data: { type: 'created' } },
      { id: ids[0], at: 1001, data: { type: 'paid' } },
      { id: ids[1], at: 1002, data: { type: 'shipped' } },
    ])
    expect((await collect(orders.child('o1').read({ after: ids[0] }))).map((e) => e.data)).toEqual([{ type: 'shipped' }])
    expect((await collect(orders.read('o1', { reverse: true, limit: 2 }))).map((e) => e.id)).toEqual([ids[1], ids[0]])
    expect((await collect(orders.read('o1', { reverse: true, after: ids[0] }))).map((e) => e.id)).toEqual([created])
  })

  it('ids are the time and a hash of the time and content', async () => {
    const { kv, events } = setup()
    const [id] = await events.child('s').append([{ b: 1, a: 2 }])
    expect(id).toMatch(/^000000000001000_[0-9a-f]{64}$/)
    expect(id).toBe(await EventStorageKV.id(1000, { a: 2, b: 1 }))
    expect((await collect(kv.scan())).map(([k]) => k)).toEqual([`s/~e/${id}`])
  })

  it('one append is one write; one instance never reuses a time', async () => {
    const kv = new KVStorageCounting()
    const events = new EventStorageKV(kv, { now: () => 5 })
    const ids = await events.child('s').append(['a', 'a'])
    expect(kv.calls).toEqual({ writeMany: 1 })
    expect(ids.map((id) => id.slice(0, 15))).toEqual(['000000000000005', '000000000000006'])
    expect((await collect(events.child('s').read())).map((e) => e.data)).toEqual(['a', 'a'])
  })

  it('keeps concurrent appends from different writers, ordered by time', async () => {
    const kv = new KVStorageInMemory()
    const a = setup(kv, 1000).events.child('s')
    const b = setup(kv, 1000).events.child('s')
    await Promise.all([a.append(['a1', 'a2']), b.append(['b1', 'b2'])])
    const read = await collect(a.read())
    expect(read).toHaveLength(4)
    expect(read.map((e) => e.at)).toEqual([1000, 1000, 1001, 1001])
    expect(read.map((e) => e.id)).toEqual([...read.map((e) => e.id)].sort())
    expect(await collect(b.read())).toEqual(read)
  })

  it('writing the same event again does not duplicate it', async () => {
    const kv = new KVStorageInMemory()
    await setup(kv).events.child('s').append(['x'])
    await setup(kv).events.child('s').append(['x'])
    expect(await collect(new EventStorageKV(kv).child('s').read())).toHaveLength(1)
  })

  it('checks the arity rules', async () => {
    const { events } = setup()
    await expect(events.append(['x'])).rejects.toThrow(/root/)
    await expect(events.child('o').append(undefined as never, ['x'] as never)).rejects.toThrow(TypeError)
  })

  it('lists child streams', async () => {
    const orders = setup().events.child('orders')
    await orders.append('o1', ['a'])
    await orders.append('o2', ['b'])
    await orders.child('o1').append('notes', ['n'])
    expect(await collect(orders.keys())).toEqual(['o1', 'o2'])
    expect(await collect(orders.child('o1').keys())).toEqual(['notes'])
  })

  it('reads any window correctly (property)', async () => {
    await fc.assert(
      fc.asyncProperty(
        fc.array(fc.integer({ min: 1, max: 4 }), { maxLength: 20 }),
        fc.record({
          after: fc.option(fc.nat(60), { nil: undefined }),
          limit: fc.option(fc.nat(10), { nil: undefined }),
          reverse: fc.boolean(),
        }),
        async (sizes, { after, limit, reverse }) => {
          const s = setup().events.child('s')
          const ids: string[] = []
          for (const size of sizes) ids.push(...(await s.append(Array.from({ length: size }, () => ids.length))))
          const all = await collect(s.read())
          expect(all.map((e) => e.id)).toEqual(ids)
          const ordered = reverse ? [...ids].reverse() : ids
          const afterId = after === undefined ? undefined : ids[after]
          let expected = afterId === undefined ? ordered : ordered.slice(ordered.indexOf(afterId) + 1)
          if (limit !== undefined) expected = expected.slice(0, limit)
          expect((await collect(s.read({ after: afterId, limit, reverse }))).map((e) => e.id)).toEqual(expected)
        },
      ),
      { numRuns: 200 },
    )
  })
})