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

runKVStorageConformance('KVStorageInMemory', () => new KVStorageInMemory())
runKVStorageConformance('wrapper (KVStorageCounting)', () => new KVStorageCounting())

describe('costs', () => {
  it('single-key operations are one primitive call', async () => {
    const db = new KVStorageCounting()
    const users = db.child('users')
    await users.set('1', 'x')
    await users.get('1')
    await users.child('1').get()
    await users.delete('1')
    expect(db.calls).toEqual({ writeMany: 2, readMany: 2 })
  })

  it('keys() seeks once per child with descendants, not once per key', async () => {
    const db = new KVStorageCounting()
    const writes: KVChange[] = []
    for (let c = 0; c < 50; c++) for (let d = 0; d < 20; d++) writes.push({ key: `n/c${c}/d${d}`, value: d })
    for (let c = 0; c < 50; c++) writes.push({ key: `n/leaf${c}`, value: c })
    await db.writeMany(writes)
    db.reset()
    expect(await collect(db.child('n').keys())).toHaveLength(100)
    expect(db.calls).toEqual({ scan: 51 })
  })
})

describe('model-based: random writes vs a reference map', () => {
  const segment = fc.constantFrom('a', 'a-1', 'a.b', 'b', 'x/y', '%', '~e', '1', '10', '9', 'ab', 'a!', 'é')
  const path = fc.array(segment, { minLength: 1, maxLength: 3 })
  const op = fc.oneof(
    fc.record({ t: fc.constant('set' as const), path, value: fc.integer() }),
    fc.record({ t: fc.constant('delete' as const), path }),
    fc.record({ t: fc.constant('deleteTree' as const), path }),
  )
  const at = (db: BaseKVStorage, p: string[]) => p.reduce<BaseKVStorage>((n, s) => n.child(s), db)

  it('get, keys and entries agree with the model', async () => {
    await fc.assert(
      fc.asyncProperty(fc.array(op, { maxLength: 30 }), fc.array(segment, { maxLength: 2 }), async (ops, parent) => {
        const db = new KVStorageInMemory()
        const model = new Map<string, number>()
        const isUnder = (p: string[], q: string[]) => q.length >= p.length && p.every((s, i) => q[i] === s)
        for (const o of ops) {
          if (o.t === 'set') (await at(db, o.path).set(o.value), model.set(JSON.stringify(o.path), o.value))
          else if (o.t === 'delete') (await at(db, o.path).delete(), model.delete(JSON.stringify(o.path)))
          else {
            await at(db, o.path).deleteTree()
            for (const k of [...model.keys()]) if (isUnder(o.path, JSON.parse(k))) model.delete(k)
          }
        }
        for (const [k, v] of model) expect(await at(db, JSON.parse(k)).get()).toBe(v)
        const children = new Map<string, number | undefined>()
        for (const [k, v] of model) {
          const p = JSON.parse(k) as string[]
          if (p.length <= parent.length || !isUnder(parent, p)) continue
          const own = p.length === parent.length + 1
          if (own || !children.has(p[parent.length]!)) children.set(p[parent.length]!, own ? v : children.get(p[parent.length]!))
        }
        const node = at(db, parent)
        const listed = await collect(node.keys())
        expect([...listed].sort()).toEqual([...children.keys()].sort())
        expect(await collect(node.keys({ reverse: true }))).toEqual([...listed].reverse())
        const withValues = listed.filter((k) => children.get(k) !== undefined)
        expect(await collect(node.entries())).toEqual(withValues.map((k) => [k, children.get(k)]))
        expect(await collect(node.entries({ reverse: true }))).toEqual(withValues.reverse().map((k) => [k, children.get(k)]))
        for (let i = 0; i < listed.length; i++) expect(await collect(node.keys({ after: listed[i]! }))).toEqual(listed.slice(i + 1))
      }),
      { numRuns: 300 },
    )
  })
})

describe('child nodes', () => {
  it('are frozen, so implementations cannot accidentally shadow shared state', () => {
    const child = new KVStorageInMemory().child('a').child('b')
    expect(Object.isFrozen(child)).toBe(true)
    expect(() => ((child as unknown as { state: number }).state = 1)).toThrow(TypeError)
    expect(child.key).toBe('a/b')
  })
})