import { describe, expect, it } from 'vitest'
import { createStatCache } from './piagentui-stat-cache.js'

const stamp = (mtimeMs: number, size = 10) => ({ mtimeMs, size })

describe('createStatCache', () => {
  it('misses for unknown paths and hits for the same stamp', () => {
    const cache = createStatCache<string>()
    expect(cache.get('a', stamp(1))).toBeUndefined()
    cache.set('a', stamp(1), 'x')
    expect(cache.get('a', stamp(1))).toEqual({ value: 'x' })
  })

  it('treats a changed mtime or size as a miss and drops the stale entry', () => {
    const cache = createStatCache<string>()
    cache.set('a', stamp(1, 10), 'x')
    expect(cache.get('a', stamp(2, 10))).toBeUndefined()
    expect(cache.size).toBe(0)

    cache.set('a', stamp(1, 10), 'x')
    expect(cache.get('a', stamp(1, 11))).toBeUndefined()
  })

  it('can cache null values', () => {
    const cache = createStatCache<string | null>()
    cache.set('a', stamp(1), null)
    expect(cache.get('a', stamp(1))).toEqual({ value: null })
  })

  it('evicts the oldest entries beyond the limit', () => {
    const cache = createStatCache<number>(2)
    cache.set('a', stamp(1), 1)
    cache.set('b', stamp(1), 2)
    cache.set('c', stamp(1), 3)
    expect(cache.size).toBe(2)
    expect(cache.get('a', stamp(1))).toBeUndefined()
    expect(cache.get('b', stamp(1))).toEqual({ value: 2 })
    expect(cache.get('c', stamp(1))).toEqual({ value: 3 })
  })

  it('refreshing a key moves it to the newest position', () => {
    const cache = createStatCache<number>(2)
    cache.set('a', stamp(1), 1)
    cache.set('b', stamp(1), 2)
    cache.set('a', stamp(2), 11)
    cache.set('c', stamp(1), 3)
    expect(cache.get('b', stamp(1))).toBeUndefined()
    expect(cache.get('a', stamp(2))).toEqual({ value: 11 })
  })
})