/**
 * Node half of the HMR plugin: bundle watches follow the graph, stat changes
 * report through clientModuleHost.rebuilt, and everything dies with the fiber.
 */
import { mkdtempSync, rmSync, writeFileSync } from 'node:fs'
import { tmpdir } from 'node:os'
import { join } from 'node:path'
import { Context } from 'cordis'
import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
import type { WebBootGraph, ClientModuleHostService } from '@deepseek-ai/dsh-client-modules'
import type { WebRoute, HttpServerService } from '@deepseek-ai/dsh-host-webserver'
import { apply, Config, EVENTS_ENDPOINT, inject } from '../src/index.ts'

const POLL_MS = 20

let dir: string

beforeEach(() => { dir = mkdtempSync(join(tmpdir(), 'dsh-hmr-')) })
afterEach(() => { rmSync(dir, { recursive: true, force: true }) })

/**
 * Controllable clientModuleHost fake over a mutable id → bundle-path table.
 * Structural (Pick+cast): the plugin only touches the read/notify surface;
 * the service class carries private scan state a literal need not reproduce.
 */
type FakeHost = ClientModuleHostService & { rebuiltCalls: string[]; fireGraphChanged(): void }
function fakeClientModuleHost(rows: Map<string, string>): FakeHost {
  const graphListeners = new Set<() => void>()
  const rebuiltCalls: string[] = []
  const fake: Pick<FakeHost, 'graph' | 'clientPath' | 'rebuilt' | 'onRebuilt' | 'onGraphChanged' | 'rebuiltCalls' | 'fireGraphChanged'> = {
    rebuiltCalls,
    fireGraphChanged: () => { for (const l of graphListeners) l() },
    graph: (): WebBootGraph => ({
      rev: 'r',
      entries: [...rows.keys()].map(id => ({ id, url: `/plugins/${id}/client.js?rev=r`, rev: 'r' })),
    }),
    clientPath: id => rows.get(id),
    rebuilt: (id) => { rebuiltCalls.push(id); return 'r2' },
    onRebuilt: () => () => {},
    onGraphChanged: (listener) => {
      graphListeners.add(listener)
      return () => { graphListeners.delete(listener) }
    },
  }
  return fake as FakeHost
}

// Structural fake: the plugin only touches register(); the service class
// carries private state a literal cannot (and need not) reproduce.
function fakeHttpServer(routes: WebRoute[]): HttpServerService {
  const fake: Pick<HttpServerService, 'register' | 'tapIndex' | 'port'> = {
    register(route) {
      routes.push(route)
      return () => { routes.splice(routes.indexOf(route), 1) }
    },
    tapIndex: () => () => {},
    port: 0,
  }
  return fake as HttpServerService
}

async function mount(clientModuleHost: FakeHost, httpServer: HttpServerService) {
  const ctx = new Context()
  ctx.provide('clientModuleHost', clientModuleHost)
  ctx.provide('httpServer', httpServer)
  const fiber = ctx.plugin(
    { inject: [...inject], Config, apply },
    { pollIntervalMs: POLL_MS },
  )
  await fiber.await()
  return fiber
}

describe('hmr node half', () => {
  it('watches graph bundles, reports stat changes, and unwatches on dispose', async () => {
    const bundle = join(dir, 'a.js')
    writeFileSync(bundle, 'v1')
    const clientModuleHost = fakeClientModuleHost(new Map([['pkg-a', bundle]]))
    const routes: WebRoute[] = []
    const fiber = await mount(clientModuleHost, fakeHttpServer(routes))

    expect(routes).toHaveLength(1)
    expect(routes[0]).toMatchObject({ kind: 'exact', path: EVENTS_ENDPOINT })

    // Nudge mtime past stat granularity so the poller sees a content signal.
    await new Promise(resolve => setTimeout(resolve, POLL_MS * 2))
    writeFileSync(bundle, 'v2-longer')
    await vi.waitFor(() => { expect(clientModuleHost.rebuiltCalls).toContain('pkg-a') }, { timeout: 3_000 })

    await fiber.dispose()
    expect(routes).toHaveLength(0)
    // Watcher gone: further file changes report nothing.
    clientModuleHost.rebuiltCalls.length = 0
    writeFileSync(bundle, 'v3-even-longer')
    await new Promise(resolve => setTimeout(resolve, POLL_MS * 4))
    expect(clientModuleHost.rebuiltCalls).toHaveLength(0)
  })

  it('follows graph changes: rows added after activation get watched', async () => {
    const early = join(dir, 'early.js')
    const late = join(dir, 'late.js')
    writeFileSync(early, 'v1')
    const rows = new Map([['pkg-early', early]])
    const clientModuleHost = fakeClientModuleHost(rows)
    const fiber = await mount(clientModuleHost, fakeHttpServer([]))

    writeFileSync(late, 'v1')
    rows.set('pkg-late', late)
    clientModuleHost.fireGraphChanged()

    await new Promise(resolve => setTimeout(resolve, POLL_MS * 2))
    writeFileSync(late, 'v2-longer')
    await vi.waitFor(() => { expect(clientModuleHost.rebuiltCalls).toContain('pkg-late') }, { timeout: 3_000 })
    await fiber.dispose()
  })
})