import type { Page } from '@playwright/test'

// Keep a response open; the browser test controls sample delivery independently of HTTP routes.
export async function installOpenLiveStream(page: Page, path: string, sample: unknown, sendImmediately = true) {
  await page.clock.install()
  await page.addInitScript(({ path, sample, sendImmediately }) => {
    const originalFetch = window.fetch.bind(window)
    window.fetch = async (input, init) => {
      const url = new URL(input instanceof Request ? input.url : String(input), location.href)
      if (url.pathname !== path) return originalFetch(input, init)
      const stream = new ReadableStream<Uint8Array>({
        start(controller) {
          const encode = (value: string) => new TextEncoder().encode(value)
          const send = () => {
            // A comment may precede an event; CRLF delimiters may cross chunks.
            controller.enqueue(encode(': heartbeat\r\nevent: sample\r\ndata: ' + JSON.stringify(sample) + '\r\n\r'))
            controller.enqueue(encode('\n'))
          }
          const heartbeat = () => controller.enqueue(encode(': heartbeat\r\n\r\n'))
          Object.assign(window, { sendLiveSample: send, sendLiveHeartbeat: heartbeat })
          if (sendImmediately) send()
        },
      })
      return new Response(stream, { headers: { 'Content-Type': 'text/event-stream' } })
    }
  }, { path, sample, sendImmediately })
}

export async function resumeLiveStream(page: Page) {
  await page.evaluate(() => (window as unknown as { sendLiveSample: () => void }).sendLiveSample())
}

export async function sendLiveHeartbeat(page: Page) {
  await page.evaluate(() => (window as unknown as { sendLiveHeartbeat: () => void }).sendLiveHeartbeat())
}