import type { SessionStatus } from './session.svelte.js'
import { withSpace } from './space.js'

interface SessionTarget {
  status: SessionStatus
  space: { uri: string } | undefined
}

/**
 * URLs choose a space when navigation changes. Session publications are deliberately not inputs:
 * polling and picker opens rebuild the current space without turning the old URL into a command.
 */
export function createSpaceNavigationObserver(open: (url: URL) => void): (url: URL, openUri?: string) => void {
  let observed = ''
  return (url, openUri) => {
    const href = url.href
    if (href === observed) return
    observed = href
    const target = url.searchParams.get('space')
    if (target && target !== openUri) open(url)
  }
}

/** A picker choice owns both halves of a switch: opening the fold, then naming it in the URL. */
export async function selectSpace(
  uri: string,
  open: (uri: string) => Promise<void>,
  navigate: (href: string, options: { replaceState: true }) => Promise<void>,
  state: SessionTarget,
): Promise<boolean> {
  await open(uri)
  if (state.status !== 'ready' || state.space?.uri !== uri) return false
  await navigate(withSpace('/', uri), { replaceState: true })
  return true
}