/**
 * Reading the client's own session state: the pure derivations the observer
 * and the delivery path both ask questions of.
 *
 * @module @dsh-plugin/session-notify/client/core/session
 */

import { PENDING_KINDS } from '../constants.js'

/**
 * Discriminate a pending interaction the client published.
 *
 * The domains that can ask the user something are `@deepseek-ai/dsh-client-ui-approval`
 * (a tool authorisation) and `@deepseek-ai/dsh-client-ui-user-questions` (a
 * question batch, or the plan review its `planReviewOf` marks); each publishes a
 * literal `kind` on its pending value. Anything else is ignored rather than
 * guessed at.
 * @param value - `status.pendingInteraction`.
 * @returns a served kind, or undefined.
 */
export function servedPendingKind(value) {
  if (value === undefined || value === null || typeof value !== 'object') return undefined
  const kind = value.kind
  return typeof kind === 'string' && PENDING_KINDS.includes(kind) ? kind : undefined
}

/** Trim free text down to one popup line. */
export function preview(value) {
  if (typeof value !== 'string') return ''
  const flat = value.replace(/\s+/g, ' ').trim()
  return flat.length > 80 ? `${flat.slice(0, 79)}…` : flat
}

/** The first question text a pending interaction exposes, across its shapes. */
export function questionText(interaction) {
  if (interaction === null || typeof interaction !== 'object') return ''
  const first = Array.isArray(interaction.questions) ? interaction.questions[0] : undefined
  if (typeof first?.question === 'string') return preview(first.question)
  if (typeof first?.text === 'string') return preview(first.text)
  if (typeof interaction.question === 'string') return preview(interaction.question)
  if (typeof interaction.prompt === 'string') return preview(interaction.prompt)
  return preview(interaction.displayReason?.text ?? interaction.reason?.text ?? '')
}

/** Copy one session title, falling back to its identity. */
export function titleOf(summary, sessionId) {
  const title = typeof summary?.title === 'string' ? summary.title.trim() : ''
  return title === '' ? sessionId.slice(0, 8) : title
}

/** Whether the user is looking at this exact conversation right now. */
export function isOnScreen(sessionId, list) {
  if (list === undefined) return false
  for (const id of Object.keys(list.byId ?? {})) {
    const summary = list.byId[id]
    if (summary !== undefined && (summary.retainedBy?.mainView ?? 0) > 0) return id === sessionId
  }
  return false
}

/**
 * Whether a queued candidate is still owed, read from the LIVE snapshot rather
 * than the one captured when the transition was seen.
 *
 * The two triggers are owed for different reasons, so they are checked for
 * different things:
 *
 * - A **pending interaction** (approval, question, plan review) is owed until
 *   the user answers it. It is deliberately NOT gated on the run state: the
 *   session is `running` while it waits — the client's own `observeRunning`
 *   only mirrors `api-session/status` and says nothing about a pending request —
 *   so a running gate would silently drop every approval and question alert.
 * - A **completion** is owed only while the conversation stayed idle. A
 *   conversation that resumed inside the settle window owes no alert, and the
 *   snapshot the transition was derived from still carries the pre-transition
 *   `running` flag of the session record.
 * @param candidate - the alert waiting for its settle tick.
 * @param live - the freshest `{ list, status }` the observer has seen.
 * @returns whether the alert is still owed.
 */
export function stillOwed(candidate, live) {
  if (candidate.test === true) return true

  if (candidate.pendingKind !== '') {
    const sessionStatus = live.status?.get?.(candidate.sessionId)
    // No status entry contradicts the request, so it is still the user's move.
    if (sessionStatus === undefined) return true
    return servedPendingKind(sessionStatus.pendingInteraction) === candidate.pendingKind
  }

  const list = live.list
  if (list === undefined) return true
  const summary = list.byId?.[candidate.sessionId]
  if (summary === undefined) return true
  const running = live.status?.get?.(candidate.sessionId)?.running ?? summary.running
  return running !== true
}