import { useCallback, useEffect, useState } from 'react'
import type { AlertState, RiskAlert } from './api'
import { alertsFor } from './demo/ops'

/*
 * Officer actions on the alert queue.
 *
 * The queue itself is derived from the portfolio; only the state changes an
 * officer makes (acknowledge / escalate / snooze / close) and their audit trail
 * are persisted, which is exactly the split the deck describes — the model
 * proposes, the officer disposes, and every disposal is auditable.
 */

const KEY = 'ul-alert-states'
const AUDIT_KEY = 'ul-alert-audit'

export interface AuditEntry {
  alertId: string
  from: AlertState
  to: AlertState
  actor: string
  note: string | null
  at: string
}

function readStates(): Record<string, AlertState> {
  try {
    return JSON.parse(localStorage.getItem(KEY) ?? '{}') as Record<string, AlertState>
  } catch {
    return {}
  }
}

export function readAudit(): AuditEntry[] {
  try {
    return JSON.parse(localStorage.getItem(AUDIT_KEY) ?? '[]') as AuditEntry[]
  } catch {
    return []
  }
}

export function setAlertState(alert: RiskAlert, to: AlertState, actor: string, note?: string) {
  const states = readStates()
  const from = states[alert.alertId] ?? alert.state
  states[alert.alertId] = to
  localStorage.setItem(KEY, JSON.stringify(states))

  const audit: AuditEntry = { alertId: alert.alertId, from, to, actor, note: note ?? null, at: new Date().toISOString() }
  localStorage.setItem(AUDIT_KEY, JSON.stringify([audit, ...readAudit()].slice(0, 200)))
  window.dispatchEvent(new Event('ul-alerts-changed'))
}

/** The alert queue for a block, with any officer actions applied on top. */
export function useAlerts(block: string) {
  const [version, setVersion] = useState(0)

  const bump = useCallback(() => setVersion((v) => v + 1), [])

  useEffect(() => {
    window.addEventListener('ul-alerts-changed', bump)
    return () => window.removeEventListener('ul-alerts-changed', bump)
  }, [bump])

  const states = readStates()
  // `version` is read so the memo-free derivation re-runs after every action.
  void version
  const alerts = alertsFor(block).map((a) => ({ ...a, state: states[a.alertId] ?? a.state }))

  return { alerts, audit: readAudit() }
}