type RequestIds = {
  requestId: string
  correlationId?: string
  traceparent?: string
}

const LAST_IDS_STORAGE_KEY = 'control:last_request_ids'

export class ApiError extends Error {
  status: number
  requestId: string
  correlationId?: string
  traceparent?: string

  constructor(args: {
    status: number
    message: string
    requestId: string
    correlationId?: string
    traceparent?: string
  }) {
    super(args.message)
    this.name = 'ApiError'
    this.status = args.status
    this.requestId = args.requestId
    this.correlationId = args.correlationId
    this.traceparent = args.traceparent
  }
}

const state: {
  last?: RequestIds
} = {}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null
}

function loadLastIds(): RequestIds | undefined {
  try {
    const raw = localStorage.getItem(LAST_IDS_STORAGE_KEY)
    if (!raw) return undefined
    const parsed = JSON.parse(raw) as unknown
    if (isRecord(parsed) && typeof parsed.requestId === 'string') {
      const correlationId =
        typeof parsed.correlationId === 'string' ? parsed.correlationId : undefined
      const traceparent =
        typeof parsed.traceparent === 'string' ? parsed.traceparent : undefined
      return { requestId: parsed.requestId, correlationId, traceparent }
    }
  } catch {
    return undefined
  }
  return undefined
}

function persistLastIds(ids: RequestIds) {
  try {
    localStorage.setItem(LAST_IDS_STORAGE_KEY, JSON.stringify(ids))
  } catch {
    return
  }
}

function newRequestId(): string {
  if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) {
    return crypto.randomUUID()
  }
  return `${Date.now()}-${Math.random().toString(16).slice(2)}`
}

export function getLastRequestIds(): RequestIds | undefined {
  return state.last ?? loadLastIds()
}

type ApiRequestInit = RequestInit & {
  correlationId?: string
  traceparent?: string
  useLastCorrelationId?: boolean
  useLastTraceparent?: boolean
}

export async function apiFetch(
  input: RequestInfo | URL,
  init?: ApiRequestInit,
) {
  const requestId = newRequestId()

  const headers = new Headers(init?.headers)
  headers.set('x-request-id', requestId)
  const last = getLastRequestIds()
  const correlationId =
    init?.correlationId ?? (init?.useLastCorrelationId ? last?.correlationId : undefined)
  const traceparent =
    init?.traceparent ?? (init?.useLastTraceparent ? last?.traceparent : undefined)

  if (correlationId) headers.set('x-correlation-id', correlationId)
  if (traceparent) headers.set('traceparent', traceparent)

  const res = await fetch(input, { ...init, headers })
  const resCorrelationId = res.headers.get('x-correlation-id') ?? correlationId ?? undefined
  const resTraceparent = res.headers.get('traceparent') ?? traceparent ?? undefined
  const ids = { requestId, correlationId: resCorrelationId, traceparent: resTraceparent }
  state.last = ids
  persistLastIds(ids)

  if (!res.ok) {
    const text = await res.text().catch(() => '')
    const err = new ApiError({
      status: res.status,
      requestId,
      correlationId: resCorrelationId,
      traceparent: resTraceparent,
      message: `API error ${res.status}${text ? `: ${text}` : ''} (request_id=${requestId}${
        resCorrelationId ? ` correlation_id=${resCorrelationId}` : ''
      })`,
    })
    throw err
  }

  return res
}