import type http from 'http'

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

export function readString(value: unknown): string | undefined {
  return typeof value === 'string' ? value : undefined
}

export function getFormDataHeaders(formData: import('form-data')): http.OutgoingHttpHeaders {
  const raw: unknown = formData.getHeaders()
  if (!isRecord(raw)) {
    return {}
  }
  const headers: http.OutgoingHttpHeaders = {}
  for (const [key, value] of Object.entries(raw)) {
    const str = readString(value)
    if (str !== undefined) {
      headers[key] = str
    }
  }
  return headers
}

export function getRedirectLocation(headers: unknown): string | undefined {
  if (!isRecord(headers)) {
    return undefined
  }
  const { location } = headers
  if (typeof location === 'string') {
    return location
  }
  if (Array.isArray(location) && typeof location[0] === 'string') {
    return location[0]
  }
  return undefined
}