import * as Timeout from './Timeout.js'

/** Installs the default outbound fetch timeout once for this runtime. */
export function install(): void {
  if (isInstalled(globalThis.fetch)) return

  const fetch = withTimeout(globalThis.fetch.bind(globalThis), { timeout: Timeout.duration })
  Object.defineProperty(fetch, timeoutMarker, { value: true })
  globalThis.fetch = fetch
}

/** Adds a default maximum duration to fetch calls that do not carry a signal. */
export function withTimeout(
  fetch: typeof globalThis.fetch,
  options: withTimeout.Options,
): typeof globalThis.fetch {
  return ((input, init) => {
    const signal = resolveSignal(input, { init, timeout: options.timeout })
    return fetch(input, { ...init, signal })
  }) as typeof globalThis.fetch
}

/** Resolves a caller signal or creates the default fetch deadline signal. */
export function resolveSignal(
  input: Parameters<typeof globalThis.fetch>[0],
  options: resolveSignal.Options,
): AbortSignal {
  return (
    options.init?.signal ??
    (input instanceof Request ? input.signal : Timeout.signal({ timeout: options.timeout }))
  )
}

export declare namespace resolveSignal {
  /** Options for {@link resolveSignal}. */
  type Options = {
    /** Optional fetch initialization carrying a caller signal. */
    init?: Parameters<typeof globalThis.fetch>[1]
    /** Default maximum duration in milliseconds. */
    timeout: number
  }
}

export declare namespace withTimeout {
  /** Options for {@link withTimeout}. */
  type Options = {
    /** Maximum fetch duration in milliseconds. */
    timeout: number
  }
}

const timeoutMarker = Symbol.for('tempo.api.fetch.timeout')

function isInstalled(fetch: typeof globalThis.fetch): boolean {
  return timeoutMarker in fetch
}