import { isError } from "./is.ts"

const internalErrorMessages = new Set([
  "network error", // Chrome
  "Failed to fetch", // Chrome
  "NetworkError when attempting to fetch resource.", // Firefox
  "The Internet connection appears to be offline.", // Safari 16
  "Load failed", // Safari 17+
  "Network request failed", // `cross-fetch`
  "fetch failed", // Undici (Node.js)
  "terminated", // Undici (Node.js)
])

/**
 * @description Checks if an error is a network error.
 *
 * @see {@link https://github.com/sindresorhus/is-network-error}
 */
export const errorIsNetworkError = (error: unknown): error is Error => {
  if (error === null || error === undefined) {
    return false
  }

  if (isError(error) === false) {
    return false
  }

  if (error.name !== "TypeError" || typeof error.message !== "string") {
    return false
  }

  // We do an extra check for Safari 17+ as it has a very generic error message.
  // Network errors in Safari have no stack.
  if (error.message === "Load failed") {
    return error.stack === undefined
  }

  return internalErrorMessages.has(error.message)
}

/**
 * @description Stringifies an error into a readable format.
 */
export const errorStringify = (error: unknown): string => {
  if (isError(error)) {
    return `${error.name}: ${error.message}`
  } else {
    return `${String(error)}`
  }
}

/**
 * @description Converts a value to an Error object. If the value is already an Error,
 * it is returned as is. Otherwise, a new Error is created with the
 * stringified value as its message.
 */
export const toError = (value: unknown): Error => {
  if (isError(value)) {
    return value
  } else {
    return new Error(String(value))
  }
}