/**
 * Wrap whatever the generated client decoded from a non-2xx error body
 * into a real `Error` so downstream formatters (TUI, plugins) get a
 * useful `.message` instead of `[object Object]` or blank. The original
 * parsed body and status live under `.cause` for callers that need
 * structured fields.
 *
 * Only fires when the caller used `{ throwOnError: true }`. Callers that
 * read `result.error` directly (the result-tuple path) get the parsed
 * body unchanged so existing field-level reads (`.error.name`,
 * `JSON.stringify(error)`, etc.) are byte-for-byte identical to before.
 */
export function wrapClientError(
  error: unknown,
  response: Response | undefined,
  request: Request | undefined,
  opts: { throwOnError?: boolean } | undefined,
): unknown {
  if (!opts?.throwOnError) return error
  if (error instanceof Error) return error

  // NamedError-shaped responses (the common case for opencode 4xx) come
  // through as POJOs — extract a useful message first, then wrap.
  if (typeof error === "object" && error !== null && Object.keys(error).length > 0) {
    const obj = error as { data?: { message?: unknown }; message?: unknown; name?: unknown }
    const message =
      (typeof obj.data?.message === "string" && obj.data.message) ||
      (typeof obj.message === "string" && obj.message) ||
      (typeof obj.name === "string" && obj.name) ||
      describe(request, response)
    return new Error(message, { cause: { body: error, status: response?.status } })
  }

  if (typeof error === "string" && error.length > 0) {
    return new Error(error, { cause: { body: error, status: response?.status } })
  }

  // Empty body / network failure / undefined / null / empty object.
  const reason = response ? "(empty response body)" : "network error (no response)"
  return new Error(`opencode server ${describe(request, response)}: ${reason}`, {
    cause: { body: error, status: response?.status },
  })
}

function describe(request: Request | undefined, response: Response | undefined) {
  const method = request?.method ?? "?"
  const url = request?.url ?? "?"
  const status = response?.status
  const statusText = response?.statusText
  return `${method} ${url}${status ? " → " + status : ""}${statusText ? " " + statusText : ""}`
}