import type {
  LanguageModelV4Message,
  LanguageModelV4Prompt,
} from '@ai-sdk/provider';
import { convertDataContentToBase64String } from 'ai';

/**
 * Helper utility to serialize prompt content for OpenTelemetry tracing.
 * It is initially created because normalized LanguageModelV4Prompt carries
 * images as Uint8Arrays, on which JSON.stringify acts weirdly, converting
 * them to objects with stringified indices as keys, e.g. {"0": 42, "1": 69 }.
 */
export function stringifyForTelemetry(prompt: LanguageModelV4Prompt): string {
  return JSON.stringify(
    prompt.map((message: LanguageModelV4Message) => ({
      ...message,
      content:
        typeof message.content === 'string'
          ? message.content
          : message.content.map(part =>
              part.type === 'file'
                ? {
                    ...part,
                    data: serializeFileData(part.data),
                  }
                : part,
            ),
    })),
  );
}

function serializeFileData(
  data:
    | { type: 'data'; data: string | Uint8Array }
    | { type: 'url'; url: URL }
    | { type: 'reference'; reference: Record<string, string> }
    | { type: 'text'; text: string },
): unknown {
  switch (data.type) {
    case 'data':
      return data.data instanceof Uint8Array
        ? convertDataContentToBase64String(data.data)
        : data.data;
    case 'url':
      return data.url.toString();
    case 'reference':
      return data.reference;
    case 'text':
      return data.text;
  }
}