export function prepareConversation(messages) {
  const imageUrls = [];
  const preparedMessages = messages.map(message => {
    if (!Array.isArray(message.content)) {
      const prepared = { role: message.role, content: message.content };
      if (message.tool_calls) prepared.tool_calls = message.tool_calls;
      return prepared;
    }

    const imageCount = message.content.filter(item => item.type === 'image').length;
    let imageIndex = 0;
    const content = message.content.flatMap(item => {
      if (item.type !== 'image') return [{ type: 'text', text: item.value || '' }];
      imageUrls.push(item.value);
      imageIndex += 1;
      if (imageCount < 2) return [{ type: 'image' }];
      return [
        { type: 'text', text: `Media-${imageIndex}` },
        { type: 'image' },
        { type: 'text', text: '\n' },
      ];
    });
    const prepared = { role: message.role, content };
    if (message.tool_calls) prepared.tool_calls = message.tool_calls;
    return prepared;
  });
  return { messages: preparedMessages, imageUrls };
}