import { hostApiFetch, hostApiFetchBytes } from './host-api';

export const CODING_ATTACHMENT_MAX_BYTES = 16 * 1024 * 1024;
export const CODING_ATTACHMENT_MAX_COUNT = 16;
export const CODING_ATTACHMENT_UPLOAD_CONCURRENCY = 4;
export const CODING_ATTACHMENT_MIMES = new Set([
  'image/png',
  'image/jpeg',
  'image/webp',
  'image/gif',
]);

export interface CodingAttachmentRef {
  attachmentId: string;
  mime: string;
  byteLength: number;
}

export async function uploadCodingAttachment(file: File): Promise<CodingAttachmentRef> {
  const mime = file.type.trim().toLowerCase();
  if (!CODING_ATTACHMENT_MIMES.has(mime)) throw new Error('仅支持 PNG、JPEG、WebP 或 GIF 图片。');
  if (file.size <= 0 || file.size > CODING_ATTACHMENT_MAX_BYTES) {
    throw new Error('图片不能超过 16 MB。');
  }
  return await hostApiFetch<CodingAttachmentRef>(
    '/api/coding/attachments',
    {
      method: 'POST',
      headers: { 'Content-Type': mime },
      body: await file.arrayBuffer(),
    },
  );
}

export async function loadCodingAttachmentPreview(
  attachmentId: string,
): Promise<{ bytes: Uint8Array; mime: string }> {
  const response = await hostApiFetchBytes(
    `/api/coding/attachments/${encodeURIComponent(attachmentId)}/content`,
  );
  if (!CODING_ATTACHMENT_MIMES.has(response.contentType)) {
    throw new Error('图片附件格式无效。');
  }
  return { bytes: response.bytes, mime: response.contentType };
}