/**
 * Attachment types shared between api and web (issue #27, ADR 0011). M2
 * accepted images only; M6 (#61) adds a configurable allowlist for general
 * attachments (PDF, office files, …) plus an SVG policy.
 */
export const ATTACHMENT_IMAGE_MIME_TYPES = [
  'image/png',
  'image/jpeg',
  'image/gif',
  'image/webp',
] as const;

export type AttachmentMimeType = (typeof ATTACHMENT_IMAGE_MIME_TYPES)[number];

export function isImageMimeType(mimeType: string): boolean {
  return (ATTACHMENT_IMAGE_MIME_TYPES as readonly string[]).includes(mimeType);
}

/**
 * SVG is an image but also an XML document that can carry scripts and event
 * handlers, so it is never treated like a raster image: it is sanitized or
 * rejected on upload (instance setting) and always served as a download,
 * never inline (security.md §Uploads).
 */
export const SVG_MIME_TYPE = 'image/svg+xml';

/** How the instance handles SVG uploads (ADR 0011, security.md §Uploads). */
export type SvgPolicy = 'reject' | 'sanitize';

/**
 * Extension → served MIME type for the non-image allowlist. The allowlist is
 * keyed on the lowercase extension (what an admin configures and what names
 * the download); the MIME here only sets the response `Content-Type`, and
 * non-images are always sent with `Content-Disposition: attachment` +
 * `nosniff`, so a wrong guess can never cause inline execution.
 */
export const ATTACHMENT_EXTENSION_MIME_TYPES: Readonly<Record<string, string>> = {
  pdf: 'application/pdf',
  txt: 'text/plain',
  md: 'text/markdown',
  csv: 'text/csv',
  rtf: 'application/rtf',
  doc: 'application/msword',
  docx: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
  odt: 'application/vnd.oasis.opendocument.text',
  xls: 'application/vnd.ms-excel',
  xlsx: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
  ods: 'application/vnd.oasis.opendocument.spreadsheet',
  ppt: 'application/vnd.ms-powerpoint',
  pptx: 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
  odp: 'application/vnd.oasis.opendocument.presentation',
  zip: 'application/zip',
};

/**
 * Default non-image allowlist (extensions, lowercase, no dot). Images from
 * {@link ATTACHMENT_IMAGE_MIME_TYPES} are always allowed regardless of this
 * list; SVG is governed separately by the SVG policy.
 */
export const DEFAULT_ATTACHMENT_EXTENSIONS: readonly string[] = [
  'pdf',
  'txt',
  'md',
  'csv',
  'doc',
  'docx',
  'odt',
  'xls',
  'xlsx',
  'ods',
  'ppt',
  'pptx',
  'odp',
  'zip',
];

/** Lowercase extension without the leading dot, or '' when the name has none. */
export function fileExtension(fileName: string): string {
  const dot = fileName.lastIndexOf('.');
  if (dot <= 0 || dot === fileName.length - 1) return '';
  return fileName.slice(dot + 1).toLowerCase();
}

/**
 * Hard ceiling on the raw multipart body the api will buffer in memory,
 * independent of the per-pond/user `max_file_bytes` quota (QuotaService)
 * that governs the actually accepted size — mirrors how
 * `MAX_PAGE_DOCUMENT_BYTES` relates to the JSON body-parser limit (pages.ts).
 */
export const MAX_UPLOAD_PARSE_BYTES = 64 * 1024 * 1024;

export interface AttachmentView {
  id: string;
  pondId: string;
  pageId: string | null;
  fileName: string;
  mimeType: string;
  sizeBytes: number;
  createdAt: string;
}

/**
 * A row in the page-attachments section and the pond file manager (#61):
 * carries the uploader's display name and, for the pond manager, the title
 * of the page currently referencing the file (null = orphan candidate).
 */
export interface AttachmentListItemView extends AttachmentView {
  uploaderName: string;
  pageTitle: string | null;
}

/** Pond-wide file manager payload (Pond Admin, #61). */
export interface PondFilesView {
  files: AttachmentListItemView[];
  storageBytesUsed: number;
  storageBytesLimit: number;
}