import { getTextAttachmentType } from './attachment-upload.js';

export type AttachmentDeliveryMode = 'inline_native' | 'reference_only';
export type AttachmentArchiveType = 'gz' | 'tgz' | 'zip';

const ARCHIVE_MIME_TYPES_BY_TYPE: Record<AttachmentArchiveType, Set<string>> = {
  gz: new Set(['application/gzip', 'application/x-gzip']),
  tgz: new Set([
    'application/tar+gzip',
    'application/x-compressed-tar',
    'application/x-gtar',
    'application/x-tar+gzip',
    'application/x-tgz'
  ]),
  zip: new Set(['application/x-zip', 'application/x-zip-compressed', 'application/zip'])
};

type AttachmentTypeInput = {
  fileName?: string;
  mimeType?: string | null;
};

function normalizeMimeType(mimeType?: string | null): string {
  return mimeType?.trim().toLowerCase() ?? '';
}

function normalizeFileName(fileName?: string): string {
  return fileName?.trim().toLowerCase() ?? '';
}

function hasAnyFileName(input: AttachmentTypeInput): boolean {
  return normalizeFileName(input.fileName).length > 0;
}

export function detectAttachmentArchiveType(input: AttachmentTypeInput): AttachmentArchiveType | null {
  const fileName = normalizeFileName(input.fileName);
  if (fileName.endsWith('.tar.gz') || fileName.endsWith('.tgz')) {
    return 'tgz';
  }
  if (fileName.endsWith('.zip')) {
    return 'zip';
  }
  if (fileName.endsWith('.gzip') || fileName.endsWith('.gz')) {
    return 'gz';
  }

  const mimeType = normalizeMimeType(input.mimeType);
  if (!mimeType) {
    return null;
  }

  if (ARCHIVE_MIME_TYPES_BY_TYPE.zip.has(mimeType)) {
    return 'zip';
  }
  if (ARCHIVE_MIME_TYPES_BY_TYPE.tgz.has(mimeType)) {
    return 'tgz';
  }
  if (ARCHIVE_MIME_TYPES_BY_TYPE.gz.has(mimeType)) {
    return 'gz';
  }
  return null;
}

export function classifyAttachmentDelivery(input: AttachmentTypeInput): AttachmentDeliveryMode {
  if (detectAttachmentArchiveType(input)) {
    return 'reference_only';
  }

  const mimeType = normalizeMimeType(input.mimeType);
  if (mimeType.startsWith('image/') || mimeType === 'application/pdf') {
    return 'inline_native';
  }

  if (
    getTextAttachmentType({
      fileName: input.fileName,
      mimeType
    }) !== null
  ) {
    return 'inline_native';
  }

  return 'reference_only';
}

export function isSupportedAttachmentUploadType(input: AttachmentTypeInput): boolean {
  if (detectAttachmentArchiveType(input)) {
    return true;
  }

  if (!hasAnyFileName(input) && !normalizeMimeType(input.mimeType)) {
    return false;
  }

  return classifyAttachmentDelivery(input) === 'inline_native';
}