/**
 * useFileViewer — resolves which registered viewer can handle a given MIME type.
 *
 * Other modules register viewers at the `documents_file_viewer` integration
 * point by including an entry in their `integrations.ts`:
 *
 * ```ts
 * documents_file_viewer: [{
 *   id: 'my_viewer',
 *   meta: { mimeTypes: ['application/pdf'] },
 *   component: () => import('./components/MyViewer.vue'),
 * }]
 * ```
 *
 * Viewer components receive the props:  `url: string`, `entity: EntityObject`, `mime: string`.
 */

import { useIntegrationStore } from '@KTXC'
import type { EntityObject } from '@DocumentsManager/models/entity'

const INTEGRATION_POINT = 'documents_file_viewer'

function mimeMatchesPattern(mime: string, pattern: string): boolean {
  if (pattern.endsWith('/*')) {
    // e.g. 'image/*' matches 'image/png', 'image/jpeg', …
    return mime.startsWith(pattern.slice(0, -1))
  }
  return mime === pattern
}

function viewerMatchesMime(
  mime: string,
  mimeTypes?: string[],
  mimePatterns?: string[],
): boolean {
  if (mimeTypes?.includes(mime)) return true
  if (mimePatterns) {
    for (const pattern of mimePatterns) {
      if (mimeMatchesPattern(mime, pattern)) return true
    }
  }
  return false
}

export function useFileViewer() {
  const integrationStore = useIntegrationStore()

  /**
   * Returns the highest-priority registered viewer that can handle `mime`,
   * or `null` if none is found.
   */
  function findViewer(mime: string) {
    // getItems() already returns items sorted by priority (ascending)
    const viewers = integrationStore.getItems(INTEGRATION_POINT)
    for (const viewer of viewers) {
      if (
        viewerMatchesMime(
          mime,
          viewer.meta?.mimeTypes as string[] | undefined,
          viewer.meta?.mimePatterns as string[] | undefined,
        )
      ) {
        return viewer
      }
    }
    return null
  }

  /**
   * Convenience: returns true if any registered viewer can open this entity.
   */
  function canOpen(entity: EntityObject): boolean {
    const mime = entity.properties.mime
    if (!mime) return false
    return findViewer(mime) !== null
  }

  return { findViewer, canOpen }
}

export type UseFileViewerReturn = ReturnType<typeof useFileViewer>