/**
 * File selectors - Pure functions for accessing file state
 */

import { FileId } from '../../types/file';
import {
  FileRecord,
  FileContextState,
  FileContextSelectors
} from '../../types/fileContext';

/**
 * Create stable selectors using stateRef and filesRef
 */
export function createFileSelectors(
  stateRef: React.MutableRefObject<FileContextState>,
  filesRef: React.MutableRefObject<Map<FileId, File>>
): FileContextSelectors {
  return {
    getFile: (id: FileId) => filesRef.current.get(id),

    getFiles: (ids?: FileId[]) => {
      const currentIds = ids || stateRef.current.files.ids;
      return currentIds.map(id => filesRef.current.get(id)).filter(Boolean) as File[];
    },

    getFileRecord: (id: FileId) => stateRef.current.files.byId[id],

    getFileRecords: (ids?: FileId[]) => {
      const currentIds = ids || stateRef.current.files.ids;
      return currentIds.map(id => stateRef.current.files.byId[id]).filter(Boolean);
    },

    getAllFileIds: () => stateRef.current.files.ids,

    getSelectedFiles: () => {
      return stateRef.current.ui.selectedFileIds
        .map(id => filesRef.current.get(id))
        .filter(Boolean) as File[];
    },

    getSelectedFileRecords: () => {
      return stateRef.current.ui.selectedFileIds
        .map(id => stateRef.current.files.byId[id])
        .filter(Boolean);
    },

    // Pinned files selectors
    getPinnedFileIds: () => {
      return Array.from(stateRef.current.pinnedFiles);
    },

    getPinnedFiles: () => {
      return Array.from(stateRef.current.pinnedFiles)
        .map(id => filesRef.current.get(id))
        .filter(Boolean) as File[];
    },

    getPinnedFileRecords: () => {
      return Array.from(stateRef.current.pinnedFiles)
        .map(id => stateRef.current.files.byId[id])
        .filter(Boolean);
    },

    isFilePinned: (file: File) => {
      // Find FileId by matching File object properties
      const fileId = (Object.keys(stateRef.current.files.byId) as FileId[]).find(id => {
        const storedFile = filesRef.current.get(id);
        return storedFile &&
               storedFile.name === file.name &&
               storedFile.size === file.size &&
               storedFile.lastModified === file.lastModified;
      });
      return fileId ? stateRef.current.pinnedFiles.has(fileId) : false;
    },

    // Stable signature for effects - prevents unnecessary re-renders
    getFilesSignature: () => {
      return stateRef.current.files.ids
        .map(id => {
          const record = stateRef.current.files.byId[id];
          return record ? `${id}:${record.size}:${record.lastModified}` : '';
        })
        .join('|');
    },

  };
}

/**
 * Helper for building quickKey sets for deduplication
 */
export function buildQuickKeySet(fileRecords: Record<FileId, FileRecord>): Set<string> {
  const quickKeys = new Set<string>();
  Object.values(fileRecords).forEach(record => {
    if (record.quickKey) {
      quickKeys.add(record.quickKey);
    }
  });
  return quickKeys;
}

/**
 * Helper for building quickKey sets from IndexedDB metadata
 */
export function buildQuickKeySetFromMetadata(metadata: Array<{ name: string; size: number; lastModified: number }>): Set<string> {
  const quickKeys = new Set<string>();
  metadata.forEach(meta => {
    // Format: name|size|lastModified (same as createQuickKey)
    const quickKey = `${meta.name}|${meta.size}|${meta.lastModified}`;
    quickKeys.add(quickKey);
  });
  return quickKeys;
}

/**
 * Get primary file (first in list) - commonly used pattern
 */
export function getPrimaryFile(
  stateRef: React.MutableRefObject<FileContextState>,
  filesRef: React.MutableRefObject<Map<FileId, File>>
): { file?: File; record?: FileRecord } {
  const primaryFileId = stateRef.current.files.ids[0];
  if (!primaryFileId) return {};

  return {
    file: filesRef.current.get(primaryFileId),
    record: stateRef.current.files.byId[primaryFileId]
  };
}