import 'dart:convert';

import 'package:flutter/foundation.dart';

import '../../../../api/cache_store.dart';
import '../../../../api/marianumcloud/webdav/queries/list_files/cacheable_file.dart';
import '../../../../api/marianumcloud/webdav/queries/list_files/list_files_response.dart';

/// Document key prefix used by `ListFilesCache._documentId`.
const String _folderCachePrefix = 'wd-folder-';

/// Every file and folder from the cached folder listings, deduplicated by
/// path. Built once per search session: reading and parsing all listings on
/// each keystroke used to stall typing.
Future<List<CacheableFile>> loadLocalCacheIndex() async {
  final entries = await CacheStore.instance.readAll(prefix: _folderCachePrefix);
  if (entries.isEmpty) return const [];
  final payloads = [for (final entry in entries.values) entry.json];
  return compute(buildLocalCacheIndex, payloads);
}

/// Parses cached `ListFilesResponse` payloads into a deduplicated file list.
/// Unparsable payloads are skipped.
List<CacheableFile> buildLocalCacheIndex(List<String> payloads) {
  final byPath = <String, CacheableFile>{};
  for (final json in payloads) {
    final ListFilesResponse listing;
    try {
      listing = ListFilesResponse.fromJson(
        jsonDecode(json) as Map<String, dynamic>,
      );
    } on Object {
      continue;
    }
    for (final file in listing.files) {
      byPath[file.path] ??= file;
    }
  }
  return byPath.values.toList();
}

/// Files in [index] whose name contains [query] (case-insensitive).
///
/// [pathScope] restricts results to entries whose WebDAV path starts with
/// the given folder. Pass an empty list (or null) to search globally.
List<CacheableFile> searchLocalCacheIndex(
  List<CacheableFile> index,
  String query, {
  List<String>? pathScope,
}) {
  final trimmed = query.trim();
  if (trimmed.isEmpty) return const [];
  final needle = trimmed.toLowerCase();
  final scopePrefix = pathScope == null || pathScope.isEmpty
      ? ''
      : '${pathScope.join('/')}/';
  return [
    for (final file in index)
      if (file.lowerName.contains(needle) &&
          (scopePrefix.isEmpty || file.path.startsWith(scopePrefix)))
        file,
  ];
}