// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using Microsoft.Search.Interop;

namespace Microsoft.Plugin.Indexer.SearchHelper
{
    public class WindowsSearchAPI
    {
        public bool DisplayHiddenFiles { get; set; }

        private readonly ISearch windowsIndexerSearch;
        private readonly object _lock = new object();
        private const uint _fileAttributeHidden = 0x2;

        public WindowsSearchAPI(ISearch windowsIndexerSearch, bool displayHiddenFiles = false)
        {
            this.windowsIndexerSearch = windowsIndexerSearch;
            DisplayHiddenFiles = displayHiddenFiles;
        }

        public List<SearchResult> ExecuteQuery(ISearchQueryHelper queryHelper, string keyword)
        {
            if (queryHelper == null)
            {
                throw new ArgumentNullException(paramName: nameof(queryHelper));
            }

            List<SearchResult> results = new List<SearchResult>();

            // Generate SQL from our parameters, converting the userQuery from AQS->WHERE clause
            string sqlQuery = queryHelper.GenerateSQLFromUserQuery(keyword);

            // execute the command, which returns the results as an OleDBResults.
            List<OleDBResult> oleDBResults = windowsIndexerSearch.Query(queryHelper.ConnectionString, sqlQuery);

            // Loop over all records from the database
            foreach (OleDBResult oleDBResult in oleDBResults)
            {
                if (oleDBResult.FieldData[0] == DBNull.Value || oleDBResult.FieldData[1] == DBNull.Value || oleDBResult.FieldData[2] == DBNull.Value)
                {
                    continue;
                }

                uint fileAttributes = (uint)((long)oleDBResult.FieldData[2]);
                bool isFileHidden = (fileAttributes & _fileAttributeHidden) == _fileAttributeHidden;

                if (DisplayHiddenFiles || !isFileHidden)
                {
                    var uri_path = new Uri((string)oleDBResult.FieldData[0]);
                    var result = new SearchResult
                    {
                        Path = uri_path.LocalPath,
                        Title = (string)oleDBResult.FieldData[1],
                    };

                    results.Add(result);
                }
            }

            return results;
        }

        public static void ModifyQueryHelper(ref ISearchQueryHelper queryHelper, string pattern)
        {
            if (pattern == null)
            {
                throw new ArgumentNullException(paramName: nameof(pattern));
            }

            if (queryHelper == null)
            {
                throw new ArgumentNullException(paramName: nameof(queryHelper));
            }

            // convert file pattern if it is not '*'. Don't create restriction for '*' as it includes all files.
            if (pattern != "*")
            {
                pattern = pattern.Replace("*", "%", StringComparison.InvariantCulture);
                pattern = pattern.Replace("?", "_", StringComparison.InvariantCulture);

                if (pattern.Contains("%", StringComparison.InvariantCulture) || pattern.Contains("_", StringComparison.InvariantCulture))
                {
                    queryHelper.QueryWhereRestrictions += " AND System.FileName LIKE '" + pattern + "' ";
                }
                else
                {
                    // if there are no wildcards we can use a contains which is much faster as it uses the index
                    queryHelper.QueryWhereRestrictions += " AND Contains(System.FileName, '" + pattern + "') ";
                }
            }
        }

        public static void InitQueryHelper(out ISearchQueryHelper queryHelper, int maxCount)
        {
            // This uses the Microsoft.Search.Interop assembly
            CSearchManager manager = new CSearchManager();

            // SystemIndex catalog is the default catalog in Windows
            ISearchCatalogManager catalogManager = manager.GetCatalog("SystemIndex");

            // Get the ISearchQueryHelper which will help us to translate AQS --> SQL necessary to query the indexer
            queryHelper = catalogManager.GetQueryHelper();

            // Set the number of results we want. Don't set this property if all results are needed.
            queryHelper.QueryMaxResults = maxCount;

            // Set list of columns we want to display, getting the path presently
            queryHelper.QuerySelectColumns = "System.ItemUrl, System.FileName, System.FileAttributes";

            // Set additional query restriction
            queryHelper.QueryWhereRestrictions = "AND scope='file:'";

            // To filter based on title for now
            queryHelper.QueryContentProperties = "System.FileName";

            // Set sorting order
            queryHelper.QuerySorting = "System.DateModified DESC";
        }

        public IEnumerable<SearchResult> Search(string keyword, string pattern = "*", int maxCount = 30)
        {
            lock (_lock)
            {
                ISearchQueryHelper queryHelper;
                InitQueryHelper(out queryHelper, maxCount);
                ModifyQueryHelper(ref queryHelper, pattern);
                return ExecuteQuery(queryHelper, keyword);
            }
        }
    }
}