// Copyright (C) 2025, The Duplicati Team
// https://duplicati.com, hello@duplicati.com
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// DEALINGS IN THE SOFTWARE.
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Threading.Tasks;
using Duplicati.Library.Utility;
using Microsoft.Data.Sqlite;

#nullable enable

namespace Duplicati.Library.Main.Database;

/// <summary>
/// A list of values that can be used in a query
/// </summary>
internal class TemporaryDbValueList : IDisposable
{
    /// <summary>
    /// The tag used for logging
    /// </summary>
    private static readonly string LOGTAG = Logging.Log.LogTagFromType(typeof(TemporaryDbValueList));

    /// <summary>
    /// The command to use
    /// </summary>
    private SqliteCommand? _cmd;
    private readonly LocalDatabase _db;
    /// <summary>
    /// The table to use
    /// </summary>
    private readonly string _tableName = $"TemporaryList-{Guid.NewGuid():N}";

    /// <summary>
    /// Flag indicating if the object has been disposed
    /// </summary>
    private bool _disposed = false;
    /// <summary>
    /// Flag indicating if the values are in a table
    /// </summary>
    private bool _isTable = false;
    /// <summary>
    /// The values to use
    /// </summary>
    private readonly IEnumerable<object> _values;
    /// <summary>
    /// The type of the values
    /// </summary>
    private readonly string _valuesType;

    /// <summary>
    /// Creates a new reusable transaction
    /// </summary>
    /// <param name="cmd">The command to use</param>
    /// <param name="con">The connection to use</param>
    /// <param name="values">The values to use</param>
    private TemporaryDbValueList(LocalDatabase db, IEnumerable<object> values, string valuesType)
    {
        _db = db;
        _valuesType = valuesType;
        _values = values;

        ArgumentNullException.ThrowIfNull(values);
    }

    internal static async Task<TemporaryDbValueList> CreateAsync(LocalDatabase db, IEnumerable<long> values)
    {
        return await DoCreateAsync(new TemporaryDbValueList(db, values.Cast<object>(), "INTEGER"));
    }

    internal static async Task<TemporaryDbValueList> CreateAsync(LocalDatabase db, IEnumerable<string> values)
    {
        return await DoCreateAsync(new TemporaryDbValueList(db, values.Cast<object>(), "TEXT"));
    }

    private static async Task<TemporaryDbValueList> DoCreateAsync(TemporaryDbValueList valueList)
    {
        if (valueList._values.Count() > LocalDatabase.CHUNK_SIZE)
            await valueList.ForceToTable();

        return valueList;
    }

    /// <summary>
    /// The values in the list
    /// </summary>
    public IEnumerable<object> Values => _values;

    /// <summary>
    /// Flag indicating if the table has been created
    /// </summary>
    public bool IsTableCreated => _isTable;

    /// <summary>
    /// Get the in clause for the values, creating the table if needed
    /// </summary>
    /// <returns>The in clause for the values</returns>
    public async Task<string> GetInClause()
    {
        if (_disposed)
            throw new ObjectDisposedException(nameof(TemporaryDbValueList));

        await ForceToTable();

        return $@"
            SELECT ""Value""
            FROM ""{_tableName}""
        ";
    }

    /// <summary>
    /// Force the values to be written to a table, if not already done
    /// </summary>
    public async Task ForceToTable()
    {
        if (_disposed)
            throw new ObjectDisposedException(nameof(TemporaryDbValueList));

        if (_isTable)
            return;

        _cmd = _db.Connection.CreateCommand(_db.Transaction);
        await _cmd.ExecuteNonQueryAsync($@"
            CREATE TEMPORARY TABLE ""{_tableName}"" (""Value"" {_valuesType})
        ");
        _isTable = true;
        foreach (var slice in _values.Chunk(LocalDatabase.CHUNK_SIZE))
        {
            var parameterNames = slice.Select((_, i) => $"@p{i}").ToArray();
            var sql = $@"
                INSERT INTO ""{_tableName}"" (""Value"")
                VALUES {string.Join(", ", parameterNames.Select(p => $"({p})"))}
            ";

            _cmd.SetCommandAndParameters(sql);
            for (int i = 0; i < slice.Length; i++)
                _cmd.SetParameterValue(parameterNames[i], slice[i]);

            await _cmd.ExecuteNonQueryAsync();
        }
    }

    /// <summary>
    /// The table name to use
    /// </summary>
    public string TableName => _tableName;

    /// <inheritdoc/>
    public void Dispose()
    {
        DisposeAsync().Await();
    }

    public async Task DisposeAsync()
    {
        if (_disposed)
            return;
        _disposed = true;
        if (!_isTable)
            return;

        try
        {
            if (_cmd != null)
            {
                await _cmd.ExecuteNonQueryAsync($@"DROP TABLE ""{_tableName}""");
                await _cmd.DisposeAsync();
            }
            _cmd = null;
        }
        catch (Exception ex)
        {
            Logging.Log.WriteErrorMessage(LOGTAG, "DropTableFailed", ex, "Failed to drop temporary table {0}: {1}", _tableName, ex.Message);
        }
    }
}