using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace SunlightCentralizedControlManagement_SCCM_.UserClass
{
    /// <summary>
    /// 线程安全的 DataTable 管理器
    /// 提供对 DataTable 的安全并发访问
    /// </summary>
    public class DataTableManager : IDisposable
    {
        private DataTable _dataTable;
        private readonly ReaderWriterLockSlim _lock = new ReaderWriterLockSlim();
        private bool _disposed = false;

        #region 构造函数
        public DataTableManager()
        {
            _dataTable = new DataTable();
        }

        public DataTableManager(DataTable dataTable)
        {
            _dataTable = dataTable ?? throw new ArgumentNullException(nameof(dataTable));
        }

        public DataTableManager(string tableName)
        {
            _dataTable = new DataTable(tableName);
        }
        #endregion

        #region 基本操作
        /// <summary>
        /// 安全地添加列
        /// </summary>
        public void AddColumn(string columnName, Type dataType)
        {
            ExecuteWriteOperation(table =>
            {
                table.Columns.Add(columnName, dataType);
            });
        }

        /// <summary>
        /// 安全地添加行
        /// </summary>
        public void AddRow(params object[] values)
        {
            ExecuteWriteOperation(table =>
            {
                DataRow newRow = table.NewRow();
                for (int i = 0; i < Math.Min(values.Length, table.Columns.Count); i++)
                {
                    newRow[i] = values[i] ?? DBNull.Value;
                }
                table.Rows.Add(newRow);
            });
        }

        /// <summary>
        /// 安全地更新单元格值
        /// </summary>
        public bool UpdateCell(int rowIndex, string columnName, object value)
        {
            return ExecuteWriteOperation(table =>
            {
                if (IsValidRowIndex(table, rowIndex) && table.Columns.Contains(columnName))
                {
                    table.Rows[rowIndex][columnName] = value ?? DBNull.Value;
                    return true;
                }
                return false;
            });
        }

        /// <summary>
        /// 安全地删除行
        /// </summary>
        public bool DeleteRow(int rowIndex)
        {
            return ExecuteWriteOperation(table =>
            {
                if (IsValidRowIndex(table, rowIndex))
                {
                    table.Rows[rowIndex].Delete();
                    return true;
                }
                return false;
            });
        }
        #endregion

        #region 查询操作
        /// <summary>
        /// 安全地获取行
        /// </summary>
        public DataRow GetRow(int rowIndex)
        {
            return ExecuteReadOperation(table =>
            {
                return IsValidRowIndex(table, rowIndex) ? table.Rows[rowIndex] : null;
            });
        }

        /// <summary>
        /// 安全地查找行（使用筛选条件）
        /// </summary>
        public DataRow[] FindRows(string filterExpression)
        {
            return ExecuteReadOperation(table =>
            {
                try
                {
                    return string.IsNullOrEmpty(filterExpression)
                        ? table.Select()
                        : table.Select(filterExpression);
                }
                catch (EvaluateException)
                {
                    return new DataRow[0];
                }
            });
        }

        /// <summary>
        /// 安全地获取行数
        /// </summary>
        public int GetRowCount()
        {
            return ExecuteReadOperation(table => table.Rows.Count);
        }

        /// <summary>
        /// 安全地检查行是否存在
        /// </summary>
        public bool RowExists(int rowIndex)
        {
            return ExecuteReadOperation(table => IsValidRowIndex(table, rowIndex));
        }
        #endregion

        #region 批量操作
        /// <summary>
        /// 安全地批量添加行
        /// </summary>
        public void BulkAddRows(IEnumerable<object[]> rowsData)
        {
            ExecuteWriteOperation(table =>
            {
                foreach (var rowData in rowsData)
                {
                    DataRow newRow = table.NewRow();
                    for (int i = 0; i < Math.Min(rowData.Length, table.Columns.Count); i++)
                    {
                        newRow[i] = rowData[i] ?? DBNull.Value;
                    }
                    table.Rows.Add(newRow);
                }
            });
        }

        /// <summary>
        /// 安全地清空所有数据
        /// </summary>
        public void Clear()
        {
            ExecuteWriteOperation(table =>
            {
                table.Clear();
            });
        }
        #endregion

        #region 数据导出
        /// <summary>
        /// 获取数据快照（线程安全的副本）
        /// </summary>
        public DataTable GetSnapshot()
        {
            return ExecuteReadOperation(table =>
            {
                return table.Copy(); // 创建数据的独立副本
            });
        }

        /// <summary>
        /// 获取只读视图
        /// </summary>
        public DataView GetReadOnlyView()
        {
            return ExecuteReadOperation(table =>
            {
                return new DataView(table) { AllowEdit = false };
            });
        }

        /// <summary>
        /// 导出到新 DataTable（包含结构）
        /// </summary>
        public DataTable ExportToDataTable()
        {
            return ExecuteReadOperation(table =>
            {
                DataTable exported = table.Clone();
                exported.Merge(table, false, MissingSchemaAction.Add);
                return exported;
            });
        }
        #endregion

        #region 锁操作核心
        /// <summary>
        /// 执行读取操作（共享锁）
        /// </summary>
        private T ExecuteReadOperation<T>(Func<DataTable, T> operation)
        {
            _lock.EnterReadLock();
            try
            {
                return operation(_dataTable);
            }
            finally
            {
                _lock.ExitReadLock();
            }
        }

        /// <summary>
        /// 执行写入操作（独占锁）
        /// </summary>
        private void ExecuteWriteOperation(Action<DataTable> operation)
        {
            _lock.EnterWriteLock();
            try
            {
                operation(_dataTable);
                _dataTable.AcceptChanges();
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        private T ExecuteWriteOperation<T>(Func<DataTable, T> operation)
        {
            _lock.EnterWriteLock();
            try
            {
                var result = operation(_dataTable);
                _dataTable.AcceptChanges();
                return result;
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }

        private bool IsValidRowIndex(DataTable table, int rowIndex)
        {
            return rowIndex >= 0 && rowIndex < table.Rows.Count;
        }
        #endregion

        #region 高级功能
        /// <summary>
        /// 带超时的安全操作
        /// </summary>
        public bool TryUpdateCell(int rowIndex, string columnName, object value, int timeoutMs = 5000)
        {
            if (_lock.TryEnterWriteLock(timeoutMs))
            {
                try
                {
                    if (IsValidRowIndex(_dataTable, rowIndex) && _dataTable.Columns.Contains(columnName))
                    {
                        _dataTable.Rows[rowIndex][columnName] = value ?? DBNull.Value;
                        _dataTable.AcceptChanges();
                        return true;
                    }
                    return false;
                }
                finally
                {
                    _lock.ExitWriteLock();
                }
            }
            return false;
        }

        /// <summary>
        /// 执行事务性操作
        /// </summary>
        public void ExecuteTransaction(Action<DataTable> transaction)
        {
            _lock.EnterWriteLock();
            try
            {
                // 开始事务
                _dataTable.BeginLoadData();

                try
                {
                    transaction(_dataTable);
                    _dataTable.AcceptChanges();
                }
                catch
                {
                    _dataTable.RejectChanges();
                    throw;
                }
                finally
                {
                    _dataTable.EndLoadData();
                }
            }
            finally
            {
                _lock.ExitWriteLock();
            }
        }
        #endregion

        #region 属性和清理
        public string TableName
        {
            get => ExecuteReadOperation(table => table.TableName);
            set => ExecuteWriteOperation(table => table.TableName = value);
        }

        public DataColumnCollection Columns
        {
            get => ExecuteReadOperation(table => table.Columns);
        }

        public void Dispose()
        {
            if (!_disposed)
            {
                _lock?.Dispose();
                _dataTable?.Dispose();
                _disposed = true;
            }
            GC.SuppressFinalize(this);
        }

        ~DataTableManager()
        {
            Dispose();
        }
        #endregion
    }
}