using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using DatabaseUnitTesting.Utilities;
using DatabaseUnitTesting.Utilities.Results;

namespace DatabaseUnitTesting
{
    public class DatabaseModificationTester : IDisposable
    {

        private readonly DatabaseComparer _dataComparer;
        private SqlTransaction _transaction;
        private SqlConnection _connection;
        private readonly string _snapshotName;
        private readonly DatabaseAdapter _databaseAdapter;
        private bool _activeSnapshot = false;
        /// <summary>
        /// Used to establish the objects required to create a unit test running compares between a stored XML database file and an SQL transaction.
        /// </summary>
        /// <param name="connection"></param>
        /// <param name="databaseName"></param>
        /// <param name="snapshotName"></param>
        public DatabaseModificationTester(SqlConnection connection, string databaseName, string snapshotName)
        {
            _connection = connection;
            _snapshotName = snapshotName;
            _dataComparer = new DatabaseComparer(connection, databaseName, snapshotName);
            _databaseAdapter = new DatabaseAdapter(connection);
            _databaseAdapter.CreateSnapshot(databaseName, snapshotName);
            _activeSnapshot = true;
        }
        /// <summary>
        /// establishes the command transaction to be compared and rolled back on end
        /// </summary>
        /// <returns></returns>
        public SqlTransaction BeginTestTransaction()
        {
            if (_transaction != null)
                EndTestTransaction();

            return (_transaction = _connection.BeginTransaction());
        }
        /// <summary>
        /// Once the compare is complete this method cleans up, rollsback, and disposes the transaction
        /// </summary>
        public void EndTestTransaction()
        {
            if (_transaction == null)
                throw new InvalidOperationException("Transaction does not exist");

            _dataComparer.CleanUp();
            _transaction.Rollback();
            _transaction.Dispose();
            _transaction = null;
        }
        /// <summary>
        /// Method to write XML file to use during unit testing. Writes differences between current database and the completed transaction.
        /// The file generated here should be manually verified
        /// </summary>
        /// <param name="filename"></param>
        public void WriteDiffsToXml(string filename)
        {
            XmlFileAdapter.Write(filename, _dataComparer.GenerateDifferences(_transaction));
        }
        /// <summary>
        /// Return true/false based on compare of transaction and stored XML expected test results.
        /// </summary>
        /// <param name="filename"></param>
        /// <returns></returns>
        public bool CompareDiffsToXml(string filename)
        {
            return XmlFileAdapter.Read(filename).Equals(_dataComparer.GenerateDifferences(_transaction));
        }

        public bool AreEqual()
        {
            return _dataComparer.GenerateDifferences(_transaction).TableCount == 0;
        }
        /// <summary>
        /// Enables test to ignore defined columns in database tables
        /// </summary>
        /// <param name="schemaName"></param>
        /// <param name="objectName"></param>
        /// <param name="columnName"></param>
        public void AddColumnToIgnore(string schemaName, string objectName, string columnName)
        {
            _dataComparer.AddColumnToIgnore(schemaName, objectName, columnName);
        }
        /// <summary>
        /// Enables test to ignore defined columns in database tables
        /// </summary>
        /// <param name="schema1"></param>
        /// <param name="name1"></param>
        /// <param name="columnNames"></param>
        public void AddColumnsToIgnore(string schema1, string name1, List<string> columnNames)
        {
            _dataComparer.AddColumnsToIgnore(schema1, name1, columnNames);
        }

        public void AddObjectComparison(string schemaName, string tableName)
        {
            _dataComparer.AddObjectComparison(schemaName, tableName, schemaName, tableName);
        }

        public void Dispose()
        {
            if (_activeSnapshot)
            {
                _activeSnapshot = false;
                _databaseAdapter.DropSnapshot(_snapshotName);
            }
        }
    }
}