using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using Dapper;
using DataModel.Models;
using DataModel.Process;
using WorkerService.Models;

namespace WorkerService.Process
{
    /// <summary>
    /// Data update entry management functionality for data update processor
    /// </summary>
    public partial class UpdateProcessor
    {
        /// <summary>
        /// SQL to close any open update entries (identified by number records = -2)
        /// </summary>
        private const string SQL_CLOSE_OPEN_UPDATE_ENTRIES = @"
            UPDATE dbo.DataUpdate 
            SET EndDT = GETDATE(), WasSuccessful = 0, NumberRecords = -1 
            WHERE NumberRecords = -2";

        /// <summary>
        /// Closes any open data update entries
        /// </summary>
        private static void CloseOpenUpdateEntries()
        {
            try
            {
                using (SqlConnection connection = LotFinderDB.GetConnection())
                {
                    //Close any open update entries
                    connection.Execute(SQL_CLOSE_OPEN_UPDATE_ENTRIES);
                }
            }
            catch (Exception error)
            {
                //Log but do not forward error
                logger.Error("CloseOpenUpdateEntries: failed to close open data update entries: {0}.", error.Message);
            }
        }

        /// <summary>
        /// SQL to purge data update records
        /// </summary>
        private const string SQL_PURGE_UPDATE_ENTRIES = @"
            DELETE FROM dbo.DataUpdate 
            WHERE StartDT < DATEADD(DAY, @maxAge * -1, GETDATE())";

        /// <summary>
        /// Purges any data update entries older than given max age
        /// </summary>
        /// <param name="maxAge">Maximum entry age (in days)</param>
        private static void PurgeUpdateEntries(int maxAge)
        {
            try
            {
                using (SqlConnection connection = LotFinderDB.GetConnection())
                {
                    //Purge the records
                    connection.Execute(SQL_PURGE_UPDATE_ENTRIES, new { maxAge });
                }
            }
            catch (Exception error)
            {
                //Log but do not forward error
                logger.Error("PurgeUpdateEntries: failed to purge data update entries older than {0} days: {1}.", maxAge, error.Message);
            }
        }

        /// <summary>
        /// SQL to insert data update record
        /// </summary>
        private const string SQL_LOG_DATA_UPDATE_START = @"
            INSERT INTO dbo.DataUpdate(SourceSystem, SourceData, TableName, StartDT, EndDT, UpdateType, WasSuccessful, NumberRecords)
            OUTPUT INSERTED.*
            VALUES(@sourceSystem, @sourceData, @tableName, GETDATE(), '1970-01-01', @updateType, 0, -2);";

        /// <summary>
        /// Logs the data update entry at the start of the update
        /// </summary>
        /// <param name="connection">SQL connection to execute commands on</param>
        /// <param name="dataUpdate">Data update entry to log</param>
        public static void LogDataUpdateStart(SqlConnection connection, DataUpdate dataUpdate)
        {
            try
            {
                //Update the record
                DataUpdate inserted = connection.QueryFirst<DataUpdate>(SQL_LOG_DATA_UPDATE_START,
                    new
                    {
                        sourceSystem = dataUpdate.SourceSystem,
                        sourceData = dataUpdate.SourceData,
                        tableName = dataUpdate.TableName,
                        updateType = dataUpdate.UpdateType
                    });

                //Copy output values to model
                dataUpdate.ID = inserted.ID;
                dataUpdate.StartDT = inserted.StartDT;
            }
            catch (Exception error)
            {
                //Log but do not forward error
                logger.Error("LogDataUpdateStart: failed to log starting data update entry: {0}.", error.Message);
            }
        }

        /// <summary>
        /// SQL to update data update record with results
        /// </summary>
        private const string SQL_LOG_DATA_UPDATE_END = @"
            UPDATE dbo.DataUpdate 
            SET EndDT = GETDATE(), WasSuccessful = @wasSuccessful, NumberRecords = @numberRecords
            OUTPUT INSERTED.*
            WHERE ID = @id";

        /// <summary>
        /// Logs the data update entry at the end of the update
        /// </summary>
        /// <param name="connection">SQL connection to execute commands on</param>
        /// <param name="dataUpdate">Data update entry to log</param>
        public static void LogDataUpdateEnd(SqlConnection connection, DataUpdate dataUpdate)
        {
            try
            {
                //Update the record
                DataUpdate updated = connection.QueryFirst<DataUpdate>(SQL_LOG_DATA_UPDATE_END,
                    new
                    {
                        id = dataUpdate.ID,
                        wasSuccessful = dataUpdate.WasSuccessful,
                        numberRecords = dataUpdate.NumberRecords
                    });

                //Copy output values to model
                dataUpdate.EndDT = updated.EndDT;
            }
            catch (Exception error)
            {
                //Log but do not forward error
                logger.Error("LogDataUpdateEnd: failed to log ending data update entry: {0}.", error.Message);
            }
        }

        /// <summary>
        /// Gets set of last successful data updates for all tables
        /// </summary>
        /// <param name="connection">SQL connection to execute commands on</param>
        /// <returns>Set of last successful data updates for all tables</returns>
        private static List<LastDataUpdate> GetLastDataUpdates(SqlConnection connection)
        {
            return connection.Query<LastDataUpdate>("SELECT * FROM dbo.LastDataUpdates").ToList();
        }
    }
}