using System;
using System.Data;
using System.Collections;
using System.Configuration;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Threading;
using System.Diagnostics;


namespace WmData {
    public abstract class WmDataLinkPage : System.Web.UI.Page {
        protected WmGenericData data = null;
        protected WmDataLink dataLink = null;

        protected abstract void initDataLinkPage();

        protected void Page_Load(object sender, EventArgs e) {}

        protected override void OnInit(EventArgs e) {
            base.OnInit(e);
            initDataLinkPage();

            DataLinkCommand command = DataLinkCommand.STATUS;
            if (Request["command"] != null) {
                try {
                    string commandText = Request["command"];
                    commandText = commandText.ToUpper();
                    command = (DataLinkCommand)Enum.Parse(typeof(DataLinkCommand), commandText);
                } catch { }
            }

            switch (command) {
                case DataLinkCommand.CURRENT_ROLE:
                    handleCommandCurrentRole();
                    break;
                case DataLinkCommand.STATUS:
                    handleCommandStatus();
                    break;
                case DataLinkCommand.LIST_SERVERS:
                    handleCommandListServers();
                    break;
                case DataLinkCommand.GET_CHECKSUM:
                    handleCommandGetChecksum();
                    break;
                case DataLinkCommand.GET_TRANSACTIONS:
                    handleCommandGetTransactions();
                    break;
                case DataLinkCommand.GET_DATATABLE:
                    handleCommandGetDataTable();
                    break;
                case DataLinkCommand.GET_CURRENT_MAXIMUM_ID:
                    handleCommandGetCurrentMaximumId();
                    break;
                case DataLinkCommand.GET_ROW_COUNT:
                    handleCommandGetRowCount();
                    break;
                case DataLinkCommand.LINK_HEALTH:
                    handleCommandLinkHealth();
                    break;
            }
        }


        public void handleCommandLinkHealth() {
            // link ok if:
            // - active role
            // - backup role AND:
            //   - all tables are OK
            //   - if OUT OF SYNC and last transaction is less then 10 minutes old
            // 

            bool isHealthy = false;
            string reason = "";

            if (dataLink.CurrentRole == WmDataLinkRole.ACTIVE) {
                isHealthy = true;
                reason = "This is the active server.";
            } else if (dataLink.CurrentRole == WmDataLinkRole.BACKUP) {
                if (areSyncObjectTypesSynced()) {
                    isHealthy = true;
                    reason = "This server is entirely in sync.";
                } else {
                    long fiveMinutesAgoInUtcTicks = DateTime.UtcNow.AddMinutes(-5).Ticks;

                    if (dataLink.LastSyncMomentUtcTicks < fiveMinutesAgoInUtcTicks) { // if the last sync round is less then five minutes ago
                        isHealthy = false;
                        reason = "Last transaction was more than five minutes ago.";
                    } else {
                        isHealthy = true;
                        reason = "Awaiting next sync round.";
                    }

                }
            } else {
                isHealthy = false;
                reason = "This server is currently "+dataLink.CurrentRole.ToString()+".";
            }

            string response = null;

            if (isHealthy) {
                response = "[HEALTHY] " + reason;
            } else {
                response = "[SICK] " + reason;
            }

            Response.Write(response);

        }


        public void handleCommandCurrentRole() {
            Response.Write(dataLink.CurrentRole.ToString());
        }
        public void handleCommandListServers() {
            foreach (WmDataLinkServer server in dataLink.DataLinkServers) {
                Response.Write(server.ServerUrl + Environment.NewLine);
            }
        }
        public void handleCommandGetChecksum() {
            string dataTableName = "";
            if (Request["table"] != null) {
                dataTableName = Request["table"];
            }
            Response.Write(data.getChecksum(dataTableName));
        }
        public void handleCommandGetCurrentMaximumId() {
            string dataTableName = "";
            if (Request["table"] != null) {
                dataTableName = Request["table"];
            }
            Response.Write(data.getCurrentMaximumId(dataTableName));
        }
        public void handleCommandGetRowCount() {
            string dataTableName = "";
            if (Request["table"] != null) {
                dataTableName = Request["table"];
            }
            WmIntermediateObject intermediateObject =data.IntermediateObjectManager.getExistingIntermediateObjectByTableName(dataTableName);
            if (intermediateObject != null) {
                Type objectType = intermediateObject.ObjectType;
                Response.Write(data.getRowCount(objectType));
            } else {
                Response.Write("0");
            }
        }
        public void handleCommandGetTransactions() {
            long sinceUtcTicks = 0;
            if (Request["since"] != null) {
                try {
                    sinceUtcTicks = long.Parse(Request["since"]);
                } catch { }
            }
            
            string transactionsAsXml = dataLink.getTransactionsAsXmlSince(sinceUtcTicks);

            transactionsAsXml = WmDataTools.compress(transactionsAsXml);

            Response.Write(transactionsAsXml);
        }

        public void handleCommandGetDataTable() {
            string dataTableName = "";
            if (Request["table"] != null) {
                dataTableName = Request["table"];
            }

            WmIntermediateObject intermediateObject = data.IntermediateObjectManager.getExistingIntermediateObjectByTableName(dataTableName);
            if (intermediateObject == null) {
                throw new NullReferenceException("WmDataTransactionManager: Attempt to import object that is unknown at the Intermediate Object Manager, try to issue a local get select call first");
            }
            string dataTableAsXml = dataLink.getDataTableAsXml(intermediateObject.ObjectType);

           dataTableAsXml = WmDataTools.compress(dataTableAsXml);

            Response.Write(dataTableAsXml);
        }

        protected bool areSyncObjectTypesSynced() {
            bool inSync = false;

            WmDataLinkServer activeServer = dataLink.getActiveServer();
            if (activeServer != null) {
                inSync = true;

                List<Type> syncObjectTypes = data.DataLink.SyncObjectTypes;
                foreach (Type syncObjectType in syncObjectTypes) {
                    string syncObjectTableName = WmDataTools.getTableName(syncObjectType);
                    string localChecksum = data.getChecksum(syncObjectTableName).ToString();
                    string remoteChecksum = activeServer.getChecksum(syncObjectTableName).ToString();

                    if (!remoteChecksum.Equals(localChecksum)) {
                        inSync = false;
                        break; // does not make sense to look further, we're out of sync. 
                    }
                }

            }

            return inSync;
        }

        public void handleCommandStatus() {
            WmDataLinkServer activeServer = dataLink.getActiveServer();
            string activeServerDisplayName = "none";
            if (activeServer != null) { activeServerDisplayName = activeServer.ServerUrl; }
            Response.Write("<pre>");
            Response.Write("WmDataLink v" + System.Reflection.Assembly.GetExecutingAssembly().GetName().Version+" - (c) W.L. Middelkoop" +Environment.NewLine);
            Response.Write("Data engine in use:     " + data.GetType().Name + Environment.NewLine);
            Response.Write("Active server:          " + activeServerDisplayName + Environment.NewLine);
            Response.Write("This server address:    " + dataLink.ThisServerAddress + Environment.NewLine);
            Response.Write("This server role:       " + dataLink.CurrentRole.ToString() + Environment.NewLine);
            
            DateTime lastSyncMoment = new DateTime(dataLink.Status.LastSyncMomentUtcTicks);
            TimeSpan delay = DateTime.UtcNow-lastSyncMoment;

            Response.Write("Last transaction (UTC): " + lastSyncMoment.ToString() + " (difference: " + delay.ToString() + ")" + Environment.NewLine);
            Response.Write(Environment.NewLine);
            Response.Write("The following object types are linked:"+Environment.NewLine);
            Response.Write(Environment.NewLine);
            int column1Width = 25;
            int column2Width = 19;
            int column3Width = 19;
            int column4Width = 8;
            int column5Width = 15;
            int column6Width = 15;
            int column7Width = 17;
            int column8Width = 17;
            int column9Width = 13;

            string heading1Text = WmDataTools.makeSureStringHasMinimumLength("OBJECTTYPE",column1Width,true);
            string heading2Text = WmDataTools.makeSureStringHasMinimumLength("LOCAL ROW COUNT",column2Width,false);
            string heading3Text = WmDataTools.makeSureStringHasMinimumLength("ACTIVE ROW COUNT", column3Width, false);
            string heading4Text = WmDataTools.makeSureStringHasMinimumLength("ROWS", column4Width, false);
            string heading5Text = WmDataTools.makeSureStringHasMinimumLength("LOCAL MAX ID",column5Width,false);
            string heading6Text = WmDataTools.makeSureStringHasMinimumLength("ACTIVE MAX ID", column6Width, false);
            string heading7Text = WmDataTools.makeSureStringHasMinimumLength("LOCAL CHECKSUM",column7Width,false);
            string heading8Text = WmDataTools.makeSureStringHasMinimumLength("ACTIVE CHECKSUM",column8Width,false);
            string heading9Text = WmDataTools.makeSureStringHasMinimumLength("CHECK", column9Width, false);
            
            Response.Write(heading1Text+heading2Text+heading3Text+heading4Text+heading5Text+heading6Text+heading7Text+heading8Text+ heading9Text+Environment.NewLine);

            List<Type> syncObjectTypes = data.DataLink.SyncObjectTypes;
            foreach (Type syncObjectType in syncObjectTypes) {
                string syncObjectTableName = WmDataTools.getTableName(syncObjectType);

                int localRowCount = data.getRowCount(syncObjectType);
                int remoteRowCount = 0;
                int remoteCurrentMaximumId = 0;

                string rowCountPercentageText = "-";
                string localChecksum = data.getChecksum(syncObjectTableName).ToString();
                string remoteChecksum = "n/a";
                string checkText = "-";

                if (activeServer != null) {
                    remoteRowCount = activeServer.getRowCount(syncObjectTableName);
                    remoteCurrentMaximumId = activeServer.getCurrentMaximumId(syncObjectTableName);
                    rowCountPercentageText = Math.Round(((double)localRowCount / remoteRowCount) * 100, 2).ToString(".0") + "%";
                    remoteChecksum = activeServer.getChecksum(syncObjectTableName).ToString();

                    if (remoteChecksum.Equals(localChecksum)) {
                        checkText = "OK";
                    } else {
                        checkText = "OUT OF SYNC";
                    }
                }

                string column1Text = WmDataTools.makeSureStringHasMinimumLength(syncObjectType.Name,column1Width,true);
                string column2Text = WmDataTools.makeSureStringHasMinimumLength(localRowCount.ToString(), column2Width, false);
                string column3Text = WmDataTools.makeSureStringHasMinimumLength(remoteRowCount.ToString(), column3Width, false);
                string column4Text = WmDataTools.makeSureStringHasMinimumLength(rowCountPercentageText, column4Width, false);
                
                string column5Text = WmDataTools.makeSureStringHasMinimumLength(data.getCurrentMaximumId(syncObjectTableName).ToString(), column5Width, false);
                string column6Text = WmDataTools.makeSureStringHasMinimumLength(remoteCurrentMaximumId.ToString(), column5Width, false);
                
                string column7Text = WmDataTools.makeSureStringHasMinimumLength(localChecksum, column7Width, false);
                string column8Text = WmDataTools.makeSureStringHasMinimumLength(remoteChecksum, column8Width, false);

                string column9Text = WmDataTools.makeSureStringHasMinimumLength(checkText, column9Width, false);

                Response.Write(column1Text + column2Text + column3Text + column4Text + column5Text +  column6Text+column7Text+column8Text+column9Text+ Environment.NewLine);
                

            }

            Response.Write("</pre>");
        }

        public WmGenericData Data {
            get { return data; }
        }

    }

    public enum DataLinkCommand {
        CURRENT_ROLE = 1,
        STATUS = 2,
        LIST_SERVERS = 10,
        GET_TRANSACTIONS = 20,
        GET_CHECKSUM = 30,
        GET_DATATABLE = 40,
        GET_CURRENT_MAXIMUM_ID = 50,
        GET_ROW_COUNT = 60,
        LINK_HEALTH = 70
    }
}