using System;

using System.Linq;

using Raven.Server.Documents;

using Voron;

using Voron.Impl;



namespace Raven.Server.Storage.Schema

{

    public static class SchemaUpgrader

    {

        internal class CurrentVersion

        {

            public const int ServerVersion = 11;



            public const int ConfigurationVersion = 10;



            public const int DocumentsVersion = 15;



            public const int IndexVersion = 12;

        }



        private static readonly int[] SkippedDocumentsVersion = { 12 };

        

        public enum StorageType

        {

            Server,

            Configuration,

            Documents,

            Index,

        }



        private class InternalUpgrader

        {

            private readonly StorageType _storageType;

            private readonly ConfigurationStorage _configurationStorage;

            private readonly DocumentsStorage _documentsStorage;



            internal InternalUpgrader(StorageType storageType, ConfigurationStorage configurationStorage, DocumentsStorage documentsStorage)

            {

                _storageType = storageType;

                _configurationStorage = configurationStorage;

                _documentsStorage = documentsStorage;

            }



            internal bool Upgrade(Transaction readTx, Transaction writeTx, int currentVersion, out int versionAfterUpgrade)

            {

                switch (_storageType)

                {

                    case StorageType.Server:

                        break;

                    case StorageType.Configuration:

                        break;

                    case StorageType.Documents:

                        if (SkippedDocumentsVersion.Contains(currentVersion))

                        {

                            throw new NotSupportedException($"Documents schema upgrade from version {currentVersion} is not supported, use the recovery tool to dump the data and then import it into a new database");

                        }

                        break;

                    case StorageType.Index:

                        break;

                    default:

                        throw new ArgumentOutOfRangeException(nameof(_storageType), _storageType, null);

                }

                

                versionAfterUpgrade = currentVersion;

                var name = $"Raven.Server.Storage.Schema.Updates.{_storageType.ToString()}.From{currentVersion}";

                var schemaUpdateType = typeof(SchemaUpgrader).Assembly.GetType(name);

                if (schemaUpdateType == null)

                    return false;



                versionAfterUpgrade++;



                switch (_storageType)

                {

                    case StorageType.Server:

                        break;

                    case StorageType.Configuration:

                        break;

                    case StorageType.Documents:

                        while (SkippedDocumentsVersion.Contains(versionAfterUpgrade))

                        {

                            versionAfterUpgrade++;

                        }

                        break;

                    case StorageType.Index:

                        break;

                    default:

                        throw new ArgumentOutOfRangeException(nameof(_storageType), _storageType, null);

                }

                

                var schemaUpdate = (ISchemaUpdate)Activator.CreateInstance(schemaUpdateType);

                return schemaUpdate.Update(new UpdateStep

                {

                    ReadTx = readTx,

                    WriteTx = writeTx,

                    ConfigurationStorage = _configurationStorage,

                    DocumentsStorage = _documentsStorage,

                });

            }

        }

        

        public static UpgraderDelegate Upgrader(StorageType storageType, ConfigurationStorage configurationStorage, DocumentsStorage documentsStorage)

        {

            var upgrade = new InternalUpgrader(storageType, configurationStorage, documentsStorage);

            return upgrade.Upgrade;

        }

    }

}