DatabaseSystem.cs

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// 
//  Copyright 2010-2015 Deveel
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//

using System;
using System.Collections.Generic;
using System.Net;

using Deveel.Data.Configuration;
using Deveel.Data.Diagnostics;
using Deveel.Data.Services;

namespace Deveel.Data {
    public sealed class DatabaseSystem : ISystem {
        private IDictionary<string, object> metadata;

        private IDictionary<string, IDatabase> databases; 

        internal DatabaseSystem(ISystemContext context, IEnumerable<ModuleInfo> modules) {
            Context = context;
            Modules = modules;
            CreateMetadata();
        }

        ~DatabaseSystem() {
            Dispose(false);
        }

        private void CreateMetadata() {
            metadata = new Dictionary<string, object>();

#if !PCL
            metadata["[env]:os.platform"] = Environment.OSVersion.Platform;
            metadata["[env]:os.version"] = Environment.OSVersion.VersionString;
            metadata["[env]:os.sp"] = Environment.OSVersion.ServicePack;
            metadata["[env]:runtime.version"] = Environment.Version.ToString();
            metadata["[env]:machineName"] = Environment.MachineName;
            metadata["[env]:hostName"] = Dns.GetHostName();

#endif
            metadata["[env]processors"] = Environment.ProcessorCount;

            foreach (var config in Configuration) {
                metadata[String.Format("[config]:{0}", config.Key)] = config.Value;
            }

            foreach (var module in Modules) {
                metadata[String.Format("[module]:{0}", module.ModuleName)] = module.Version;
            }
        }

        public IDatabase GetDatabase(string databaseName) {
            lock (this) {
                if (databases == null)
                    return null;

                IDatabase database;
                if (!databases.TryGetValue(databaseName, out database))
                    return null;

                return database;
            }
        }

        public IEnumerable<ModuleInfo> Modules { get; private set; } 
            
        IEventSource IEventSource.ParentSource {
            get { return null; }
        }

        IEnumerable<KeyValuePair<string, object>> IEventSource.Metadata {
            get { return metadata; }
        }

        public void Dispose() {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        private void Dispose(bool disposing) {
            if (disposing) {
                lock (this) {
                    if (databases != null) {
                        foreach (var database in databases.Values) {
                            if (database != null)
                                database.Dispose();
                        }

                        databases.Clear();
                    }

                    if (Context != null)
                        Context.Dispose();
                }
            }

            databases = null;
            Context = null;
        }

        IContext IEventSource.Context {
            get { return Context; }
        }

        public ISystemContext Context { get; private set; }

        private IConfiguration Configuration {
            get { return Context.Configuration; }
        }

        public IEnumerable<string> GetDatabases() {
            lock (this) {
                if (databases == null)
                    return new string[0];

                return databases.Keys;
            }
        }

        public IDatabase CreateDatabase(IConfiguration configuration, string adminUser, string adminPassword) {
            lock (this) {
                if (configuration == null)
                    throw new ArgumentNullException("configuration");

                var databaseName = configuration.GetString("database.name");
                if (String.IsNullOrEmpty(databaseName))
                    throw new ArgumentException("The configuration must specify a database name.");

                if (DatabaseExists(databaseName))
                    throw new InvalidOperationException(String.Format("Database '{0}' already exists in the system.", databaseName));

                var dbContext = Context.CreateDatabaseContext(configuration);
                var database = new Database(this, dbContext);

                if (database.Exists)
                    throw new InvalidOperationException(String.Format("The database '{0}' was already created.", databaseName));

                database.Create(adminUser, adminPassword);
                database.Open();
                
                if (databases == null)
                    databases = new Dictionary<string, IDatabase>();

                databases[databaseName] = database;

                return database;
            }
        }

        public IDatabase OpenDatabase(IConfiguration configuration) {
            lock (this) {
                if (configuration == null)
                    throw new ArgumentNullException("configuration");

                var databaseName = configuration.GetString("database.name");
                if (String.IsNullOrEmpty(databaseName))
                    throw new ArgumentException("The configuration must specify a database name.");
                
                IDatabase database;
                if (databases == null || 
                    !databases.TryGetValue(databaseName, out database))
                    throw new InvalidOperationException(String.Format("Database '{0}' does not exist in the system.", databaseName));

                if (!database.IsOpen)
                    database.Open();

                return database;
            }
        }

        public bool DatabaseExists(string databaseName) {
            lock (this) {
                if (String.IsNullOrEmpty(databaseName))
                    throw new ArgumentNullException("databaseName");

                if (databases == null)
                    return false;

                return databases.ContainsKey(databaseName);
            }
        }

        public bool DeleteDatabase(string databaseName) {
            lock (this) {
                if (String.IsNullOrEmpty(databaseName))
                    throw new ArgumentNullException("databaseName");

                if (databases == null)
                    return false;

                IDatabase database;
                if (!databases.TryGetValue(databaseName, out database))
                    return false;

                if (!database.Exists)
                    return false;

                // TODO: Implement the delete function in the IDatabase

                return databases.Remove(databaseName);
            }
        }

        internal void RemoveDatabase(Database database) {
            lock (this) {

                databases.Remove(database.Name);
            }
        }
    }
}