apewer-dotnet/Apewer.Source/Source/Sqlite.cs

/* 2021.11.07 */

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Data.SQLite;
using System.Text;
//using Mono.Data.Sqlite;

using static Apewer.Source.SourceUtility;

namespace Apewer.Source
{

    /// <summary>用于快速连接 SQLite 数据库的辅助。</summary>
    public class Sqlite : IDbClient
    {

        #region 基础

        private Timeout _timeout = null;
        private string _connstring = "";
        private string _path = "";
        private string _pass = "";

        private object _locker = new object();

        /// <summary>获取或设置日志记录。</summary>
        public Logger Logger { get; set; }

        /// <summary>超时设定。</summary>
        public Timeout Timeout { get => _timeout; }

        /// <summary>创建连接实例。</summary>
        /// <remarks>注意：<br />- 构造函数不会创建不存在的文件；<br />- 参数 path 为文件路径，指定为空时将使用 :memory: 作为路径连接内存。</remarks>
        public Sqlite(string path = null, string pass = null, Timeout timeout = null)
        {
            _timeout = timeout ?? Timeout.Default;
            _path = path.IsEmpty() ? Memory : path;
            _pass = pass;
            if (pass.IsEmpty()) _connstring = $"data source='{_path}'; version=3; ";
            else _connstring = $"data source='{_path}'; password={_pass}; version=3; ";
        }

        #endregion

        #region 连接

        private SQLiteConnection _db = null;

        /// <summary>数据库已经连接。</summary>
        public bool Online { get => _db != null && _db.State == ConnectionState.Open; }

        /// <summary>连接字符串。</summary>
        public string ConnectionString { get => _connstring; }

        /// <summary>获取当前的 SQLiteConnection 对象。</summary>
        public IDbConnection Connection { get => _db; }

        /// <summary>连接数据库，若未连接则尝试连接。</summary>
        /// <returns>是否已连接。</returns>
        public string Connect()
        {
            if (_db == null)
            {
                _db = new SQLiteConnection();
                _db.ConnectionString = ConnectionString;
            }
            else
            {
                if (_db.State == ConnectionState.Open) return null;
            }
            try
            {
                _db.Open();
                switch (_db.State)
                {
                    case ConnectionState.Open: return null;
                    default: return $"连接失败，当前处于 {_db.State} 状态。";
                }
            }
            catch (Exception ex)
            {
                Logger.Error(nameof(Sqlite), "Connection", ex, _db.ConnectionString);
                Close();
                return ex.Message;
            }
        }

        /// <summary>关闭连接，并释放对象所占用的系统资源。</summary>
        public void Close()
        {
            if (_db != null)
            {
                if (_transaction != null)
                {
                    if (_autocommit) Commit();
                    else Rollback();
                }
                lock (_locker)
                {
                    _db.Dispose();
                }
                _db = null;
            }
        }

        /// <summary>关闭连接，释放对象所占用的系统资源，并清除连接信息。</summary>
        public void Dispose() { Close(); }

        #endregion

        #region Transaction

        private IDbTransaction _transaction = null;
        private bool _autocommit = false;

        /// <summary>启动事务。</summary>
        public string Begin(bool commit = true) => Begin(commit, null);

        /// <summary>启动事务。</summary>
        public string Begin(bool commit, Class<IsolationLevel> isolation)
        {
            var connect = Connect();
            if (connect.NotEmpty()) return connect;
            if (_transaction != null) return "存在已启动的事务，无法再次启动。";
            try
            {
                _transaction = isolation ? _db.BeginTransaction(isolation.Value) : _db.BeginTransaction();
                _autocommit = commit;
                return null;
            }
            catch (Exception ex)
            {
                Logger.Error(nameof(Sqlite), "Begin", ex.Message());
                return ex.Message();
            }
        }

        /// <summary>提交事务。</summary>
        public string Commit()
        {
            if (_transaction == null) return "事务不存在。";
            try
            {
                _transaction.Commit();
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                return null;
            }
            catch (Exception ex)
            {
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                Logger.Error(nameof(Sqlite), "Commit", ex.Message());
                return ex.Message();
            }
        }

        /// <summary>从挂起状态回滚事务。</summary>
        public string Rollback()
        {
            if (_transaction == null) return "事务不存在。";
            try
            {
                _transaction.Rollback();
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                return null;
            }
            catch (Exception ex)
            {
                RuntimeUtility.Dispose(_transaction);
                _transaction = null;
                Logger.Error(nameof(Sqlite), "Rollback", ex.Message());
                return ex.Message();
            }
        }

        #endregion

        #region SQL

        /// <summary>查询。</summary>
        public IQuery Query(string sql) => Query(sql, null);

        /// <summary>查询。</summary>
        public IQuery Query(string sql, IEnumerable<IDataParameter> parameters)
        {
            if (string.IsNullOrEmpty(sql)) return Example.InvalidQueryStatement;

            var connected = Connect();
            if (connected.NotEmpty()) return new Query(false, connected);

            var query = new Query();
            try
            {
                using (var command = new SQLiteCommand())
                {
                    command.Connection = _db;
                    command.CommandTimeout = _timeout.Query;
                    command.CommandText = sql;
                    if (parameters != null)
                    {
                        foreach (var p in parameters)
                        {
                            if (p != null) command.Parameters.Add(p);
                        }
                    }
                    using (var dataset = new DataSet())
                    {
                        using (var da = new SQLiteDataAdapter(command))
                        {
                            var name = "table_" + Guid.NewGuid().ToString("n");
                            da.Fill(dataset, name);
                            var table = dataset.Tables[name];
                            return new Query(table);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Logger.Error(nameof(Sqlite), "Query", ex, sql);
                return new Query(ex);
            }
        }

        /// <summary>执行单条 Transact-SQL 语句。</summary>
        public IExecute Execute(string sql) => Execute(sql, null);

        /// <summary>执行单条 Transact-SQL 语句，并加入参数。</summary>
        public IExecute Execute(string sql, IEnumerable<IDataParameter> parameters)
        {
            if (string.IsNullOrEmpty(sql)) return Example.InvalidExecuteStatement;

            var connected = Connect();
            if (connected.NotEmpty()) return new Execute(false, connected);

            lock (_locker)
            {
                var inTransaction = _transaction != null;
                if (!inTransaction) Begin();
                try
                {
                    using (var command = new SQLiteCommand())
                    {
                        command.Connection = _db;
                        command.Transaction = (SQLiteTransaction)_transaction;
                        command.CommandTimeout = _timeout.Execute;
                        command.CommandText = sql;
                        if (parameters != null)
                        {
                            foreach (var p in parameters)
                            {
                                if (p != null) command.Parameters.Add(p);
                            }
                        }
                        var rows = command.ExecuteNonQuery();
                        if (!inTransaction) Commit(); // todo 此处应该检查事务提交产生的错误。
                        return new Execute(true, rows);
                    }
                }
                catch (Exception ex)
                {
                    Logger.Error(nameof(Sqlite), "Execute", ex, sql);
                    if (!inTransaction) Rollback();
                    return new Execute(ex);
                }
            }
        }

        #endregion

        #region 属性。

        /// <summary>保存当前数据库到文件，若文件已存在则将重写文件。</summary>
        public bool Save(string path, string pass = null)
        {
            if (!StorageUtility.CreateFile(path, 0, true))
            {
                Logger.Error(nameof(Sqlite), "Save", TextUtility.Merge("创建文件 ", path, " 失败。"));
                return false;
            }

            using (var destination = new Sqlite(path, pass)) return Save(destination);
        }

        /// <summary>保存当前数据库到目标数据库。</summary>
        public bool Save(Sqlite destination) => string.IsNullOrEmpty(Backup(this, destination));

        /// <summary>加载文件到当前数据库。</summary>
        public bool Load(string path, string pass = null)
        {
            using (var source = new Sqlite(path, pass)) return Load(source);
        }

        /// <summary>加载源数据库到当前数据库。</summary>
        public bool Load(Sqlite source) => string.IsNullOrEmpty(Backup(source, this));

        #endregion

        #region ORM

        /// <summary>查询数据库中的所有表名。</summary>
        public string[] TableNames()
        {
            var list = new List<string>();
            if (Connect().IsEmpty())
            {
                var sql = "select name from sqlite_master where type='table' order by name; ";
                var query = (Query)Query(sql);
                for (int r = 0; r < query.Rows; r++)
                {
                    var cell = query.Text(r, 0);
                    if (TextUtility.IsBlank(cell)) continue;
                    list.Add(cell);
                }
                query.Dispose();
            }
            return list.ToArray();
        }

        /// <summary>查询数据库中的所有视图名。</summary>
        public string[] ViewNames()
        {
            var list = new List<string>();
            if (Connect().IsEmpty())
            {
                var sql = "select name from sqlite_master where type='view' order by name; ";
                var query = (Query)Query(sql);
                for (int r = 0; r < query.Rows; r++)
                {
                    var cell = query.Text(r, 0);
                    if (TextUtility.IsBlank(cell)) continue;
                    list.Add(cell);
                }
                query.Dispose();
            }
            return list.ToArray();
        }

        /// <summary>查询表中的所有列名。</summary>
        public string[] ColumnNames(string table)
        {
            var list = new List<string>();
            if (Connect().IsEmpty())
            {
                var t = TextUtility.AntiInject(table);
                var sql = TextUtility.Merge("pragma table_info('", TextUtility.AntiInject(t), "'); ");
                using (var query = Query(sql) as Query)
                {
                    for (int r = 0; r < query.Rows; r++)
                    {
                        var cell = query.Text(r, "name");
                        if (TextUtility.IsBlank(cell)) continue;
                        list.Add(cell);
                    }
                }
            }
            return list.ToArray();
        }

        /// <summary>创建表，不修改已存在表。成功时返回空字符串，发生异常时返回异常信息。</summary>
        public string Initialize(Record model) => model == null ? "参数无效。" : Initialize(model.GetType());

        /// <summary>创建表，不修改已存在表。成功时返回空字符串，发生异常时返回异常信息。</summary>
        public string Initialize<T>() where T : class, new() => Initialize(typeof(T));

        /// <summary>创建表，不修改已存在表。当现存表中缺少模型中属性对应的列时增加列。成功时返回空字符串，发生异常时返回异常信息。</summary>
        public string Initialize(Type model)
        {
            var structure = TableStructure.Parse(model);
            if (structure == null) return "无法解析记录模型。";

            // 连接数据库。
            var connect = Connect();
            if (connect.NotEmpty()) return connect;

            // 检查现存表。
            var exists = false;
            var tables = TableNames();
            if (tables.Length > 0)
            {
                var lower = structure.Name.ToLower();
                foreach (var table in tables)
                {
                    if (TextUtility.IsBlank(table)) continue;
                    if (table.ToLower() == lower)
                    {
                        exists = true;
                        break;
                    }
                }
            }

            if (exists)
            {
                return TextUtility.Merge("指定的表已经存在。");
            }
            else
            {
                var sqlcolumns = new List<string>();
                foreach (var column in structure.Columns)
                {
                    var type = Declaration(column);
                    if (string.IsNullOrEmpty(type))
                    {
                        return TextUtility.Merge("类型 ", column.Type.ToString(), " 不受支持。");
                    }
                    sqlcolumns.Add(type);
                }
                var sql = TextUtility.Merge("create table [", structure.Name, "](", TextUtility.Join(", ", sqlcolumns), "); ");
                var execute = Execute(sql);
                if (execute.Success) return TextUtility.Empty;
                return execute.Message;
            }
        }

        /// <summary>插入记录。返回错误信息。</summary>
        public string Insert(object record, string table = null)
        {
            if (record == null) return "参数无效。";
            SourceUtility.FixProperties(record);

            // 解析模型，获取表名。
            var structure = TableStructure.Parse(record.GetType());
            if (structure == null) return "无法解析记录模型。";
            if (string.IsNullOrEmpty(table)) table = structure.Name;
            if (string.IsNullOrEmpty(table)) return "表名称无效。";

            // 准备参数。
            var ps = structure.CreateParameters(record, Parameter);
            var psc = ps.Length;
            if (psc < 1) return "数据模型不包含字段。";

            // 合成 SQL 语句。
            var sb = new StringBuilder();
            sb.Append("insert into [");
            sb.Append(table);
            sb.Append("](");
            for (var i = 0; i < psc; i++)
            {
                if (i > 0) sb.Append(", ");
                sb.Append(ps[i].ParameterName);
            }
            sb.Append(") values(");
            for (var i = 0; i < psc; i++)
            {
                if (i > 0) sb.Append(", ");
                sb.Append("@");
                sb.Append(ps[i].ParameterName);
            }
            sb.Append("); ");
            var sql = sb.ToString();

            // 执行。
            var execute = Execute(sql, ps);
            if (execute.Success && execute.Rows > 0) return TextUtility.Empty;
            return execute.Message;
        }

        /// <summary>更新记录，实体中的 Key 属性不被更新。返回错误信息。</summary>
        /// <remarks>无法更新带有 Independent 特性的模型（缺少 Key 属性）。</remarks>
        public string Update(IRecord record, string table = null)
        {
            if (record == null) return "参数无效。";
            FixProperties(record);
            SetUpdated(record);

            // 解析模型，获取表名。
            var structure = TableStructure.Parse(record.GetType());
            if (structure == null) return "无法解析记录模型。";
            if (structure.Independent) return "无法更新带有 Independent 特性的模型。";
            if (string.IsNullOrEmpty(table)) table = structure.Name;
            if (string.IsNullOrEmpty(table)) return "表名称无效。";

            // 准备参数。
            var ps = structure.CreateParameters(record, Parameter, "_key");
            var psc = ps.Length;
            if (psc < 1) return "数据模型不包含字段。";

            // 合成 SQL 语句。
            var sb = new StringBuilder();
            sb.Append("update [");
            sb.Append(table);
            sb.Append("] set ");
            for (var i = 0; i < psc; i++)
            {
                if (i > 0) sb.Append(", ");
                sb.Append("[");
                sb.Append(ps[i].ParameterName);
                sb.Append("] = @");
                sb.Append(ps[i].ParameterName);
            }
            sb.Append(" where [_key] = '");
            sb.Append(record.Key.SafeKey());
            sb.Append("'; ");
            var sql = sb.ToString();

            // 执行。
            var execute = Execute(sql, ps);
            if (execute.Success && execute.Rows > 0) return TextUtility.Empty;
            return execute.Message;
        }

        /// <summary>获取按指定语句查询到的所有记录。</summary>
        public Result<object[]> Query(Type model, string sql, IEnumerable<IDataParameter> parameters = null) => SourceUtility.Query(this, model, sql, parameters);

        /// <summary>获取按指定语句查询到的所有记录。</summary>
        public Result<T[]> Query<T>(string sql, IEnumerable<IDataParameter> parameters = null) where T : class, new()
        {
            var query = Query(sql);
            if (!query.Success) return new Result<T[]>(query.Message);
            var records = query.Fill<T>();
            query.Dispose();

            var result = new Result<T[]>(records);
            return result;
        }

        /// <summary>查询多条记录。</summary>
        public Result<object[]> Query(Type model, long flag = 0) => SourceUtility.Query(this, model, (tn) =>
        {
            if (flag == 0) return $"select * from [{tn}]; ";
            return $"select * from [{tn}] where _flag={flag}; ";
        });

        /// <summary>查询多条记录。</summary>
        public Result<T[]> Query<T>(long flag = 0) where T : class, IRecord, new() => SourceUtility.Query<T>(this, (tn) =>
        {
            if (flag == 0) return $"select * from [{tn}]; ";
            return $"select * from [{tn}] where _flag={flag}; ";
        });

        /// <summary>获取具有指定 Key 的记录。</summary>
        public Result<object> Get(Type model, string key, long flag = 0) => SourceUtility.Get(this, model, key, (tn, sk) =>
        {
            if (flag == 0) return $"select * from [{tn}] where _key='{sk}' limit 1; ";
            return $"select * from [{tn}] where _flag={flag} and _key='{sk}' limit 1; ";
        });

        /// <summary>获取具有指定 Key 的记录。</summary>
        public Result<T> Get<T>(string key, long flag) where T : class, IRecord, new() => SourceUtility.Get<T>(this, key, (tn, sk) =>
        {
            if (flag == 0) return $"select * from [{tn}] where _key='{sk}' limit 1; ";
            return $"select * from [{tn}] where _flag={flag} and _key='{sk}' limit 1; ";
        });

        /// <summary>获取指定类型的主键，按 Flag 属性筛选。</summary>
        public Result<string[]> Keys(Type model, long flag = 0) => SourceUtility.Keys(this, model, (tn) =>
        {
            if (flag == 0) return $"select _key from [{tn}] where _flag={flag}; ";
            return $"select _key from [{tn}]; ";
        });

        /// <summary>>获取指定类型的主键，按 Flag 属性筛选。</summary>
        public Result<string[]> Keys<T>(long flag = 0) where T : class, IRecord, new() => Keys(typeof(T), flag);

        #endregion

        #region static

        /// <summary>对文本转义，符合 SQL 安全性。可根据字段类型限制 UTF-8 字节数，默认为 0 时不限制字节数。</summary>
        public static string Escape(string text, int bytes = 0)
        {
            if (text.IsEmpty()) return "";

            var t = text ?? "";
            t = t.Replace("\\", "\\\\");
            t = t.Replace("'", "\\'");
            t = t.Replace("\n", "\\n");
            t = t.Replace("\r", "\\r");
            t = t.Replace("\b", "\\b");
            t = t.Replace("\t", "\\t");
            t = t.Replace("\f", "\\f");

            if (bytes > 5)
            {
                if (t.Bytes(Encoding.UTF8).Length > bytes)
                {
                    while (true)
                    {
                        t = t.Substring(0, t.Length - 1);
                        if (t.Bytes(Encoding.UTF8).Length <= (bytes - 4)) break;
                    }
                    t = t + " ...";
                }
            }

            return t;
        }

        private static string GetColumnTypeName(ColumnType type)
        {
            switch (type)
            {
                case ColumnType.Bytes:
                    return "blob";
                case ColumnType.Integer:
                    return "integer";
                case ColumnType.Float:
                    return "float";
                case ColumnType.VarChar:
                case ColumnType.VarChar191:
                case ColumnType.VarCharMax:
                    return "varchar";
                case ColumnType.Text:
                    return "text";
                case ColumnType.NVarChar:
                case ColumnType.NVarChar191:
                case ColumnType.NVarCharMax:
                    return "nvarchar";
                case ColumnType.NText:
                    return "ntext";
                default:
                    return null;
            }
        }

        private static string Declaration(ColumnAttribute column)
        {
            var type = TextUtility.Empty;
            var length = NumberUtility.Restrict(column.Length, 0, 255).ToString();
            switch (column.Type)
            {
                case ColumnType.Bytes:
                    type = "blob";
                    break;
                case ColumnType.Integer:
                    type = "integer";
                    break;
                case ColumnType.Float:
                    type = "real";
                    break;
                case ColumnType.DateTime:
                    type = "datetime";
                    break;
                case ColumnType.VarChar:
                    type = TextUtility.Merge("varchar(", length, ")");
                    break;
                case ColumnType.VarChar191:
                    type = TextUtility.Merge("varchar(191)");
                    break;
                case ColumnType.VarCharMax:
                    type = TextUtility.Merge("varchar(255)");
                    break;
                case ColumnType.Text:
                    type = TextUtility.Merge("text");
                    break;
                case ColumnType.NVarChar:
                    type = TextUtility.Merge("nvarchar(", length, ")");
                    break;
                case ColumnType.NVarChar191:
                    type = TextUtility.Merge("nvarchar(191)");
                    break;
                case ColumnType.NVarCharMax:
                    type = TextUtility.Merge("nvarchar(255)");
                    break;
                case ColumnType.NText:
                    type = TextUtility.Merge("ntext");
                    break;
                default:
                    return TextUtility.Empty;
            }
            return TextUtility.Merge("[", column.Field, "] ", type);
        }

        /// <summary>创建参数。</summary>
        /// <exception cref="ArgumentNullException"></exception>
        /// <exception cref="InvalidOperationException"></exception>
        public static SQLiteParameter Parameter(Parameter parameter)
        {
            if (parameter == null) throw new InvalidOperationException("参数无效。");
            return Parameter(parameter.Name, parameter.Type, parameter.Size, parameter.Value);
        }

        /// <summary>创建参数。</summary>
        public static SQLiteParameter Parameter(string name, ColumnType type, int size, object value)
        {
            var n = TextUtility.Trim(name);
            if (TextUtility.IsBlank(n)) return null;

            var t = GetColumnTypeName(type);

            var s = size;
            switch (type)
            {
                case ColumnType.VarChar:
                    s = NumberUtility.Restrict(s, 0, 8000);
                    break;
                case ColumnType.NVarChar:
                    s = NumberUtility.Restrict(s, 0, 4000);
                    break;
                case ColumnType.VarChar191:
                case ColumnType.NVarChar191:
                    s = NumberUtility.Restrict(s, 0, 191);
                    break;
                case ColumnType.VarCharMax:
                case ColumnType.NVarCharMax:
                    s = NumberUtility.Restrict(s, 0, 255);
                    break;
                default:
                    s = 0;
                    break;
            }

            var v = value;
            if (v is string && v != null && s > 0)
            {
                v = TextUtility.Left((string)v, s);
            }

            var p = new SQLiteParameter();
            p.ParameterName = n;
            p.TypeName = t;
            p.Value = v;
            if (s > 0) p.Size = s;
            return p;
        }

        /// <summary>创建参数。</summary>
        public static IDbDataParameter Parameter(string field, DbType type, int size, object value)
        {
            var p = new SQLiteParameter();
            p.ParameterName = field;
            p.DbType = type;
            p.Size = size;
            p.Value = value;
            return p;
        }

        /// <summary>创建参数。</summary>
        public static IDbDataParameter Parameter(string field, DbType type, object value)
        {
            var p = new SQLiteParameter();
            p.ParameterName = field;
            p.DbType = type;
            p.Value = value;
            return p;
        }

        /// <summary>备份数据库，返回错误信息。</summary>
        public static string Backup(Sqlite source, Sqlite destination)
        {
            if (source == null) return "备份失败：源无效。";
            if (destination == null) return "备份失败：目标无效。";
            var sConnect = source.Connect();
            if (sConnect.NotEmpty()) return sConnect;
            var dConnect = source.Connect();
            if (dConnect.NotEmpty()) return dConnect;

            lock (source._locker)
            {
                lock (destination._locker)
                {
                    try
                    {
                        source._db.BackupDatabase(destination._db, "main", "main", -1, null, 0);
                        return "";
                    }
                    catch (Exception ex)
                    {
                        return "SQLite Load Failed: " + ex.Message;
                    }
                }
            }
        }

        /// <summary>整理数据库，压缩未使用的空间。</summary>
        public const string Vacuum = "vacuum";

        /// <summary>内存数据库的地址。</summary>
        public const string Memory = ":memory:";

        #endregion

    }

}