using System;
using System.Collections.Generic;
using System.Linq.Expressions;

using Vit.Linq;
using Vit.Linq.ExpressionNodes.ComponentModel;

using Vitorm.Entity;
using Vitorm.MySql.TranslateService;
using Vitorm.Sql.SqlTranslate;

namespace Vitorm.MySql
{
    public class SqlTranslateService : Vitorm.Sql.SqlTranslate.SqlTranslateService
    {
        public static readonly SqlTranslateService Instance = new SqlTranslateService();

        protected override BaseQueryTranslateService queryTranslateService { get; }
        protected override BaseQueryTranslateService executeUpdateTranslateService { get; }
        protected override BaseQueryTranslateService executeDeleteTranslateService { get; }

        public SqlTranslateService()
        {
            queryTranslateService = new QueryTranslateService(this);
            executeUpdateTranslateService = new ExecuteUpdateTranslateService(this);
            executeDeleteTranslateService = new ExecuteDeleteTranslateService(this);
        }
        /// <summary>
        ///     Generates the delimited SQL representation of an identifier (column name, table name, etc.).
        /// </summary>
        /// <param name="identifier">The identifier to delimit.</param>
        /// <returns>
        ///     The generated string.
        /// </returns>
        public override string DelimitIdentifier(string identifier) => $"`{EscapeIdentifier(identifier)}`"; // Interpolation okay; strings

        /// <summary>
        ///     Generates the escaped SQL representation of an identifier (column name, table name, etc.).
        /// </summary>
        /// <param name="identifier">The identifier to be escaped.</param>
        /// <returns>
        ///     The generated string.
        /// </returns>
        public override string EscapeIdentifier(string identifier) => identifier?.Replace("`", "\\`");


        #region EvalExpression
        /// <summary>
        /// read where or value or on
        /// </summary>
        /// <param name="arg"></param>
        /// <returns></returns>
        /// <exception cref="NotSupportedException"></exception>
        /// <param name="node"></param>
        public override string EvalExpression(QueryTranslateArgument arg, ExpressionNode node)
        {
            switch (node.nodeType)
            {
                case NodeType.MethodCall:
                    {
                        ExpressionNode_MethodCall methodCall = node;
                        switch (methodCall.methodName)
                        {
                            // ##1 ToString
                            case nameof(object.ToString):
                                {
                                    return $"cast({EvalExpression(arg, methodCall.@object)} as char)";
                                }

                            #region ##2 String method:  StartsWith EndsWith Contains
                            case nameof(string.StartsWith): // String.StartsWith
                                {
                                    var str = methodCall.@object;
                                    var value = methodCall.arguments[0];
                                    return $"{EvalExpression(arg, str)} like concat({EvalExpression(arg, value)},'%')";
                                }
                            case nameof(string.EndsWith): // String.EndsWith
                                {
                                    var str = methodCall.@object;
                                    var value = methodCall.arguments[0];
                                    return $"{EvalExpression(arg, str)} like concat('%',{EvalExpression(arg, value)})";
                                }
                            case nameof(string.Contains) when methodCall.methodCall_typeName == "String": // String.Contains
                                {
                                    var str = methodCall.@object;
                                    var value = methodCall.arguments[0];
                                    return $"{EvalExpression(arg, str)} like concat('%',{EvalExpression(arg, value)},'%')";
                                }
                                #endregion
                        }
                        break;
                    }

                #region Read Value
                case NodeType.Convert:
                    {
                        // cast( 4.1 as signed)

                        ExpressionNode_Convert convert = node;

                        Type targetType = convert.valueType?.ToType();

                        if (targetType == typeof(object)) return EvalExpression(arg, convert.body);

                        // Nullable
                        if (targetType.IsGenericType) targetType = targetType.GetGenericArguments()[0];

                        string targetDbType = GetColumnDbType(targetType);

                        var sourceType = convert.body.Member_GetType();
                        if (sourceType != null)
                        {
                            if (sourceType.IsGenericType) sourceType = sourceType.GetGenericArguments()[0];

                            if (targetDbType == GetColumnDbType(sourceType)) return EvalExpression(arg, convert.body);
                        }

                        if (targetType == typeof(string))
                        {
                            return $"cast({EvalExpression(arg, convert.body)} as char)";
                        }

                        return $"cast({EvalExpression(arg, convert.body)} as {targetDbType})";
                    }
                case nameof(ExpressionType.Add):
                    {
                        ExpressionNode_Binary binary = node;

                        // ##1 String Add
                        if (node.valueType?.ToType() == typeof(string))
                        {
                            //  select ifNull( cast( (userFatherId) as char ) , '' )  from `User`

                            return $"CONCAT( {BuildSqlSentence(binary.left)} , {BuildSqlSentence(binary.right)} )";

                            string BuildSqlSentence(ExpressionNode node)
                            {
                                if (node.nodeType == NodeType.Constant)
                                {
                                    ExpressionNode_Constant constant = node;
                                    if (constant.value == null) return "''";
                                    else return $"cast( ({EvalExpression(arg, node)}) as char )";
                                }
                                else
                                    return $"ifNull( cast( ({EvalExpression(arg, node)}) as char ) , '')";
                            }
                        }

                        // ##2 Numeric Add
                        return $"{EvalExpression(arg, binary.left)} + {EvalExpression(arg, binary.right)}";
                    }
                case nameof(ExpressionType.Coalesce):
                    {
                        ExpressionNode_Binary binary = node;
                        return $"COALESCE({EvalExpression(arg, binary.left)},{EvalExpression(arg, binary.right)})";
                    }
                case nameof(ExpressionType.Conditional):
                    {
                        // IF(500<1000,true,false)
                        ExpressionNode_Conditional conditional = node;
                        return $"IF({EvalExpression(arg, conditional.Conditional_GetTest())},{EvalExpression(arg, conditional.Conditional_GetIfTrue())},{EvalExpression(arg, conditional.Conditional_GetIfFalse())})";
                    }
                    #endregion

            }

            return base.EvalExpression(arg, node);
        }
        #endregion



        #region PrepareCreate
        public override string PrepareTryCreateTable(IEntityDescriptor entityDescriptor)
        {
            /* //sql
CREATE TABLE IF NOT EXISTS `User` (
  id int PRIMARY KEY AUTO_INCREMENT NOT NULL,
  name varchar(100) DEFAULT NULL,
  birth date DEFAULT NULL,
  fatherId int DEFAULT NULL,
  motherId int DEFAULT NULL
) ;
              */
            List<string> sqlFields = new();

            // #1 primary key
            if (entityDescriptor.key != null)
                sqlFields.Add(GetColumnSql(entityDescriptor.key));

            // #2 columns
            entityDescriptor.propertiesWithoutKey?.ForEach(column => sqlFields.Add(GetColumnSql(column)));

            return $@"
CREATE TABLE IF NOT EXISTS {DelimitTableName(entityDescriptor)} (
  {string.Join(",\r\n  ", sqlFields)}
)";

            string GetColumnSql(IPropertyDescriptor column)
            {
                var isNullable = !column.isKey && column.isNullable;
                var columnDbType = column.columnDbType ?? GetColumnDbType(column);
                var defaultValue = isNullable ? "default null" : "";
                if (column.isIdentity)
                {
                    var type = TypeUtil.GetUnderlyingType(column.type);
                    if (type == typeof(Guid)) { }
                    else defaultValue = "AUTO_INCREMENT";
                }
                var nullable = isNullable ? "" : "not null";

                // https://mysql.net.cn/doc/refman/8.0/en/create-table.html
                /*
                  name  type    primaryKey      defaultValue    nullable
                  id    int     primary key     default null    not null/null
                                                AUTO_INCREMENT
                 */

                return $"  {DelimitIdentifier(column.columnName)}  {columnDbType}  {(column.isKey ? "primary key" : "")}  {defaultValue}  {nullable}";
            }
        }
        public readonly static Dictionary<Type, string> columnDbTypeMap = new()
        {
            [typeof(DateTime)] = "DATETIME",
            [typeof(string)] = "varchar(1000)",

            [typeof(float)] = "FLOAT",
            [typeof(double)] = "DOUBLE",
            [typeof(decimal)] = "DOUBLE",

            [typeof(Int32)] = "INTEGER",
            [typeof(Int16)] = "SMALLINT",
            [typeof(byte)] = "TINYINT",
            [typeof(bool)] = "TINYINT",

            [typeof(Guid)] = "binary(16)",

        };
        protected override string GetColumnDbType(IPropertyDescriptor column)
        {
            Type type = column.type;

            if (column.isKey && column.type == typeof(string))
            {
                // avoid issue: SQL Error [1071] [42000]: Specified key was too long; max key length is 3072 bytes.
                // example "CREATE TABLE test ( `name` varchar(1000)  primary key);"
                return "varchar(200)";
            }

            if (column.columnLength.HasValue && type == typeof(string))
            {
                // varchar(1000)
                return $"varchar({(column.columnLength.Value)})";
            }
            return GetColumnDbType(type);
        }

        protected override string GetColumnDbType(Type type)
        {
            var underlyingType = TypeUtil.GetUnderlyingType(type);

            if (columnDbTypeMap.TryGetValue(underlyingType, out var dbType)) return dbType;
            if (underlyingType.Name.ToLower().Contains("int")) return "INTEGER";

            throw new NotSupportedException("unsupported column type:" + underlyingType.Name);
        }
        #endregion

        public override string PrepareTryDropTable(IEntityDescriptor entityDescriptor)
        {
            // drop table if exists `User`;
            return $@"drop table if exists {DelimitTableName(entityDescriptor)};";
        }


        public override (string sql, Func<object, Dictionary<string, object>> GetSqlParams) PrepareAdd(SqlTranslateArgument arg, EAddType addType)
        {
            if (addType == EAddType.identityKey)
            {
                // insert into user(name,fatherId,motherId) values('',0,0); select last_insert_id();

                var entityDescriptor = arg.entityDescriptor;
                var (columnNames, sqlColumnParams, GetSqlParams) = PrepareAdd_Columns(arg, entityDescriptor.propertiesWithoutKey);
                string sql = $@"insert into {DelimitTableName(entityDescriptor)}({string.Join(",", columnNames)}) values({string.Join(",", sqlColumnParams)});";

                // get generated id
                sql += "select last_insert_id();";
                return (sql, GetSqlParams);
            }
            else
            {
                // insert into user(name,fatherId,motherId) values('',0,0);

                var entityDescriptor = arg.entityDescriptor;
                var (columnNames, sqlColumnParams, GetSqlParams) = PrepareAdd_Columns(arg, entityDescriptor.properties);
                string sql = $@"insert into {DelimitTableName(entityDescriptor)}({string.Join(",", columnNames)}) values({string.Join(",", sqlColumnParams)});";
                return (sql, GetSqlParams);
            }
        }

    }
}