// Copyright (c) 2020 Oracle and/or its affiliates.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0, as
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// Without limiting anything contained in the foregoing, this file,
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// Universal FOSS Exception, version 1.0, a copy of which can be found at
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// See the GNU General Public License, version 2.0, for more details.
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using Microsoft.EntityFrameworkCore.Query;
using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
using System;
using System.Collections.Generic;
using System.Reflection;

namespace MySql.EntityFrameworkCore.Query.Internal
{
  internal class MySQLMathMethodTranslator : IMethodCallTranslator
  {
    private static readonly Dictionary<MethodInfo, string> _supportedMethodTranslations = new Dictionary<MethodInfo, string>
        {
            { typeof(Math).GetRuntimeMethod(nameof(Math.Abs), new[] { typeof(decimal) }), "ABS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Abs), new[] { typeof(double) }), "ABS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Abs), new[] { typeof(float) }), "ABS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Abs), new[] { typeof(int) }), "ABS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Abs), new[] { typeof(long) }), "ABS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Abs), new[] { typeof(short) }), "ABS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Acos), new[] { typeof(double) }), "ACOS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Asin), new[] { typeof(double) }), "ASIN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Atan), new[] { typeof(double) }), "ATAN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Atan2), new[] { typeof(double), typeof(double) }), "ATAN2" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Ceiling), new[] { typeof(decimal) }), "CEILING" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Ceiling), new[] { typeof(double) }), "CEILING" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Cos), new[] { typeof(double) }), "COS" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Exp), new[] { typeof(double) }), "EXP" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Floor), new[] { typeof(decimal) }), "FLOOR" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Floor), new[] { typeof(double) }), "FLOOR" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Log), new[] { typeof(double) }), "LOG" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Log), new[] { typeof(double), typeof(double) }), "LOG" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Log10), new[] { typeof(double) }), "LOG10" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Max), new[] { typeof(decimal), typeof(decimal) }), "GREATEST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Max), new[] { typeof(double), typeof(double) }), "GREATEST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Max), new[] { typeof(float), typeof(float) }), "GREATEST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Max), new[] { typeof(int), typeof(int) }), "GREATEST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Max), new[] { typeof(long), typeof(long) }), "GREATEST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Max), new[] { typeof(short), typeof(short) }), "GREATEST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Min), new[] { typeof(decimal), typeof(decimal) }), "LEAST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Min), new[] { typeof(double), typeof(double) }), "LEAST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Min), new[] { typeof(float), typeof(float) }), "LEAST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Min), new[] { typeof(int), typeof(int) }), "LEAST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Min), new[] { typeof(long), typeof(long) }), "LEAST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Min), new[] { typeof(short), typeof(short) }), "LEAST" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Pow), new[] { typeof(double), typeof(double) }), "POWER" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Round), new[] { typeof(double) }), "ROUND" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Round), new[] { typeof(double), typeof(int) }), "ROUND" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Round), new[] { typeof(decimal) }), "ROUND" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Round), new[] { typeof(decimal), typeof(int) }), "ROUND" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sign), new[] { typeof(decimal) }), "SIGN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sign), new[] { typeof(double) }), "SIGN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sign), new[] { typeof(float) }), "SIGN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sign), new[] { typeof(int) }), "SIGN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sign), new[] { typeof(long) }), "SIGN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sign), new[] { typeof(sbyte) }), "SIGN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sign), new[] { typeof(short) }), "SIGN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sin), new[] { typeof(double) }), "SIN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Sqrt), new[] { typeof(double) }), "SQRT" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Tan), new[] { typeof(double) }), "TAN" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Truncate), new[] { typeof(double) }), "TRUNCATE" },
            { typeof(Math).GetRuntimeMethod(nameof(Math.Truncate), new[] { typeof(decimal) }), "TRUNCATE" },
        };

    private readonly ISqlExpressionFactory _sqlExpressionFactory;

    public MySQLMathMethodTranslator(ISqlExpressionFactory sqlExpressionFactory)
        => _sqlExpressionFactory = sqlExpressionFactory;

    /// <inheritdoc />
    public SqlExpression Translate(SqlExpression instance, MethodInfo method, IReadOnlyList<SqlExpression> arguments)
    {
      if (_supportedMethodTranslations.TryGetValue(method, out var sqlFunctionName))
      {
        var targetArgumentsCount = arguments.Count;

        if (sqlFunctionName == "TRUNCATE")
        {
          targetArgumentsCount = 2;
        }

        var newArguments = new SqlExpression[targetArgumentsCount];
        newArguments[0] = arguments[0];

        if (targetArgumentsCount == 2)
        {
          if (arguments.Count == 2)
          {
            newArguments[1] = arguments[1];
          }
          else
          {
            newArguments[1] = _sqlExpressionFactory.Constant(0);
          }
        }

        return _sqlExpressionFactory.Function(
            sqlFunctionName,
            newArguments,
            method.ReturnType);
      }

      return null;
    }
  }
}