// Copyright (c) 2009 Andrew Nurse
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using System;
using System.Globalization;
using System.Linq.Expressions;
using System.Diagnostics;

namespace Utils {
    internal static class Arg {
        public static void NotNull(object value, string paramName) {
            if (value == null) {
                throw new ArgumentNullException(paramName);
            }
        }
        public static void NotNullOrEmpty(string value, string paramName) {
            if (String.IsNullOrEmpty(value)) {
                // Replace Resources.Error_StringArgumentNullOrEmpty with your own message OR
                //  Set the "Error_StringArgumentNullOrEmpty" key in your project's resources file
                //  (see the Project properties section)
                throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, Resources.Error_StringArgumentNullOrEmpty, paramName), paramName);
            }
        }

        // Lambda contract checkers.  These are less performant than the above, but enable refactoring and more compact code
        // They can be replaced by non-lambda versions in runtime code with the following Visual Studio regex replacement:
        //   Find: ^{:b*}Arg\.{(NotNull)|(NotNullOrEmpty)}\(:b*\(:b*\):b*\=\>:b*{:i}:b*\):b*;:b*$
        //   Replace with: \1Arg.\2(\3, "\3");
        // And to convert back:
        //   Find: ^{:b*}Arg\.{(NotNull)|(NotNullOrEmpty)}\(:b*{:i}:b*\,:b*\":b*:i:b*\":b*\):b*;:b*$
        //   Replace with: \1Arg.\2(() => \3);

        public static void NotNullOrEmpty(Expression<Func<string>> paramExpr) {
            string paramName = GetParameterName(paramExpr);

            // Compile the lambda (to get the value)
            Func<string> compiledLambda = paramExpr.Compile();

            // Check for a string argument
            NotNullOrEmpty(compiledLambda(), paramName);
        }

        public static void NotNull(Expression<Func<object>> paramExpr) {
            string paramName = GetParameterName(paramExpr);

            // Compile the lambda (to get the value)
            Func<object> compiledLambda = paramExpr.Compile();
            
            // Run the contract check
            NotNull(compiledLambda(), paramName);
        }

        private static string GetParameterName<T>(Expression<Func<T>> paramExpr) {
            LambdaExpression lambda = paramExpr as LambdaExpression;
            Debug.Assert(lambda != null, "The expression passed to NotNull<T> must be a lambda containing a single variable reference");
            MemberExpression paramRef = lambda.Body as MemberExpression;
            Debug.Assert(paramRef != null, "The expression passed to NotNull<T> must be a lambda containing a single variable reference");

            // Get the parameter name
            string paramName = paramRef.Member.Name;
            return paramName;
        }
    }
}