using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.Emit;
using DFM = Dapper.FluentMap.Mapping;

namespace Fips.ORM.Dapper
{
    public class MappersCreator
    {
        private Type CreateType(Type type, string name, Dictionary<string,string> mappings)
        {
            var assemblyName = type.Assembly.FullName;
            var nspace = type.Namespace;
            var sb = new StringBuilder();
            foreach (var kv in mappings) {
                sb.Append($"            Map(m => m.{kv.Key}).ToColumn(\"{kv.Value}\");\n");
            }
            var code = $@"using Dapper.FluentMap.Mapping;

namespace {nspace}
{{
    public class {name}Mapper : EntityMap<{name}>
    {{
        public {name}Mapper()
        {{
{sb.ToString()}
        }}
    }}
}}";
            SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(code);
            CSharpCompilation compilation = CSharpCompilation.Create(
                assemblyName,
                new[] { syntaxTree },
                new MetadataReference[] {
                    MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
                    MetadataReference.CreateFromFile(type.Assembly.Location),
                    MetadataReference.CreateFromFile(typeof(DFM.EntityMap<Type>).Assembly.Location),
                    MetadataReference.CreateFromFile(typeof(Expression<Type>).Assembly.Location),
                    MetadataReference.CreateFromFile(typeof(Enumerable).Assembly.Location),
                },
                new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary)
            );
            using (var memoryStream = new MemoryStream()) {
                EmitResult result = compilation.Emit(memoryStream);
                if (result.Success) {
                    memoryStream.Seek(0, SeekOrigin.Begin);
                    Assembly assembly = Assembly.Load(memoryStream.ToArray());
                    Type ret = assembly.GetType($"{nspace}.{name}");
                    return ret;
                } else {
                    foreach (var diagnostic in result.Diagnostics) {
                        Console.WriteLine(diagnostic);
                    }
                    return null;
                }
            }
        }
    }
}

                MetadataReference.CreateFromFile(Assembly.Load("netstandard").Location),
                MetadataReference.CreateFromFile(Assembly.Load("System.Runtime").Location)