using System.Reflection;
using meowlang.parser;


var className = args[0];
var destinatinDir = args[1] ?? ".";
var destinationPath = Path.Join(destinatinDir, $"{className}.cs");


var parserType = typeof(Parser);
var nameSpace = parserType.Namespace;
var modelTypes = parserType.Assembly.DefinedTypes.Where(t => t.IsAssignableTo(typeof(ModelBase))).Where(t => !t.IsAbstract);

string UnModelifyName(string name)
{
    var nameWithoutModel = name;
    var modelIndex = nameWithoutModel.LastIndexOf("Model", StringComparison.Ordinal);
    if (modelIndex > -1)
    {
        nameWithoutModel = nameWithoutModel.Remove(modelIndex);
    }

    return nameWithoutModel;
}

string MakeVisitorMethod(TypeInfo model, bool isVoid)
{
    if (model == null) throw new ArgumentNullException(nameof(model));
    var typeName = model.Name;
    var visitorName = $"Visit{UnModelifyName(typeName)}";
    return isVoid ? @$"
    public virtual void {visitorName}({typeName} m)
    {{
        foreach (var modelBase in m.GetChildren())
        {{
            Visit(modelBase);
        }}
    }}
" : @$"
    public virtual T {visitorName}({typeName} m)
    {{
        T result = default;
        foreach (var modelBase in m.GetChildren())
        {{
            result = Visit(modelBase);
        }}

        return result;
    }}
";
}


string MakeSwitchArm(TypeInfo model, bool isVoid)
{
    if (model == null) throw new ArgumentNullException(nameof(model));
    var typeName = model.Name;
    var visitorName = $"Visit{UnModelifyName(typeName)}";
    return isVoid ? $@"
                case {typeName} x: {visitorName}(x); break;" : $@"
                case {typeName} x: return {visitorName}(x);";
}

var arms = new List<string>();
var voidArms = new List<string>();
var methods = new List<string>();
var voidMethods = new List<string>();

foreach (var modelType in modelTypes)
{
    arms.Add(MakeSwitchArm(modelType, false));
    voidArms.Add(MakeSwitchArm(modelType, true));
    methods.Add(MakeVisitorMethod(modelType, false));
    voidMethods.Add(MakeVisitorMethod(modelType, true));
}


var sourceCode = $@"// automatically generated

// ReSharper disable MemberCanBeProtected.Global
// ReSharper disable MemberCanBePrivate.Global
#pragma warning disable CS8603
#pragma warning disable CS8600
#pragma warning disable CS8509

using System.CodeDom.Compiler;
namespace {nameSpace};

[GeneratedCode(""meow-visitorgenerator"", ""1"")]
public class {className}<T>
{{

    public T? TryVisit(ModelBase? m)
    {{
        return m == null ? default : Visit(m);
    }}

    public T Visit(ModelBase m)
    {{
        try {{
            switch(m)
            {{
{string.Join("", arms)}
            }}
        }} catch(Exception e) {{
            if (e is MeowModelVisitorException) throw;
            throw new MeowModelVisitorException(m, e);
        }}
        return default;
    }}
{string.Join("", methods)}
}}

[GeneratedCode(""meow-visitorgenerator"", ""1"")]
public class {className}
{{
    public void Visit(ModelBase m)
    {{
        try {{
            switch(m)
            {{
{string.Join("", voidArms)}
            }}
        }} catch(Exception e) {{
            if (e is MeowModelVisitorException) throw;
            throw new MeowModelVisitorException(m, e);
        }}
    }}
{string.Join("", voidMethods)}
}}
";

File.WriteAllText(destinationPath, sourceCode);
Console.WriteLine($"output written to {destinationPath}");