FileMaker.cs

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

public class FileMaker
{
    private readonly GeneratorConfig.ConfigSection config;
    private readonly string filename;
    private readonly string @namespace;
    private readonly List<ClassMaker> classMakers = new List<ClassMaker>();
    private readonly List<string> usings = new List<string>();

    public FileMaker(GeneratorConfig.ConfigSection config, string filename, string @namespace)
    {
        this.config = config;
        this.filename = filename;
        this.@namespace = @namespace;
    }

    public ClassMaker AddClass(string className)
    {
        var cm = new ClassMaker(className);
        classMakers.Add(cm);
        return cm;
    }

    public ClassMaker AddInterface(string className)
    {
        var cm = new ClassMaker(className, true);
        classMakers.Add(cm);
        return cm;
    }

    public void AddUsing(string name)
    {
        if (!string.IsNullOrWhiteSpace(name))
        {
            usings.Add(name);
        }
    }

    public void Build()
    {
        var liner = new Liner();
        var allUsings = classMakers.SelectMany(c => c.GetUsings()).Concat(usings).Distinct().ToList();
        allUsings.Sort();
        foreach (var u in allUsings)
        {
            liner.Add("using " + EndStatement(u));
        }
        liner.AddBlankLine();

        AddHeaderComment(liner);

        liner.StartClosure("namespace " + @namespace);
        
        foreach (var c in classMakers)
        {
            c.Write(liner);
        }
        
        liner.EndClosure();

        liner.Write(filename);
    }

    private string EndStatement(string s)
    {
        if (s.EndsWith(";")) return s;
        return s + ";";
    }
    private void AddHeaderComment(Liner liner)
    {
        if (string.IsNullOrWhiteSpace(config.HeaderComment)) return;
        var comment = config.HeaderComment;
        if (!comment.StartsWith("//")) comment = "//" + comment;

        liner.Add(comment);
        liner.Add("");
    }
}