using System;
using System.Collections.Generic;
using System.Reflection;
using HeuristicLab.Persistence.Interfaces;

namespace HeuristicLab.Persistence {

  public class Configuration {

    private readonly Dictionary<Type, IFormatter> formatters;
    private readonly List<IDecomposer> decomposers;
    private readonly Dictionary<Type, IDecomposer> decomposerCache;
    public readonly IFormat Format;

    public Configuration(Dictionary<Type, IFormatter> formatters, IEnumerable<IDecomposer> decomposers) {      
      this.formatters = new Dictionary<Type, IFormatter>();
      foreach ( var pair in formatters ) {
        if (Format == null) {
          Format = pair.Value.Format;
        } else if (pair.Value.Format != Format ) {
          throw new ArgumentException("All formatters must have the same IFormat.");
        }
        this.formatters.Add(pair.Key, pair.Value);
      }
      this.decomposers = new List<IDecomposer>(decomposers);
      decomposerCache = new Dictionary<Type, IDecomposer>();      
    }    

    public IFormatter GetFormatter(Type type) {
      IFormatter formatter;
      formatters.TryGetValue(type, out formatter);
      return formatter;
    }

    public IDecomposer GetDecomposer(Type type) {
      IDecomposer decomposer;
      decomposerCache.TryGetValue(type, out decomposer);
      if (decomposer != null)
        return decomposer;
      foreach (IDecomposer d in decomposers) {
        if (d.CanDecompose(type)) {
          decomposerCache.Add(type, d);
          return d;
        }
      }
      return null;
    }
    
  }

  public class ConfigurationService {

    private static ConfigurationService instance;
    private readonly Dictionary<IFormat, List<IFormatter>> formatters;
    private readonly List<IDecomposer> decomposers;

    public Dictionary<IFormat, List<IFormatter>> AllFormatters {
      get {
        return formatters;
      }
    }

    public List<IDecomposer> AllDecomposers {
      get {
        return decomposers;
      }
    }
    
    public static ConfigurationService Instance {
      get {
        if (instance == null) {
          instance = new ConfigurationService();
        }
        return instance;
      }
    }

    public ConfigurationService() {
      formatters = new Dictionary<IFormat, List<IFormatter>>();
      decomposers = new List<IDecomposer>();
      Reset();
    }

    public void Reset() {
      Assembly defaultAssembly = Assembly.GetExecutingAssembly();
      DiscoverFrom(defaultAssembly);
      foreach (Assembly a in AppDomain.CurrentDomain.GetAssemblies())
        if ( a != defaultAssembly )
          DiscoverFrom(a);
    }

    protected void DiscoverFrom(Assembly a) {
      foreach (Type t in a.GetTypes()) {
        if (t.GetInterface(typeof (IFormatter).FullName) != null) {
          try {
            IFormatter formatter = (IFormatter) Activator.CreateInstance(t, true);
            if ( ! formatters.ContainsKey(formatter.Format) ) {
              formatters.Add(formatter.Format, new List<IFormatter>());
            }
            formatters[formatter.Format].Add(formatter);
          } catch (MissingMethodException) {
            Console.WriteLine("WARNING: Could not instantiate {0}", t.FullName);
          }          
        }
        if (t.GetInterface(typeof (IDecomposer).FullName) != null) {
          try {
            decomposers.Add((IDecomposer) Activator.CreateInstance(t, true));
          } catch (MissingMethodException) {
            Console.WriteLine("WARNING: Could not instantiate {0}", t.FullName);
          }
        }
      }
    }

    public Configuration GetDefaultConfig(IFormat format) {
      Dictionary<Type, IFormatter> formatterConfig = new Dictionary<Type, IFormatter>();
      foreach ( IFormatter f in formatters[format] ) {
        if ( ! formatterConfig.ContainsKey(f.Type) )
          formatterConfig.Add(f.Type, f);
      }
      return new Configuration(formatterConfig, decomposers);
    }

  }
  
}