using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using HeuristicLab.BioBoost.Data;
using HeuristicLab.Core;
using HeuristicLab.Data;
using SharpMap.Data;

namespace HeuristicLab.BioBoost.ProblemDescription {
  public class SolutionSpaceDiscoverer {

    private enum ProductCheck { None, NonFeasible, InProgress, Feasible };

    // caches
    private readonly List<Product> products;
    private readonly HashSet<string> transportableProductNames;
    private readonly List<Conversion> conversions;
    private readonly Dictionary<string, double> prices;
    private readonly Dictionary<Product, List<Conversion>> choices;  

    // status
    private readonly Dictionary<Product, ProductCheck> currentChecks;

    // results
    public List<string> FeasibleFeedstocks { get; private set; }
    public List<string> FeasibleTransports { get; private set; } 
    public Dictionary<string, List<string>> FeasibleChoices { get; private set; } 
    public Dictionary<string, string> FeasibilityAnalysis { get; private set; }
    public int MaxDepth { get; private set; }

    public SolutionSpaceDiscoverer(IEnumerable<string> feedstockNames, List<Product> products, IEnumerable<Logistic> logistics, IEnumerable<Conversion> conversions) {
      this.products = products.ToList();
      transportableProductNames = new HashSet<string>();
      foreach (var l in logistics) {
        transportableProductNames.Add(l.Product);
      }
      this.conversions = conversions.ToList();
      this.prices = products.ToDictionary(p => p.Label, p => p.Price);
      this.choices = new Dictionary<Product, List<Conversion>>();

      this.currentChecks = products.ToDictionary(p => p, p => ProductCheck.None);

      this.FeasibilityAnalysis = products.ToDictionary(p => p.Label, p => string.Empty);
      this.FeasibleFeedstocks = new List<string>();
      this.FeasibleTransports = new List<string>();
      this.MaxDepth = 0;
      var feedstocks = new HashSet<string>(feedstockNames);
      var feedstockProducts = products.Where(p => feedstocks.Contains(p.Label)).ToList();
      foreach (var input in feedstockProducts) {
        if (CheckProduct(input)) {
          FeasibleFeedstocks.Add(input.Label);
        }
      }
      foreach (var pair in currentChecks) {
        if (pair.Value == ProductCheck.Feasible) {
          FeasibleTransports.Add(pair.Key.Label);
          List<Conversion> newChoices = null;
          if (choices.TryGetValue(pair.Key, out newChoices)) {
            FeasibleChoices.Add(pair.Key.Label, newChoices.Select(c => c.Label).ToList());
          }
        }
      }
    }

    public SolutionSpaceDiscoverer(IEnumerable<string> feedstockNames, List<DataItem> dataItems)
      : this(feedstockNames, dataItems.OfType<Product>().ToList(), dataItems.OfType<Logistic>(), dataItems.OfType<Conversion>()) {}


    private bool CheckProduct(Product inputProduct, int currentDepth = 1) {

      switch (currentChecks[inputProduct]) {
        case ProductCheck.Feasible:
          return true;
        case ProductCheck.NonFeasible:
          return false;
        case ProductCheck.InProgress:
          FeasibilityAnalysis[inputProduct.Label] += "not checked recursively: circular dependency";
          return false;
        case ProductCheck.None:
          break;
      }
      currentChecks[inputProduct] = ProductCheck.InProgress;

      // transportable?
      if (!transportableProductNames.Contains(inputProduct.Label)) {
        currentChecks[inputProduct] = ProductCheck.NonFeasible;
        FeasibilityAnalysis[inputProduct.Label] += "NOT transportable";
        return false; // not transportable
      }

      // convertable?
      var otherOutputProducts = new HashSet<Product>();
      var profitableOutputProducts = new HashSet<Product>();
      var profitableConversions = new List<Conversion>();
      foreach (var c in conversions.Where(c => c.Feedstock == inputProduct.Label)) {

        // outputs?
        foreach (var outputProductParameter in c.Products) {
          var outputProductName = outputProductParameter.Name;
          var outputAmount = outputProductParameter.Value as DoubleValue;
          if (string.IsNullOrEmpty(outputProductName))
            continue; // no product
          var product = products.FirstOrDefault(p2 => p2.Label == outputProductName);
          if (product == null || outputAmount == null)
            continue; // not a real product
          double amount = outputAmount.Value;
          double price;
          if (prices.TryGetValue(product.Label, out price) && price*amount > 0) {
            profitableOutputProducts.Add(product);
          } else {
            otherOutputProducts.Add(product);
          }
        }
        // recurse
        foreach (var p in profitableOutputProducts)
          CheckProduct(p, currentDepth + 1);
        var otherProfits = otherOutputProducts.Any(p => CheckProduct(p, currentDepth + 1));

        // analyze
        if (profitableOutputProducts.Count == 0 && !otherProfits) {
          currentChecks[inputProduct] = ProductCheck.NonFeasible;
          FeasibilityAnalysis[inputProduct.Label] += "NO profitable direct or indirect output products";
        } else {
          currentChecks[inputProduct] = ProductCheck.Feasible;
          MaxDepth = Math.Max(MaxDepth, currentDepth);
          profitableConversions.Add(c);
          if (profitableOutputProducts.Count > 0) FeasibilityAnalysis[inputProduct.Label] += "profitable direct output products ";
          if (otherProfits) FeasibilityAnalysis[inputProduct.Label] += "profitable indirect output products";
        }
      }

      // conclusion
      if (profitableConversions.Count > 1)
        choices.Add(inputProduct, profitableConversions);
      return profitableConversions.Count > 0;
    }
  }
}