using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Content;

namespace FaceOff
{
    /// <summary>
    /// Loads and maintains emotion category information
    /// and face textures for each emotion category.
    /// </summary>
    class FaceLoader
    {
        private const string FACES_DIR = @"Texture\Faces\";

        private List<string> categoryNames;
        /// <summary>
        /// The list of emotion category names 
        /// </summary>
        public static List<string> CategoryNames
        {
            get { return _i.categoryNames; }
        }

        private List<int> numCategoryFaces;
        /// <summary>
        /// The list containing the number of faces per emotion category
        /// </summary>
        public static List<int> NumCategoryFaces
        {
            get { return _i.numCategoryFaces; }
        }

        private int numCategories;
        /// <summary>
        /// The total number of emotion categories
        /// </summary>
        public static int NumCategories
        {
            get { return _i.numCategories; }
        }

        private ContentManager content;

        /// <summary>
        /// Singleton instance
        /// </summary>
        private static FaceLoader _i;

        /// <summary>
        /// Static constructor
        /// </summary>
        static FaceLoader() { _i = new FaceLoader(); }

        /// <summary>
        /// Hidden constructor - prevents outside instantiation
        /// </summary>
        private FaceLoader() { }

        /// <summary>
        /// Determines NumCategories and populates CategoryNames and NumCategoryFaces.
        /// </summary>
        public static void Initialize(ContentManager content)
        {
            _i.content = content;

            string[] categoryDirs = Directory.GetDirectories(content.RootDirectory + FACES_DIR, "*", SearchOption.TopDirectoryOnly);
            _i.numCategories = categoryDirs.Length;

            _i.categoryNames = new List<string>();
            _i.numCategoryFaces = new List<int>();

            foreach (string categoryDir in categoryDirs)
            {
                _i.categoryNames.Add(categoryDir.Substring(categoryDir.LastIndexOf(@"\") + 1));
                string[] faces = Directory.GetFiles(categoryDir);
                _i.numCategoryFaces.Add(faces.Length);
            }            
        }

        /// <summary>
        /// Loads all face textures into the ContentManager.
        /// </summary>
        public static void LoadTextures(ContentManager content)
        {
            for(int i = 0; i < _i.categoryNames.Count; ++i)
            {
                string category = _i.categoryNames[i];
                for (int k = 0; k < _i.numCategoryFaces[i]; ++k)
                    content.Load<Texture2D>(FACES_DIR + category + @"\" + category + "_" + k);
            }
        }

        /// <summary>
        /// Gets a random Texture2D of the given Categories
        /// </summary>
        /// <param name="category"></param>
        /// <returns></returns>
        public static Texture2D GetRandomTexture(int categoryIndex)
        {
            int picNum = 1 + Util.Random.Next(_i.numCategoryFaces[categoryIndex]);
            string categoryName = _i.categoryNames[categoryIndex];
                        
            return _i.content.Load<Texture2D>(FACES_DIR + categoryName + @"\" + categoryName + "_" + picNum);
        }
    }
}