using System.IO;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text.RegularExpressions;
using DesertPaintCodex.Models;
using DesertPaintCodex.Util;

namespace DesertPaintCodex.Services
{
    internal static class PaletteService
    {
        private static readonly Regex ColorEntry = new(@"\#(?<red>\w\w)(?<green>\w\w)(?<blue>\w\w)\s*(?<name>\w+)");

        public static List<PaintColor> Colors { get; } = new();
        
        private static bool _initialized = false;
        
        
        public static void Initialize()
        {
            if (_initialized) return;

            string? colorsPath = FileUtils.FindApplicationResourceFile("colors.txt");
            Debug.Assert(colorsPath != null);
    
            Load(colorsPath);
        }

        public static void Load(string file)
        {
            using StreamReader reader = new StreamReader(file);
            string? line;
            while ((line = reader.ReadLine()) != null)
            {
                Match match = ColorEntry.Match(line);
                if (match.Success)
                {
                    Colors.Add(new PaintColor(match.Groups["name"].Value,
                        match.Groups["red"].Value,
                        match.Groups["green"].Value,
                        match.Groups["blue"].Value));
                }
            }
        }

        public static int Count => Colors.Count;

        public static string FindNearest(PaintColor color)
        {
            int bestDistSq = int.MaxValue;
            PaintColor? bestColor = null;
            
            foreach (PaintColor paintColor in Colors)
            {
                int distSq = paintColor.GetDistanceSquared(color);
                
                if (distSq >= bestDistSq) continue;
                
                bestDistSq = distSq;
                bestColor  = paintColor;
            }
            
            Debug.Assert(bestColor != null);
            
            return bestColor.Name;
        }
    }
}