using System;
using System.Collections.Generic;
using BlockOutReplica.Domain;
using UnityEngine;

namespace BlockOutReplica.Infrastructure
{
    public static class OriginalLevelRepository
    {
        private const string LevelRoot = "OriginalLevels/";
        private static IReadOnlyList<string> cachedLevelIds;

        public static LevelDefinition LoadLevelOne() => Load("t140-level-1");

        public static IReadOnlyList<string> GetLevelIds()
        {
            if (cachedLevelIds != null) return cachedLevelIds;
            TextAsset[] assets = Resources.LoadAll<TextAsset>("OriginalLevels");
            List<string> ids = new List<string>(assets.Length);
            for (int i = 0; i < assets.Length; i++) ids.Add(assets[i].name);
            ids.Sort(CompareLevelIds);
            cachedLevelIds = ids;
            return cachedLevelIds;
        }

        public static LevelDefinition Load(string levelId)
        {
            if (string.IsNullOrWhiteSpace(levelId) || levelId.Contains("/") || levelId.Contains("\\"))
                throw new ArgumentException("Level id must be a plain resource name.", nameof(levelId));

            string resourcePath = LevelRoot + levelId;
            TextAsset asset = Resources.Load<TextAsset>(resourcePath);
            if (asset == null)
                throw new InvalidOperationException("Missing Resources/" + resourcePath + ".json");
            return OriginalLevelJsonParser.Parse(asset.text);
        }

        private static int CompareLevelIds(string left, string right)
        {
            SplitLevelId(left, out string leftFamily, out int leftNumber);
            SplitLevelId(right, out string rightFamily, out int rightNumber);
            int family = string.CompareOrdinal(leftFamily, rightFamily);
            return family != 0 ? family : leftNumber.CompareTo(rightNumber);
        }

        private static void SplitLevelId(string id, out string family, out int number)
        {
            int marker = id.LastIndexOf("-level-", StringComparison.Ordinal);
            if (marker < 0 || !int.TryParse(id.Substring(marker + 7), out number))
            {
                family = id;
                number = int.MaxValue;
                return;
            }
            family = id.Substring(0, marker);
        }
    }
}