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

namespace BlockOutReplica.Infrastructure
{
    public static class OriginalLevelJsonParser
    {
        public static LevelDefinition Parse(string json)
        {
            if (string.IsNullOrWhiteSpace(json))
                throw new ArgumentException("Original level JSON is empty.", nameof(json));
            // Bundled t238-level-19 uses X/Y while neighboring seeds use x/y.
            // Normalize property names, not numeric values: zero remains valid
            // and mixed-case coordinates cannot be mistaken for missing data.
            json = Regex.Replace(json, "\"([XY])\"\\s*:", match => "\"" + match.Groups[1].Value.ToLowerInvariant() + "\":");
            OriginalLevelDto source = JsonUtility.FromJson<OriginalLevelDto>(json);
            if (source == null || source.BMS == null || source.DMS == null || source.CMS == null)
                throw new FormatException("Original level JSON is missing BMS, DMS or CMS.");
            if (source.CMS.Length == 0)
                throw new FormatException("Original level contains no board cells.");

            List<GridPosition> cells = ConvertCells(source.CMS);
            GetBounds(cells, out int minX, out int maxX, out int minY, out int maxY);
            List<PieceDefinition> pieces = new List<PieceDefinition>(source.BMS.Length);
            foreach (BlockDto block in source.BMS)
                pieces.Add(new PieceDefinition(block.BCT, ConvertPositions(block.BPMS), block.BIC, block.ILE, block.LBCT));
            List<DoorDefinition> doors = new List<DoorDefinition>(source.DMS.Length);
            foreach (DoorDto door in source.DMS)
            {
                List<GridPosition> positions = ConvertPositions(door.BPMS);
                doors.Add(new DoorDefinition(door.BCT, positions,
                    ResolveDoorSide(positions, minX, maxX, minY, maxY), door.DIC));
            }
            var curtains = new List<CurtainLockDefinition>();
            if (source.CLMS != null)
                foreach (CurtainDto curtain in source.CLMS)
                    curtains.Add(new CurtainLockDefinition(ConvertPositions(curtain.BPMS), curtain.CLC));
            List<GridPosition> walls = source.WMS == null
                ? new List<GridPosition>() : ConvertWalls(source.WMS);
            GridPosition start = source.BSP != null && source.BSP.Length > 0
                ? Convert(source.BSP[0]) : new GridPosition(minX - 1, minY - 1);
            return new LevelDefinition(pieces, doors, walls, cells, start,
                minX, maxX, minY, maxY, curtains);
        }

        private static DoorSide ResolveDoorSide(IReadOnlyList<GridPosition> positions,
            int minX, int maxX, int minY, int maxY)
        {
            float x = 0f, y = 0f;
            for (int i = 0; i < positions.Count; i++) { x += positions[i].X; y += positions[i].Y; }
            x /= positions.Count; y /= positions.Count;
            if (y > maxY) return DoorSide.Top;
            if (y < minY) return DoorSide.Bottom;
            if (x < minX) return DoorSide.Left;
            if (x > maxX) return DoorSide.Right;
            throw new FormatException("Door is not outside the board boundary.");
        }

        private static void GetBounds(IReadOnlyList<GridPosition> cells,
            out int minX, out int maxX, out int minY, out int maxY)
        {
            minX = maxX = cells[0].X; minY = maxY = cells[0].Y;
            for (int i = 1; i < cells.Count; i++)
            {
                minX = Mathf.Min(minX, cells[i].X); maxX = Mathf.Max(maxX, cells[i].X);
                minY = Mathf.Min(minY, cells[i].Y); maxY = Mathf.Max(maxY, cells[i].Y);
            }
        }

        private static List<GridPosition> ConvertCells(CellDto[] values)
        {
            List<GridPosition> result = new List<GridPosition>(values.Length);
            var unique = new HashSet<GridPosition>();
            foreach (CellDto value in values)
            {
                GridPosition position = Convert(value.BPM);
                if (unique.Add(position)) result.Add(position);
            }
            return result;
        }

        private static List<GridPosition> ConvertWalls(WallDto[] values)
        {
            List<GridPosition> result = new List<GridPosition>(values.Length);
            var unique = new HashSet<GridPosition>();
            foreach (WallDto value in values)
            {
                GridPosition position = Convert(value.BPM);
                if (unique.Add(position)) result.Add(position);
            }
            return result;
        }

        private static List<GridPosition> ConvertPositions(GridPositionDto[] values)
        {
            if (values == null || values.Length == 0)
                throw new FormatException("Piece or door contains no positions.");
            List<GridPosition> result = new List<GridPosition>(values.Length);
            var unique = new HashSet<GridPosition>();
            foreach (GridPositionDto value in values)
            {
                GridPosition position = Convert(value);
                if (unique.Add(position)) result.Add(position);
            }
            return result;
        }

        private static GridPosition Convert(GridPositionDto value)
        {
            if (value == null) throw new FormatException("Level contains a null grid position.");
            return new GridPosition(value.x, value.y);
        }

        [Serializable] private sealed class OriginalLevelDto
        { public BlockDto[] BMS; public DoorDto[] DMS; public WallDto[] WMS; public CellDto[] CMS; public GridPositionDto[] BSP; public CurtainDto[] CLMS; }
        [Serializable] private sealed class BlockDto
        { public int BCT; public GridPositionDto[] BPMS; public int BIC; public bool ILE; public int LBCT; }
        [Serializable] private sealed class DoorDto { public int BCT; public GridPositionDto[] BPMS; public int DIC; }
        [Serializable] private sealed class CurtainDto { public GridPositionDto[] BPMS; public int CLC; }
        [Serializable] private sealed class WallDto { public GridPositionDto BPM; }
        [Serializable] private sealed class CellDto { public GridPositionDto BPM; }
        [Serializable] private sealed class GridPositionDto { public int x; public int y; }
    }
}