using CharacterApi.Models;
using MongoDB.Bson;
using MongoDB.Driver;

namespace CharacterApi.Services;

public class CharacterStore
{
    private readonly IMongoCollection<Character> _col;
    private readonly IMongoCollection<VisibleLocation> _locations;

    public CharacterStore(IConfiguration cfg)
    {
        var cs = cfg["MongoDB:ConnectionString"] ?? "mongodb://127.0.0.1:27017";
        var dbName = cfg["MongoDB:DatabaseName"] ?? "GameDb";
        var client = new MongoClient(cs);
        var db = client.GetDatabase(dbName);
        _col = db.GetCollection<Character>("Characters");
        _locations = db.GetCollection<VisibleLocation>("Locations");

        var ownerIndex = Builders<Character>.IndexKeys.Ascending(c => c.OwnerUserId);
        _col.Indexes.CreateOne(new CreateIndexModel<Character>(ownerIndex));
    }

    public Task CreateAsync(Character character) => _col.InsertOneAsync(character);

    public Task<List<Character>> GetForOwnerAsync(string ownerUserId) =>
        _col.Find(c => c.OwnerUserId == ownerUserId).ToListAsync();

    public async Task<Character?> GetForOwnerByIdAsync(string id, string ownerUserId, bool allowAnyOwner)
    {
        var filter = Builders<Character>.Filter.Eq(c => c.Id, id);
        if (!allowAnyOwner)
        {
            filter = Builders<Character>.Filter.And(
                filter,
                Builders<Character>.Filter.Eq(c => c.OwnerUserId, ownerUserId)
            );
        }

        return await _col.Find(filter).FirstOrDefaultAsync();
    }

    public Task<List<VisibleLocation>> GetVisibleLocationsAsync(Character character)
    {
        return GetVisibleLocationsInternalAsync(character, ensureGenerated: false);
    }

    public async Task<List<VisibleLocation>> GetOrCreateVisibleLocationsAsync(Character character)
    {
        await EnsureVisibleLocationsExistAsync(character);
        return await GetVisibleLocationsInternalAsync(character, ensureGenerated: true);
    }

    private Task<List<VisibleLocation>> GetVisibleLocationsInternalAsync(Character character, bool ensureGenerated)
    {
        var radius = character.VisionRadius > 0 ? character.VisionRadius : 3;
        var minX = character.Coord.X - radius;
        var maxX = character.Coord.X + radius;
        var minY = character.Coord.Y - radius;
        var maxY = character.Coord.Y + radius;

        var filter = Builders<VisibleLocation>.Filter.And(
            Builders<VisibleLocation>.Filter.Gte(l => l.Coord.X, minX),
            Builders<VisibleLocation>.Filter.Lte(l => l.Coord.X, maxX),
            Builders<VisibleLocation>.Filter.Gte(l => l.Coord.Y, minY),
            Builders<VisibleLocation>.Filter.Lte(l => l.Coord.Y, maxY)
        );

        return _locations.Find(filter).ToListAsync();
    }

    private async Task EnsureVisibleLocationsExistAsync(Character character)
    {
        var radius = character.VisionRadius > 0 ? character.VisionRadius : 3;

        for (var x = character.Coord.X - radius; x <= character.Coord.X + radius; x++)
        {
            for (var y = character.Coord.Y - radius; y <= character.Coord.Y + radius; y++)
            {
                var filter = Builders<VisibleLocation>.Filter.And(
                    Builders<VisibleLocation>.Filter.Eq(l => l.Coord.X, x),
                    Builders<VisibleLocation>.Filter.Eq(l => l.Coord.Y, y)
                );

                var update = Builders<VisibleLocation>.Update
                    .SetOnInsert(l => l.Name, DefaultLocationName(x, y))
                    .SetOnInsert(l => l.Coord, new LocationCoord { X = x, Y = y })
                    .SetOnInsert(l => l.Id, ObjectId.GenerateNewId().ToString())
                    .SetOnInsert("createdUtc", DateTime.UtcNow);

                try
                {
                    await _locations.UpdateOneAsync(filter, update, new UpdateOptions { IsUpsert = true });
                }
                catch (MongoWriteException ex) when (ex.WriteError.Category == ServerErrorCategory.DuplicateKey)
                {
                    // Another request or service instance created it first.
                }
            }
        }
    }

    private static string DefaultLocationName(int x, int y)
    {
        if (x == 0 && y == 0)
            return "Origin";
        return $"Location {x},{y}";
    }

    public async Task<bool> DeleteForOwnerAsync(string id, string ownerUserId, bool allowAnyOwner)
    {
        var filter = Builders<Character>.Filter.Eq(c => c.Id, id);
        if (!allowAnyOwner)
        {
            filter = Builders<Character>.Filter.And(
                filter,
                Builders<Character>.Filter.Eq(c => c.OwnerUserId, ownerUserId)
            );
        }

        var result = await _col.DeleteOneAsync(filter);
        return result.DeletedCount > 0;
    }
}