CatLink/Api/FutariLobby.cs

using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using CatLink.Models;
using Microsoft.AspNetCore.Mvc;

namespace CatLink.Api
{
    [ApiController]
    [Route("recruit")]
    public class FutariLobby : ControllerBase
    {
        private static readonly Dictionary<uint, RecruitRecord> _recruits = new();
        private static readonly object _recruitsLock = new();
        private static readonly string _logFilePath = "recruit.log";
        private readonly ILogger<FutariLobby> _logger;
        private readonly JsonSerializerOptions _jsonOptions = new()
        {
            PropertyNameCaseInsensitive = true,
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
        };

        public FutariLobby(ILogger<FutariLobby> logger)
        {
            _logger = logger;
        }

        [HttpPost("start")]
        public IActionResult StartRecruit([FromBody] JsonElement json)
        {
            try
            {
                var record = JsonSerializer.Deserialize<RecruitRecord>(json.GetRawText(), _jsonOptions);
                if (record == null)
                {
                    throw new ApiException(400, "Invalid request body");
                }

                record.Time = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();

                var key = record.RecruitInfo.MechaInfo.IpAddress;

                lock (_recruitsLock)
                {
                    var isNew = !_recruits.ContainsKey(key);
                    _recruits[key] = record;

                    if (isNew)
                    {
                        LogRecruit("START", record);
                    }
                }

                // Hash user IDs (commented out - client already sends numeric IDs)
                // if (record.RecruitInfo.MechaInfo.UserIDs != null)
                // {
                //     record.RecruitInfo.MechaInfo.UserIDs = record.RecruitInfo.MechaInfo.UserIDs
                //         .Select(HashUserId)
                //         .ToList();
                // }

                return Ok(new { success = true });
            }
            catch (ApiException ex)
            {
                return StatusCode(ex.Code, ex.Message);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error starting recruit");
                return StatusCode(500, "Internal server error");
            }
        }

        [HttpPost("finish")]
        public IActionResult FinishRecruit([FromBody] JsonElement json)
        {
            try
            {
                var record = JsonSerializer.Deserialize<RecruitRecord>(json.GetRawText(), _jsonOptions);
                if (record == null)
                {
                    throw new ApiException(400, "Invalid request body");
                }

                var key = record.RecruitInfo.MechaInfo.IpAddress;

                lock (_recruitsLock)
                {
                    if (!_recruits.ContainsKey(key))
                    {
                        throw new ApiException(404, "Recruit not found");
                    }

                    var existing = _recruits[key];
                    if (existing.Keychip != record.Keychip)
                    {
                        throw new ApiException(403, "Keychip mismatch");
                    }

                    _recruits.Remove(key);
                    LogRecruit("FINISH", existing);
                }

                return Ok(new { success = true });
            }
            catch (ApiException ex)
            {
                return StatusCode(ex.Code, ex.Message);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error finishing recruit");
                return StatusCode(500, "Internal server error");
            }
        }

        [HttpGet("list")]
        public IActionResult GetRecruitList()
        {
            try
            {
                var now = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
                var timeout = 30000; // 30 seconds

                List<RecruitRecord> records;

                lock (_recruitsLock)
                {
                    // Remove expired records
                    var expiredKeys = _recruits
                        .Where(kvp => now - kvp.Value.Time > timeout)
                        .Select(kvp => kvp.Key)
                        .ToList();

                    foreach (var key in expiredKeys)
                    {
                        _recruits.Remove(key);
                    }

                    records = _recruits.Values.ToList();
                }

                // Return NDJSON format (newline-delimited JSON)
                var sb = new System.Text.StringBuilder();
                foreach (var record in records)
                {
                    var json = System.Text.Json.JsonSerializer.Serialize(record, new System.Text.Json.JsonSerializerOptions
                    {
                        PropertyNamingPolicy = System.Text.Json.JsonNamingPolicy.CamelCase
                    });
                    sb.AppendLine(json);
                }

                return Content(sb.ToString(), "text/plain");
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error getting recruit list");
                return StatusCode(500, "Internal server error");
            }
        }

        private static string HashUserId(long userId)
        {
            var hash = MD5.HashData(Encoding.UTF8.GetBytes(userId.ToString()));
            return Convert.ToHexString(hash).ToLowerInvariant();
        }

        private void LogRecruit(string action, RecruitRecord record)
        {
            try
            {
                var line = $"[{DateTimeOffset.UtcNow:yyyy-MM-dd HH:mm:ss}] {action} {record.RecruitInfo.MechaInfo.IpAddress} {record.Keychip} MusicID={record.RecruitInfo.MusicID}";

                lock (_recruitsLock)
                {
                    System.IO.File.AppendAllText(_logFilePath, line + Environment.NewLine);
                }

                _logger.LogInformation(line);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error writing to recruit log");
            }
        }
    }
}