using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace YBEE.EQM.Application;

public class ExamSampleWorker(ILogger<ExamSampleWorker> logger, IServiceScopeFactory scopeFactory) : IHostedService, IDisposable
{
    private readonly Dictionary<int, Task> _executingTasks = [];
    private readonly Dictionary<int, CancellationTokenSource> _cancellationTokenSources = [];

    /// <summary>
    /// StartAsync 方法不再直接启动任务，而是保持服务初始化
    /// </summary>
    /// <param name="cancellationToken"></param>
    /// <returns></returns>
    public Task StartAsync(CancellationToken cancellationToken)
    {
        logger.LogInformation("抽样执行服务已初始化");
        return Task.CompletedTask;
    }

    /// <summary>
    /// 外部控制：通过参数启动后台任务
    /// </summary>
    /// <param name="examPlanId">监测计划ID</param>
    /// <returns></returns>
    public int StartTask(int examPlanId)
    {
        if (_executingTasks.TryGetValue(examPlanId, out Task value) && !value.IsCompleted)
        {
            logger.LogInformation("监测计划ID：{examPlanId}，执行中，不能重复启动！", examPlanId);
            return -1;
        }

        logger.LogInformation("监测计划ID：{examPlanId}，开始执行...", examPlanId);
        var cancellationTokenSource = new CancellationTokenSource();
        var executingTask = ExecuteAsync(examPlanId, cancellationTokenSource.Token);

        // 保存任务和取消令牌源，以便可以后续控制
        _executingTasks[examPlanId] = executingTask;
        _cancellationTokenSources[examPlanId] = cancellationTokenSource;

        return 0;
    }

    /// <summary>
    /// 外部控制：通过任务参数停止任务
    /// </summary>
    /// <param name="examPlanId"></param>
    /// <returns></returns>
    public int StopTask(int examPlanId)
    {
        if (!_executingTasks.TryGetValue(examPlanId, out Task value) || value.IsCompleted)
        {
            logger.LogInformation("监测计划ID：{examPlanId}，未运行！", examPlanId);
            return -1;
        }

        logger.LogInformation("监测计划ID：{examPlanId}，开始停止...", examPlanId);

        // 停止任务
        _cancellationTokenSources[examPlanId]?.Cancel();
        _executingTasks.Remove(examPlanId);
        _cancellationTokenSources.Remove(examPlanId);

        return 0;
    }

    /// <summary>
    /// 任务执行逻辑
    /// </summary>
    /// <param name="examPlanId"></param>
    /// <param name="cancellationToken"></param>
    /// <returns></returns>
    private async Task ExecuteAsync(int examPlanId, CancellationToken cancellationToken)
    {
        try
        {
            while (!cancellationToken.IsCancellationRequested)
            {
                using var scope = scopeFactory.CreateScope();
                var services = scope.ServiceProvider;
                var examSampleService = services.GetService<IExamSampleService>();
                await examSampleService.ExecuteSampleByExamPlanId(examPlanId);
                logger.LogInformation("监测计划ID：{examPlanId}，执行完成。", examPlanId);
                StopTask(examPlanId);
            }
        }
        catch (TaskCanceledException)
        {
            logger.LogInformation("监测计划ID：{examPlanId}，已取消。", examPlanId);
        }
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        // 停止所有正在运行的任务
        foreach (var key in _executingTasks.Keys.ToList())
        {
            StopTask(key);
        }

        return Task.CompletedTask;
    }

    public void Dispose()
    {
        foreach (var cancellationTokenSource in _cancellationTokenSources.Values)
        {
            cancellationTokenSource?.Dispose();
        }
    }
}