using Microsoft.Extensions.Options;
using Serilog;
using System.Numerics;
using System.Threading.Channels;
using TriliumMind.Models;
using TriliumMind.Services;

namespace TriliumMind.Workers;

public class JiraWorker : BackgroundService
{
    private readonly Serilog.ILogger _log;
    private readonly AppConfigs _configs;
    private readonly IServiceScopeFactory _scopeFactory; // Singleton services cannot directly inject Scoped services.
    private readonly JiraService _jira;
    private readonly Channel<Issue> _issueChannel;

    public JiraWorker(AppConfigs configs, IServiceScopeFactory serviceScopeFactory,
        JiraService jaraService, Channel<Issue> issueChannel)
    {
        _log = Log.ForContext<JiraWorker>(); ;
        _configs = configs;
        _scopeFactory = serviceScopeFactory;
         _jira = jaraService;
        _issueChannel = issueChannel;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            _log.Debug("Worker running at: {time}", DateTimeOffset.Now);

            var configLastFetchTime = _configs.RuntimeConfigs.GetValueOrDefault(Consts.ConfigLastFetchTimeKey);
            if (string.IsNullOrEmpty(configLastFetchTime))
            {
                using (var scope = _scopeFactory.CreateScope())
                {
                    var db = scope.ServiceProvider.GetRequiredService<AppDbService>();
                    var lastFetchTimeText = await db.GetConfigAsync(Consts.ConfigLastFetchTimeKey);
                    configLastFetchTime = (lastFetchTimeText != null) 
                        ? lastFetchTimeText : DateTimeOffset.Now.AddDays(-1).ToString("yyyy-MM-ddTHH:mm:sszzz");
                }
            }
            var lastFetchTime = DateTimeOffset.Parse(configLastFetchTime);

            var issueList = new List<Issue>();
            var currentFetchTime = DateTimeOffset.Now;
            foreach (var targetProject in _configs.AppSettings.Jira.TargetProjects)
            {
                int startAt = 0, total = 0;
                do
                {
                    var response = await _jira.FetchJiraIssuesAsync(lastFetchTime, targetProject, startAt, stoppingToken);
                    if (response != null)
                    {
                        total = response.total;
                        startAt += response.maxResults;
                        issueList.AddRange(response.issues);
                    }
                } while(startAt < total);
            }
            foreach (var item in issueList)
            {
                await _issueChannel.Writer.WriteAsync(item, stoppingToken);
            }

            using (var scope = _scopeFactory.CreateScope())
            {
                var db = scope.ServiceProvider.GetRequiredService<AppDbService>();
                // Update last fetch time
                await db.SetConfigAsync(Consts.ConfigLastFetchTimeKey, currentFetchTime.ToString("yyyy-MM-ddTHH:mm:sszzz"));
                _configs.RuntimeConfigs[Consts.ConfigLastFetchTimeKey] = currentFetchTime.ToString("yyyy-MM-ddTHH:mm:sszzz");
            }
            await Task.Delay(_configs.AppSettings.Jira.FetchInterval * 1000, stoppingToken);
        }
    }
}