using Asp.Versioning;
using Cronos;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Mirea.Api.DataAccess.Persistence;
using Mirea.Api.Dto.Common;
using Mirea.Api.Dto.Responses.Configuration;
using Mirea.Api.Endpoint.Common.Exceptions;
using Mirea.Api.Endpoint.Common.MapperDto;
using Mirea.Api.Endpoint.Common.Services;
using Mirea.Api.Endpoint.Configuration.Model;
using Mirea.Api.Endpoint.Configuration.Model.GeneralSettings;
using Mirea.Api.Endpoint.Sync;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace Mirea.Api.Endpoint.Controllers.V1.Configuration;

[ApiVersion("1.0")]
public class ScheduleController(ILogger<ScheduleController> logger, IOptionsSnapshot<GeneralConfig> config, UberDbContext dbContext, IServiceProvider provider) : ConfigurationBaseController
{
    /// <summary>
    /// Retrieves the cron update schedule and calculates the next scheduled tasks based on the provided depth.
    /// </summary>
    /// <param name="depth">The depth of the next tasks to retrieve.</param>
    /// <returns>Cron expression and the list of next scheduled task dates.</returns>
    [HttpGet("CronUpdateSchedule")]
    public ActionResult<CronUpdateScheduleResponse> CronUpdateSchedule([FromQuery][Range(0, 10)] int depth = 5)
    {
        var cronExpression = CronExpression.Parse(config.Value.ScheduleSettings!.CronUpdateSchedule);
        var nextTasks = config.Value.ScheduleSettings!.CronUpdateSkipDateList.GetNextTask(cronExpression, depth);

        return new CronUpdateScheduleResponse()
        {
            Cron = config.Value.ScheduleSettings!.CronUpdateSchedule,
            NextStart = nextTasks.Select(x => DateTime.SpecifyKind(x.DateTime, DateTimeKind.Local)).ToList()
        };
    }

    /// <summary>
    /// Updates the cron update schedule with the provided cron expression.
    /// </summary>
    /// <param name="cron">The cron expression to set as the new schedule.</param>
    /// <returns>Cron expression and the list of next scheduled task dates.</returns>
    /// <exception cref="ControllerArgumentException">Thrown if the provided cron expression is invalid.</exception>
    [HttpPost("CronUpdateSchedule")]
    public ActionResult<CronUpdateScheduleResponse> CronUpdateSchedule([FromQuery] string cron)
    {
        cron = cron.Trim();
        if (!CronExpression.TryParse(cron, CronFormat.Standard, out _))
            throw new ControllerArgumentException("Incorrect cron value.");

        if (config.Value.ScheduleSettings!.CronUpdateSchedule == cron)
            return CronUpdateSchedule();

        config.Value.ScheduleSettings!.CronUpdateSchedule = cron;
        config.Value.SaveSetting();

        return CronUpdateSchedule();
    }

    /// <summary>
    /// Retrieves the start term date from the configuration.
    /// </summary>
    /// <returns>Start term date.</returns>
    [HttpGet("StartTerm")]
    public ActionResult<DateOnly> StartTerm() =>
        config.Value.ScheduleSettings!.StartTerm;

    /// <summary>
    /// Updates the start term date in the configuration.
    /// </summary>
    /// <param name="startTerm">The new start term date to set.</param>
    /// <param name="force">If true, forces an update by deleting all existing lessons.</param>
    /// <returns>Success or failure.</returns>
    /// <exception cref="ControllerArgumentException">Thrown if the start term date is more than 6 months in the past or future.</exception>
    [HttpPost("StartTerm")]
    public ActionResult StartTerm([FromQuery] DateOnly startTerm, [FromQuery] bool force = false)
    {
        var differentByTime = DateTime.Now - startTerm.ToDateTime(new TimeOnly(0, 0, 0));
        if (differentByTime > TimeSpan.FromDays(190) || differentByTime.Multiply(-1) > TimeSpan.FromDays(190))
            throw new ControllerArgumentException("The semester can't start more than 6 months from now, and it can't have started more than 6 months ago either.");

        config.Value.ScheduleSettings!.StartTerm = startTerm;
        config.Value.SaveSetting();

        if (!force)
            return Ok();

        logger.LogWarning("A force update is being performed at the beginning of the semester (all classes will be deleted).");

        dbContext.Lessons.RemoveRange(dbContext.Lessons.ToList());
        dbContext.SaveChanges();

        return Ok();
    }

    /// <summary>
    /// Retrieves the list of cron update skip dates filtered by the current date.
    /// </summary>
    /// <returns>Cron update skip dates.</returns>
    [HttpGet("CronUpdateSkip")]
    public ActionResult<List<CronUpdateSkip>> CronUpdateSkip()
    {
        var generalConfig = config.Value;

        generalConfig.ScheduleSettings!.CronUpdateSkipDateList =
            generalConfig.ScheduleSettings.CronUpdateSkipDateList.Filter();
        generalConfig.SaveSetting();

        return generalConfig.ScheduleSettings!.CronUpdateSkipDateList
            .ConvertToDto();
    }


    /// <summary>
    /// Updates the list of cron update skip dates in the configuration.
    /// </summary>
    /// <param name="cronUpdateDate">The list of cron update skip dates to set.</param>
    /// <returns>Success or failure.</returns>
    /// <exception cref="ControllerArgumentException">Thrown if the provided list of cron update skip dates is invalid.</exception>
    [HttpPost("CronUpdateSkip")]
    public ActionResult CronUpdateSkip([FromBody] List<CronUpdateSkip> cronUpdateDate)
    {
        List<ScheduleSettings.CronUpdateSkip> result;
        try
        {
            result = cronUpdateDate.ConvertFromDto();
        }
        catch (ArgumentException ex)
        {
            throw new ControllerArgumentException(ex.Message);
        }

        config.Value.ScheduleSettings!.CronUpdateSkipDateList = result.Filter();
        config.Value.SaveSetting();

        return Ok();
    }

    /// <summary>
    /// Uploads schedule files and initiates synchronization.
    /// </summary>
    /// <param name="files">The list of schedule files to upload.</param>
    /// <param name="defaultCampus">The default campus for each uploaded file. Must match the number of files.</param>
    /// <param name="force">If true, removes all existing lessons before synchronization. Default is false.</param>
    /// <returns>Success or failure.</returns>
    /// <exception cref="ControllerArgumentException">
    /// Thrown if:
    /// - No files are provided.
    /// - The number of default campuses does not match the number of files.
    /// - Any default campus is null or empty.
    /// </exception>
    [HttpPost("Upload")]
    public async Task<ActionResult> UploadScheduleFiles(List<IFormFile>? files, [FromQuery] string[]? defaultCampus, [FromQuery] bool force = false)
    {
        if (files == null || files.Count == 0)
            throw new ControllerArgumentException("No files were found.");

        if (defaultCampus == null || files.Count != defaultCampus.Length)
            throw new ControllerArgumentException("No default campuses are specified for the file.");

        if (defaultCampus.Any(string.IsNullOrEmpty))
            throw new ControllerArgumentException("Each file should have a default campus.");

        var tempDirectory = Path.Combine(Path.GetTempPath(), Path.GetFileNameWithoutExtension(Path.GetRandomFileName()));

        if (!Directory.Exists(tempDirectory))
            Directory.CreateDirectory(tempDirectory);

        List<(string, string)> filePaths = [];

        for (var i = 0; i < files.Count; i++)
        {
            if (files[i].Length <= 0)
                continue;

            var filePath = Path.Combine(tempDirectory, files[i].FileName);

            await using var stream = new FileStream(filePath, FileMode.Create);
            await files[i].CopyToAsync(stream);

            filePaths.Add((filePath, defaultCampus[i]));
        }

        if (force)
        {
            dbContext.Lessons.RemoveRange(await dbContext.Lessons.ToListAsync());
            await dbContext.SaveChangesAsync();
        }

        var scopeFactory = provider.GetRequiredService<IServiceScopeFactory>();
        ThreadPool.QueueUserWorkItem(async void (_) =>
        {
            try
            {
            using var scope = scopeFactory.CreateScope();
                var sync = (ScheduleSynchronizer)ActivatorUtilities.GetServiceOrCreateInstance(scope.ServiceProvider, typeof(ScheduleSynchronizer));

            await sync.StartSync(filePaths, CancellationToken.None);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        });

        return Ok();
    }
}