using System.Text.Json;
#if POSTGRES
using Events.EF.Data.Postgres;
#else
using Events.EF.Data.MSSQL;
#endif
using Events.EF.Models;
using Events.MVC.Models;
using Events.MVC.Models.Events;
using Events.MVC.Util.Extensions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using Sieve.Models;
using Sieve.Services;

namespace Events.MVC.Controllers;

public class EventsController : Controller
{
    private readonly EventsContext ctx;
    private readonly ISieveProcessor sieveProcessor;
    private readonly PagingSettings pagingSettings;

    public EventsController(EventsContext ctx, ISieveProcessor sieveProcessor, IOptionsSnapshot<PagingSettings> pagingSettings)
    {
        this.ctx = ctx;
        this.sieveProcessor = sieveProcessor;
        this.pagingSettings = pagingSettings.Value;
    }

    public async Task<IActionResult> Index(SieveModel sieveModel)
    {
        var viewModel = await BuildEventsListAsync(sieveModel);
        if (Request.Headers.ContainsKey(Constants.HtmxHeaders.Request))
        {
            return PartialView("_EventsList", viewModel);
        }

        return View(viewModel);
    }

    [HttpGet]
    public async Task<IActionResult> Row(int id)
    {
        var eventModel = await ctx.Events
            .Select(e => new EventViewModel
            {
                Id = e.Id,
                Name = e.Name,
                EventDate = e.EventDate,
                ParticipantsCount = e.Registrations.Count
            })
            .FirstOrDefaultAsync(e => e.Id == id);

        if (eventModel is null)
        {
            return NotFound();
        }

        return PartialView("_EventRow", eventModel);
    }

    [HttpGet]
    public async Task<IActionResult> EditRow(int id)
    {
        var eventModel = await ctx.Events
            .Select(e => new EventViewModel
            {
                Id = e.Id,
                Name = e.Name,
                EventDate = e.EventDate
            })
            .FirstOrDefaultAsync(e => e.Id == id);

        if (eventModel is null)
        {
            return NotFound();
        }

        return PartialView("_EventEditRow", eventModel);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Create(EventViewModel model, SieveModel sieveModel)
    {
        if (!ModelState.IsValid)
        {
            Response.Headers[Constants.HtmxHeaders.Retarget] = "#create-event-form";
            Response.Headers[Constants.HtmxHeaders.Reswap] = Constants.HtmxSwap.OuterHtml;
            return PartialView("_CreateEventForm", model);
        }

        var eventEntity = new Event
        {
            Name = model.Name,
            EventDate = model.EventDate
        };
        ctx.Events.Add(eventEntity);
        await ctx.SaveChangesAsync();

        Response.Headers[Constants.HtmxHeaders.Trigger] = JsonSerializer.Serialize(new Dictionary<string, object?>
        {
            [Constants.HtmxEvents.EventCreated] = true,
            [Constants.HtmxEvents.ShowToast] = new
            {
                variant = Constants.ToastVariants.Success,
                title = Constants.ToastTitles.Success,
                message = $"Event '{model.Name}' was added successfully."
            }
        });

        var viewModel = await BuildEventsListAsync(sieveModel);
        return PartialView("_EventsList", viewModel);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Edit(int id, EventViewModel model)
    {
        if (id != model.Id)
        {
            return BadRequest();
        }

        if (!ModelState.IsValid)
        {
            return PartialView("_EventEditRow", model);
        }

        var existingEvent = await ctx.Events.FirstOrDefaultAsync(e => e.Id == id);
        if (existingEvent is null)
        {
            return NotFound();
        }

        existingEvent.Name = model.Name;
        existingEvent.EventDate = model.EventDate;
        await ctx.SaveChangesAsync();

        return PartialView("_EventRow", new EventViewModel
        {
            Id = existingEvent.Id,
            Name = existingEvent.Name,
            EventDate = existingEvent.EventDate,
            ParticipantsCount = await ctx.Registrations.CountAsync(r => r.EventId == existingEvent.Id)
        });
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Delete(int id, SieveModel sieveModel)
    {
        var eventEntity = await ctx.Events
            .Include(e => e.Registrations)
            .FirstOrDefaultAsync(e => e.Id == id);

        if (eventEntity is null)
        {
            return NotFound();
        }

        if (eventEntity.Registrations.Count > 0)
        {
            Response.StatusCode = StatusCodes.Status409Conflict;
            return Content("The event cannot be deleted because registrations exist.");
        }

        ctx.Events.Remove(eventEntity);
        var deletedName = eventEntity.Name;
        await ctx.SaveChangesAsync();

        Response.Headers[Constants.HtmxHeaders.Trigger] = JsonSerializer.Serialize(new Dictionary<string, object?>
        {
            [Constants.HtmxEvents.ShowToast] = new
            {
                variant = Constants.ToastVariants.Success,
                title = Constants.ToastTitles.Success,
                message = $"Event '{deletedName}' was deleted successfully."
            }
        });

        var viewModel = await BuildEventsListAsync(sieveModel);
        return PartialView("_EventsList", viewModel);
    }

    private async Task<PagedList<EventViewModel>> BuildEventsListAsync(SieveModel sieveModel)
    {
        sieveModel.SetDefaultPagingAndSorting(pagingSettings.PageSize, "EventDate");
        var normalizedFilters = sieveModel.Filters?.Trim() ?? string.Empty;
        var nameFilter = SieveModelExtensions.ExtractFilterValue(normalizedFilters, "Name");

        var baseQuery = ctx.Events
            .Select(e => new EventViewModel
            {
                Id = e.Id,
                Name = e.Name,
                EventDate = e.EventDate,
                ParticipantsCount = e.Registrations.Count
            });

        var totalCount = await baseQuery.CountAsync();
        var filteredCount = string.IsNullOrWhiteSpace(normalizedFilters)
            ? totalCount
            : await sieveProcessor
                .Apply(
                    sieveModel,
                    baseQuery,
                    applyFiltering: true,
                    applySorting: false,
                    applyPagination: false)
                .CountAsync();

        var pagingInfo = new PagingInfo
        {
            FilteredItemsCount = filteredCount,
            TotalItemsCount = totalCount,
            ItemsPerPage = sieveModel.PageSize!.Value,
            CurrentPage = sieveModel.Page!.Value,
            Sorts = sieveModel.Sorts ?? "EventDate",
            Filters = normalizedFilters,
            NameFilter = nameFilter
        };

        if (pagingInfo.CurrentPage > pagingInfo.TotalPages)
        {
            pagingInfo.CurrentPage = pagingInfo.TotalPages;
            sieveModel.Page = pagingInfo.CurrentPage;
        }

        var events = await sieveProcessor
            .Apply(sieveModel, baseQuery)
            .ToListAsync();

        return new PagedList<EventViewModel>(events, pagingInfo);
    }
}