using HrynCo.NotificationService.Services.TemplateDefinitions;
using System.Text.Json;
using HrynCo.NotificationService.DAL.Abstract.Repositories;
using HrynCo.NotificationService.DAL.Abstract.Templates;
using HrynCo.NotificationService.Services.EmailTemplates.Delete;
using HrynCo.NotificationService.Services.EmailTemplates.SaveDefinition;
using HrynCo.NotificationService.Web.Controllers.Admin.ViewModels;
using MediatR;
using Microsoft.AspNetCore.Mvc;

namespace HrynCo.NotificationService.Web.Controllers.Admin;

[Route("admin/services/{serviceId:guid}/templates")]
public sealed class AdminTemplatesController(IMediator mediator, IEmailTemplateDefinitionRepository definitions,
    ILogger<AdminTemplatesController> logger, INotificationServiceRepository services, IPushTemplateDefinitionRepository pushes) : Controller
{
    private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web) { WriteIndented = true };

    [HttpGet("/admin/services/{serviceId:guid}")]
    public async Task<IActionResult> Index([FromRoute] Guid serviceId, [FromQuery] string? key, CancellationToken ct)
    {
        var service = await services.GetAsync(serviceId, ct);
        if (service is null)
            return NotFound();
        var model = new ServiceTemplatesViewModel { Service = service, KeyFilter = key };
        if (TempData["TemplateError"] is string previousError)
            ModelState.AddModelError("", previousError);
        try
        {
            var filter = key?.Trim() ?? "";
            model.PushDefinitions = (await pushes.GetDefinitionsAsync(serviceId, ct))
                .Where(d => d.Key.Contains(filter, StringComparison.OrdinalIgnoreCase)).ToList();
            model.Definitions = (await definitions.GetDefinitionsAsync(serviceId, ct))
                .Where(d => d.Key.Contains(filter, StringComparison.OrdinalIgnoreCase)).ToList();
        }
        catch (Exception error) when (error is not OperationCanceledException)
        {
            logger.LogError(error, "Failed to load service template definitions.");
            ModelState.AddModelError("", "Could not load templates. Try again when the service is available.");
        }
        return View(model);
    }

    [HttpGet("create")]
    public async Task<IActionResult> Create([FromRoute] Guid serviceId, [FromQuery] string? keyFilter, CancellationToken ct, [FromQuery] string? templateKey = null)
    {
        var service = await services.GetAsync(serviceId, ct);
        return service is null ? NotFound() : EditorView(new EmailTemplateEditViewModel
        {
            ServiceId = service.Id, ServiceName = service.Name, KeyFilter = keyFilter, Key = templateKey ?? "", LockKey = !string.IsNullOrEmpty(templateKey)
        }, service);
    }

    [HttpGet("{definitionId:guid}")]
    public async Task<IActionResult> Edit([FromRoute] Guid serviceId, [FromRoute] Guid definitionId, [FromQuery] string? languageCode,
        [FromQuery] string? keyFilter, CancellationToken ct)
    {
        var service = await services.GetAsync(serviceId, ct);
        var definition = await OwnedDefinitionAsync(service, definitionId, ct);
        if (definition is null)
            return NotFound();
        var model = ToViewModel(definition);
        model.KeyFilter = keyFilter;
        model.ActiveLanguageIndex = Math.Max(0, model.Languages.FindIndex(l => l.LanguageCode == languageCode));
        return EditorView(model, service!);
    }

    [HttpPost("save")]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Save([FromRoute] Guid serviceId, EmailTemplateEditViewModel model, CancellationToken ct)
    {
        var service = await services.GetAsync(serviceId, ct);
        if (service is null || model.ServiceId != serviceId || model.ServiceName != service.Name)
            return NotFound();
        var persisted = model.Id is Guid definitionId ? await OwnedDefinitionAsync(service, definitionId, ct) : null;
        if (model.Id is not null && persisted is null)
            return NotFound();
        model.LockKey = model.Id is not null || await pushes.GetAsync(serviceId, model.Key, ct) is not null;
        var presentCodes = persisted?.Languages.Select(l => l.LanguageCode).ToHashSet(StringComparer.Ordinal);
        foreach (var language in model.Languages)
            language.IsPresent = presentCodes?.Contains(language.LanguageCode) == true;
        ValidateLanguageCatalog(model, service);
        if (!ModelState.IsValid)
            return EditorView(model, service);
        var definition = ParseDefinition(model);
        if (definition is null)
            return EditorView(model, service);
        return await SaveDefinitionAsync(definition, model, service, ct);
    }

    [HttpPost("{definitionId:guid}/languages/{languageCode}/delete")]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Delete([FromRoute] Guid serviceId, [FromRoute] Guid definitionId, [FromRoute] string languageCode,
        [FromForm] string? keyFilter, CancellationToken ct)
    {
        var service = await services.GetAsync(serviceId, ct);
        var definition = await OwnedDefinitionAsync(service, definitionId, ct);
        var language = definition?.Languages.SingleOrDefault(l => l.LanguageCode == languageCode);
        if (language is null)
            return NotFound();
        var result = await mediator.Send(new DeleteEmailTemplateCommand(service!.Name, definition!.Key, languageCode, language.Id), ct);
        if (!result.IsSuccess)
            TempData["TemplateError"] = result.Error?.Message ?? "Failed to delete language version.";
        return RedirectToAction(nameof(Index), new { serviceId, key = keyFilter });
    }

    [HttpGet("{definitionId:guid}/delete")]
    public async Task<IActionResult> ConfirmDefinitionDelete([FromRoute] Guid serviceId, [FromRoute] Guid definitionId,
        [FromQuery] string? keyFilter, CancellationToken ct)
    {
        var model = await DefinitionDeleteModelAsync(serviceId, definitionId, keyFilter, ct);
        return model is null ? NotFound() : View("DeleteDefinition", model);
    }

    [HttpPost("{definitionId:guid}/delete")]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> DeleteDefinition([FromRoute] Guid serviceId, [FromRoute] Guid definitionId,
        EmailTemplateDefinitionDeleteViewModel model, CancellationToken ct)
    {
        var current = await DefinitionDeleteModelAsync(serviceId, definitionId, model.KeyFilter, ct);
        if (current is null)
            return NotFound();
        if (!ModelState.IsValid || !model.ConfirmDelete)
            return await DefinitionDeleteErrorAsync(serviceId, definitionId, model.KeyFilter, "Confirm deletion of this template and its translations to continue.", ct);
        try
        {
            var result = await mediator.Send(new DeleteEmailTemplateDefinitionCommand(serviceId, current.Key, model.Revision), ct);
            if (result.IsSuccess)
                return RedirectToAction(nameof(Index), new { serviceId, key = model.KeyFilter });
            return await DefinitionDeleteErrorAsync(serviceId, definitionId, model.KeyFilter, result.Error!.Message, ct);
        }
        catch (Exception error) when (error is not OperationCanceledException)
        {
            logger.LogError(error, "Failed to delete email template definition.");
            return await DefinitionDeleteErrorAsync(serviceId, definitionId, model.KeyFilter, "Could not complete deletion. Review the current template before trying again.", ct);
        }
    }

    private async Task<EmailTemplateDefinitionDeleteViewModel?> DefinitionDeleteModelAsync(Guid serviceId, Guid definitionId, string? keyFilter, CancellationToken ct)
    {
        var service = await services.GetAsync(serviceId, ct);
        var definition = await OwnedDefinitionAsync(service, definitionId, ct);
        return definition is null ? null : new EmailTemplateDefinitionDeleteViewModel
        {
            ServiceId = serviceId, DefinitionId = definition.Id, ServiceName = definition.ServiceName, Key = definition.Key,
            Revision = definition.Revision, KeyFilter = keyFilter, LanguageCodes = definition.Languages.Select(l => l.LanguageCode).ToList()
        };
    }

    private async Task<IActionResult> DefinitionDeleteErrorAsync(Guid serviceId, Guid definitionId, string? keyFilter, string error, CancellationToken ct)
    {
        var model = await DefinitionDeleteModelAsync(serviceId, definitionId, keyFilter, ct);
        if (model is null)
            return NotFound();
        ModelState.Clear();
        ModelState.AddModelError("", error);
        return View("DeleteDefinition", model);
    }

    private async Task<IActionResult> SaveDefinitionAsync(EmailTemplateDefinition definition, EmailTemplateEditViewModel model,
        NotificationServiceInfo service, CancellationToken ct)
    {
        try
        {
            var result = await mediator.Send(new SaveEmailTemplateDefinitionCommand(definition, model.IsNew), ct);
            if (result.IsSuccess)
                return RedirectToAction(nameof(Index), new { serviceId = service.Id, key = model.KeyFilter });
            ModelState.AddModelError("", result.Error?.Message ?? "Failed to save template.");
        }
        catch (Exception error) when (error is not OperationCanceledException)
        {
            logger.LogError(error, "Failed to save email template definition.");
            ModelState.AddModelError("", "Could not save the template. Your entered values are retained; try again when the service is available.");
        }
        return EditorView(model, service);
    }

    private async Task<EmailTemplateDefinition?> OwnedDefinitionAsync(NotificationServiceInfo? service, Guid definitionId, CancellationToken ct)
    {
        if (service is null)
            return null;
        return (await definitions.GetDefinitionsAsync(service.Id, ct))
            .SingleOrDefault(d => d.Id == definitionId && d.ServiceId == service.Id);
    }

    private IActionResult EditorView(EmailTemplateEditViewModel model, NotificationServiceInfo service)
    {
        foreach (var language in service.Languages)
            if (!model.Languages.Any(l => l.LanguageCode == language.Code))
                model.Languages.Add(new EmailTemplateLanguageEditViewModel { LanguageCode = language.Code });
        return View("Edit", model);
    }

    private void ValidateLanguageCatalog(EmailTemplateEditViewModel model, NotificationServiceInfo service)
    {
        var codes = model.Languages.Select(l => l.LanguageCode).ToHashSet(StringComparer.Ordinal);
        if (codes.Count != model.Languages.Count)
            ModelState.AddModelError("", "Language codes must be unique within a template.");
        if (!codes.SetEquals(service.Languages.Select(l => l.Code)))
            ModelState.AddModelError("", "The service language catalog changed or the submitted tabs are invalid. Reload before saving.");
    }

    private EmailTemplateDefinition? ParseDefinition(EmailTemplateEditViewModel model)
    {
        try
        {
            return new EmailTemplateDefinition
            {
                Id = model.Id ?? Guid.NewGuid(), ServiceId = model.ServiceId, Revision = model.Revision,
                ServiceName = model.ServiceName, Key = model.Key,
                Variables = EmailTemplateValidation.ParseVariables(model.VariablesJson),
                Languages = model.Languages.Where(l => l.HasContent).Select(l => new EmailTemplate
                {
                    ServiceName = model.ServiceName, Key = model.Key, LanguageCode = l.LanguageCode,
                    Subject = l.Subject, HtmlBody = l.HtmlBody, TextBody = l.TextBody, Created = DateTimeOffset.UtcNow
                }).ToList()
            };
        }
        catch (JsonException)
        {
            ModelState.AddModelError(nameof(model.VariablesJson), "Invalid variables JSON. Use an array of objects with name and required properties.");
        }
        catch (EmailTemplateWriteException error)
        {
            ModelState.AddModelError(nameof(model.VariablesJson), error.Message);
        }
        return null;
    }

    private static EmailTemplateEditViewModel ToViewModel(EmailTemplateDefinition definition) => new()
    {
        Id = definition.Id, ServiceId = definition.ServiceId, Revision = definition.Revision,
        ServiceName = definition.ServiceName, Key = definition.Key,
        VariablesJson = JsonSerializer.Serialize(definition.Variables, JsonOptions),
        Languages = definition.Languages.Select(l => new EmailTemplateLanguageEditViewModel
        {
            LanguageCode = l.LanguageCode, Subject = l.Subject, HtmlBody = l.HtmlBody, TextBody = l.TextBody,
            IsPresent = true
        }).ToList()
    };
}