using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using PhoneToolMX.Data;
using PhoneToolMX.Helpers;
using PhoneToolMX.Models;
using PhoneToolMX.Models.ViewModels;
using System.Security.Authentication;
using System.Security.Claims;

namespace PhoneToolMX.Controllers
{
    [Authorize]
    [Route("[controller]")]
    public abstract class BaseController<T, TViewModel> : Controller
        where T: OwnedBase, IModel
        where TViewModel : IViewModel, new()
    {
        protected private readonly PTMXContext _context;
        private readonly UserManager<User> _userManager;

        protected BaseController(UserManager<User> mgr, PTMXContext ctx)
        {
            _context = ctx;
            _userManager = mgr;
        }

        protected private virtual Task PreForm(TViewModel vm)
        {
            throw new NotImplementedException();
        }
        
        #region Helper methods

        /// <summary>
        /// Gets the "friendly" name for an owned model object.
        /// </summary>
        /// <param name="vm">The model object to inspect</param>
        /// <returns>The friendly name, or its ID if none was defined</returns>
        private static string GetFriendlyName(IViewModel vm)
        {
            if (vm is not TViewModel model) return vm.Id.ToString();
            return typeof(TViewModel).GetProperties().Where(pi =>
            {
                var headers = pi.GetCustomAttributes(typeof(HeaderAttribute), false);
                return headers.Length != 0 && ((HeaderAttribute)headers[0]).Primary;
            }).Select(pi => pi.GetValue(model)?.ToString()).FirstOrDefault() ?? model.Id.ToString();
        }

        private static string GetFriendlyName(IOwnedModel model)
        {
            var vm = new TViewModel().FromEntity(model);
            return GetFriendlyName(vm);
        }

        protected private async Task<User> CurrentUser()
        {
            var claim = HttpContext.User.Claims.FirstOrDefault(c => c.Type.Equals(ClaimTypes.NameIdentifier));
            if (claim == null) {
                throw new InvalidCredentialException("fuck this noise, nameid claim missing");
            }
            var user = await _userManager.FindByIdAsync(claim.Value);
            return user;
        }

        private async Task<IActionResult> FormView(TViewModel vm)
        {
            await PreForm(vm);
            return View("_Form", vm);
        }

        private void SetMessage(FormMessage msg)
        {
            TempData["Message"] = msg.ToString();
        }

        private void SetMessage(FormMessageType type, string msg)
        {
            SetMessage(new FormMessage
            {
                Type = type,
                Message = msg,
            });
        }

        private async Task<IActionResult> ValidationError(TViewModel vm)
        {
            var plural = ModelState.ErrorCount > 1 ? "s" : string.Empty;
            SetMessage(
                FormMessageType.Error,
                $"Error{plural} occurred in validation. Make the changes required and click Submit to try again."
            );
            return await FormView(vm);
        }

        #endregion

        #region Create
        
        [HttpGet("New")]
        public async Task<IActionResult> New()
        {
            ViewData["Action"] = "add";
            ViewData["Title"] = $"Add new {typeof(T).Name.ToLower()}";
            return await FormView(default);
        }
        
        [HttpPost("New")]
        public async Task<IActionResult> NewPost(TViewModel vm)
        {
            ViewData["Title"] = $"New {typeof(T).Name}";
            
            if (!ModelState.IsValid) return await ValidationError(vm);

            if (vm.ToEntity(_context) is not T model) throw new InvalidOperationException($"{typeof(TViewModel).FullName}.ToEntity() somehow produced something other than a {typeof(T).FullName}");
            var entity = await _context.AddOwnable(await CurrentUser(), model);
            await _context.SaveChangesAsync();
            
            SetMessage(
                FormMessageType.Success,
                $"{typeof(T).Name} {GetFriendlyName(new TViewModel().FromEntity(entity.Entity))} was created."
            );
            
            return RedirectToAction("Edit",  new { id = entity.Entity.Id });
        }
        
        #endregion

        #region Read

        [HttpGet]
        public async Task<IActionResult> Index()
        {
            ViewData["Title"] = $"My {typeof(T).Name}s";
            return View("Index", _context
                .GetOwned<T>(await CurrentUser())
                .Select(m => (TViewModel)new TViewModel().FromEntity(m))
                .ToList());
        }

        #endregion
        
        #region Update

        [HttpGet("Edit")]
        public async Task<IActionResult> Edit(int id)
        {
            ViewData["Action"] = "update";
            var model = _context.GetOwned<T>(await CurrentUser()).FirstOrDefault(o => o.Id == id);
            if (model == null) return NotFound();
            ViewData["Title"] = $"Editing {typeof(T).Name.ToLower()} {GetFriendlyName(new TViewModel().FromEntity(model))}";
            return await FormView((TViewModel)new TViewModel().FromEntity(model));
        }

        [HttpPost("Edit")]
        public async Task<IActionResult> EditPost(TViewModel vm)
        {
            if (vm?.Id == null) {
                return BadRequest();
            }

            if (!ModelState.IsValid) return await ValidationError(vm);
            
            // merge VM's changes with DbModel
            var currentModel = _context.GetEntityById<T>(vm.Id);
            if (vm.ToEntity(_context, currentModel) is not T entity) throw new InvalidOperationException($"{typeof(TViewModel).FullName}.ToEntity() somehow produced something other than a {typeof(T).FullName}");
            currentModel.Commit(entity);

            // and commit back
            _context.Set<T>().Update(currentModel);
            await _context.SaveChangesAsync();
            
            SetMessage(
                FormMessageType.Success,
                $"{typeof(T).Name} {GetFriendlyName(vm)} was updated."
            );
            
            return RedirectToAction("Edit",  new { id = entity.Id });
        }
        
        #endregion

        #region Delete

        [HttpGet("Delete")]
        public async Task<IActionResult> Delete(int id)
        {
            var model = _context.GetEntityById<T>(id);

            if (model?.IsOwnedBy(await CurrentUser()) != true) {
                return NotFound();
            }
            
            ViewData["Title"] = $"Delete {GetFriendlyName(model)}";
            TempData["ModelDelete"] = model.Id;
            return View("DeleteConfirm", model);
        }
    
        [HttpPost("Delete")]
        public async Task<IActionResult> PostDelete(int id)
        {
            if ((int?)TempData["ModelDelete"] != id) {
                return BadRequest();
            }

            var model = _context.GetEntityById<T>(id);

            if (model?.IsOwnedBy(await CurrentUser()) != true) {
                return NotFound();
            }

            _context.Set<T>().Remove(model);
            await _context.SaveChangesAsync();
            SetMessage(
                FormMessageType.Success,
                $"{typeof(T).Name} {GetFriendlyName(new TViewModel().FromEntity(model))} was successfully deleted."
            );

            return RedirectToAction("Index");
        }



        #endregion

    }
}