using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using InternshipSystem.Api.Queries;
using InternshipSystem.Api.Security;
using InternshipSystem.Api.Service;
using InternshipSystem.Core;
using InternshipSystem.Repository;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace InternshipSystem.Api.Controllers
{
    [ApiController]
    [Route("document")]
    public class DocumentsController : ControllerBase
    {
        private readonly InternshipDbContext _context;
        private readonly FileValidator _fileValidator;

        public DocumentsController(InternshipDbContext context, FileValidator fileValidator)
        {
            _context = context;
            _fileValidator = fileValidator;
        }

        /// <summary>
        /// Fill out required document, 
        /// </summary>
        /// <param name="documentRequest">Documents Scan and description, and Id of filled document</param>
        /// <response code="200">If change was successfully registered</response>
        /// <response code="400">If the provided query was malformed</response>
        /// <response code="404">Id doesn't match any required document</response>
        /// <response code="401">This action is only available for authorized student registered for current edition</response>
        [HttpPost]
        [ProducesResponseType(StatusCodes.Status200OK)]
        [ProducesResponseType(StatusCodes.Status400BadRequest)]
        [ProducesResponseType(StatusCodes.Status404NotFound)]
        [ProducesResponseType(StatusCodes.Status401Unauthorized)]
        [Authorize(Policy = Policies.RegisteredOnly)]
        public async Task<ActionResult> AddDocumentToInternship(
            [FromBody] DocumentPublishRequest documentRequest,
            [FromServices] User user, 
            CancellationToken cancellationToken)
        {
            var validator = new DocumentPublishRequest.Validator();
            var result = await validator.ValidateAsync(documentRequest, cancellationToken);     

            if (!result.IsValid)
            {
                return BadRequest(result.ToString());
            }

            var edition = await _context.Editions.FirstAsync(e => e.Id == user.EditionId, cancellationToken);

            var internship =
                await _context.Entry(edition)
                    .Collection(e => e.Internships)
                    .Query()
                    .Include(i => i.Documentation)
                    .FirstAsync(i => i.Student.Id == user.PersonNumber, cancellationToken);

            internship.AddNewDocument(documentRequest.Description, documentRequest.Type);
            await _context.SaveChangesAsync(cancellationToken);

            return Ok();
        }

        [HttpPut("{documentId}/scan")]
        [Authorize(Policy = Policies.RegisteredOnly)]
        public async Task<ActionResult> AddDocumentScan(long documentId, IFormFile documentScan, [FromServices] User user, CancellationToken cancellationToken)
        {
            await using var memoryStream = new MemoryStream();
            await documentScan.CopyToAsync(memoryStream, cancellationToken);
            
            if (!_fileValidator.IsValidFile(memoryStream.ToArray()))
            {
                return BadRequest("error.document.scan");
            }
            
            var edition = await _context.Editions.FirstAsync(e => e.Id == user.EditionId, cancellationToken);

            var internship =
                await _context.Entry(edition)
                    .Collection(e => e.Internships)
                    .Query()
                    .Include(i => i.Documentation)
                    .FirstAsync(i => i.Student.Id == user.PersonNumber, cancellationToken);

            var document = internship.Documentation.First(d => d.Id == documentId);

            document.Scan = new DocumentScan { File = memoryStream.ToArray() };
            document.State = DocumentState.Submitted;
            
            await _context.SaveChangesAsync(cancellationToken);
            
            return Ok();
        }
        
        [HttpGet("{documentId}/scan")]
        [Authorize(Policy = Policies.RegisteredOnly)]
        public async Task<ActionResult> GetDocumentScan(long documentId, [FromServices] User user, CancellationToken cancellationToken)
        {
            var edition = await _context.Editions.FirstAsync(e => e.Id == user.EditionId, cancellationToken);

            var internship =
                await _context.Entry(edition)
                    .Collection(e => e.Internships)
                    .Query()
                    .FirstAsync(i => i.Student.Id == user.PersonNumber, cancellationToken);

            var document =
                await _context.Entry(internship)
                    .Collection(i => i.Documentation)
                    .Query()
                    .Include(d => d.Scan)
                    .FirstOrDefaultAsync(d => d.Id == documentId, cancellationToken);

            var stream = new MemoryStream(document.Scan.File);
            
            return File(stream, "application/pdf");
        }
    }
}