using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace ScrumTaskboard.Controllers
{
    [Route("[controller]")]
    [ApiController]
    public class TasksController : ControllerBase
    {
        private readonly TaskContext _context;

        public TasksController(TaskContext context)
        {
            _context = context;
        }

        // GET: api/tasks
        [HttpGet]
        public async Task<ActionResult<IEnumerable<ScrumTask>>> GetTasks([FromQuery]string? title, [FromQuery]int? userstoryid, [FromQuery]int? statusid, [FromQuery]int? assignedtoid, [FromQuery]int? projectid, [FromQuery]ScrumPrio? priority)
        {
            var filtered = _context.Tasks.AsQueryable();

            if (title != null)
            {
                filtered = filtered.Where<ScrumTask>(t => t.title.Contains(title));
            }
            if (userstoryid != null)
            {
                filtered = filtered.Where<ScrumTask>(t => t.userstoryid == userstoryid);
            }
            if (statusid != null)
            {
                filtered = filtered.Where<ScrumTask>(t => t.statusid == statusid);
            }
            if (assignedtoid != null)
            {
                filtered = filtered.Where<ScrumTask>(t => t.assignedtoid == assignedtoid);
            }
            if (projectid != null)
            {
                filtered = filtered.Where<ScrumTask>(t => t.projectid == projectid);
            }
            if (priority != null)
            {
                filtered = filtered.Where<ScrumTask>(t => t.priority == priority);
            }


            return await filtered.ToListAsync();
        }

        // GET: api/tasks/5
        [HttpGet("{id}")]
        public async Task<ActionResult<ScrumTask>> GetTask(int id)
        {
            var task = await _context.Tasks.FindAsync(id);

            if (task == null)
            {
                return NotFound();
            }

            return task;
        }

        // PUT: api/tasks/5
        [HttpPut("{id}")]
        public async Task<IActionResult> PutTask(int id, ScrumTask task)
        {
            // Die ID des Tasks darf nicht geändert werden
            if (id != task.id)
            {
                return BadRequest();
            }

            // Speichere den geänderten Task im Context
            _context.Entry(task).State = EntityState.Modified;

            try
            {
                // Übernehme die Änderungen in die Datenbank
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                // Wenn der Task nicht existiert, gib Statuscode 404 zurück
                if (!TaskExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return NoContent();
        }

        // POST: api/tasks
        [HttpPost]
        public async Task<ActionResult<ScrumTask>> PostTask(ScrumTask task)
        {
            _context.Tasks.Add(task);
            await _context.SaveChangesAsync();

            // Der neue Task wurde erstellt und kann über die GetTask Methode abgerufen werden.
            return CreatedAtAction("GetTask", new { id = task.id }, task);
        }

        // DELETE: api/tasks/5
        [HttpDelete("{id}")]
        public async Task<ActionResult<ScrumTask>> DeleteTask(int id)
        {
            var scrumTask = await _context.Tasks.FindAsync(id);
            if (scrumTask == null)
            {
                return NotFound();
            }

            // Entferne den Task aus dem Context
            _context.Tasks.Remove(scrumTask);
            // Speichere die Änderungen in der Datenbank
            await _context.SaveChangesAsync();

            return scrumTask;
        }

        /// <summary>
        /// Prüft, ob ein Task mit der angegebenen ID bereits existiert.
        /// </summary>
        private bool TaskExists(int id)
        {
            return _context.Tasks.Any(e => e.id == id);
        }
    }
}