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

namespace ScrumTaskboard.Controllers
{
    /// <summary>
    /// This is a controller of Users class includes all API's related to the Users.
    /// </summary>
    [Route("[controller]")]
    [ApiController]
    public class UsersController : ControllerBase
    {
        private readonly TaskContext _context;

        /// <summary>
        /// Initializes a new instance of the class.
        /// </summary>
        /// <param name="context"></param>
        public UsersController(TaskContext context)
        {
            _context = context;
        }

        // GET: api/sprint
        /// <summary>
        /// Retrieve all Users in DB.
        /// Result can be filtered using the Params.
        /// </summary>
        /// <param name="name">string value</param>
        /// <returns>JSON list of all matching Users</returns>
#nullable enable
        [HttpGet]
        public async Task<ActionResult<IEnumerable<ScrumUser>>> GetUser([FromQuery]string? name)
        {
            var filtered = _context.Users.AsQueryable();
            if (name != null)
            {
                filtered = filtered.Where<ScrumUser>(u => u.Name.Contains(name));
            }

            return await filtered.ToListAsync();
        }
#nullable disable

        // GET: api/sprint/5
        /// <summary>
        /// Retrieve the User by it's ID.
        /// </summary>
        /// <param name="id">ID of searched User</param>
        /// <returns>JSON object</returns>
        [HttpGet("{id}")]
        public async Task<ActionResult<ScrumUser>> GetUser(int id)
        {
            var user = await _context.Users.FindAsync(id);

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

            return user;
        }

        // PUT: api/sprint/5
        /// <summary>
        /// Update the User identified by it's ID.
        /// </summary>
        /// <param name="id">to edit User's ID</param>
        /// <param name="sprint">modified Sprint</param>
        /// <returns>the proper status code</returns>
        [HttpPut("{id}")]
        public async Task<IActionResult> PutUser(int id, ScrumUser sprint)
        {
            // The user's ID must not be changed
            if (id != sprint.Id)
            {
                return BadRequest();
            }

            // Save the changed user in the context
            _context.Entry(sprint).State = EntityState.Modified;

            try
            {
                // Apply the changes to the database
                await _context.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                // If the user does not exist, return status code 404
                if (!UserExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return NoContent();
        }

        // POST: api/User
        /// <summary>
        /// Create a new User.
        /// </summary>
        /// <param name="sprint">new Sprint</param>
        /// <returns>the proper status code</returns>
        [HttpPost]
        public async Task<ActionResult<ScrumUser>> PostUser(ScrumUser sprint)
        {
            _context.Users.Add(sprint);
            await _context.SaveChangesAsync();

            // The new user has been created and can be called up using the GetUser method
            return CreatedAtAction("GetUser", new { id = sprint.Id }, sprint);
        }

        // DELETE: api/User/5
        /// <summary>
        /// Delete a User identified by it's ID.
        /// </summary>
        /// <param name="id">to delete User's ID</param>
        /// <returns>the proper status code</returns>
        [HttpDelete("{id}")]
        public async Task<ActionResult<ScrumUser>> DeleteUser(int id)
        {
            var scrumUser = await _context.Users.FindAsync(id);
            if (scrumUser == null)
            {
                return NotFound();
            }

            // Remove the user from the context
            _context.Users.Remove(scrumUser);
            // Save the changes in the database
            await _context.SaveChangesAsync();

            return scrumUser;
        }

        /// <summary>
        /// Checks whether a user with the specified ID already exists.
        /// </summary>
        private bool UserExists(int id)
        {
            return _context.Users.Any(e => e.Id == id);
        }
    }
}