using System;
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 Userstories class includes all API's related to the Userstories.
    /// </summary>
    [Route("[controller]")]
    [ApiController]
    public class UserstoriesController : ControllerBase
    {
        private readonly TaskContext _context;

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

        // GET: api/userstories
        /// <summary>
        /// Retrieve all Userstories in DB.
        /// Result can be filtered using the Params.
        /// </summary>
        /// <param name="title">string value</param>
        /// <param name="statusid">ID of created Status</param>
        /// <param name="categoryid">ID of created Category</param>
        /// <param name="createdbyid">ID of the Author</param>
        /// <param name="projectid">ID of created Project</param>
        /// <param name="sprintid">ID of created Project</param>
        /// <param name="priority">enum value</param>
        /// <returns>JSON list of all matching Userstories</returns>
#nullable enable
        [HttpGet]
        public async Task<ActionResult<IEnumerable<ScrumUserstory>>> GetUserstory([FromQuery]string? title, [FromQuery]int? statusid, [FromQuery]int? categoryid, [FromQuery]int? createdbyid, [FromQuery]int? projectid, [FromQuery]int? sprintid, [FromQuery]ScrumPrio? priority)
        {
            var filtered = _context.Userstories.AsQueryable();

            if (title != null)
            {
                filtered = filtered.Where<ScrumUserstory>(t => t.Title.Contains(title));
            }
            if (statusid != null)
            {
                filtered = filtered.Where<ScrumUserstory>(t => t.StatusId == statusid);
            }
            if (categoryid != null)
            {
                filtered = filtered.Where<ScrumUserstory>(t => t.CategoryId == categoryid);
            }
            if (createdbyid != null)
            {
                filtered = filtered.Where<ScrumUserstory>(t => t.CreatedById == createdbyid);
            }
            if (projectid != null)
            {
                filtered = filtered.Where<ScrumUserstory>(t => t.ProjectId == projectid);
            }
            if (sprintid != null)
            {
                filtered = filtered.Where<ScrumUserstory>(t => t.SprintId == sprintid);
            }
            if (priority != null)
            {
                filtered = filtered.Where<ScrumUserstory>(t => t.Priority == priority);
            }


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

        // GET: api/userstories/1
        /// <summary>
        /// Retrieve the Userstory by it's ID.
        /// </summary>
        /// <param name="id">ID of searched Userstory</param>
        /// <returns>JSON object</returns>
        [HttpGet("{id}")]
        public async Task<ActionResult<ScrumUserstory>> GetUserstory(int id)
        {
            var userstory = await _context.Userstories.FindAsync(id);

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

            return userstory;
        }

        // PUT: api/userstories/1
        /// <summary>
        /// Update the Userstory identified by it's ID.
        /// </summary>
        /// <param name="id">to edit Userstory's ID</param>
        /// <param name="userstory">modified Userstory</param>
        /// <returns>the proper status code</returns>
        [HttpPut("{id}")]
        public async Task<IActionResult> PutUserstory(int id, ScrumUserstory userstory)
        {
            // The userstory's ID must not be changed
            if (id != userstory.Id)
            {
                return BadRequest();
            }

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

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

            return NoContent();
        }

        // POST: api/userstories
        /// <summary>
        /// Create a new Userstory.
        /// </summary>
        /// <param name="userstory">new Userstory</param>
        /// <returns>the proper status code</returns>
        [HttpPost]
        public async Task<ActionResult<ScrumUserstory>> PostTask(ScrumUserstory userstory)
        {
            _context.Userstories.Add(userstory);
            await _context.SaveChangesAsync();

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

        // DELETE: api/userstories/1
        /// <summary>
        /// Delete a Userstory identified by it's ID.
        /// </summary>
        /// <param name="id">to delete Userstory's ID</param>
        /// <returns>the proper status code</returns>
        [HttpDelete("{id}")]
        public async Task<ActionResult<ScrumUserstory>> DeleteUserstory(int id)
        {
            var userstory = await _context.Userstories.FindAsync(id);
            if (userstory == null)
            {
                return NotFound();
            }

            // Remove the userstory from the context
            _context.Userstories.Remove(userstory);
            // Save the changes in the database
            await _context.SaveChangesAsync();

            return userstory;
        }

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