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

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

        // GET: api/category
        /// <summary>
        /// Retrieve all Categories in DB.
        /// Result can be filtered using the Params.
        /// </summary>
        /// <param name="title">string value</param>
        /// <param name="projectid">ID of created Project</param>
        /// <param name="color">string value</param>
        /// <returns>JSON list of all matching Categories</returns>
#nullable enable
        [HttpGet]
        public async Task<ActionResult<IEnumerable<ScrumCategory>>> GetCategory([FromQuery]string? title, [FromQuery]int? projectid, [FromQuery] string? color)
        {
            var filtered = _context.Categories.AsQueryable();

            if (title != null)
            {
                filtered = filtered.Where<ScrumCategory>(c => c.Title.Contains(title));
            }
            if (projectid != null)
            {
                filtered = filtered.Where<ScrumCategory>(c => c.ProjectId == projectid);
            }
            if (color != null)
            {
                filtered = filtered.Where<ScrumCategory>(c => c.Color == color);

            }

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

        // GET: api/category/1
        /// <summary>
        /// Retrieve the Category by it's ID.
        /// </summary>
        /// <param name="id">ID of searched Category</param>
        /// <returns>JSON object</returns>
        [HttpGet("{id}")]
        public async Task<ActionResult<ScrumCategory>> GetCategory(int id)
        {
            var category = await _context.Categories.FindAsync(id);

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

            return category;
        }

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

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

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

            return NoContent();
        }

        // POST: api/category
        /// <summary>
        /// Create a new Category.
        /// </summary>
        /// <param name="category">new Category</param>
        /// <returns>the proper status code</returns>
        [HttpPost]
        public async Task<ActionResult<ScrumUserstory>> PostCategory(ScrumCategory category)
        {
            _context.Categories.Add(category);
            await _context.SaveChangesAsync();

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

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

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

            return category;
        }

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