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

using YTManager;
using YTManager.Models;

namespace YTManager.Controllers {
    [Produces("application/json")]
    [Route("api/Channels")]
    public class ChannelsController : Controller {
        // DB context used for all these calls.
        private readonly MediaDB db;

        // Constructor to fetch the db context.
        public ChannelsController(MediaDB context) => db = context;

        // GET api/Channels
        [HttpGet]
        public async Task<IActionResult> Get() {
            return Ok(await db.Channels.OrderByDescending(c => c.AddedtoDB).ToListAsync());
        }

        // GET api/Channels/5
        [HttpGet("{YTchannelID}")]
        public async Task<IActionResult> Get([FromQuery] string YTchannelID) {
            var channel = await db.Channels.SingleOrDefaultAsync(c => c.YoutubeID == YTchannelID);
            if (channel == null)
                return NotFound();
            else
                return Ok(channel);
        }

        // GET: api/Channels/sdfs6DFS65f/Videos (using YouTube channel ID)
        [HttpGet("{YTChannelID}/Videos")]
        public async Task<IActionResult> GetVideos([FromRoute] string YTchannelID) {
            if (!ModelState.IsValid)
                return BadRequest(ModelState);

            // Attempt to get the video from the database.
            var channel = await db.Channels.SingleOrDefaultAsync(m => m.YoutubeID == YTchannelID);

            // If the channel wasn't found then send back not found.
            if (channel == null)
                return NotFound();

            // Send back the videos from the channel.
            return Ok(db.Entry(channel).Collection(c => c.Videos).LoadAsync());
        }

        // POST api/Channels/sdfs6DFS65f
        [HttpPost("{YTchannelID}")]
        public async Task<IActionResult> Post([FromRoute] string YTchannelID) {
            // Check if we were able to parse.
            if (!ModelState.IsValid) return BadRequest(ModelState);

            // Verify the channel doesn't already exist.
            if (db.Channels.Any(c => c.YoutubeID == YTchannelID))
                return BadRequest();

            // Get the channel info.
            var ch = await Tasks.FetchVideos.Get_YTChannel(YTchannelID);

            // Seems good, so add it.
            db.Channels.Add(ch);
            await db.SaveChangesAsync();

            // And all is well.
            return Ok();
        }

        // DELETE api/Channels/5
        [HttpDelete("{YTChannelID}")]
        public async Task<IActionResult> Delete([FromRoute] string YTChannelID) {
            // Check if we were able to parse.
            if (!ModelState.IsValid) return BadRequest(ModelState);

            // Attempt to find the channel.
            var channel = await db.Channels.Include(c => c.Videos).SingleOrDefaultAsync(c => c.YoutubeID == YTChannelID);

            // Check if such an entry exists already.
            if (channel == null)
                return NotFound();

            // Remove all the channels videos.
            channel.Videos.ForEach(v => db.Videos.Remove(v));

            // Remove the channel itself.
            db.Channels.Remove(channel);

            // Save all the changes.
            await db.SaveChangesAsync();
            return Ok(channel);
        }
    }
}