using System;
using System.Linq;
using System.Threading.Tasks;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Infrastructure.Extensions;
using LanguageExt;
using Microsoft.EntityFrameworkCore;
using static LanguageExt.Prelude;

namespace ErsatzTV.Infrastructure.Data.Repositories
{
    public class ConfigElementRepository : IConfigElementRepository
    {
        private readonly IDbContextFactory<TvContext> _dbContextFactory;

        public ConfigElementRepository(IDbContextFactory<TvContext> dbContextFactory) =>
            _dbContextFactory = dbContextFactory;

        public async Task<Unit> Upsert<T>(ConfigElementKey configElementKey, T value)
        {
            await using TvContext dbContext = _dbContextFactory.CreateDbContext();

            Option<ConfigElement> maybeElement = await dbContext.ConfigElements
                .SelectOneAsync(c => c.Key, c => c.Key == configElementKey.Key);

            await maybeElement.Match(
                async element =>
                {
                    element.Value = value.ToString();
                    await dbContext.SaveChangesAsync();
                },
                async () =>
                {
                    var configElement = new ConfigElement
                    {
                        Key = configElementKey.Key,
                        Value = value.ToString()
                    };

                    await dbContext.ConfigElements.AddAsync(configElement);
                    await dbContext.SaveChangesAsync();
                });

            return Unit.Default;
        }

        public async Task<Option<ConfigElement>> Get(ConfigElementKey key)
        {
            await using TvContext dbContext = _dbContextFactory.CreateDbContext();
            return await dbContext.ConfigElements
                .OrderBy(ce => ce.Key)
                .SingleOrDefaultAsync(ce => ce.Key == key.Key)
                .Map(Optional);
        }

        public Task<Option<T>> GetValue<T>(ConfigElementKey key) =>
            Get(key).MapT(ce => (T) Convert.ChangeType(ce.Value, typeof(T)));

        public async Task Delete(ConfigElement configElement)
        {
            await using TvContext dbContext = _dbContextFactory.CreateDbContext();
            dbContext.ConfigElements.Remove(configElement);
            await dbContext.SaveChangesAsync();
        }

        public async Task<Unit> Delete(ConfigElementKey configElementKey)
        {
            await using TvContext dbContext = _dbContextFactory.CreateDbContext();
            Option<ConfigElement> maybeExisting = await dbContext.ConfigElements
                .SelectOneAsync(ce => ce.Key, ce => ce.Key == configElementKey.Key);
            foreach (ConfigElement element in maybeExisting)
            {
                dbContext.ConfigElements.Remove(element);
            }

            await dbContext.SaveChangesAsync();

            return Unit.Default;
        }
    }
}