using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Primitives;

namespace Infrastructure.Configuration
{
    public class EFConfigurationProvider : ConfigurationProvider
    {
        private readonly List<EFConfigurationValue> _configValues;
        private readonly DbContextOptionsBuilder<EFConfigurationContext> _builder;

        public EFConfigurationProvider(Action<DbContextOptionsBuilder> optionsAction, List<EFConfigurationValue> configValues)
        {
            this._configValues = configValues;
            this._builder = new DbContextOptionsBuilder<EFConfigurationContext>();
            if (optionsAction != null)
            {
                optionsAction(_builder);
            }
            ChangeToken.OnChange(
           () => this.GetReloadToken(),
           () =>
            {
                this.Load(true);
                this.OnReload();
            });
        }

        public override void Load()
        {
            this.Load();
        }

        private void Load(bool reload = false)
        {
            using (var dbContext = GetDbContext())
            {
                if (!reload)
                {
                    dbContext.Database.EnsureCreated();
                }
                Data = (dbContext.Values.Any() ? dbContext.Values.ToList() : CreateAndSaveDefaultValues(dbContext)).ToDictionary(o => o.Id, o => o.Value);
            }
        }

        private EFConfigurationContext GetDbContext()
        {
            var dbContext = new EFConfigurationContext(_builder.Options);
            return dbContext;
        }

        private List<EFConfigurationValue> CreateAndSaveDefaultValues(EFConfigurationContext dbContext)
        {
            dbContext.Values.AddRange(_configValues.ToArray());
            dbContext.SaveChanges();
            return _configValues;
        }
    }
}