chaosbot/ChaosBot/WebServer/App/ApiControllers/BaseApiController.cs

using System;
using System.Collections.Generic;
using System.Dynamic;
using System.Linq;
using System.Text.Json;
using System.Threading.Tasks;
using ChaosBot.Models;
using ChaosBot.WebServer.Services;
using FlexLabs.EntityFrameworkCore.Upsert;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Microsoft.Net.Http.Headers;
using Newtonsoft.Json;

namespace ChaosBot.WebServer.App.ApiControllers
{
    public abstract class BaseApiController<T, TDeleteParameter> : Controller where T : class, new()
    {
        protected readonly AccessTokenCache AccessTokenCache;
        protected readonly ValidationService ValidationService;

        protected BaseApiController(
            AccessTokenCache accessTokenCache,
            ValidationService validationService
        )
        {
            AccessTokenCache = accessTokenCache;
            ValidationService = validationService;
        }

        public async Task<IActionResult> Index(ulong guildId)
        {
            if (!CheckPermissions.GetResult(AccessTokenCache, Request, guildId, out IActionResult result))
                return result;

            await using ChaosbotContext dbContext = new ChaosbotContext();

            IQueryable<T> query = GetBasicQuery(dbContext);
            List<T> list = ApplyFilterForCurrentGuild(query, guildId).ToList();

            LoggingFacade.Info("Received request");
            List<dynamic> response = list.Select(element =>
            {
                Dictionary<string, object> responseDict = new Dictionary<string, object>();

                foreach (string field in GetIndexFields())
                {
                    responseDict.Add(field, element.GetType().GetProperty(field)?.GetValue(element, null));
                }

                dynamic dynamicResponseElement = new DynamicResponse(responseDict);
                return dynamicResponseElement;
            }).ToList();

            return Content(JsonConvert.SerializeObject(response), new MediaTypeHeaderValue("application/json"));
        }

        public async Task<IActionResult> Upsert(ulong guildId, JsonElement requestBody)
        {
            if (!CheckPermissions.GetResult(AccessTokenCache, Request, guildId, out IActionResult result))
                return result;

            if (!ValidationService.Validate(requestBody, GetValidationRules(), out string errors))
                return BadRequest(errors);
            
            await using ChaosbotContext dbContext = new ChaosbotContext();

            T databaseObject = SetDefaultFieldsForUpsert(new T(), guildId);

            foreach (string key in GetValidationRules().Keys)
            {
                Type type = databaseObject?.GetType()?.GetProperty(key)?.PropertyType;
                if (type == null) continue;

                dynamic value;
                if (type.IsEnum)
                    value = Convert.ChangeType(Enum.ToObject(type, JsonElementHelper.GetValueFromRequest(requestBody, key)), type);
                else
                    value = Convert.ChangeType(JsonElementHelper.GetValueFromRequest(requestBody, key), type);
                
                databaseObject
                    .GetType()
                    .GetProperty(key)
                    ?.SetValue(databaseObject, value);
            }

            await ApplyFilterForUpsert(GetBasicQuery(dbContext).Upsert(databaseObject)).RunAsync();
            await dbContext.SaveChangesAsync();

            return NoContent();
        }

        public async Task<IActionResult> Delete(ulong guildId, TDeleteParameter deleteParameter)
        {
            if (!CheckPermissions.GetResult(AccessTokenCache, Request, guildId, out IActionResult result))
                return result;
            
            await using ChaosbotContext dbContext = new ChaosbotContext();

            List<T> toDelete = FilterQueryMultipleForDeletion(GetBasicQuery(dbContext), guildId, deleteParameter);
            toDelete.Add(FilterQueryForDeletion(GetBasicQuery(dbContext), guildId, deleteParameter));

            if (toDelete.Count == 0)
                return NotFound();

            foreach (T obj in toDelete)
            {
                GetBasicQuery(dbContext).Remove(obj);
            }
            await dbContext.SaveChangesAsync();

            return NoContent();
        }

        protected abstract DbSet<T> GetBasicQuery(ChaosbotContext context);
        protected abstract IQueryable<T> ApplyFilterForCurrentGuild(IQueryable<T> query, ulong guildId);
        protected abstract List<string> GetIndexFields();
        protected abstract Dictionary<string, List<string>> GetValidationRules();
        protected abstract UpsertCommandBuilder<T> ApplyFilterForUpsert(UpsertCommandBuilder<T> builder);
        protected abstract T FilterQueryForDeletion(IQueryable<T> query, ulong guildId, TDeleteParameter deleteParameter);
        protected abstract List<T> FilterQueryMultipleForDeletion(IQueryable<T> query, ulong guildId, TDeleteParameter deleteParameter);
        protected abstract T SetDefaultFieldsForUpsert(T obj, ulong guildId);

        private class DynamicResponse : DynamicObject
        {
            private readonly Dictionary<string, object> _properties;

            public DynamicResponse(Dictionary<string, object> properties)
            {
                _properties = properties;
            }

            public override IEnumerable<string> GetDynamicMemberNames()
            {
                return _properties.Keys;
            }

            public override bool TryGetMember(GetMemberBinder binder, out object result)
            {
                if (_properties.ContainsKey(binder.Name))
                {
                    result = _properties[binder.Name];
                    return true;
                }

                result = null;
                return false;
            }

            public override bool TrySetMember(SetMemberBinder binder, object value)
            {
                if (_properties.ContainsKey(binder.Name))
                {
                    _properties[binder.Name] = value;
                    return true;
                }

                return false;
            }
        }
    }
}