luticate2-api/Luticate2.Auth/Business/FieldsExpressions/LuFieldsExpressions.cs

using System;
using System.Linq.Expressions;
using Luticate2.Auth.Business.Fields;
using Luticate2.Auth.Dbo;
using Luticate2.Auth.Dbo.Fields;
using Luticate2.Auth.Dbo.Result;
using Luticate2.Auth.Interfaces;
using Microsoft.Extensions.DependencyInjection;

namespace Luticate2.Auth.Business.FieldsExpressions
{
    public class LuFieldsExpressions<TDbo, TModel> : ILuFieldsExpressions<TDbo, TModel>
    {
        protected IServiceProvider ServiceProvider { get; }

        public LuFieldsExpressions(IServiceProvider serviceProvider)
        {
            ServiceProvider = serviceProvider;
        }
        
        public ILuFieldsExpressions<TDbo2, TModel2> GetService<TDbo2, TModel2>()
        {
            var service = ServiceProvider.GetService<ILuFieldsExpressions<TDbo2, TModel2>>();
            return service;
        }

        protected LuResult<Expression<Func<TType1, object>>> GetSubField<TType1, TType2, TType3>(
            Expression<Func<TType1, TModel>> modelProperty, LuFieldDbo field, Expression<Func<TModel, TType3>> modelSubProperty)
        {
            var subPropExprResult = LuExpressionUtils.GetSingleMemberFromExpression(modelSubProperty);
            if (subPropExprResult == null)
            {
                return LuResult<Expression<Func<TType1, object>>>.Error(LuStatus.InternalError.ToInt(), "Bad field expression");
            }

            var prop = Expression.Property(modelProperty.Body, subPropExprResult.Name);
            var exp = Expression.Lambda<Func<TType1, TType3>>(prop, modelProperty.Parameters[0]);
            var service = GetService<TType2, TType3>();
            var finalExpResult = service.GetExpression(exp, field.Popped());
            return finalExpResult;
        }

        protected virtual LuResult<Expression<Func<TType1, object>>> GetExpressionInternal<TType1>(
            Expression<Func<TType1, TModel>> modelProperty, LuFieldDbo field)
        {
            return LuResult<Expression<Func<TType1, object>>>.Error(LuStatus.InputError.ToInt(), $"Unknown field: {field}", "");
        }

        public virtual LuResult<Expression<Func<TType1, object>>> GetExpression<TType1>(Expression<Func<TType1, TModel>> modelProperty, LuFieldDbo field)
        {
            if (field.IsRoot())
            {
                var converted = Expression.Convert(modelProperty.Body, typeof(object));
                var exp = Expression.Lambda<Func<TType1, object>>(converted, modelProperty.Parameters[0]);
                return LuResult<Expression<Func<TType1, object>>>.Ok(exp);
            }
            return GetExpressionInternal(modelProperty, field);
        }
    }
}