using CsvHelper.Configuration;
using InABox.Core;
using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Text;

namespace InABox.Poster.CSV
{
    public interface ICSVClassMap
    {
        ClassMap ClassMap { get; }
    }

    public interface ICSVClassMap<T> : ICSVClassMap
    {
        new ClassMap<T> ClassMap { get; }

        ClassMap ICSVClassMap.ClassMap => ClassMap;

        void Map(string name, Expression<Func<T, object>> expr);
    }

    public class CSVClassMap<T> : ClassMap<T>, ICSVClassMap<T>
    {
        public ClassMap<T> ClassMap => this;

        public void Map(string name, Expression<Func<T, object>> expr)
        {
            Map(expr).Name(name);
        }
    }

    public interface ICSVExport
    {
        Type Type { get; }

        ICSVClassMap ClassMap { get; }

        IEnumerable<object> Records { get; }
    }

    public interface ICSVExport<T> : ICSVExport
        where T : class
    {
        new Type Type => typeof(T);
        new CSVClassMap<T> ClassMap { get; }
        new IEnumerable<T> Records { get; }

        Type ICSVExport.Type => Type;
        ICSVClassMap ICSVExport.ClassMap => ClassMap;
        IEnumerable<object> ICSVExport.Records => Records;
    }

    public class CSVExport<T> : ICSVExport<T>
        where T : class
    {
        public CSVClassMap<T> ClassMap { get; } = new CSVClassMap<T>();

        public IEnumerable<T> Records => Items;

        public List<T> Items { get; } = new List<T>();

        public void DefineMapping(List<Tuple<string, Expression<Func<T, object>>>> mappings)
        {
            foreach(var (name, expr) in mappings)
            {
                ClassMap.Map(name, expr);
            }
        }
        public void Map(string name,  Expression<Func<T, object>> expr)
        {
            ClassMap.Map(name, expr);
        }

        public void Add(T item)
        {
            Items.Add(item);
        }
        public void AddRange(IEnumerable<T> items)
        {
            Items.AddRange(items);
        }
    }

    /// <summary>
    /// Defines an interface for posters that can export to CSV.
    /// </summary>
    /// <typeparam name="TEntity"></typeparam>
    public interface ICSVPoster<TEntity> : IPoster<TEntity, CSVPosterSettings<TEntity>>
        where TEntity : Entity, IPostable
    {
        ICSVExport Process(IEnumerable<TEntity> entities);
    }
}