using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace Elwig.Models.Dtos {
    public class DataTable<T> {

        public string Name { get; set; }
        public string FullName { get; set; }
        public IEnumerable<T> Rows { get; private set; }
        public int RowNum => Rows.Count();
        public IEnumerable<string> ColumnNames => _fieldMap.Select(m => m.Item2);
        public int ColNum => ColumnNames.Count();
        private readonly FieldInfo[] _fields;
        private readonly (FieldInfo, string)[] _fieldMap;

        public DataTable(string name, string fullName, IEnumerable<T> rows, IEnumerable<(string, string)>? colNames = null) {
            _fields = typeof(T).GetFields();
            var dict = colNames?.ToDictionary(n => n.Item1, n => n.Item2);
            _fieldMap = (dict == null ? _fields.Select(f => (f, f.Name)) : _fields.Select(f => (f, dict[f.Name]))).ToArray();
            Name = name;
            FullName = fullName;
            Rows = rows;
        }

        public DataTable(string name, IEnumerable<T> rows, IEnumerable<(string, string)>? colNames = null) :
            this(name, name, rows, colNames) { }

        protected IEnumerable<(string, object?)> GetNamedRowData(T row) {
            return _fieldMap.Select(i => (i.Item2, i.Item1.GetValue(row)));
        }

        protected IEnumerable<object?> GetRowData(T row) {
            return GetNamedRowData(row).Select(i => i.Item2);
        }

        public IEnumerable<IEnumerable<object?>> GetData() {
            return Rows.Select(GetRowData);
        }

        public IEnumerable<IEnumerable<(string, object?)>> GetNamedData() {
            return Rows.Select(GetNamedRowData);
        }
    }
}