using System.Collections.Immutable;
using System.Text.Json;

namespace Yuanshen.Common.Data.Excel;

public sealed class ExcelTable
{
    private readonly ImmutableArray<ExcelItem> _items;
    private readonly ImmutableDictionary<uint, ExcelItem> _itemsById;

    public ExcelTable(JsonDocument document, Type type)
    {
        ImmutableArray<ExcelItem>.Builder items = ImmutableArray.CreateBuilder<ExcelItem>();

        foreach (JsonElement element in document.RootElement.EnumerateArray())
        {
            if (element.ValueKind != JsonValueKind.Object)
                throw new ArgumentException("Excel table root must be an array of objects");

            items.Add((element.Deserialize(type) as ExcelItem)!);
        }

        _items = items.ToImmutable();
        _itemsById = _items.ToImmutableDictionary(item => item.ExcelId);
    }

    public IReadOnlyList<ExcelItem> Items => _items;

    public TExcel? GetById<TExcel>(uint id) where TExcel : ExcelItem
        => _itemsById.TryGetValue(id, out ExcelItem? item) ? item as TExcel : null;
}