Libation/Source/AudibleUtilities/AudibleApiValidators.cs

using AudibleApi.Common;
using System;
using System.Collections.Generic;
using System.Linq;

namespace AudibleUtilities;

public interface IValidator
{
	IEnumerable<Exception> Validate(IEnumerable<Item> items);

	public static IValidator[] GetAllValidators() => [
		new LibraryValidator(),
		new BookValidator(),
		new CategoryValidator(),
		new SeriesValidator(),
	];
}

/// <summary>
/// To be used when no validation is desired
/// </summary>
public class ClearValidator : IValidator
{
	public IEnumerable<Exception> Validate(IEnumerable<Item> items) => [];
}
public class LibraryValidator : IValidator
{
	public IEnumerable<Exception> Validate(IEnumerable<Item> items)
	{
		var exceptions = new List<Exception>();

		if (items.Any(i => string.IsNullOrWhiteSpace(i.ProductId)))
			exceptions.Add(new ArgumentException($"Collection contains item(s) with null or blank {nameof(Item.ProductId)}", nameof(items)));
		//// unfortunately, an actual user has a title with a beginning-of-time 'purchase_date'
		//if (items.Any(i => i.DateAdded < new DateTime(1980, 1, 1)))
		//	exceptions.Add(new ArgumentException($"Collection contains item(s) with invalid {nameof(Item.DateAdded)}", nameof(items)));

		return exceptions;
	}
}
public class BookValidator : IValidator
{
	public IEnumerable<Exception> Validate(IEnumerable<Item> items)
	{
		var exceptions = new List<Exception>();

		// a book having no authors is rare but allowed

		if (items.Any(i => string.IsNullOrWhiteSpace(i.ProductId)))
			exceptions.Add(new ArgumentException($"Collection contains item(s) with blank {nameof(Item.ProductId)}", nameof(items)));

		// this can happen with podcast episodes
		foreach (var i in items.Where(i => string.IsNullOrWhiteSpace(i.Title)))
			i.Title = "[blank title]";

		return exceptions;
	}
}
public class CategoryValidator : IValidator
{
	public IEnumerable<Exception> Validate(IEnumerable<Item> items)
	{
		var exceptions = new List<Exception>();

		var distinct = items.GetCategoriesDistinct();
		if (distinct.Any(s => s.CategoryId is null))
			exceptions.Add(new ArgumentException($"Collection contains {nameof(Item.Categories)} with null {nameof(Ladder.CategoryId)}", nameof(items)));
		if (distinct.Any(s => s.CategoryName is null))
			exceptions.Add(new ArgumentException($"Collection contains {nameof(Item.Categories)} with null {nameof(Ladder.CategoryName)}", nameof(items)));

		return exceptions;
	}
}
public class SeriesValidator : IValidator
{
	public IEnumerable<Exception> Validate(IEnumerable<Item> items)
	{
		var exceptions = new List<Exception>();

		var distinct = items.GetSeriesDistinct();
		if (distinct.Any(s => s.SeriesId is null))
			exceptions.Add(new ArgumentException($"Collection contains {nameof(Item.Series)} with null {nameof(Series.SeriesId)}", nameof(items)));

		//// unfortunately, an actual user has a series with no name
		//if (distinct.Any(s => s.SeriesName is null))
		//    exceptions.Add(new ArgumentException($"Collection contains {nameof(Item.Series)} with null {nameof(Series.SeriesName)}", nameof(items)));

		return exceptions;
	}
}