// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.Extensions.AI;
using Xunit;
 
namespace Microsoft.Extensions.DataIngestion.Processors.Tests;
 
public class AlternativeTextEnricherTests
{
    [Fact]
    public void ThrowsOnNullChatClient()
    {
        Assert.Throws<ArgumentNullException>("chatClient", () => new ImageAlternativeTextEnricher(null!));
    }
 
    [Fact]
    public async Task ThrowsOnNullDocument()
    {
        using TestChatClient chatClient = new();
 
        ImageAlternativeTextEnricher sut = new(chatClient);
 
        await Assert.ThrowsAsync<ArgumentNullException>("document", async () => await sut.ProcessAsync(null!));
    }
 
    [Fact]
    public async Task CanGenerateImageAltText()
    {
        const string PreExistingAltText = "Pre-existing alt text";
        ReadOnlyMemory<byte> imageContent = new byte[256];
 
        int counter = 0;
        string[] descriptions = { "First alt text", "Second alt text" };
        using TestChatClient chatClient = new()
        {
            GetResponseAsyncCallback = (messages, options, cancellationToken) =>
            {
                var materializedMessages = messages.ToArray();
 
                Assert.Equal(2, materializedMessages.Length);
                Assert.Equal(ChatRole.System, materializedMessages[0].Role);
                Assert.Equal(ChatRole.User, materializedMessages[1].Role);
                var content = Assert.Single(materializedMessages[1].Contents);
                DataContent dataContent = Assert.IsType<DataContent>(content);
                Assert.Equal("image/png", dataContent.MediaType);
                Assert.Equal(imageContent.ToArray(), dataContent.Data.ToArray());
 
                return Task.FromResult(new ChatResponse(new[]
                {
                    new ChatMessage(ChatRole.Assistant, descriptions[counter++])
                }));
            }
        };
        ImageAlternativeTextEnricher sut = new(chatClient);
 
        IngestionDocumentImage documentImage = new($"![](nonExisting.png)")
        {
            AlternativeText = null,
            Content = imageContent,
            MediaType = "image/png"
        };
 
        IngestionDocumentImage tableCell = new($"![](another.png)")
        {
            AlternativeText = null,
            Content = imageContent,
            MediaType = "image/png"
        };
 
        IngestionDocumentImage imageWithAltText = new($"![](noChangesNeeded.png)")
        {
            AlternativeText = PreExistingAltText,
            Content = imageContent,
            MediaType = "image/png"
        };
 
        IngestionDocumentImage imageWithNoContent = new($"![](noImage.png)")
        {
            AlternativeText = null,
            Content = default,
            MediaType = "image/png"
        };
 
        IngestionDocument document = new("withImage")
        {
            Sections =
            {
                new IngestionDocumentSection
                {
                    Elements =
                    {
                        documentImage,
                        new IngestionDocumentTable("nvm", new[,] { { tableCell } })
                    }
                }
            }
        };
 
        await sut.ProcessAsync(document);
 
        Assert.Equal(descriptions[0], documentImage.AlternativeText);
        Assert.Equal(descriptions[1], tableCell.AlternativeText);
        Assert.Same(PreExistingAltText, imageWithAltText.AlternativeText);
        Assert.Null(imageWithNoContent.AlternativeText);
    }
}