ttui/test/TinyTUI.Tests/Autocomplete/AutocompleteProviderTests.cs

using TinyTUI.Autocomplete;

namespace TinyTUI.Tests.Autocomplete;

public sealed class AutocompleteProviderTests : IDisposable
{
    private readonly string _basePath = Path.Combine(Path.GetTempPath(), "ttui-autocomplete-" + Guid.NewGuid().ToString("N"));

    public AutocompleteProviderTests()
    {
        Directory.CreateDirectory(_basePath);
    }

    [Fact]
    public async Task FilePathProviderExtractsForcedPathPrefixes()
    {
        WriteFile("alpha.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);

        var dotSlash = await GetSuggestions(provider, "./a", force: true);
        var parent = await GetSuggestions(provider, "../", force: true);
        var slash = await GetSuggestions(provider, "/", force: true);

        Assert.Equal("./a", dotSlash?.Prefix);
        Assert.Equal("../", parent?.Prefix);
        Assert.Equal("/", slash?.Prefix);
    }

    [Fact]
    public async Task FilePathProviderReturnsDirectoriesFirstThenFiles()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "src"));
        WriteFile("src.txt");
        WriteFile("alpha.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);

        var result = await GetSuggestions(provider, "s", force: true);
        Assert.NotNull(result);
        var values = result.Items.Select(static item => item.Value).ToArray();

        Assert.Equal(["src/", "src.txt"], values);
        Assert.Equal("src/", result.Items[0].Label);
    }

    [Fact]
    public async Task FilePathProviderPreservesPathPrefixForNestedCompletion()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "src"));
        WriteFile("src/index.cs");
        WriteFile("src/input.cs");
        var provider = new FilePathAutocompleteProvider(_basePath);

        var result = await GetSuggestions(provider, "./src/i", force: true);
        Assert.NotNull(result);
        var values = result.Items.Select(static item => item.Value).ToArray();

        Assert.Equal("./src/i", result.Prefix);
        Assert.Equal(["./src/index.cs", "./src/input.cs"], values);
    }

    [Fact]
    public async Task FilePathProviderCompletesAttachmentPrefix()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "src"));
        WriteFile("src.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);

        var result = await GetSuggestions(provider, "@src");
        Assert.NotNull(result);
        var values = result.Items.Select(static item => item.Value).ToArray();

        Assert.Equal("@src", result.Prefix);
        Assert.Equal(["@src/", "@src.txt"], values);
    }

    [Fact]
    public async Task FilePathProviderQuotesPathsWithSpaces()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "my folder"));
        WriteFile("my folder/test.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);

        var regular = await GetSuggestions(provider, "my", force: true);
        var attachment = await GetSuggestions(provider, "@my");

        Assert.Contains("\"my folder/\"", regular?.Items.Select(static item => item.Value) ?? []);
        Assert.Contains("@\"my folder/\"", attachment?.Items.Select(static item => item.Value) ?? []);
    }

    [Fact]
    public async Task FilePathProviderContinuesInsideQuotedAttachmentPath()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "my folder"));
        WriteFile("my folder/other.txt");
        WriteFile("my folder/test.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);
        const string line = "@\"my folder/\"";

        var result = await GetSuggestions(provider, line, cursorColumn: line.Length - 1);
        Assert.NotNull(result);
        var values = result.Items.Select(static item => item.Value).ToArray();

        Assert.Equal("@\"my folder/", result.Prefix);
        Assert.Equal(["@\"my folder/other.txt\"", "@\"my folder/test.txt\""], values);
    }

    [Fact]
    public async Task FilePathProviderAppliesDirectoryAndFileCompletions()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "src"));
        WriteFile("src.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);
        var result = await GetSuggestions(provider, "@src");

        var directory = provider.ApplyCompletion(new AutocompleteApplyContext(["see @src"], 0, "see @src".Length, result!.Items[0], result.Prefix));
        var file = provider.ApplyCompletion(new AutocompleteApplyContext(["see @src"], 0, "see @src".Length, result.Items[1], result.Prefix));

        Assert.Equal("see @src/", directory.Lines[0]);
        Assert.Equal("see @src.txt ", file.Lines[0]);
        Assert.Equal("see @src/".Length, directory.CursorColumn);
        Assert.Equal("see @src.txt ".Length, file.CursorColumn);
    }

    [Fact]
    public async Task FilePathProviderAppliesQuotedCompletionWithoutDuplicatingClosingQuote()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "my folder"));
        WriteFile("my folder/test.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);
        const string line = "@\"my folder/te\"";
        var result = await GetSuggestions(provider, line, cursorColumn: line.Length - 1);
        var item = Assert.Single(result!.Items);

        var applied = provider.ApplyCompletion(new AutocompleteApplyContext([line], 0, line.Length - 1, item, result.Prefix));

        Assert.Equal("@\"my folder/test.txt\" ", applied.Lines[0]);
        Assert.Equal("@\"my folder/test.txt\" ".Length, applied.CursorColumn);
    }

    [Fact]
    public async Task FilePathProviderAppliesRegularQuotedCompletionWithoutDuplicatingClosingQuote()
    {
        Directory.CreateDirectory(Path.Combine(_basePath, "my folder"));
        WriteFile("my folder/test.txt");
        var provider = new FilePathAutocompleteProvider(_basePath);
        const string line = "\"my folder/te\"";
        var result = await GetSuggestions(provider, line, force: true, cursorColumn: line.Length - 1);
        var item = Assert.Single(result!.Items);

        var applied = provider.ApplyCompletion(new AutocompleteApplyContext([line], 0, line.Length - 1, item, result.Prefix));

        Assert.Equal("\"my folder/test.txt\" ", applied.Lines[0]);
        Assert.Equal("\"my folder/test.txt\" ".Length, applied.CursorColumn);
    }

    [Fact]
    public async Task CompositeProviderUsesFirstProviderWithSuggestions()
    {
        WriteFile("src.txt");
        var provider = new CompositeAutocompleteProvider(
        [
            new SlashCommandAutocompleteProvider([new SlashCommand("help")]),
            new FilePathAutocompleteProvider(_basePath),
        ]);

        var command = await GetSuggestions(provider, "/h");
        var path = await GetSuggestions(provider, "src", force: true);

        Assert.Equal("/h", command?.Prefix);
        Assert.Equal("help", command?.Items.Single().Value);
        Assert.Equal("src", path?.Prefix);
        Assert.Equal("src.txt", path?.Items.Single().Value);
    }

    [Fact]
    public async Task SlashCommandProviderReturnsArgumentCompletions()
    {
        var provider = new SlashCommandAutocompleteProvider(
        [
            new SlashCommand(
                "model",
                ArgumentCompletionProvider: (prefix, _) => ValueTask.FromResult<IReadOnlyList<AutocompleteItem>?>(
                    [new AutocompleteItem("gpt-5", "gpt-5", $"prefix:{prefix}")]))
        ]);

        var result = await GetSuggestions(provider, "/model gp");

        Assert.NotNull(result);
        var item = Assert.Single(result.Items);
        Assert.Equal("gp", result.Prefix);
        Assert.Equal("gpt-5", item.Value);
        Assert.Equal("prefix:gp", item.Description);
    }

    [Fact]
    public async Task SlashCommandProviderAppliesArgumentCompletionWithoutRewritingCommandName()
    {
        var provider = new SlashCommandAutocompleteProvider(
        [
            new SlashCommand(
                "model",
                ArgumentCompletionProvider: static (_, _) => ValueTask.FromResult<IReadOnlyList<AutocompleteItem>?>(
                    [AutocompleteItem.FromText("gpt-5")]))
        ]);
        const string line = "/model gp";
        var result = await GetSuggestions(provider, line);
        var item = Assert.Single(result!.Items);

        var applied = provider.ApplyCompletion(new AutocompleteApplyContext([line], 0, line.Length, item, result.Prefix));

        Assert.Equal("/model gpt-5", applied.Lines[0]);
        Assert.Equal("/model gpt-5".Length, applied.CursorColumn);
    }

    [Fact]
    public async Task SlashCommandProviderDoesNotRewriteCommandNameWhenArgumentPrefixIsEmpty()
    {
        var provider = new SlashCommandAutocompleteProvider(
        [
            new SlashCommand(
                "model",
                ArgumentCompletionProvider: static (_, _) => ValueTask.FromResult<IReadOnlyList<AutocompleteItem>?>(
                    [AutocompleteItem.FromText("gpt-5")]))
        ]);
        const string line = "/model ";
        var result = await GetSuggestions(provider, line);
        var item = Assert.Single(result!.Items);

        var applied = provider.ApplyCompletion(new AutocompleteApplyContext([line], 0, line.Length, item, result.Prefix));

        Assert.Equal("/model gpt-5", applied.Lines[0]);
        Assert.Equal("/model gpt-5".Length, applied.CursorColumn);
    }

    [Fact]
    public async Task SlashCommandProviderReturnsNoArgumentSuggestionsWithoutCallback()
    {
        var provider = new SlashCommandAutocompleteProvider([new SlashCommand("model")]);

        var result = await GetSuggestions(provider, "/model gp");

        Assert.Null(result);
    }

    [Fact]
    public async Task SlashCommandProviderKeepsCommandNameCompletion()
    {
        var provider = new SlashCommandAutocompleteProvider(
        [
            new SlashCommand("help", "show help"),
            new SlashCommand("history", "show history"),
        ]);

        var result = await GetSuggestions(provider, "/h");

        Assert.NotNull(result);
        Assert.Equal("/h", result.Prefix);
        Assert.Equal(["help", "history"], result.Items.Select(static item => item.Value).ToArray());
    }

    public void Dispose()
    {
        if (Directory.Exists(_basePath))
            Directory.Delete(_basePath, true);
    }

    private async Task<AutocompleteSuggestions?> GetSuggestions(
        IAutocompleteProvider provider,
        string line,
        bool force = false,
        int? cursorColumn = null)
        => await provider.GetSuggestionsAsync(new AutocompleteRequest([line], 0, cursorColumn ?? line.Length, force));

    private void WriteFile(string relativePath)
    {
        var path = Path.Combine(_basePath, relativePath.Replace('/', Path.DirectorySeparatorChar));
        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
        File.WriteAllText(path, string.Empty);
    }
}