using SongTidy.Models;

namespace SongTidy.Tests;

/// <summary>
/// Contains tests for <see cref="RenameFormats"/>.
/// </summary>
[TestClass]
public sealed class RenameFormatsTests {
    #region Artist-first format

    /// <summary>
    /// Verifies the artist-first layout when both optional fields are present.
    /// </summary>
    [TestMethod]
    public void GeneratesArtistFirstWithArtistAndComment() {
        AssertStem(RenameFormat.ArtistFirst, "Artist", "Title", "Live", "Artist - Title (Live)");
    }

    /// <summary>
    /// Verifies the artist-first layout when only the artist is present.
    /// </summary>
    [TestMethod]
    public void GeneratesArtistFirstWithArtistOnly() {
        AssertStem(RenameFormat.ArtistFirst, "Artist", "Title", string.Empty, "Artist - Title");
    }

    /// <summary>
    /// Verifies the artist-first layout when only the comment is present.
    /// </summary>
    [TestMethod]
    public void GeneratesArtistFirstWithCommentOnly() {
        AssertStem(RenameFormat.ArtistFirst, string.Empty, "Title", "Live", "Title (Live)");
    }

    /// <summary>
    /// Verifies the artist-first layout when neither optional field is present.
    /// </summary>
    [TestMethod]
    public void GeneratesArtistFirstWithTitleOnly() {
        AssertStem(RenameFormat.ArtistFirst, string.Empty, "Title", string.Empty, "Title");
    }

    #endregion

    #region Title-first format

    /// <summary>
    /// Verifies the title-first layout when both optional fields are present.
    /// </summary>
    [TestMethod]
    public void GeneratesTitleFirstWithArtistAndComment() {
        AssertStem(RenameFormat.TitleFirst, "Artist", "Title", "Live", "Title (Live) - Artist");
    }

    /// <summary>
    /// Verifies the title-first layout when only the artist is present.
    /// </summary>
    [TestMethod]
    public void GeneratesTitleFirstWithArtistOnly() {
        AssertStem(RenameFormat.TitleFirst, "Artist", "Title", string.Empty, "Title - Artist");
    }

    /// <summary>
    /// Verifies the title-first layout when only the comment is present.
    /// </summary>
    [TestMethod]
    public void GeneratesTitleFirstWithCommentOnly() {
        AssertStem(RenameFormat.TitleFirst, string.Empty, "Title", "Live", "Title (Live)");
    }

    /// <summary>
    /// Verifies the title-first layout when neither optional field is present.
    /// </summary>
    [TestMethod]
    public void GeneratesTitleFirstWithTitleOnly() {
        AssertStem(RenameFormat.TitleFirst, string.Empty, "Title", string.Empty, "Title");
    }

    #endregion

    #region Registry

    /// <summary>
    /// Verifies that every enum member has a registered format definition.
    /// </summary>
    [TestMethod]
    public void RegistersEveryFormat() {
        foreach (RenameFormat format in Enum.GetValues<RenameFormat>()) {
            Assert.IsTrue(
                RenameFormats.Definitions.ContainsKey(format),
                $"Missing definition for {format}.");
        }
    }

    /// <summary>
    /// Verifies that an unregistered enum value is rejected.
    /// </summary>
    [TestMethod]
    public void ThrowsForUnregisteredFormat() {
        Assert.Throws<ArgumentOutOfRangeException>(
            () => RenameFormats.GenerateStem((RenameFormat)999, "Artist", "Title", "Live"));
    }

    #endregion

    #region Edge cases

    /// <summary>
    /// Verifies that whitespace-only optional fields are treated as missing.
    /// </summary>
    [TestMethod]
    public void TreatsWhitespaceOnlyOptionalFieldsAsMissing() {
        AssertStem(RenameFormat.ArtistFirst, "   ", "Title", "\t", "Title");
    }

    /// <summary>
    /// Verifies that a null title is rejected.
    /// </summary>
    [TestMethod]
    public void ThrowsForNullTitle() {
        Assert.Throws<ArgumentNullException>(
            () => RenameFormats.GenerateStem(RenameFormat.ArtistFirst, "Artist", null!, "Live"));
    }

    #endregion

    /// <summary>
    /// Generates a file name stem and asserts the result.
    /// </summary>
    /// <param name="format">The format to apply.</param>
    /// <param name="artist">The artist value.</param>
    /// <param name="title">The title value.</param>
    /// <param name="comment">The comment value.</param>
    /// <param name="expected">The expected generated stem.</param>
    private static void AssertStem(
        RenameFormat format,
        string artist,
        string title,
        string comment,
        string expected) {
        string actual = RenameFormats.GenerateStem(format, artist, title, comment);

        Assert.AreEqual(expected, actual, $"Unexpected stem for {format}.");
    }
}