using System.IO;

using SongTidy.Models;
using SongTidy.ViewModels;

namespace SongTidy.Tests;

/// <summary>
/// Contains tests for <see cref="SongEntryViewModel"/>.
/// </summary>
[TestClass]
public sealed class SongEntryViewModelTests {
    #region Preview

    /// <summary>
    /// Verifies the initial fields and target preview.
    /// </summary>
    [TestMethod]
    public void InitializesFieldsAndTargetPreview() {
        SongEntryViewModel entry = CreateEntry();

        Assert.AreEqual("Artist", entry.Artist);
        Assert.AreEqual("Title", entry.Title);
        Assert.AreEqual("Live", entry.Comment);
        Assert.AreEqual(RenameFormat.ArtistFirst, entry.Format);
        Assert.AreEqual("A.mp3", entry.OriginalFileName);
        Assert.AreEqual("Artist - Title (Live).mp3", entry.TargetFileName);
    }

    /// <summary>
    /// Verifies that changing a field immediately updates the target preview.
    /// </summary>
    [TestMethod]
    public void UpdatesTargetPreviewWhenFieldChanges() {
        SongEntryViewModel entry = CreateEntry();

        entry.Artist = "New Artist";

        Assert.AreEqual("New Artist - Title (Live).mp3", entry.TargetFileName);
    }

    /// <summary>
    /// Verifies that changing the format updates the target preview.
    /// </summary>
    [TestMethod]
    public void UpdatesTargetPreviewWhenFormatChanges() {
        SongEntryViewModel entry = CreateEntry();

        entry.Format = RenameFormat.TitleFirst;

        Assert.AreEqual("Title (Live) - Artist.mp3", entry.TargetFileName);
    }

    /// <summary>
    /// Verifies that the original extension is preserved for other file types.
    /// </summary>
    [TestMethod]
    public void PreservesOriginalExtension() {
        SongEntryViewModel entry = new(
            Path.Combine("Music", "A.flac"),
            string.Empty,
            "Title",
            string.Empty,
            RenameFormat.ArtistFirst);

        Assert.AreEqual("Title.flac", entry.TargetFileName);
    }

    #endregion

    #region Dirty notifications

    /// <summary>
    /// Verifies that editing any field raises the edited event.
    /// </summary>
    [TestMethod]
    public void RaisesEditedWhenFieldChanges() {
        SongEntryViewModel entry = CreateEntry();
        int editCount = 0;
        entry.Edited += (_, _) => editCount++;

        entry.Artist = "New Artist";
        entry.Title = "New Title";
        entry.Comment = "New Comment";

        Assert.AreEqual(3, editCount);
    }

    /// <summary>
    /// Verifies that assigning the current value does not raise the edited event.
    /// </summary>
    [TestMethod]
    public void DoesNotRaiseEditedWhenFieldValueIsUnchanged() {
        SongEntryViewModel entry = CreateEntry();
        int editCount = 0;
        entry.Edited += (_, _) => editCount++;

        entry.Artist = entry.Artist;

        Assert.AreEqual(0, editCount);
    }

    /// <summary>
    /// Verifies that changing the format does not itself count as a field edit.
    /// </summary>
    [TestMethod]
    public void ChangingFormatDoesNotRaiseEdited() {
        SongEntryViewModel entry = CreateEntry();
        int editCount = 0;
        entry.Edited += (_, _) => editCount++;

        entry.Format = RenameFormat.TitleFirst;

        Assert.AreEqual(0, editCount);
    }

    #endregion

    #region Swap

    /// <summary>
    /// Verifies that swapping exchanges the artist and title values.
    /// </summary>
    [TestMethod]
    public void SwapsArtistAndTitle() {
        SongEntryViewModel entry = CreateEntry();

        entry.SwapArtistAndTitle();

        Assert.AreEqual("Title", entry.Artist);
        Assert.AreEqual("Artist", entry.Title);
        Assert.AreEqual("Title - Artist (Live).mp3", entry.TargetFileName);
    }

    /// <summary>
    /// Verifies that swapping raises edited notifications for both changed fields.
    /// </summary>
    [TestMethod]
    public void SwapRaisesEditedForBothFields() {
        SongEntryViewModel entry = CreateEntry();
        int editCount = 0;
        entry.Edited += (_, _) => editCount++;

        entry.SwapArtistAndTitle();

        Assert.AreEqual(2, editCount);
    }

    #endregion

    /// <summary>
    /// Creates a standard test entry.
    /// </summary>
    /// <returns>The created entry.</returns>
    private static SongEntryViewModel CreateEntry() {
        return new SongEntryViewModel(
            Path.Combine("Music", "A.mp3"),
            "Artist",
            "Title",
            "Live",
            RenameFormat.ArtistFirst);
    }
}