using System.Windows;

namespace LiveWall.Sdk;

/// <summary>
/// A visual layer drawn on top of the wallpaper, inside LiveWall's desktop overlay window (the same
/// window that carries the desktop icons). Because that window is per-pixel transparent, only the
/// pixels you paint block the mouse - everything else falls through to the desktop.
/// </summary>
public interface IWallpaperOverlay
{
    /// <summary>Shown in the plugin's UI and the diagnostics report.</summary>
    string Name { get; }

    /// <summary>
    /// Creates the visual. Called once per display, on the UI thread. Keep it cheap and transparent.
    /// The returned element is stretched to the display and is not hit-testable by default.
    /// </summary>
    FrameworkElement CreateView(OverlayContext context);

    /// <summary>Called whenever the wallpaper, playback or interaction state changes.</summary>
    void Update(OverlayState state);

    /// <summary>Called when the user hides the overlay or the plugin is disabled.</summary>
    void OnVisibilityChanged(bool visible) { }
}

/// <summary>Display specific context handed to <see cref="IWallpaperOverlay.CreateView"/>.</summary>
public sealed class OverlayContext
{
    public int DisplayIndex { get; init; }
    public string DeviceName { get; init; } = "";
    public double Width { get; init; }
    public double Height { get; init; }
    public double DpiScale { get; init; } = 1.0;
    public bool Primary { get; init; }
}

/// <summary>State handed to <see cref="IWallpaperOverlay.Update"/>.</summary>
public sealed class OverlayState
{
    public string Kind { get; init; } = "";
    public string Source { get; init; } = "";
    public string Title { get; init; } = "";
    public bool IsPlaying { get; init; }
    public bool IsPaused { get; init; }
    public bool IsInteractive { get; init; }
    public DateTime TimestampUtc { get; init; } = DateTime.UtcNow;
}

/// <summary>A page the plugin adds to the LiveWall settings window (Plugins tab).</summary>
public interface IPluginSettingsPage
{
    string Title { get; }

    /// <summary>One or two sentences for the page header.</summary>
    string Description { get; }

    /// <summary>Builds the page content. Called once, on the UI thread.</summary>
    FrameworkElement CreateView();
}

/// <summary>
/// Rewrites wallpaper requests before the engine applies them: resolve a URL, swap a file, pin a
/// playlist entry, or veto a change by returning the previous request.
/// </summary>
public interface IWallpaperFilter
{
    /// <summary>Higher runs first. 0 is a good default.</summary>
    int Priority { get; }

    /// <summary>Return the request to apply (return the argument unchanged to leave it alone).</summary>
    WallpaperRequest Apply(WallpaperRequest request, IHostActions host);
}

/// <summary>
/// Renders wallpaper sources the built-in players cannot handle. The first renderer whose
/// <see cref="CanRender"/> returns true wins (highest <see cref="Priority"/> first), so a plugin can
/// also take over a source LiveWall would otherwise play itself.
/// </summary>
public interface IWallpaperRendererPlugin
{
    string Name { get; }

    /// <summary>Higher wins over other plugins (built-in renderers are not in this race).</summary>
    int Priority { get; }

    /// <summary>Decides whether this renderer handles the source string.</summary>
    bool CanRender(WallpaperRequest request);

    IWallpaperRenderer Create();
}

/// <summary>The renderer instance. LiveWall owns its lifetime.</summary>
public interface IWallpaperRenderer : IDisposable
{
    /// <summary>The visual shown as the wallpaper. Keep the background opaque.</summary>
    FrameworkElement View { get; }

    /// <summary>Loads the source. Throw to report a problem (it is shown to the user).</summary>
    void Load(WallpaperRequest request);

    void Play();
    void Pause();
    void Unload();

    /// <summary>Volume is 0–100, speed 0.25–4.</summary>
    void ApplyPlayback(bool muted, double volume, double speed);

    /// <summary>Raised when playback fails (message is shown in the status bar and the log).</summary>
    event EventHandler<string>? Failed;

    /// <summary>Raised when a non-looping source finished.</summary>
    event EventHandler? Ended;
}