using Sandbox;

namespace NZombies;

/// <summary>
/// When Elemental Pop's discharge fired, for <c>CherryShockHud</c> to play.
///
/// ⛔ A STATE CLASS RATHER THAN A CALL INTO THE PANEL, matching `PowerupBannerState`
/// and `HudState`. Two reasons, and the second is the one that matters:
///   • a generated razor class is not reachable from gameplay code without adding a
///     namespace to it, and nothing else in this project does that;
///   • the panel is CLIENT-SIDE and may not exist when the perk fires — mid-load, in
///     the lobby, on a spectator. A call into a panel that is not there is a crash or
///     a silent no-op depending on the day; a timestamp nothing reads simply expires.
///
/// ⚠️ STATICS SURVIVE A HOTLOAD (INSTRUCTIONS.md §1), so `FiredAt` seeds to a large
/// negative rather than 0 — at 0 the overlay would consider itself mid-burst for the
/// first frames of every session, because `Time.Now` also starts near zero.
/// </summary>
public static class CherryShockState
{
	/// <summary>
	/// Playback length, and it MUST equal the renderer's `duration`.
	///
	/// ⚠️ A const, not a tunable. The length is baked into the frames — driving
	/// playback from a knob would stretch or truncate a fixed sequence, which reads as
	/// the animation stuttering rather than as a shorter effect. Changing it means
	/// re-running `Tools/render_cherry_shock.py`.
	/// </summary>
	public const float Duration = 0.70f;

	/// <summary>Frames the bake produced. Must match the files in ui/nz/cherry.</summary>
	public const int FrameCount = 21;

	/// <summary>
	/// Screen shake in pixels at full strength.
	///
	/// ⚠️ APPLIED TO THE PANEL, NOT BAKED INTO THE FRAMES. Baking it would slide the
	/// overlay against a still world, which reads as the image slipping rather than as
	/// the player being hit. Shaking the panel is the cheap approximation; the honest
	/// version is a camera shake, which this project does not have yet.
	/// </summary>
	public static float Shake { get; set; } = 3.5f;

	/// <summary>Master switch — `nz_perk_pop_hud 0`.</summary>
	public static bool ShowOverlay { get; set; } = true;

	/// <summary>When the current burst started, or long ago if none.</summary>
	public static float FiredAt { get; private set; } = -999f;

	/// <summary>Trigger the overlay. Called from PerkEffects.ElementalPop.</summary>
	public static void Fire() => FiredAt = Time.Now;

	/// <summary>
	/// Cancel a pending burst.
	///
	/// ⚠️ NOT called `Reset`. `Component` has one, and although this class is not a
	/// component the name has already caused that exact collision twice in this project
	/// (`DamageOverlay.Enabled`, `PackAPunch.Reset`).
	/// </summary>
	public static void ClearPending() => FiredAt = -999f;

	/// <summary>How far through the sequence, or -1 when idle.</summary>
	public static float Progress
	{
		get
		{
			var since = Time.Now - FiredAt;
			return since < 0f || since > Duration ? -1f : since / Duration;
		}
	}

	/// <summary>
	/// `nz_perk_pop_hud [0/1] [shake]` — toggle the overlay, set the shake, and fire
	/// one so it can be looked at without needing a zombie or a reload.
	/// </summary>
	[ConCmd( "nz_perk_pop_hud" )]
	public static void HudCmd( int on = -1, float shake = -1f )
	{
		if ( on >= 0 ) ShowOverlay = on != 0;
		if ( shake >= 0f ) Shake = shake;

		Fire();
		Log.Info( $"[nz-perk] pop hud: {(ShowOverlay ? "on" : "off")}"
			+ $", shake {Shake:0.#}px, {FrameCount} frames over {Duration:0.##}s — fired one" );
	}
}