namespace Machines.Player;

/// <summary>
/// Decides when to boost for a bot
/// </summary>
public sealed class BotBoost
{
	/// <summary>
	/// Minimum fuel fraction to attempt a sprint boost
	/// </summary>
	private const float SprintFuelThreshold = 0.3f;

	/// <summary>
	/// Minimum fuel fraction to attempt a ram boost
	/// </summary>
	private const float RamFuelThreshold = 0.2f;

	/// <summary>
	/// Maximum steer magnitude for a sprint boost (must be going roughly straight)
	/// </summary>
	private const float SprintMaxSteer = 0.4f;

	/// <summary>
	/// Maximum distance (units) for a car to be considered rammable
	/// </summary>
	private const float RamDistance = 130f;

	/// <summary>
	/// Cooldown between boost requests; must exceed CarBoost.DashCooldown
	/// </summary>
	private const float BoostInterval = 0.8f;

	private float _nextBoostTime;
	private bool _boostedLastFrame;

	/// <summary>
	/// Decides whether to boost; writes <see cref="CarInputData.Boost"/> and may adjust <see cref="CarInputData.Steer"/> for ram targeting
	/// </summary>
	public void Apply( ref CarInputData data, CarBoost boost, ObstacleScanResult scan, float aggression, bool canSprint )
	{
		if ( data.Drift )
			return;

		if ( !boost.IsValid() || boost.IsLockedOut )
			return;

		// Must release for at least one frame between boosts (rising-edge requirement)
		if ( _boostedLastFrame )
		{
			_boostedLastFrame = false;
			return;
		}

		// Respect cooldown
		if ( Time.Now < _nextBoostTime )
			return;

		// Sprint boost: clear straight, throttling, enough fuel
		if ( canSprint && MathF.Abs( data.Steer ) < SprintMaxSteer && boost.BoostFraction > SprintFuelThreshold )
		{
			FireBoost( ref data );
			return;
		}

		// Ram boost: car nearby, aggression check passes
		if ( scan.HasFrontCar && scan.FrontDistance < RamDistance && boost.BoostFraction > RamFuelThreshold )
		{
			if ( Game.Random.Float() < aggression * 0.02f )
			{
				FireBoost( ref data );
				return;
			}
		}

		// Side ram: if a car is to our side (detected via clearance difference), steer into it + boost
		if ( aggression > 0.5f && boost.BoostFraction > RamFuelThreshold )
		{
			var sideDiff = scan.RightClearance - scan.LeftClearance;
			var closeSide = MathF.Min( scan.LeftClearance, scan.RightClearance );

			if ( closeSide < 80f && MathF.Abs( sideDiff ) > 60f )
			{
				if ( Game.Random.Float() < (aggression - 0.5f) * 0.015f )
				{
					data.Steer = (data.Steer + (sideDiff > 0f ? -0.4f : 0.4f)).Clamp( -1f, 1f );
					FireBoost( ref data );
					return;
				}
			}
		}
	}

	private void FireBoost( ref CarInputData data )
	{
		data.Boost = true;
		_boostedLastFrame = true;
		_nextBoostTime = Time.Now + BoostInterval;
	}
}

/// <summary>
/// Lightweight scan result for <see cref="BotBoost"/>, decoupled from the brain's internal struct
/// </summary>
public struct ObstacleScanResult
{
	public bool HasFrontCar;
	public float FrontDistance;
	public float LeftClearance;
	public float RightClearance;
}