Arena/Assets/_Content/Scripts/Combat/ProjectileLauncher.cs

using System;
using UnityEngine;

namespace Arena.Combat
{
    /// <summary>
    /// Weapon that fires projectiles from a muzzle, limited by the fire interval and the ammo count.
    /// Held by a Handle (usually a hand): snaps to it when enabled, then follows the orientation of the Owner
    /// while the Owner is active, otherwise the orientation of the Handle. Can be dropped with physics.
    /// The projectiles ignore the shooter and all its children.
    /// </summary>
    public class ProjectileLauncher : MonoBehaviour
    {
        [System.Serializable]
        public class Settings
        {
            [Tooltip("Weapon data: damage, fire interval, ammo, projectile.")]
            public WeaponData Weapon;

            [Tooltip("Team hurt by the projectiles: Enemy for the player, Allied for an enemy, All for everyone.")]
            public Team Target = Team.All;
        }

        [System.Serializable]
        public struct References
        {
            [Tooltip("Spawn point of the projectiles. Its forward axis gives the direction.")]
            public Transform Muzzle;

            [Tooltip("Shooter: the projectiles never hit it nor its children, and the weapon follows its orientation while it is active. Empty: the GameObject of this launcher.")]
            public GameObject Owner;

            [Tooltip("Transform that holds the weapon, usually a hand. The weapon takes its position and orientation when enabled.")]
            public Transform Handle;

            [Tooltip("Rigidbody of the weapon, kinematic while held. Drop makes it fall.")]
            public Rigidbody Body;
        }

        [System.Serializable]
        public class StateContainer
        {
            public int Ammo;

            [Tooltip("True while an action blocks the shots: running, dash, stun... Set by the owner.")]
            public bool Disabled;

            public bool IsDropped;
        }

        #region FIELDS

        [SerializeField] private Settings _settings;
        [SerializeField] private References _references;
        [SerializeField] private StateContainer _state;

        /// <summary>
        /// Raised with the current and max ammo each time the ammo changes.
        /// </summary>
        public event Action<int, int> OnAmmoChange;

        public StateContainer State => _state;
        public Transform Muzzle => _references.Muzzle;
        public int MaxAmmo => _settings.Weapon.MaxAmmo;

        private float _nextFireTime;

        #endregion

        #region UNITY LIFECYCLES

        private void Awake()
        {
            _state.Ammo = MaxAmmo;
        }

        void OnEnable()
        {
            Transform handle = _references.Handle;

            if (handle && !_state.IsDropped)
                transform.SetPositionAndRotation(handle.position, handle.rotation);
        }

        void LateUpdate()
        {
            // LateUpdate: after the animation has moved the hand
            if (_state.IsDropped)
                return;

            GameObject owner = _references.Owner;

            if (owner && owner.activeInHierarchy)
                transform.rotation = owner.transform.rotation;
            else if (_references.Handle)
                transform.rotation = _references.Handle.rotation;
        }

        #endregion

        #region PUBLIC METHODS

        /// <summary>
        /// Fires one projectile if the weapon is ready and has ammo. Returns true if a shot was fired.
        /// </summary>
        public bool TryFire()
        {
            if (_state.Disabled || _state.IsDropped || Time.time < _nextFireTime || _state.Ammo <= 0)
                return false;

            _nextFireTime = Time.time + _settings.Weapon.FireInterval;

            SetAmmo(_state.Ammo - 1);

            Transform muzzle = _references.Muzzle;
            Projectile projectile = Instantiate(_settings.Weapon.ProjectilePrefab, muzzle.position, muzzle.rotation);
            GameObject owner = _references.Owner ? _references.Owner : gameObject;
            projectile.Launch(new DamageInfo(_settings.Weapon.Damage, _settings.Weapon.DamageType, owner, _settings.Target));
            return true;
        }

        /// <summary>
        /// Blocks or allows the shots. Called by the owner when an action prevents shooting.
        /// </summary>
        public void SetDisabled(bool isDisabled)
        {
            _state.Disabled = isDisabled;
        }

        /// <summary>
        /// Lets go of the weapon: it leaves its handle and falls with physics. It can no longer fire.
        /// </summary>
        public void Drop()
        {
            if (_state.IsDropped)
                return;

            _state.IsDropped = true;
            _state.Disabled = true;
            transform.SetParent(null, true);

            Rigidbody body = _references.Body;

            if (!body)
            {
                Debug.LogWarning($"{name}: no Rigidbody referenced, the weapon cannot fall.", this);
                return;
            }

            body.isKinematic = false;
            body.useGravity = true;
        }

        /// <summary>
        /// Adds ammo without exceeding the weapon maximum.
        /// </summary>
        public void AddAmmo(int amount)
        {
            if (amount <= 0)
                return;

            SetAmmo(Mathf.Min(_state.Ammo + amount, MaxAmmo));
        }

        #endregion

        #region PRIVATE METHODS

        private void SetAmmo(int value)
        {
            _state.Ammo = value;
            OnAmmoChange?.Invoke(_state.Ammo, MaxAmmo);
        }

        [ContextMenu("Debug/Try Fire")]
        private void DebugTryFire()
        {
            TryFire();
        }

        #endregion
    }
}