using UnityEngine;

namespace Arena.Combat
{
    /// <summary>
    /// Moves straight ahead and damages the first IDamageable of the targeted team it touches.
    /// It goes through the other teams: no friendly fire.
    /// Needs a trigger collider and a kinematic Rigidbody.
    /// </summary>
    [RequireComponent(typeof(Rigidbody))]
    public class Projectile : MonoBehaviour
    {
        [System.Serializable]
        public class Settings
        {
            [Tooltip("Speed, in meters per second.")]
            [Min(0f)] public float Speed = 20f;

            [Tooltip("Time before an unused projectile is destroyed, in seconds.")]
            [Min(0.1f)] public float Lifetime = 2f;
        }

        #region FIELDS

        [SerializeField] private Settings _settings;

        private DamageInfo _damage;

        #endregion

        #region UNITY LIFECYCLES

        private void Update()
        {
            transform.position += transform.forward * _settings.Speed * Time.deltaTime;
        }

        private void OnTriggerEnter(Collider other)
        {
            // Ignore the other trigger zones, and the shooter with all its children
            if (other.isTrigger || IsFromShooter(other))
                return;

            // The collider can be on a child of the IDamageable: arm, head, model...
            IDamageable target = other.GetComponentInParent<IDamageable>();

            if (target != null)
            {
                // A friend is crossed, not hit
                if (!_damage.CanHit(target.Team))
                    return;

                target.TakeDamage(_damage);
            }

            Destroy(gameObject);
        }

        #endregion

        #region PUBLIC METHODS

        /// <summary>
        /// Starts the projectile. Called right after Instantiate by whoever fires it.
        /// </summary>
        /// <param name="damage">Damage dealt to the IDamageable it touches. Its source is the shooter, ignored by the projectile.</param>
        public void Launch(DamageInfo damage)
        {
            _damage = damage;
            Destroy(gameObject, _settings.Lifetime);
        }

        #endregion

        #region PRIVATE METHODS

        private bool IsFromShooter(Collider other)
        {
            GameObject shooter = _damage.Source;
            return shooter && other.transform.IsChildOf(shooter.transform);
        }

        #endregion
    }
}