using UnityEngine;

// Rifle held by the local player's humanoid (Y Bot): the AK47 model from Resources (falls back
// to a primitive stand-in if it's missing), posed in
// front of the right shoulder and pointed at whatever the crosshair is over, with both hands
// pinned to it via Animator IK (needs "IK Pass" on the animator layer). Also owns the
// procedural weapon animations: fire kick, muzzle flash, and the reload (mag drop / insert).
// Runs after CharacterMovement so it reads the camera pose for this frame.
[DefaultExecutionOrder(100)]
[RequireComponent(typeof(Animator))]
public class WeaponRig : MonoBehaviour
{
    const string ModelPath = "Weapons/AK47";

    public Vector3 shoulderOffset = new Vector3(0.18f, 1.45f, 0f);
    // Where the pistol grip (the gun's pivot) sits relative to the shoulder, in aim space.
    // Kept close so the Y Bot's left arm can reach the handguard.
    public Vector3 holdOffset = new Vector3(-0.02f, -0.12f, 0.24f);

    public Transform Muzzle { get; private set; }

    Animator animator;
    Transform gun;
    Transform rightGrip;
    Transform leftGrip;
    Transform magazine;
    Vector3 magazineRestPos;
    Transform flash;
    Light flashLight;

    Vector3 aimPoint;
    float kickBack;
    float kickPitch;
    float flashUntil;

    float equipProgress = 1f;
    bool equipping;
    float equipStart;
    float equipDuration;

    bool reloading;
    float reloadStart;
    float reloadDuration;
    bool magDropped;

    void Awake()
    {
        animator = GetComponent<Animator>();
        BuildGun();
    }

    void OnDestroy()
    {
        if (gun != null) Destroy(gun.gameObject);
    }

    // Gun root pivot is the pistol grip (right hand); forward +Z, up +Y.
    void BuildGun()
    {
        gun = new GameObject("Rifle").transform;
        gun.SetParent(transform, false);

        // Real model (Quaternius CC0 AK47, see Resources/Weapons/AK47_LICENSE.txt), else a primitive stand-in.
        var model = Resources.Load<GameObject>(ModelPath);
        if (model != null)
        {
            var instance = Instantiate(model, gun, false).transform;
            instance.name = model.name;
            foreach (var c in instance.GetComponentsInChildren<Collider>()) Destroy(c);
            Muzzle = instance.Find("Muzzle");
            rightGrip = instance.Find("RightHandGrip");
            leftGrip = instance.Find("LeftHandGrip");
            magazine = instance.Find("Magazine");
        }

        if (Muzzle == null || rightGrip == null || leftGrip == null || magazine == null)
        {
            if (model != null) Debug.LogWarning($"[WeaponRig] '{ModelPath}' is missing Muzzle/RightHandGrip/LeftHandGrip/Magazine; using the primitive rifle.");
            foreach (Transform child in gun) Destroy(child.gameObject);
            BuildPrimitiveGun();
        }

        magazineRestPos = magazine.localPosition;

        flash = ShootingFx.CreateVisual(PrimitiveType.Sphere, "MuzzleFlash", Muzzle, new Vector3(0f, 0f, 0.06f),
            new Vector3(0.09f, 0.09f, 0.2f), ShootingFx.GetMaterial(new Color(1f, 0.7f, 0.25f), 6f)).transform;
        flash.gameObject.SetActive(false);

        flashLight = new GameObject("MuzzleLight").AddComponent<Light>();
        flashLight.transform.SetParent(Muzzle, false);
        flashLight.type = LightType.Point;
        flashLight.color = new Color(1f, 0.75f, 0.4f);
        flashLight.range = 4f;
        flashLight.intensity = 1.5f;
        flashLight.enabled = false;
    }

    void BuildPrimitiveGun()
    {
        var dark = ShootingFx.GetMaterial(new Color(0.12f, 0.12f, 0.14f));
        var metal = ShootingFx.GetMaterial(new Color(0.32f, 0.33f, 0.36f));
        var accent = ShootingFx.GetMaterial(new Color(0.95f, 0.3f, 0.25f));

        // Parts are laid out around the receiver; offset them so the grip sits at the root pivot.
        var body = new GameObject("PrimitiveRifle").transform;
        body.SetParent(gun, false);
        body.localPosition = new Vector3(-0.01f, 0.09f, 0.05f);

        ShootingFx.CreateVisual(PrimitiveType.Cube, "Receiver", body, new Vector3(0f, 0f, 0.05f), new Vector3(0.07f, 0.1f, 0.42f), dark);
        ShootingFx.CreateVisual(PrimitiveType.Cube, "Handguard", body, new Vector3(0f, -0.005f, 0.33f), new Vector3(0.075f, 0.085f, 0.2f), metal);
        ShootingFx.CreateVisual(PrimitiveType.Cylinder, "Barrel", body, new Vector3(0f, 0.01f, 0.5f), new Vector3(0.025f, 0.13f, 0.025f), dark, new Vector3(90f, 0f, 0f));
        ShootingFx.CreateVisual(PrimitiveType.Cube, "Stock", body, new Vector3(0f, -0.025f, -0.26f), new Vector3(0.055f, 0.11f, 0.22f), metal);
        ShootingFx.CreateVisual(PrimitiveType.Cube, "Grip", body, new Vector3(0f, -0.1f, -0.06f), new Vector3(0.045f, 0.12f, 0.05f), dark, new Vector3(15f, 0f, 0f));
        ShootingFx.CreateVisual(PrimitiveType.Cube, "Sight", body, new Vector3(0f, 0.07f, 0.04f), new Vector3(0.03f, 0.04f, 0.09f), dark);
        ShootingFx.CreateVisual(PrimitiveType.Cube, "SightDot", body, new Vector3(0f, 0.08f, 0.09f), Vector3.one * 0.012f, ShootingFx.GetMaterial(Color.red, 3f));
        magazine = ShootingFx.CreateVisual(PrimitiveType.Cube, "Magazine", body, new Vector3(0f, -0.12f, 0.12f), new Vector3(0.045f, 0.16f, 0.08f), accent, new Vector3(-12f, 0f, 0f)).transform;

        Muzzle = new GameObject("Muzzle").transform;
        Muzzle.SetParent(body, false);
        Muzzle.localPosition = new Vector3(0f, 0.01f, 0.64f);

        rightGrip = new GameObject("RightHandGrip").transform;
        rightGrip.SetParent(body, false);
        rightGrip.localPosition = new Vector3(0.01f, -0.09f, -0.05f);

        leftGrip = new GameObject("LeftHandGrip").transform;
        leftGrip.SetParent(body, false);
        leftGrip.localPosition = new Vector3(-0.01f, -0.06f, 0.32f);
    }

    public void SetAimPoint(Vector3 point) => aimPoint = point;

    public void PlayFire()
    {
        kickBack = Mathf.Min(kickBack + 0.05f, 0.09f);
        kickPitch = Mathf.Min(kickPitch + 5f, 12f);
        flashUntil = Time.time + 0.04f;
        flash.localRotation = Quaternion.Euler(0f, 0f, Random.Range(0f, 360f));
        flash.localScale = new Vector3(0.09f, 0.09f, 0.2f) * Random.Range(0.8f, 1.25f);
    }

    // Holds the rifle at low-ready until PlayEquip() raises it (used by the intro cinematic).
    public void SetLowered()
    {
        equipping = false;
        equipProgress = 0f;
    }

    public void PlayEquip(float duration)
    {
        equipping = true;
        equipStart = Time.time;
        equipDuration = Mathf.Max(0.01f, duration);
    }

    static float EaseOutBack(float x)
    {
        const float c1 = 1.70158f;
        const float c3 = c1 + 1f;
        return 1f + c3 * Mathf.Pow(x - 1f, 3f) + c1 * Mathf.Pow(x - 1f, 2f);
    }

    public void PlayReload(float duration)
    {
        reloading = true;
        reloadStart = Time.time;
        reloadDuration = duration;
        magDropped = false;
    }

    void LateUpdate()
    {
        float dt = Time.deltaTime;
        kickBack = Mathf.Lerp(kickBack, 0f, 1f - Mathf.Exp(-18f * dt));
        kickPitch = Mathf.Lerp(kickPitch, 0f, 1f - Mathf.Exp(-14f * dt));

        bool flashing = Time.time < flashUntil;
        flash.gameObject.SetActive(flashing);
        flashLight.enabled = flashing;

        // Pose: in front of the right shoulder, pointed at the crosshair target.
        Vector3 shoulder = transform.TransformPoint(shoulderOffset);
        Vector3 toAim = aimPoint - shoulder;
        Quaternion aim = toAim.sqrMagnitude > 0.5f ? Quaternion.LookRotation(toAim) : transform.rotation;

        float reloadTilt = 0f;
        if (reloading) reloadTilt = UpdateReload();

        // Equip: 1 = fully lowered (muzzle down at the hip), 0 = raised. Overshoots slightly on the way up.
        if (equipping)
        {
            equipProgress = Mathf.Clamp01((Time.time - equipStart) / equipDuration);
            if (equipProgress >= 1f) equipping = false;
        }
        float lowered = 1f - EaseOutBack(equipProgress);

        Quaternion rotation = aim
                              * Quaternion.Euler(-kickPitch + reloadTilt * 25f + lowered * 55f, lowered * -15f, reloadTilt * -40f + lowered * -20f);
        Vector3 position = shoulder + aim * (holdOffset + Vector3.back * (kickBack + lowered * 0.08f)
                                             + Vector3.down * (reloadTilt * 0.08f + lowered * 0.25f));
        gun.SetPositionAndRotation(position, rotation);
    }

    // Returns 0..1 "how far the gun is tilted for the reload" and drives the magazine.
    float UpdateReload()
    {
        float t = (Time.time - reloadStart) / reloadDuration;
        if (t >= 1f)
        {
            reloading = false;
            magazine.localPosition = magazineRestPos;
            magazine.gameObject.SetActive(true);
            return 0f;
        }

        // Tilt in over the first 15%, hold, tilt back out over the last 15%.
        float tilt = Mathf.SmoothStep(0f, 1f, Mathf.Min(t / 0.15f, (1f - t) / 0.15f, 1f));

        if (t >= 0.25f && !magDropped)
        {
            magDropped = true;
            DropMagazineCopy();
            magazine.gameObject.SetActive(false);
        }

        if (t >= 0.55f)
        {
            // New mag slides up into the well.
            magazine.gameObject.SetActive(true);
            float insert = Mathf.SmoothStep(0f, 1f, Mathf.InverseLerp(0.55f, 0.8f, t));
            magazine.localPosition = magazineRestPos + Vector3.down * (0.25f * (1f - insert));
        }

        return tilt;
    }

    void DropMagazineCopy()
    {
        var dropped = Instantiate(magazine.gameObject, magazine.position, magazine.rotation);
        dropped.name = "DroppedMagazine";
        dropped.transform.localScale = magazine.lossyScale;
        dropped.AddComponent<BoxCollider>();
        var body = dropped.AddComponent<Rigidbody>();
        body.linearVelocity = -gun.up * 1.5f;
        body.angularVelocity = Random.insideUnitSphere * 5f;
        Destroy(dropped, 4f);
    }

    void OnAnimatorIK(int layerIndex)
    {
        if (gun == null) return;

        animator.SetIKPositionWeight(AvatarIKGoal.RightHand, 1f);
        animator.SetIKPosition(AvatarIKGoal.RightHand, rightGrip.position);

        // During the reload the left hand goes to the magazine well instead of the handguard.
        Vector3 leftTarget = reloading ? magazine.position : leftGrip.position;
        animator.SetIKPositionWeight(AvatarIKGoal.LeftHand, 1f);
        animator.SetIKPosition(AvatarIKGoal.LeftHand, leftTarget);

        animator.SetLookAtWeight(1f, 0.35f, 0.8f, 0f, 0.6f);
        animator.SetLookAtPosition(aimPoint);
    }
}