using System.Collections.Generic;
using UnityEngine;

namespace TKS
{
    /// <summary>
    /// 슬링샷 조작: 아군 유닛을 잡고(누름) 뒤로 당긴 뒤(드래그) 놓으면(드롭) 반대 방향으로 이동·공격.
    /// 버튼 없음. 결과 화면에서는 탭으로 계속. 추가 이동만 남았을 때 빈 곳 탭 = 건너뛰기.
    /// </summary>
    public class SlingshotInput : MonoBehaviour
    {
        BattleManager battle;
        Camera cam;
        BattleHUD hud;

        Unit selected;
        bool dragging;
        bool emptyPress;
        bool previewValid;
        Vector2 pressWorld;
        Vector2 currentTarget;

        LineRenderer aimLine;
        LineRenderer pullLine;
        SpriteRenderer targetRing;
        readonly List<Unit> highlighted = new List<Unit>();

        public Unit Selected
        {
            get { return selected; }
        }

        public void Init(BattleManager b, Camera c, BattleHUD h)
        {
            battle = b;
            cam = c;
            hud = h;
            aimLine = MakeLine("AimLine", 0.08f, new Color(1f, 1f, 1f, 0.9f), 10);
            pullLine = MakeLine("PullLine", 0.035f, new Color(1f, 1f, 1f, 0.35f), 9);
            targetRing = ProceduralSprites.NewSprite(transform, "TargetRing", ProceduralSprites.Ring, Color.white, 0.7f, 11);
            targetRing.enabled = false;
        }

        LineRenderer MakeLine(string name, float width, Color color, int order)
        {
            var go = new GameObject(name);
            go.transform.SetParent(transform, false);
            var lr = go.AddComponent<LineRenderer>();
            lr.useWorldSpace = true;
            lr.positionCount = 2;
            lr.startWidth = width;
            lr.endWidth = width;
            lr.material = new Material(Shader.Find("Sprites/Default"));
            lr.startColor = color;
            lr.endColor = color;
            lr.sortingOrder = order;
            lr.numCapVertices = 4;
            lr.enabled = false;
            return lr;
        }

        Vector2 PointerWorld()
        {
            Vector3 p = Input.mousePosition;
            p.z = -cam.transform.position.z;
            return cam.ScreenToWorldPoint(p);
        }

        void Update()
        {
            if (battle == null || battle.Config == null) return;
            var phase = battle.Phase;
            if (phase == BattlePhase.StageClear || phase == BattlePhase.Defeat)
            {
                if (Input.GetMouseButtonDown(0)) battle.ContinueAfterResult();
                return;
            }

            if (Input.GetMouseButtonDown(0)) OnPress(PointerWorld());
            else if (dragging && Input.GetMouseButton(0)) OnDrag(PointerWorld());
            if (Input.GetMouseButtonUp(0)) OnRelease(PointerWorld());
        }

        void OnPress(Vector2 w)
        {
            pressWorld = w;
            emptyPress = false;
            previewValid = false;
            var u = battle.UnitNear(w, Faction.Player);
            if (u == null) u = battle.UnitNear(w, null);
            Select(u);
            if (u != null && battle.CanAct(u))
            {
                dragging = true;
            }
            else
            {
                dragging = false;
                emptyPress = (u == null);
            }
        }

        void OnDrag(Vector2 w)
        {
            if (selected == null) return;
            Vector2 pull = w - selected.Position;
            Vector2 launch = -pull;
            float mag = launch.magnitude;
            if (mag < battle.Config.minDragDistance)
            {
                HidePreview();
                previewValid = false;
                return;
            }
            if (mag > selected.SlingMaxDistance) launch = launch / mag * selected.SlingMaxDistance;
            currentTarget = battle.Board.ClampInside(selected.Position + launch, selected.Radius);
            previewValid = true;
            ShowPreview(selected, currentTarget, w);
        }

        void OnRelease(Vector2 w)
        {
            if (dragging && selected != null && previewValid && battle.CanAct(selected))
            {
                var t = currentTarget;
                var u = selected;
                HidePreview();
                Select(null);
                battle.RequestPlayerAction(u, t);
            }
            else if (emptyPress && Vector2.Distance(w, pressWorld) < 0.3f)
            {
                battle.OnEmptyTap();
            }
            else
            {
                HidePreview();
            }
            dragging = false;
            emptyPress = false;
            previewValid = false;
        }

        void Select(Unit u)
        {
            if (selected != null && selected.View != null) selected.View.SetSelected(false);
            selected = u;
            if (u != null && u.View != null) u.View.SetSelected(true);
            if (hud != null) hud.SetSelected(u);
        }

        /// <summary>조준 표시(자동 플레이 캡처에서도 호출).</summary>
        public void ShowPreview(Unit u, Vector2 target, Vector2? pointer)
        {
            aimLine.enabled = true;
            aimLine.SetPosition(0, new Vector3(u.Position.x, u.Position.y, 0f));
            aimLine.SetPosition(1, new Vector3(target.x, target.y, 0f));
            if (pointer.HasValue)
            {
                pullLine.enabled = true;
                pullLine.SetPosition(0, new Vector3(u.Position.x, u.Position.y, 0f));
                pullLine.SetPosition(1, new Vector3(pointer.Value.x, pointer.Value.y, 0f));
            }
            else
            {
                pullLine.enabled = false;
            }
            targetRing.enabled = true;
            targetRing.transform.position = new Vector3(target.x, target.y, 0f);

            bool moveOnly = u.BonusMoveAvailable;
            var finalHit = moveOnly ? null : Combat.EnemyAtPoint(u, target, battle.Config.finalHitTolerance);
            targetRing.color = finalHit != null ? new Color(1f, 0.6f, 0.1f) : Color.white;
            targetRing.transform.localScale = finalHit != null ? new Vector3(0.9f, 0.9f, 1f) : new Vector3(0.7f, 0.7f, 1f);

            ClearHighlights();
            foreach (var e in battle.Resolver.PredictTargets(u, target, moveOnly))
            {
                if (e.View != null) e.View.SetHighlight(true);
                highlighted.Add(e);
            }
        }

        public void HidePreview()
        {
            aimLine.enabled = false;
            pullLine.enabled = false;
            targetRing.enabled = false;
            ClearHighlights();
        }

        void ClearHighlights()
        {
            foreach (var h in highlighted)
            {
                if (h != null && h.View != null) h.View.SetHighlight(false);
            }
            highlighted.Clear();
        }
    }
}