using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

// 决战玩法管理器：布阵阶段在己方半场网格放置单位，开战后生成敌方阵型，全灭判定胜负。
public class BattleSetupManager : MonoBehaviour
{
    public static BattleSetupManager Instance { get; private set; }

    public enum BattleState { Setup, Battle, Ended }

    [Header("布阵网格")]
    public float cellSize = 2f;
    public Vector2 xRange = new Vector2(-8f, 8f);
    public Vector2 zRange = new Vector2(-20f, -8f);

    [Header("人口")]
    public int maxPopulation = 30;

    [Header("可用兵种（生成底部卡片）")]
    public CharacterData[] availableCharacters;

    [Header("敌方阵型")]
    public CharacterData[] enemyFrontLine;
    public CharacterData[] enemyBackLine;
    public float enemyFrontZ = 14f;
    public float enemyBackZ = 18f;
    public float enemySpacing = 2f;

    public BattleState State { get; private set; } = BattleState.Setup;
    public int RemainingPopulation => maxPopulation - usedPopulation;

    // 已放置单位 -> 格子与数据，移除时退回人口。
    private class PlacementRecord
    {
        public Vector2Int cell;
        public CharacterData data;
    }

    private readonly HashSet<Vector2Int> occupiedCells = new HashSet<Vector2Int>();
    private readonly Dictionary<GameObject, PlacementRecord> placements = new Dictionary<GameObject, PlacementRecord>();
    private readonly Dictionary<CharacterData, Image> cardImages = new Dictionary<CharacterData, Image>();

    private CharacterData selectedCharacter;
    private int usedPopulation;
    private Camera mainCamera;
    private GameObject cellHighlight;
    private Material highlightMaterial;
    private GameObject startButton;
    private Text populationText;
    private Text resultText;
    private float endCheckTimer;

    private static readonly Color ValidCellColor = new Color(0.2f, 1f, 0.3f, 0.35f);
    private static readonly Color InvalidCellColor = new Color(1f, 0.25f, 0.2f, 0.35f);
    private static readonly Color CardNormalColor = new Color(0.15f, 0.15f, 0.2f, 0.85f);
    private static readonly Color CardSelectedColor = new Color(0.2f, 0.55f, 0.25f, 0.95f);

    private void Awake()
    {
        if (Instance != null && Instance != this)
        {
            Destroy(gameObject);
            return;
        }

        Instance = this;
    }

    private void Start()
    {
        mainCamera = Camera.main;
        CreateCellHighlight();
        CreateCardUI();
        CreateStartButton();
        CreateResultText();
    }

    private void Update()
    {
        if (State == BattleState.Setup)
        {
            HandleSetupInput();
        }
        else if (State == BattleState.Battle)
        {
            CheckBattleEnd();
        }
    }

    // 布阵阶段输入：选兵种后点格子放置，点击已放单位移除。
    private void HandleSetupInput()
    {
        if (mainCamera == null)
        {
            mainCamera = Camera.main;
            if (mainCamera == null) return;
        }

        bool overUI = EventSystem.current != null && EventSystem.current.IsPointerOverGameObject();
        bool highlightVisible = !overUI && selectedCharacter != null;
        if (cellHighlight != null)
        {
            cellHighlight.SetActive(highlightVisible);
        }

        if (!highlightVisible) return;
        if (!RaycastGround(out Vector3 groundPoint)) return;

        Vector2Int cell = WorldToCell(groundPoint);
        bool cellValid = IsCellInRange(cell) && !occupiedCells.Contains(cell);

        cellHighlight.transform.position = new Vector3(cell.x * cellSize, 0.02f, cell.y * cellSize);
        highlightMaterial.color = cellValid ? ValidCellColor : InvalidCellColor;

        if (Input.GetMouseButtonDown(0))
        {
            // 优先移除点中的己方单位。
            if (TryRemoveUnitAtMouse()) return;

            if (cellValid)
            {
                PlaceUnit(selectedCharacter, cell);
            }
        }
    }

    // 卡片点击入口：选中/再点取消。
    public void SelectCharacter(CharacterData data)
    {
        if (State != BattleState.Setup || data == null) return;

        if (selectedCharacter == data)
        {
            selectedCharacter = null;
        }
        else if (RemainingPopulation >= data.manaCost)
        {
            selectedCharacter = data;
        }
        else
        {
            Debug.Log($"人口不足，{data.characterName}需要{data.manaCost}人口，剩余{RemainingPopulation}");
            return;
        }

        RefreshCardSelection();
    }

    // 人口是否足够，供卡片按钮判断可用性。
    public bool CanAfford(CharacterData data)
    {
        return data != null && RemainingPopulation >= data.manaCost;
    }

    public void StartBattle()
    {
        if (State != BattleState.Setup) return;
        if (placements.Count == 0)
        {
            Debug.Log("请先放置至少一个单位再开战");
            return;
        }

        selectedCharacter = null;
        RefreshCardSelection();
        SpawnEnemyLine(enemyFrontLine, enemyFrontZ);
        SpawnEnemyLine(enemyBackLine, enemyBackZ);

        State = BattleState.Battle;
        if (startButton != null) startButton.SetActive(false);
        if (populationText != null) populationText.gameObject.SetActive(false);
        if (cellHighlight != null) cellHighlight.SetActive(false);
        Debug.Log("战斗开始！");
    }

    // 每0.5秒统计双方存活，全灭判定胜负。
    private void CheckBattleEnd()
    {
        endCheckTimer += Time.deltaTime;
        if (endCheckTimer < 0.5f) return;
        endCheckTimer = 0f;

        int friends = CountActiveUnits("Friend");
        int enemies = CountActiveUnits("Enemy");

        if (friends == 0 && enemies == 0)
        {
            EndBattle("平局！");
        }
        else if (enemies == 0)
        {
            EndBattle("胜利！");
        }
        else if (friends == 0)
        {
            EndBattle("失败");
        }
    }

    private static int CountActiveUnits(string tag)
    {
        // 单位死亡时会被立即隐藏并销毁，只统计激活对象。
        GameObject[] objects = GameObject.FindGameObjectsWithTag(tag);
        int count = 0;
        foreach (GameObject obj in objects)
        {
            if (obj.activeInHierarchy) count++;
        }
        return count;
    }

    private void EndBattle(string result)
    {
        State = BattleState.Ended;
        if (resultText != null)
        {
            resultText.text = result;
            resultText.gameObject.SetActive(true);
        }
        Debug.Log($"战斗结束：{result}");
    }

    // ===== 放置与移除 =====

    private void PlaceUnit(CharacterData data, Vector2Int cell)
    {
        if (data == null || data.unitPrefab == null) return;
        if (RemainingPopulation < data.manaCost) return;
        if (!occupiedCells.Add(cell)) return;

        Vector3 position = CellToWorld(cell);
        GameObject unit = Instantiate(data.unitPrefab, position, Quaternion.identity);
        unit.name = "Friend_" + data.characterName;
        unit.tag = "Friend";

        var unitBase = unit.GetComponent<UnitBase>();
        if (unitBase != null)
        {
            unitBase.InitializeFromPlayerData(
                data.GetMaxHealth(1),
                data.GetAttackPower(1),
                data.GetMoveSpeed(1));
        }

        placements[unit] = new PlacementRecord { cell = cell, data = data };
        usedPopulation += data.manaCost;
        UpdatePopulationText();

        if (RemainingPopulation <= 0)
        {
            selectedCharacter = null;
            RefreshCardSelection();
        }
    }

    private bool TryRemoveUnitAtMouse()
    {
        Ray ray = mainCamera.ScreenPointToRay(Input.mousePosition);
        RaycastHit[] hits = Physics.RaycastAll(ray, 200f);

        GameObject closest = null;
        float closestDistance = float.MaxValue;
        foreach (RaycastHit hit in hits)
        {
            var unitBase = hit.collider.GetComponentInParent<UnitBase>();
            if (unitBase != null && unitBase.CompareTag("Friend") && placements.ContainsKey(unitBase.gameObject))
            {
                if (hit.distance < closestDistance)
                {
                    closestDistance = hit.distance;
                    closest = unitBase.gameObject;
                }
            }
        }

        if (closest == null) return false;

        if (placements.TryGetValue(closest, out PlacementRecord record))
        {
            occupiedCells.Remove(record.cell);
            usedPopulation -= record.data.manaCost;
            placements.Remove(closest);
            UpdatePopulationText();
        }

        Destroy(closest);
        return true;
    }

    // ===== 敌方阵型 =====

    private void SpawnEnemyLine(CharacterData[] line, float z)
    {
        if (line == null) return;

        float startX = -(line.Length - 1) * 0.5f * enemySpacing;
        for (int i = 0; i < line.Length; i++)
        {
            CharacterData data = line[i];
            if (data == null || data.unitPrefab == null) continue;

            GameObject unit = Instantiate(
                data.unitPrefab,
                new Vector3(startX + i * enemySpacing, 0f, z),
                Quaternion.Euler(0f, 180f, 0f));
            unit.name = "Enemy_" + data.characterName;
            unit.tag = "Enemy";

            var unitBase = unit.GetComponent<UnitBase>();
            if (unitBase != null)
            {
                unitBase.InitializeFromPlayerData(
                    data.GetMaxHealth(1),
                    data.GetAttackPower(1),
                    data.GetMoveSpeed(1));
            }
        }
    }

    // ===== 网格工具 =====

    private Vector2Int WorldToCell(Vector3 world)
    {
        return new Vector2Int(
            Mathf.RoundToInt(world.x / cellSize),
            Mathf.RoundToInt(world.z / cellSize));
    }

    private Vector3 CellToWorld(Vector2Int cell)
    {
        return new Vector3(cell.x * cellSize, 0f, cell.y * cellSize);
    }

    private bool IsCellInRange(Vector2Int cell)
    {
        float x = cell.x * cellSize;
        float z = cell.y * cellSize;
        return x >= xRange.x && x <= xRange.y && z >= zRange.x && z <= zRange.y;
    }

    private bool RaycastGround(out Vector3 point)
    {
        point = Vector3.zero;
        if (mainCamera == null) return false;

        Ray ray = mainCamera.ScreenPointToRay(Input.mousePosition);
        if (Physics.Raycast(ray, out RaycastHit hit, 200f))
        {
            point = hit.point;
            return true;
        }
        return false;
    }

    // ===== UI 创建（代码生成，无需场景预制） =====

    private Canvas EnsureCanvas()
    {
        Canvas canvas = FindObjectOfType<Canvas>();
        if (canvas == null)
        {
            GameObject canvasObject = new GameObject("Canvas", typeof(Canvas), typeof(CanvasScaler), typeof(GraphicRaycaster));
            canvas = canvasObject.GetComponent<Canvas>();
            canvas.renderMode = RenderMode.ScreenSpaceOverlay;

            var scaler = canvasObject.GetComponent<CanvasScaler>();
            scaler.uiScaleMode = CanvasScaler.ScaleMode.ScaleWithScreenSize;
            scaler.referenceResolution = new Vector2(1080f, 1920f);
            scaler.matchWidthOrHeight = 0.5f;
        }

        if (FindObjectOfType<EventSystem>() == null)
        {
            new GameObject("EventSystem", typeof(EventSystem), typeof(StandaloneInputModule));
        }

        return canvas;
    }

    private void CreateCellHighlight()
    {
        cellHighlight = GameObject.CreatePrimitive(PrimitiveType.Quad);
        cellHighlight.name = "CellHighlight";
        // 高亮块不能挡射线，删掉自带的碰撞体。
        Destroy(cellHighlight.GetComponent<Collider>());
        cellHighlight.transform.rotation = Quaternion.Euler(90f, 0f, 0f);
        cellHighlight.transform.localScale = new Vector3(cellSize * 0.95f, cellSize * 0.95f, 1f);
        cellHighlight.transform.position = new Vector3(0f, 0.02f, 0f);

        highlightMaterial = new Material(Shader.Find("Sprites/Default"));
        highlightMaterial.color = ValidCellColor;
        cellHighlight.GetComponent<Renderer>().sharedMaterial = highlightMaterial;
        cellHighlight.SetActive(false);
    }

    private void CreateCardUI()
    {
        if (availableCharacters == null || availableCharacters.Length == 0) return;

        Canvas canvas = EnsureCanvas();
        const float cardWidth = 108f;
        const float cardHeight = 150f;
        const float gap = 10f;

        int count = availableCharacters.Length;
        float totalWidth = count * cardWidth + (count - 1) * gap;
        float startX = -totalWidth * 0.5f + cardWidth * 0.5f;

        for (int i = 0; i < count; i++)
        {
            CharacterData data = availableCharacters[i];
            if (data == null) continue;

            GameObject card = new GameObject("卡片_" + data.characterName, typeof(RectTransform), typeof(Image), typeof(Button));
            card.transform.SetParent(canvas.transform, false);

            var cardRect = card.GetComponent<RectTransform>();
            cardRect.anchorMin = cardRect.anchorMax = new Vector2(0.5f, 0f);
            cardRect.pivot = new Vector2(0.5f, 0f);
            cardRect.anchoredPosition = new Vector2(startX + i * (cardWidth + gap), 24f);
            cardRect.sizeDelta = new Vector2(cardWidth, cardHeight);

            var cardImage = card.GetComponent<Image>();
            cardImage.color = CardNormalColor;
            cardImages[data] = cardImage;

            // 头像占上半部。
            GameObject iconObject = new GameObject("Icon", typeof(RectTransform), typeof(Image));
            iconObject.transform.SetParent(card.transform, false);
            var iconRect = iconObject.GetComponent<RectTransform>();
            iconRect.anchorMin = new Vector2(0.08f, 0.35f);
            iconRect.anchorMax = new Vector2(0.92f, 0.95f);
            iconRect.offsetMin = Vector2.zero;
            iconRect.offsetMax = Vector2.zero;
            var iconImage = iconObject.GetComponent<Image>();
            if (data.cardIcon != null)
            {
                iconImage.sprite = data.cardIcon;
                iconImage.preserveAspect = true;
            }
            else
            {
                iconImage.color = new Color(0.4f, 0.4f, 0.45f, 1f);
            }

            // 名字占底部。
            CreateChildText(card.transform, "Name", data.characterName, 26,
                new Vector2(0.05f, 0.02f), new Vector2(0.95f, 0.28f));

            // 人口占顶部。
            CreateChildText(card.transform, "Cost", data.manaCost + "人口", 28,
                new Vector2(0.05f, 0.72f), new Vector2(0.95f, 0.98f), new Color(1f, 0.85f, 0.3f));

            // 挂通用卡片按钮：点击进入选兵，人口不足自动置灰。
            var summonButton = card.AddComponent<SummonCardButton>();
            summonButton.characterData = data;
        }
    }

    private void CreateStartButton()
    {
        Canvas canvas = EnsureCanvas();

        startButton = new GameObject("开战按钮", typeof(RectTransform), typeof(Image), typeof(Button));
        startButton.transform.SetParent(canvas.transform, false);

        var buttonRect = startButton.GetComponent<RectTransform>();
        buttonRect.anchorMin = buttonRect.anchorMax = new Vector2(0.5f, 1f);
        buttonRect.pivot = new Vector2(0.5f, 1f);
        buttonRect.anchoredPosition = new Vector2(0f, -30f);
        buttonRect.sizeDelta = new Vector2(220f, 90f);

        startButton.GetComponent<Image>().color = new Color(0.75f, 0.2f, 0.15f, 0.95f);
        CreateChildText(startButton.transform, "Label", "开 战", 44,
            Vector2.zero, Vector2.one, Color.white);

        startButton.GetComponent<Button>().onClick.AddListener(StartBattle);

        // 人口显示在开战按钮下方。
        GameObject populationObject = new GameObject("PopulationText", typeof(RectTransform), typeof(Text));
        populationObject.transform.SetParent(canvas.transform, false);
        var populationRect = populationObject.GetComponent<RectTransform>();
        populationRect.anchorMin = populationRect.anchorMax = new Vector2(0.5f, 1f);
        populationRect.pivot = new Vector2(0.5f, 1f);
        populationRect.anchoredPosition = new Vector2(0f, -130f);
        populationRect.sizeDelta = new Vector2(300f, 50f);

        populationText = populationObject.GetComponent<Text>();
        populationText.alignment = TextAnchor.MiddleCenter;
        populationText.fontSize = 34;
        populationText.color = Color.white;
        UpdatePopulationText();
    }

    private void CreateResultText()
    {
        Canvas canvas = EnsureCanvas();

        GameObject resultObject = new GameObject("ResultText", typeof(RectTransform), typeof(Text));
        resultObject.transform.SetParent(canvas.transform, false);
        var resultRect = resultObject.GetComponent<RectTransform>();
        resultRect.anchorMin = resultRect.anchorMax = Vector2.one * 0.5f;
        resultRect.sizeDelta = new Vector2(600f, 160f);

        resultText = resultObject.GetComponent<Text>();
        resultText.alignment = TextAnchor.MiddleCenter;
        resultText.fontSize = 90;
        resultText.fontStyle = FontStyle.Bold;
        resultText.color = new Color(1f, 0.9f, 0.3f);
        resultText.gameObject.SetActive(false);
    }

    private static Text CreateChildText(Transform parent, string name, string content, int fontSize,
        Vector2 anchorMin, Vector2 anchorMax, Color? color = null)
    {
        GameObject textObject = new GameObject(name, typeof(RectTransform), typeof(Text));
        textObject.transform.SetParent(parent, false);

        var rect = textObject.GetComponent<RectTransform>();
        rect.anchorMin = anchorMin;
        rect.anchorMax = anchorMax;
        rect.offsetMin = Vector2.zero;
        rect.offsetMax = Vector2.zero;

        Text text = textObject.GetComponent<Text>();
        text.text = content;
        text.fontSize = fontSize;
        text.alignment = TextAnchor.MiddleCenter;
        text.color = color ?? Color.white;
        return text;
    }

    private void RefreshCardSelection()
    {
        foreach (var pair in cardImages)
        {
            pair.Value.color = pair.Key == selectedCharacter ? CardSelectedColor : CardNormalColor;
        }
    }

    private void UpdatePopulationText()
    {
        if (populationText != null)
        {
            populationText.text = $"人口 {usedPopulation}/{maxPopulation}";
        }
    }
}