using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using TMPro;
public enum UGameState
{
    Uninitialized,
    Playing,
    Win,
    Lose
}

public class UntangleGameManager : MonoBehaviour
{
    [Header("Prefabs & Parents")]
    public GameObject pointPrefab;
    public LineRenderer linePrefab;
    public Transform spawnParent;

    [Header("UI Elements")]
    public Text statusText;
    // public GameObject winUI;
    // public GameObject loseUI;
    public Button newGameButton;
    public Button solveButton;

    [Header("Audio")]
    public AudioClip winSound;
    // public AudioClip loseSound;

    [Header("Game Settings")]
    public int pointCount = 10;

    // Runtime state
    public UGameState gameState = UGameState.Uninitialized;
    private List<Point> points = new List<Point>();
    public List<Connection> connections = new List<Connection>();
    private Vector3[] solutionPositions;

    private void Awake()
    {
        newGameButton.onClick.AddListener(StartGame);
        solveButton.onClick.AddListener(AutoSolve);
    }

    private void Start()
    {
        StartGame();
    }

    public void SetGameState(UGameState state)
    {
        gameState = state;
    }

    public void StartGame()
    {
        ResetPuzzle();
    }
    public void ResetPuzzle()
    {
        gameState = UGameState.Uninitialized;
        statusText.text = "Generating new game...";
        GenerateRandomGame();
        gameState = UGameState.Playing;
        statusText.text = "";
    }

    void GenerateRandomGame()
    { 
        ClearOldGame();
        statusText.text = "";
        points.Clear();
        connections.Clear();
        solutionPositions = new Vector3[pointCount];

        // Step 1: Place points randomly (solution layout)
        for (int i = 0; i < pointCount; i++)
        {
            Vector2 pos;
            int tries = 0;
            do
            {
                pos = Random.insideUnitCircle * 4f;
                tries++;
                if (tries > 1000) break;
            }
            while (IsTooClose(pos));

            // instantiate as child of spawnParent
            Vector3 worldPos = new Vector3(pos.x, pos.y, 0f);
            GameObject obj = Instantiate(pointPrefab, worldPos, Quaternion.identity, spawnParent);
            Point p = obj.GetComponent<Point>();
            p.id = i;
            p.manager = this;
            points.Add(p);
            solutionPositions[i] = worldPos;
        }

        // Step 2: Create a Minimum Spanning Tree (MST)
        List<(int, int, float)> edges = new List<(int, int, float)>();
        for (int i = 0; i < pointCount; i++)
        {
            for (int j = i + 1; j < pointCount; j++)
            {
                float dist = Vector2.Distance(points[i].transform.position, points[j].transform.position);
                edges.Add((i, j, dist));
            }
        }
        edges.Sort((a, b) => a.Item3.CompareTo(b.Item3));

        int[] parent = new int[pointCount];
        for (int i = 0; i < pointCount; i++) parent[i] = i;
        int Find(int x) => parent[x] == x ? x : parent[x] = Find(parent[x]);
        void Union(int x, int y) => parent[Find(x)] = Find(y);

        int edgeCount = 0;
        foreach (var (a, b, _) in edges)
        {
            if (Find(a) != Find(b))
            {
                Union(a, b);
                AddConnection(a, b);
                edgeCount++;
                if (edgeCount == pointCount - 1) break;
            }
        }

        // Step 3: Ensure every point has at least degree 2
        int[] degrees = new int[pointCount];
        foreach (var c in connections)
        {
            degrees[c.a.id]++;
            degrees[c.b.id]++;
        }

        for (int i = 0; i < pointCount; i++)
        {
            while (degrees[i] < 2)
            {
                bool added = false;

                // Try to add a non-crossing edge
                for (int j = 0; j < pointCount; j++)
                {
                    if (i == j || IsConnected(i, j)) continue;

                    Connection temp = new Connection { a = points[i], b = points[j] };
                    if (DoesIntersectAny(temp)) continue;

                    AddConnection(i, j);
                    degrees[i]++;
                    degrees[j]++;
                    added = true;
                    break;
                }

                // If no valid non-crossing edge found, allow one forced connection (rare case)
                if (!added)
                {
                    for (int j = 0; j < pointCount; j++)
                    {
                        if (i == j || IsConnected(i, j)) continue;

                        AddConnection(i, j);
                        degrees[i]++;
                        degrees[j]++;
                        break;
                    }
                }
            }
        }
        // Step 4: Shuffle point positions to create the puzzle
        foreach (var p in points)
            p.transform.localPosition = Random.insideUnitCircle * 400f;  // localPosition keeps them under spawnParent

        foreach (var c in connections)
            c.UpdateLine();
    }
    private void AddConnection(int a, int b)
    {
        var c = new Connection { a = points[a], b = points[b] };
        var lr = Instantiate(linePrefab, spawnParent);
        c.line = lr;
        c.UpdateLine();
        connections.Add(c);
    }

    private bool IsConnected(int a, int b)
    {
        return connections.Exists(c =>
            (c.a.id == a && c.b.id == b) ||
            (c.a.id == b && c.b.id == a));
    }

    private bool DoesIntersectAny(Connection cand)
    {
        foreach (var c in connections)
        {
            if (cand.SharesPointWith(c)) continue;
            if (LinesIntersect(cand, c)) return true;
        }
        return false;
    }

    private bool IsTooClose(Vector2 pos)
    {
        return points.Exists(p => Vector2.Distance(p.transform.position, pos) < 0.5f);
    }

    private void ClearOldGame()
    {
        foreach (var p in points)    Destroy(p.gameObject);
        foreach (var c in connections) Destroy(c.line.gameObject);
    }

    public void CheckIfSolved()
    {
        if (gameState != UGameState.Playing) return;
        foreach (var c1 in connections)
            foreach (var c2 in connections)
                if (c1 != c2 && !c1.SharesPointWith(c2) && LinesIntersect(c1, c2))
                    return;

        // no intersections found!
        statusText.text = "Completed!";
        // if (loseUI != null)
        //     loseUI.SetActive(false);
        // if (winUI != null)
        //     winUI.SetActive(true);
        SetGameState(UGameState.Win);
        Debug.Log("Puzzle Untangle solved!");
        if (winSound != null) {
            SoundFXManager.instance.PlaySound(winSound, transform, 1f);
        }
    }

    private void AutoSolve()
    {
        if (gameState != UGameState.Playing) return;
        for (int i = 0; i < points.Count; i++)
            points[i].transform.position = solutionPositions[i];
        connections.ForEach(c => c.UpdateLine());
        CheckIfSolved();
    }

    #region Line‑intersection helpers
    private bool LinesIntersect(Connection c1, Connection c2)
    {
        Vector2 p1 = c1.a.transform.position;
        Vector2 q1 = c1.b.transform.position;
        Vector2 p2 = c2.a.transform.position;
        Vector2 q2 = c2.b.transform.position;
        return DoIntersect(p1, q1, p2, q2);
    }

    private bool DoIntersect(Vector2 a, Vector2 b, Vector2 c, Vector2 d)
    {
        int o1 = Orientation(a, b, c);
        int o2 = Orientation(a, b, d);
        int o3 = Orientation(c, d, a);
        int o4 = Orientation(c, d, b);
        return o1 != o2 && o3 != o4;
    }

    private int Orientation(Vector2 a, Vector2 b, Vector2 c)
    {
        float v = (b.y - a.y) * (c.x - b.x) - (b.x - a.x) * (c.y - b.y);
        if (Mathf.Abs(v) < 1e-4f) return 0;
        return (v > 0) ? 1 : 2;
    }
    #endregion
}