using UnityEngine;

/// <summary>
/// Attach this to any world object (NPC, terminal, sign, corpse, etc.)
/// to make it interactable. The player presses E when looking at it
/// from within interactRange to start the dialogue.
///
/// The component draws a small world-space "[E]" prompt via OnGUI
/// when the player is close enough and looking at the object.
/// </summary>
public class DialogueNPC : MonoBehaviour
{
    [Header("Dialogue")]
    public DialogueLine[] lines = new DialogueLine[]
    {
        new DialogueLine { speakerName = "STRANGER", pages = new[] { "Hey." } }
    };

    [Header("Interaction")]
    [Tooltip("Maximum distance from which the player can interact.")]
    public float interactRange = 3.5f;
    [Tooltip("Maximum angle (degrees) between player forward and direction to this object.")]
    public float interactAngle = 45f;
    [Tooltip("Layer mask used for the line-of-sight raycast.")]
    public LayerMask occlusionMask = ~0;

    [Header("Prompt Style")]
    public string promptText    = "[E] Talk";
    public Color  colPrompt     = new Color(0.20f, 0.95f, 0.40f, 1f);
    public Color  colPromptBg   = new Color(0f, 0f, 0f, 0.70f);

    // ── Private ──────────────────────────────────────────────────────
    private Transform   _playerTransform;
    private Camera      _playerCamera;
    private bool        _promptVisible;
    private Texture2D   _white;

    // ─────────────────────────────────────────────────────────────────
    void Start()
    {
        _white = Texture2D.whiteTexture;

        // Find the player by component
        var player = FindObjectOfType<FirstPersonController>();
        if (player != null)
        {
            _playerTransform = player.transform;
            _playerCamera    = player.GetComponentInChildren<Camera>();
        }
        else
        {
            Debug.LogWarning($"[DialogueNPC] '{name}': Could not find FirstPersonController in scene.");
        }
    }

    void Update()
    {
        if (_playerTransform == null || DialogueManager.Instance == null) return;
        if (DialogueManager.Instance.IsOpen) { _promptVisible = false; return; }

        _promptVisible = CanInteract();

        if (_promptVisible && Input.GetKeyDown(KeyCode.E))
            DialogueManager.Instance.StartDialogue(lines);
    }

    // ─────────────────────────────────────────────────────────────────
    bool CanInteract()
    {
        if (_playerTransform == null || _playerCamera == null) return false;

        // Distance check
        float dist = Vector3.Distance(_playerTransform.position, transform.position);
        if (dist > interactRange) return false;

        // Angle check — is the player roughly facing this object?
        Vector3 dir = (transform.position - _playerCamera.transform.position).normalized;
        float   dot = Vector3.Dot(_playerCamera.transform.forward, dir);
        if (dot < Mathf.Cos(interactAngle * Mathf.Deg2Rad)) return false;

        // Line-of-sight (optional — fire a ray toward us)
        if (Physics.Raycast(_playerCamera.transform.position, dir, out RaycastHit hit, interactRange, occlusionMask))
        {
            // Allow if the hit object is us or a child of us
            if (!hit.transform.IsChildOf(transform) && hit.transform != transform)
                return false;
        }

        return true;
    }

    // ─────────────────────────────────────────────────────────────────
    void OnGUI()
    {
        if (!_promptVisible || _playerCamera == null) return;

        // Project to screen
        Vector3 worldPos  = transform.position + Vector3.up * 0.5f; // slightly above pivot
        Vector3 screenPos = _playerCamera.WorldToScreenPoint(worldPos);

        if (screenPos.z <= 0f) return; // behind camera

        // Flip Y (GUI vs screen coords)
        float sx = screenPos.x;
        float sy = Screen.height - screenPos.y;

        GUIStyle style = new GUIStyle();
        style.fontSize  = 13;
        style.fontStyle = FontStyle.Bold;
        style.normal.textColor = colPrompt;
        style.alignment = TextAnchor.MiddleCenter;

        Vector2 size   = style.CalcSize(new GUIContent(promptText));
        float   padX   = 8f;
        float   padY   = 4f;
        float   bgW    = size.x + padX * 2f;
        float   bgH    = size.y + padY * 2f;
        Rect    bgRect = new Rect(sx - bgW * 0.5f, sy - bgH * 0.5f, bgW, bgH);
        Rect    txRect = new Rect(sx - size.x * 0.5f, sy - size.y * 0.5f, size.x, size.y);

        // Background
        Color prev = GUI.color;
        GUI.color = colPromptBg;
        GUI.DrawTexture(bgRect, _white);
        GUI.color = prev;

        GUI.Label(txRect, promptText, style);
    }

    void OnDrawGizmosSelected()
    {
        Gizmos.color = new Color(0f, 1f, 0.4f, 0.25f);
        Gizmos.DrawWireSphere(transform.position, interactRange);
    }
}