using UnityEngine;

/// <summary>
/// Singleton. Manages the dialogue UI box.
/// Attach to any persistent GameObject in the scene (e.g. a "Managers" object),
/// or drop it on the Player — it will survive fine either way.
///
/// Controls:
///   E or Space or Enter  — advance to next page / close
///   Escape               — close immediately
///
/// While dialogue is open:
///   - Cursor is unlocked and visible
///   - FirstPersonController mouse look is blocked (via IsOpen flag)
/// </summary>
public class DialogueManager : MonoBehaviour
{
    // ── Singleton ─────────────────────────────────────────────────────
    public static DialogueManager Instance { get; private set; }

    // ── Inspector ─────────────────────────────────────────────────────
    [Header("Box Layout")]
    [Tooltip("Height of the dialogue box as a fraction of screen height.")]
    public float boxHeightFraction = 0.22f;
    public float boxMargin         = 24f;
    public float innerPad          = 18f;

    [Header("Colours — Cruelty Squad palette")]
    public Color colBoxBg      = new Color(0.04f, 0.06f, 0.04f, 0.94f);
    public Color colBoxBorder  = new Color(0.18f, 0.75f, 0.22f, 0.90f);
    public Color colNameBg     = new Color(0.10f, 0.28f, 0.10f, 1.00f);
    public Color colNameText   = new Color(0.25f, 1.00f, 0.30f, 1.00f);
    public Color colBodyText   = new Color(0.78f, 0.90f, 0.78f, 1.00f);
    public Color colHintText   = new Color(0.35f, 0.55f, 0.35f, 0.85f);
    public Color colPageDots   = new Color(0.28f, 0.65f, 0.30f, 0.80f);

    [Header("Text")]
    public int   nameFontSize = 13;
    public int   bodyFontSize = 14;
    public int   hintFontSize = 10;

    [Header("Typewriter Effect")]
    public bool  useTypewriter     = true;
    public float charsPerSecond    = 40f;

    // ── Public state ──────────────────────────────────────────────────
    public bool IsOpen { get; private set; }

    // ── Private ───────────────────────────────────────────────────────
    private DialogueLine[] _lines;
    private int            _lineIndex;
    private int            _pageIndex;

    // Typewriter
    private float  _charTimer;
    private int    _visibleChars;
    private bool   _pageComplete;

    private Texture2D _white;

    // ── Current text shortcuts ─────────────────────────────────────────
    private string CurrentSpeaker => (_lines != null && _lineIndex < _lines.Length)
        ? _lines[_lineIndex].speakerName : "";
    private string CurrentPage    => (_lines != null && _lineIndex < _lines.Length
        && _pageIndex < _lines[_lineIndex].pages.Length)
        ? _lines[_lineIndex].pages[_pageIndex] : "";
    private int TotalPages => (_lines != null && _lineIndex < _lines.Length)
        ? _lines[_lineIndex].pages.Length : 1;

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

    void Start()
    {
        _white = Texture2D.whiteTexture;
    }

    // ─────────────────────────────────────────────────────────────────
    public void StartDialogue(DialogueLine[] lines)
    {
        if (lines == null || lines.Length == 0) return;

        _lines      = lines;
        _lineIndex  = 0;
        _pageIndex  = 0;
        IsOpen      = true;

        BeginPage();

        Cursor.lockState = CursorLockMode.None;
        Cursor.visible   = true;
    }

    void BeginPage()
    {
        _charTimer    = 0f;
        _visibleChars = useTypewriter ? 0 : int.MaxValue;
        _pageComplete = !useTypewriter;
    }

    // ─────────────────────────────────────────────────────────────────
    void Update()
    {
        if (!IsOpen) return;

        // Advance typewriter
        if (useTypewriter && !_pageComplete)
        {
            _charTimer    += Time.deltaTime;
            _visibleChars  = Mathf.FloorToInt(_charTimer * charsPerSecond);
            if (_visibleChars >= CurrentPage.Length)
            {
                _visibleChars = CurrentPage.Length;
                _pageComplete = true;
            }
        }

        // Advance or close on E / Space / Return
        bool advance = Input.GetKeyDown(KeyCode.E)
                    || Input.GetKeyDown(KeyCode.Space)
                    || Input.GetKeyDown(KeyCode.Return);
        bool cancel  = Input.GetKeyDown(KeyCode.Escape);

        if (cancel)
        {
            CloseDialogue();
            return;
        }

        if (advance)
        {
            // If typewriter is still running, skip to end of page first
            if (useTypewriter && !_pageComplete)
            {
                _visibleChars = CurrentPage.Length;
                _pageComplete = true;
                return;
            }

            // Try next page in current line
            _pageIndex++;
            if (_pageIndex < TotalPages)
            {
                BeginPage();
                return;
            }

            // Try next line
            _lineIndex++;
            _pageIndex = 0;
            if (_lineIndex < _lines.Length)
            {
                BeginPage();
                return;
            }

            // All done
            CloseDialogue();
        }
    }

    void CloseDialogue()
    {
        IsOpen      = false;
        _lines      = null;

        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible   = false;
    }

    // ─────────────────────────────────────────────────────────────────
    void OnGUI()
    {
        if (!IsOpen || _lines == null) return;

        float sw  = Screen.width;
        float sh  = Screen.height;
        float bh  = sh * boxHeightFraction;
        float bw  = sw - boxMargin * 2f;
        float by  = sh - bh - boxMargin;
        float bx  = boxMargin;

        // ── Outer border ─────────────────────────────────────────────
        float border = 2f;
        DrawTex(new Rect(bx - border, by - border, bw + border * 2f, bh + border * 2f), colBoxBorder);

        // ── Main background ───────────────────────────────────────────
        DrawTex(new Rect(bx, by, bw, bh), colBoxBg);

        // ── Left accent stripe ────────────────────────────────────────
        DrawTex(new Rect(bx, by, 4f, bh), colBoxBorder);

        float cx = bx + innerPad + 6f; // content X (after the stripe + pad)
        float cy = by + innerPad;
        float cw = bw - innerPad * 2f - 6f;

        // ── Speaker name bar ──────────────────────────────────────────
        string speaker = CurrentSpeaker;
        float nameH = 0f;
        if (!string.IsNullOrWhiteSpace(speaker))
        {
            GUIStyle nameStyle = new GUIStyle();
            nameStyle.fontSize  = nameFontSize;
            nameStyle.fontStyle = FontStyle.Bold;
            nameStyle.normal.textColor = colNameText;
            nameStyle.alignment = TextAnchor.MiddleLeft;

            Vector2 ns = nameStyle.CalcSize(new GUIContent(speaker));
            nameH = ns.y + 6f;
            float namePadX = 10f;

            DrawTex(new Rect(cx - 2f, cy, ns.x + namePadX * 2f + 4f, nameH), colNameBg);
            GUI.Label(new Rect(cx + namePadX, cy + 3f, ns.x + 4f, ns.y), speaker, nameStyle);
            cy += nameH + 8f;
        }

        // ── Body text (typewriter) ────────────────────────────────────
        string fullText    = CurrentPage;
        string visibleText = useTypewriter
            ? fullText.Substring(0, Mathf.Min(_visibleChars, fullText.Length))
            : fullText;

        GUIStyle bodyStyle = new GUIStyle();
        bodyStyle.fontSize  = bodyFontSize;
        bodyStyle.fontStyle = FontStyle.Normal;
        bodyStyle.normal.textColor = colBodyText;
        bodyStyle.wordWrap  = true;
        bodyStyle.richText  = true;

        float bodyH = bh - innerPad * 2f - nameH - 8f - 20f; // leave room for hint
        GUI.Label(new Rect(cx, cy, cw, bodyH), visibleText, bodyStyle);

        // ── Page indicator dots ───────────────────────────────────────
        int total = TotalPages;
        if (total > 1)
        {
            float dotR   = 4f;
            float dotGap = dotR * 2f + 4f;
            float dotsW  = total * dotGap;
            float dotX   = bx + bw * 0.5f - dotsW * 0.5f;
            float dotY   = by + bh - innerPad - dotR;

            for (int i = 0; i < total; i++)
            {
                Color dc = (i == _pageIndex) ? colBoxBorder : colPageDots;
                DrawTex(new Rect(dotX + i * dotGap, dotY - dotR, dotR * 2f, dotR * 2f), dc);
            }
        }

        // ── Advance hint ──────────────────────────────────────────────
        string hintStr = _pageComplete
            ? (_lineIndex >= _lines.Length - 1 && _pageIndex >= TotalPages - 1
                ? "[ E ] Close"
                : "[ E ] Next")
            : "[ E ] Skip";

        GUIStyle hintStyle = new GUIStyle();
        hintStyle.fontSize  = hintFontSize;
        hintStyle.fontStyle = FontStyle.Bold;
        hintStyle.normal.textColor = colHintText;
        hintStyle.alignment = TextAnchor.LowerRight;

        GUI.Label(new Rect(bx, by, bw - innerPad, bh - 6f), hintStr, hintStyle);
    }

    // ─────────────────────────────────────────────────────────────────
    void DrawTex(Rect r, Color c)
    {
        Color prev = GUI.color;
        GUI.color  = c;
        GUI.DrawTexture(r, _white);
        GUI.color  = prev;
    }
}