using UnityEngine;

/// <summary>
/// Draws the player health and stamina bars.
/// Attach to the Player GameObject alongside Player.cs
/// 
/// Deliberately ugly. This is a Cruelty Squad game.
/// </summary>
public class PlayerHUD : MonoBehaviour
{
    [Header("Layout")]
    public float barWidth       = 220f;
    public float barHeight      = 16f;
    public float barSpacing     = 10f;  // gap between health and stamina bars
    public float edgePadX       = 18f;
    public float edgePadY       = 18f;
    public AnchorCorner anchor  = AnchorCorner.BottomLeft;

    public enum AnchorCorner { BottomLeft, BottomRight, TopLeft, TopRight }

    [Header("Health Bar")]
    public Color colHealthFull      = new Color(0.15f, 0.80f, 0.25f, 1f);
    public Color colHealthMid       = new Color(0.85f, 0.75f, 0.05f, 1f);
    public Color colHealthLow       = new Color(0.90f, 0.12f, 0.12f, 1f);
    public float healthMidThreshold = 0.5f;
    public float healthLowThreshold = 0.25f;

    [Header("Stamina Bar")]
    public Color colStaminaNormal   = new Color(0.20f, 0.55f, 0.95f, 1f);
    public Color colStaminaRegen    = new Color(0.20f, 0.55f, 0.95f, 0.45f); // dimmed while regenerating
    public Color colStaminaExhaust  = new Color(0.60f, 0.18f, 0.18f, 1f);   // red flash when tapped out

    [Header("Shared Style")]
    public Color colBarBackground   = new Color(0.06f, 0.06f, 0.06f, 0.90f);
    public Color colBarBorder       = new Color(0.28f, 0.28f, 0.28f, 1.00f);
    public Color colLabel           = new Color(0.80f, 0.80f, 0.80f, 1.00f);
    public Color colLabelCritical   = new Color(1.00f, 0.25f, 0.25f, 1.00f);
    public float borderThickness    = 1.5f;

    [Header("Pulse")]
    [Tooltip("The low-health bar pulses opacity when below the low threshold.")]
    public float pulseSpeed = 3.5f;

    [Header("Speedometer")]
    public bool  showSpeedometer    = true;
    public Color colSpeedo          = new Color(0.20f, 0.95f, 0.40f, 1f);
    public Color colSpeedoFast      = new Color(0.95f, 0.80f, 0.10f, 1f);
    public Color colSpeedoCritical  = new Color(0.95f, 0.20f, 0.20f, 1f);
    public float speedoFastThreshold = 60f;
    public float speedoCritThreshold = 75f;

    // ─── Private ─────────────────────────────────────────────────────
    private Player              _player;
    private CharacterController _cc;
    private Texture2D           _white;

    // Smooth display values so bars glide rather than snap
    private float _displayHealth  = 1f;
    private float _displayStamina = 1f;
    private const float kSmoothSpeed = 8f;

    // Speed tracking
    private Vector3 _lastPos;
    private float   _displaySpeed;

    // ─────────────────────────────────────────────────────────────────
    void Start()
    {
        _player   = GetComponent<Player>();
        _cc       = GetComponent<CharacterController>();
        _white    = Texture2D.whiteTexture;
        _lastPos  = transform.position;

        if (_player == null)
            Debug.LogWarning("[PlayerHUD] No Player component found on this GameObject!");
    }

    void Update()
    {
        if (_player == null) return;

        // Smooth bar fill values towards actual values
        _displayHealth  = Mathf.Lerp(_displayHealth,  _player.HealthFraction,  Time.deltaTime * kSmoothSpeed);
        _displayStamina = Mathf.Lerp(_displayStamina, _player.StaminaFraction, Time.deltaTime * kSmoothSpeed);

        // Calculate speed from position delta (horizontal only)
        Vector3 pos = transform.position;
        float rawSpeed = new Vector3(pos.x - _lastPos.x, 0f, pos.z - _lastPos.z).magnitude / Time.deltaTime;
        _displaySpeed = Mathf.Lerp(_displaySpeed, rawSpeed, Time.deltaTime * 10f);
        _lastPos = pos;
    }

    void OnGUI()
    {
        if (_player == null) return;

        float totalH = barHeight * 2f + barSpacing + 20f; // label heights included
        float totalW = barWidth;

        float ox, oy;
        switch (anchor)
        {
            case AnchorCorner.BottomLeft:
                ox = edgePadX;
                oy = Screen.height - totalH - edgePadY;
                break;
            case AnchorCorner.BottomRight:
                ox = Screen.width - totalW - edgePadX;
                oy = Screen.height - totalH - edgePadY;
                break;
            case AnchorCorner.TopLeft:
                ox = edgePadX;
                oy = edgePadY;
                break;
            default: // TopRight
                ox = Screen.width - totalW - edgePadX;
                oy = edgePadY;
                break;
        }

        float cursor = oy;

        // ── Health bar ───────────────────────────────────────────────
        cursor = DrawStatBar(
            ox, cursor,
            label:          "HEALTH",
            value:          _player.health,
            maxValue:       _player.maxHealth,
            displayFraction: _displayHealth,
            fillColor:      GetHealthColor(),
            pulse:          _player.HealthFraction <= healthLowThreshold,
            labelCritical:  _player.HealthFraction <= healthLowThreshold
        );

        cursor += barSpacing;

        // ── Stamina bar ──────────────────────────────────────────────
        Color staminaColor;
        if (_player.isExhausted)
            staminaColor = colStaminaExhaust;
        else if (!_player.isSprinting && _player.StaminaFraction < 1f)
            staminaColor = colStaminaRegen;
        else
            staminaColor = colStaminaNormal;

        string staminaLabel = _player.isExhausted ? "STAMINA  [EXHAUSTED]" : "STAMINA";

        DrawStatBar(
            ox, cursor,
            label:          staminaLabel,
            value:          _player.stamina,
            maxValue:       _player.maxStamina,
            displayFraction: _displayStamina,
            fillColor:      staminaColor,
            pulse:          _player.isExhausted,
            labelCritical:  _player.isExhausted
        );

        // ── Speedometer ──────────────────────────────────────────────
        if (showSpeedometer && _cc != null)
            DrawSpeedometer(ox, oy - 90f);
    }

    void DrawSpeedometer(float x, float y)
    {
        float speed = _displaySpeed;

        Color col;
        if      (speed >= speedoCritThreshold) col = colSpeedoCritical;
        else if (speed >= speedoFastThreshold) col = colSpeedoFast;
        else                                   col = colSpeedo;

        float w = 130f;
        float h = 70f;

        // Dark backing box
        DrawTex(new Rect(x - 6f, y - 6f, w + 12f, h + 12f), new Color(0f, 0f, 0f, 0.55f));
        // Coloured left edge accent
        DrawTex(new Rect(x - 6f, y - 6f, 3f, h + 12f), col);

        // "SPEED" label
        GUIStyle labelStyle = new GUIStyle();
        labelStyle.fontSize  = 10;
        labelStyle.fontStyle = FontStyle.Bold;
        labelStyle.normal.textColor = new Color(col.r, col.g, col.b, 0.75f);
        GUI.Label(new Rect(x, y, w, 16f), "SPEED", labelStyle);

        // Big number
        GUIStyle numStyle = new GUIStyle();
        numStyle.fontSize  = 36;
        numStyle.fontStyle = FontStyle.Bold;
        numStyle.normal.textColor = col;
        GUI.Label(new Rect(x, y + 14f, w, 42f), $"{speed:F1}", numStyle);

        // Unit
        GUIStyle unitStyle = new GUIStyle();
        unitStyle.fontSize  = 10;
        unitStyle.fontStyle = FontStyle.Normal;
        unitStyle.normal.textColor = new Color(col.r, col.g, col.b, 0.55f);
        GUI.Label(new Rect(x, y + 54f, w, 16f), "units / sec", unitStyle);
    }

    // ─── Bar renderer ─────────────────────────────────────────────────
    /// <summary>Draws one labelled bar. Returns the Y position after the bar.</summary>
    float DrawStatBar(
        float x, float y,
        string label,
        float value, float maxValue,
        float displayFraction,
        Color fillColor,
        bool pulse,
        bool labelCritical)
    {
        float labelH  = 14f;
        float innerW  = barWidth  - borderThickness * 2f;
        float innerH  = barHeight - borderThickness * 2f;

        // ── Label ────────────────────────────────────────────────────
        GUIStyle labelStyle = new GUIStyle();
        labelStyle.fontSize  = 10;
        labelStyle.fontStyle = FontStyle.Bold;
        labelStyle.normal.textColor = labelCritical ? colLabelCritical : colLabel;

        string valueStr = $"{Mathf.CeilToInt(value)} / {Mathf.CeilToInt(maxValue)}";
        GUI.Label(new Rect(x, y, barWidth * 0.6f, labelH), label, labelStyle);

        GUIStyle valStyle = new GUIStyle(labelStyle);
        valStyle.alignment = TextAnchor.UpperRight;
        valStyle.normal.textColor = labelCritical ? colLabelCritical : colLabel;
        GUI.Label(new Rect(x, y, barWidth, labelH), valueStr, valStyle);

        float barY = y + labelH + 2f;

        // ── Background ───────────────────────────────────────────────
        DrawTex(new Rect(x, barY, barWidth, barHeight), colBarBorder);
        DrawTex(new Rect(x + borderThickness, barY + borderThickness, innerW, innerH), colBarBackground);

        // ── Fill ─────────────────────────────────────────────────────
        float fillW = Mathf.Max(0f, displayFraction * innerW);

        // Pulse alpha on low health / exhaustion
        Color drawColor = fillColor;
        if (pulse)
        {
            float alpha = Mathf.Lerp(0.35f, 1f, (Mathf.Sin(Time.time * pulseSpeed) + 1f) * 0.5f);
            drawColor = new Color(fillColor.r, fillColor.g, fillColor.b, fillColor.a * alpha);
        }

        if (fillW > 0f)
            DrawTex(new Rect(x + borderThickness, barY + borderThickness, fillW, innerH), drawColor);

        // ── Segment tick marks (every 25%) ───────────────────────────
        for (int i = 1; i < 4; i++)
        {
            float tickX = x + borderThickness + innerW * (i / 4f);
            DrawTex(new Rect(tickX - 0.5f, barY + borderThickness, 1f, innerH),
                    new Color(0f, 0f, 0f, 0.45f));
        }

        return barY + barHeight; // bottom of bar
    }

    // ─── Helpers ─────────────────────────────────────────────────────
    Color GetHealthColor()
    {
        float f = _player.HealthFraction;
        if (f <= healthLowThreshold)
            return colHealthLow;
        if (f <= healthMidThreshold)
            return Color.Lerp(colHealthLow, colHealthMid, (f - healthLowThreshold) / (healthMidThreshold - healthLowThreshold));
        return Color.Lerp(colHealthMid, colHealthFull, (f - healthMidThreshold) / (1f - healthMidThreshold));
    }

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