using UnityEngine;
using System.Collections.Generic;

/// <summary>
/// Draws a circular radar in the top-left corner of the screen.
/// Shows enemies (red) and pickups (yellow-green) relative to the player.
/// Rotates so "up" on the radar = player's forward direction.
///
/// Attach to the Player GameObject alongside Player.cs / PlayerHUD.cs.
/// Cruelty Squad aesthetic: deliberately ugly, glitchy-looking.
/// </summary>
public class RadarHUD : MonoBehaviour
{
    // ─── Inspector ────────────────────────────────────────────────────
    [Header("Layout")]
    public float edgePadX   = 18f;
    public float edgePadY   = 18f;
    public float radarRadius = 60f;   // visual radius of the radar disc (px)
    public float worldRange  = 40f;   // world-space units the radar covers

    [Header("Scan")]
    [Tooltip("How often (seconds) to re-scan the scene for enemies/pickups.")]
    public float scanInterval = 0.25f;

    [Header("Colours")]
    public Color colBackground  = new Color(0.04f, 0.10f, 0.04f, 0.88f);
    public Color colRim         = new Color(0.18f, 0.70f, 0.22f, 0.90f);
    public Color colGrid        = new Color(0.18f, 0.70f, 0.22f, 0.20f);
    public Color colForwardTick = new Color(0.18f, 0.70f, 0.22f, 0.80f);
    public Color colEnemy       = new Color(0.95f, 0.12f, 0.12f, 1.00f);
    public Color colPickup      = new Color(0.90f, 0.85f, 0.05f, 1.00f);
    public Color colNPC         = new Color(0.20f, 0.95f, 0.40f, 1.00f);
    public Color colPlayerDot   = new Color(1.00f, 1.00f, 1.00f, 1.00f);

    [Header("Blip Sizes (px)")]
    public float enemyBlipSize  = 5f;
    public float pickupBlipSize = 4f;
    public float npcBlipSize    = 4f;
    public float playerDotSize  = 5f;

    [Header("Pulse")]
    [Tooltip("Enemies pulse their blip opacity.")]
    public float blipPulseSpeed = 4f;

    // ─── Private ──────────────────────────────────────────────────────
    private Texture2D _white;

    // Cached lists — refreshed on scanInterval
    private readonly List<Transform> _enemies = new List<Transform>();
    private readonly List<Transform> _pickups  = new List<Transform>();
    private readonly List<Transform> _npcs     = new List<Transform>();
    private float _nextScan;

    // Centre and radius of the drawn disc in screen pixels (set each OnGUI call)
    private Vector2 _centre;
    private float   _r;

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

    void Update()
    {
        if (Time.time >= _nextScan)
        {
            ScanScene();
            _nextScan = Time.time + scanInterval;
        }
    }

    void ScanScene()
    {
        _enemies.Clear();
        foreach (var e in FindObjectsOfType<HumanoidEnemy>())
            if (e != null) _enemies.Add(e.transform);

        _pickups.Clear();
        foreach (var p in FindObjectsOfType<PickupItem>())
            if (p != null) _pickups.Add(p.transform);

        _npcs.Clear();
        foreach (var n in FindObjectsOfType<DialogueNPC>())
            if (n != null) _npcs.Add(n.transform);
    }

    void OnGUI()
    {
        _r = radarRadius;
        // Radar disc centre: top-left corner + padding + radius
        float cx = edgePadX + _r;
        float cy = edgePadY + _r;
        _centre = new Vector2(cx, cy);

        // ── Background disc ──────────────────────────────────────────
        DrawDisc(cx, cy, _r, colBackground);

        // ── Grid rings (2 concentric) ─────────────────────────────────
        DrawDiscOutline(cx, cy, _r * 0.5f, colGrid, 1f);

        // ── Crosshair lines (faint) ────────────────────────────────────
        Color gridCol = colGrid;
        DrawTex(new Rect(cx - _r, cy - 0.5f, _r * 2f, 1f), gridCol);
        DrawTex(new Rect(cx - 0.5f, cy - _r, 1f, _r * 2f), gridCol);

        // ── Outer rim ────────────────────────────────────────────────
        DrawDiscOutline(cx, cy, _r, colRim, 1.5f);

        // ── Player forward tick ────────────────────────────────────────
        // A small notch at the top of the disc = player's forward
        DrawTex(new Rect(cx - 1.5f, cy - _r + 1f, 3f, 6f), colForwardTick);

        // ── Blips ─────────────────────────────────────────────────────
        float yaw = transform.eulerAngles.y;   // player yaw (world Y)

        float enemyPulse = Mathf.Lerp(0.45f, 1f,
            (Mathf.Sin(Time.time * blipPulseSpeed) + 1f) * 0.5f);

        // Pickups first (rendered under everything)
        foreach (var t in _pickups)
        {   
            if (t == null) continue;
            Vector2 blipPos;
            if (WorldToRadar(t.position, yaw, out blipPos))
                DrawBlip(blipPos.x, blipPos.y, pickupBlipSize, colPickup, 1f, square: true);
        }

        // NPCs — green dots
        foreach (var t in _npcs)
        {
            if (t == null) continue;
            Vector2 blipPos;
            if (WorldToRadar(t.position, yaw, out blipPos))
                DrawBlip(blipPos.x, blipPos.y, npcBlipSize, colNPC, 1f, square: false);
        }

        // Enemies
        Color enemyDraw = new Color(colEnemy.r, colEnemy.g, colEnemy.b, colEnemy.a * enemyPulse);
        foreach (var t in _enemies)
        {
            if (t == null) continue;
            Vector2 blipPos;
            if (WorldToRadar(t.position, yaw, out blipPos))
                DrawBlip(blipPos.x, blipPos.y, enemyBlipSize, enemyDraw, 1f, square: false);
        }

        // Player dot (always at centre)
        DrawBlip(cx, cy, playerDotSize, colPlayerDot, 1f, square: false);

        // ── Label ─────────────────────────────────────────────────────
        GUIStyle labelStyle = new GUIStyle();
        labelStyle.fontSize  = 8;
        labelStyle.fontStyle = FontStyle.Bold;
        labelStyle.normal.textColor = new Color(colRim.r, colRim.g, colRim.b, 0.65f);
        GUI.Label(new Rect(cx - _r, cy + _r + 3f, _r * 2f, 12f), "RADAR", labelStyle);
    }

    // ─── Conversion ───────────────────────────────────────────────────
    /// <summary>
    /// Converts a world position to a radar screen position.
    /// Returns false if the point is outside the radar range.
    /// </summary>
    bool WorldToRadar(Vector3 worldPos, float playerYawDeg, out Vector2 screenPos)
    {
        Vector3 delta = worldPos - transform.position;
        float dx = delta.x;
        float dz = delta.z;

        // Rotate so player forward = up on radar
        float rad = playerYawDeg * Mathf.Deg2Rad;
        float rx =  dx * Mathf.Cos(rad) - dz * Mathf.Sin(rad);
        float ry =  dx * Mathf.Sin(rad) + dz * Mathf.Cos(rad);

        // Normalise to radar pixel space
        float px = _centre.x + (rx / worldRange) * _r;
        float py = _centre.y - (ry / worldRange) * _r;  // screen Y is flipped

        // Clamp to disc edge if outside range
        float dist = new Vector2(rx, ry).magnitude;
        if (dist > worldRange)
        {
            // Show as a dim edge blip
            float ex = _centre.x + (rx / dist) * (_r - 3f);
            float ey = _centre.y - (ry / dist) * (_r - 3f);
            screenPos = new Vector2(ex, ey);
            return true;   // still draw, but at edge
        }

        screenPos = new Vector2(px, py);
        return true;
    }

    // ─── Drawing helpers ──────────────────────────────────────────────

    void DrawBlip(float x, float y, float size, Color col, float alpha, bool square)
    {
        Color c = new Color(col.r, col.g, col.b, col.a * alpha);
        float half = size * 0.5f;
        if (square)
        {
            DrawTex(new Rect(x - half, y - half, size, size), c);
        }
        else
        {
            // Approximate circle with a 3x3 cross pattern
            DrawTex(new Rect(x - half,        y - half * 0.4f, size,        size * 0.4f), c);
            DrawTex(new Rect(x - half * 0.4f, y - half,        size * 0.4f, size),        c);
        }
    }

    /// <summary>Draws a filled circle approximated by a square (fast IMGUI).</summary>
    void DrawDisc(float cx, float cy, float r, Color col)
    {
        // Draw as a stack of horizontal lines to get a rough circle
        int steps = Mathf.CeilToInt(r * 2f);
        for (int i = 0; i < steps; i++)
        {
            float t  = (i / (float)steps) * 2f - 1f;  // -1 to 1
            float hw = Mathf.Sqrt(Mathf.Max(0f, 1f - t * t)) * r;
            float y  = cy + t * r;
            DrawTex(new Rect(cx - hw, y, hw * 2f, 1f), col);
        }
    }

    /// <summary>Draws a thin circle outline.</summary>
    void DrawDiscOutline(float cx, float cy, float r, Color col, float thickness)
    {
        int segments = Mathf.Max(32, Mathf.CeilToInt(r * 3f));
        for (int i = 0; i < segments; i++)
        {
            float a0 = (i       / (float)segments) * Mathf.PI * 2f;
            float a1 = ((i + 1) / (float)segments) * Mathf.PI * 2f;

            float x0 = cx + Mathf.Cos(a0) * r;
            float y0 = cy + Mathf.Sin(a0) * r;
            float x1 = cx + Mathf.Cos(a1) * r;
            float y1 = cy + Mathf.Sin(a1) * r;

            // Draw a tiny rect along each segment
            float len = Mathf.Sqrt((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0));
            if (len < 0.01f) continue;

            DrawTex(new Rect(Mathf.Min(x0, x1) - thickness * 0.5f,
                             Mathf.Min(y0, y1) - thickness * 0.5f,
                             Mathf.Abs(x1 - x0) + thickness,
                             Mathf.Abs(y1 - y0) + thickness), col);
        }
    }

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