using UnityEngine;

namespace ProjectM.Client
{
    /// <summary>
    /// Shared asset-free procedural-FX toolkit for the client presentation FEEDBACK systems (Combat / Structure /
    /// World / Ambient), which previously each carried a near-identical private copy. Pure UnityEngine (no ECS), so
    /// it stays a plain static helper. MakeBurst takes the owning FX-root transform + the per-use gravity / shape
    /// radius / size-tail that were the ONLY real differences between the old copies (Combat 0/0.06/0.2,
    /// Structure 0.3/0.18/0.15, World 0.25/0.10/0.2). MakeClip folds in the noise + envelope-decay knobs that were
    /// the only differences between the CombatFeedback MakeClip and the AmbientAudio MakeSting.
    /// </summary>
    public static class FeedbackFx
    {
        public static AudioClip MakeClip(string name, float f0, float f1, float dur, float vol, bool noise = false, float decay = 5f)
        {
            const int rate = 44100;
            int len = Mathf.Max(16, (int)(dur * rate));
            var clip = AudioClip.Create(name, len, 1, rate, false);
            var data = new float[len];
            var rng = new System.Random(name.Length * 9973 + 7);
            float phase = 0f;
            for (int i = 0; i < len; i++)
            {
                float t = i / (float)len;
                float env = Mathf.Exp(-decay * t);
                float freq = Mathf.Lerp(f0, f1, t);
                phase += 2f * Mathf.PI * freq / rate;
                float s = noise ? (float)(rng.NextDouble() * 2.0 - 1.0) : Mathf.Sin(phase);
                data[i] = s * env * vol;
            }
            clip.SetData(data, 0);
            return clip;
        }

        static Texture2D s_softDot;

        /// <summary>
        /// Sprites/Default with NO texture renders hard SQUARES — which is what the ambient drift was painting
        /// across the seabed (found at the 2026-08-07 A0 gate). Build the dot procedurally instead of referencing
        /// an asset: runtime Resources.Load is stripped from player builds, and asset-free presentation is the
        /// house rule. Self-healing across fast-enter-playmode — a destroyed texture compares == null and rebuilds.
        /// </summary>
        public static Texture2D SoftDot()
        {
            if (s_softDot != null) return s_softDot;
            const int N = 32;
            var t = new Texture2D(N, N, TextureFormat.RGBA32, false)
            {
                name = "T_SoftDotProc",
                wrapMode = TextureWrapMode.Clamp
            };
            for (int y = 0; y < N; y++)
            {
                for (int x = 0; x < N; x++)
                {
                    float dx = (x + 0.5f) / N * 2f - 1f;
                    float dy = (y + 0.5f) / N * 2f - 1f;
                    float a = Mathf.Clamp01(1f - Mathf.Sqrt(dx * dx + dy * dy));
                    t.SetPixel(x, y, new Color(1f, 1f, 1f, a * a));   // squared = softer falloff
                }
            }
            t.Apply();
            s_softDot = t;
            return t;
        }

        public static Material MakeParticleMaterial(string name = "FeedbackParticle")
        {
            // Sprites/Default is an always-included transparent vertex-coloured shader (reliable billboarded sparks;
            // HDR start colours still push past the bloom threshold); fall back through URP unlit / Unlit/Color.
            Shader sh = Shader.Find("Sprites/Default");
            if (sh == null) sh = Shader.Find("Universal Render Pipeline/Particles/Unlit");
            if (sh == null) sh = Shader.Find("Unlit/Color");
            return new Material(sh) { name = name, mainTexture = SoftDot() };
        }

        public static ParticleSystem MakeBurst(Transform parent, string name, Material mat, Color color,
            float size, float speed, float life, int max,
            float gravity = 0f, float shapeRadius = 0.06f, float sizeTail = 0.2f)
        {
            var go = new GameObject(name);
            go.transform.SetParent(parent, false);
            var ps = go.AddComponent<ParticleSystem>();

            var main = ps.main;
            main.loop = false;
            main.playOnAwake = false;
            main.startLifetime = life;
            main.startSpeed = speed;
            main.startSize = size;
            main.startColor = color;
            main.maxParticles = max;
            main.gravityModifier = gravity;
            main.simulationSpace = ParticleSystemSimulationSpace.World;

            var emission = ps.emission;
            emission.enabled = false; // manual Emit(count)

            var shape = ps.shape;
            shape.enabled = true;
            shape.shapeType = ParticleSystemShapeType.Sphere;
            shape.radius = shapeRadius;

            var colOverLife = ps.colorOverLifetime;
            colOverLife.enabled = true;
            var grad = new Gradient();
            grad.SetKeys(
                new[] { new GradientColorKey(Color.white, 0f), new GradientColorKey(Color.white, 1f) },
                new[] { new GradientAlphaKey(1f, 0f), new GradientAlphaKey(0f, 1f) });
            colOverLife.color = new ParticleSystem.MinMaxGradient(grad);

            var sizeOverLife = ps.sizeOverLifetime;
            sizeOverLife.enabled = true;
            sizeOverLife.size = new ParticleSystem.MinMaxCurve(1f, AnimationCurve.Linear(0f, 1f, 1f, sizeTail));

            var renderer = ps.GetComponent<ParticleSystemRenderer>();
            renderer.material = mat;
            renderer.renderMode = ParticleSystemRenderMode.Billboard;
            return ps;
        }

        public static void EmitTinted(ParticleSystem ps, Vector3 pos, int count, Color tint)
        {
            if (ps == null) return;
            var main = ps.main;
            main.startColor = tint;
            ps.transform.position = pos;
            ps.Emit(count);
        }

        public static void EmitAt(ParticleSystem ps, Vector3 pos, int count)
        {
            if (ps == null) return;
            ps.transform.position = pos;
            ps.Emit(count);
        }

        public static void PlayClip(AudioClip clip, Vector3 pos, float vol)
        {
            if (clip == null) return;
            AudioSource.PlayClipAtPoint(clip, pos, vol * GameVolume.Sfx);
        }

        // ---- ground DECAL primitives (Bundle 2 — explosion scorch, cover cracks, room scars) ----

        // Transparent unlit ground-decal material: Sprites/Default honours vertex colour × the per-renderer _Color
        // MPB, blends alpha, is double-sided (Cull Off) and writes no depth (ZWrite Off) — so flat, overlapping
        // ground decals never z-fight and never cast/receive shadows. Same shader family as the fuse disc.
        public static Material MakeDecalMaterial(string name = "GroundDecal")
        {
            Shader sh = Shader.Find("Sprites/Default");
            if (sh == null) sh = Shader.Find("Universal Render Pipeline/Particles/Unlit");
            if (sh == null) sh = Shader.Find("Unlit/Transparent");
            return new Material(sh) { name = name, renderQueue = 3000 }; // Transparent
        }

        // Irregular soft radial disc on the XZ plane (already flat — scale x/z, spin about Y): vertex alpha 1 at the
        // centre fading to 0 at a JITTERED rim, so it reads as an organic scorch blob with NO hard rectangle edge
        // (the feathered rim is what keeps it from ghosting over fog the way an opaque quad did). White vertex colour
        // so the caller's material/MPB tint (dark char) shows through.
        public static Mesh BuildScorchMesh(int segments = 24, float jitter = 0.3f, int seed = 1)
        {
            if (segments < 6) segments = 6;
            var rng = new System.Random(seed * 6151 + 13);
            var m = new Mesh { name = "ScorchDecal" };
            var v = new Vector3[segments + 1];
            var col = new Color[segments + 1];
            var tris = new int[segments * 3];
            v[0] = Vector3.zero;
            col[0] = new Color(1f, 1f, 1f, 1f);
            for (int i = 0; i < segments; i++)
            {
                float a = i / (float)segments * Mathf.PI * 2f;
                float r = 1f - jitter * (float)rng.NextDouble();
                v[i + 1] = new Vector3(Mathf.Cos(a) * r, 0f, Mathf.Sin(a) * r);
                col[i + 1] = new Color(1f, 1f, 1f, 0f); // transparent feathered rim
                int n = (i + 1) % segments;
                tris[i * 3] = 0; tris[i * 3 + 1] = n + 1; tris[i * 3 + 2] = i + 1;
            }
            m.vertices = v; m.colors = col; m.triangles = tris;
            m.RecalculateBounds();
            return m;
        }

        // A jagged crack star on the XZ plane: `spokes` thin tapered triangles radiating from the centre at random
        // angles/lengths, opaque at the base and feathered to nothing at the tip. Reads as surface cracking, visually
        // distinct from the scorch blob. White vertex colour; caller tints dark and scales it to the piece.
        public static Mesh BuildCrackMesh(int spokes = 3, int seed = 1)
        {
            if (spokes < 1) spokes = 1;
            var rng = new System.Random(seed * 9277 + 5);
            var m = new Mesh { name = "CrackDecal" };
            var v = new Vector3[spokes * 3];
            var col = new Color[spokes * 3];
            var tris = new int[spokes * 3];
            for (int s = 0; s < spokes; s++)
            {
                float a = (s / (float)spokes) * Mathf.PI * 2f + (float)(rng.NextDouble() - 0.5) * 1.2f;
                float len = 0.6f + 0.4f * (float)rng.NextDouble();
                float w = 0.06f + 0.05f * (float)rng.NextDouble();
                var dir = new Vector3(Mathf.Cos(a), 0f, Mathf.Sin(a));
                var perp = new Vector3(-dir.z, 0f, dir.x) * w;
                int b = s * 3;
                v[b] = perp; v[b + 1] = -perp; v[b + 2] = dir * len;
                col[b] = new Color(1f, 1f, 1f, 1f);
                col[b + 1] = new Color(1f, 1f, 1f, 1f);
                col[b + 2] = new Color(1f, 1f, 1f, 0f); // feathered tip
                tris[b] = b; tris[b + 1] = b + 2; tris[b + 2] = b + 1;
            }
            m.vertices = v; m.colors = col; m.triangles = tris;
            m.RecalculateBounds();
            return m;
        }

        // Unit-radius upward-facing disc fan on the XZ plane (centre vertex + rim) for ground telegraph / blast-radius
        // rings — scale x/z to the radius. No vertex colours (white default) so the material or a per-renderer _Color
        // MPB fully tints + fades it. Promoted from WorldFeedbackSystem so the barrel fuse ring + the geyser telegraph
        // share ONE primitive (review M6).
        public static Mesh BuildDisc(int segments)
        {
            if (segments < 6) segments = 6;
            var m = new Mesh { name = "Disc" };
            var v = new Vector3[segments + 1];
            var tris = new int[segments * 3];
            v[0] = Vector3.zero;
            for (int i = 0; i < segments; i++)
            {
                float a = i / (float)segments * Mathf.PI * 2f;
                v[i + 1] = new Vector3(Mathf.Cos(a), 0f, Mathf.Sin(a));
                int n = (i + 1) % segments;
                tris[i * 3] = 0; tris[i * 3 + 1] = n + 1; tris[i * 3 + 2] = i + 1;
            }
            m.vertices = v;
            m.triangles = tris;
            m.RecalculateBounds();
            return m;
        }

        // Unit-radius thin RING (annulus) on the XZ plane — the always-on rim of a zone telegraph (rim = the TRUE
        // damage radius, guidelines G2) while a separate fill disc grows inside it. Scale x/z to the radius; inner
        // edge fixed at innerFrac of the outer. No vertex colours (white) so an MPB _Color fully tints + fades it.
        public static Mesh BuildRing(int segments, float innerFrac = 0.92f)
        {
            if (segments < 6) segments = 6;
            innerFrac = Mathf.Clamp(innerFrac, 0.05f, 0.98f);
            var m = new Mesh { name = "Ring" };
            var v = new Vector3[segments * 2];
            var tris = new int[segments * 6];
            for (int i = 0; i < segments; i++)
            {
                float a = i / (float)segments * Mathf.PI * 2f;
                var dir = new Vector3(Mathf.Cos(a), 0f, Mathf.Sin(a));
                v[i * 2] = dir * innerFrac;
                v[i * 2 + 1] = dir;
                int n = (i + 1) % segments;
                int b = i * 6;
                tris[b] = i * 2; tris[b + 1] = n * 2 + 1; tris[b + 2] = i * 2 + 1;
                tris[b + 3] = i * 2; tris[b + 4] = n * 2; tris[b + 5] = n * 2 + 1;
            }
            m.vertices = v;
            m.triangles = tris;
            m.RecalculateBounds();
            return m;
        }
    }
}