import { YawnCore } from "@yawn/core";
import { cameraBasis } from "./math.js";

function wire(v) {
  if (Array.isArray(v)) return `(array ${v.map(wire).join(" ")})`;
  if (v && typeof v === "object")
    return `(object ${Object.entries(v)
      .map(([k, x]) => `(field ${JSON.stringify(k)} ${wire(x)})`)
      .join(" ")})`;
  return JSON.stringify(v);
}
const shader = `
struct Camera { right:vec4f, up:vec4f, forward:vec4f, center:vec4f, color:vec4f }
@group(0) @binding(0) var<uniform> camera:Camera;
struct Out { @builtin(position) position:vec4f, @location(0) normal:vec3f }
@vertex fn vertex(@location(0) p:vec3f, @location(1) n:vec3f)->Out {
  let d=p-camera.center.xyz;
  var o:Out;
  o.position=vec4f(dot(d,camera.right.xyz)/camera.right.w,dot(d,camera.up.xyz)/camera.up.w,0.5-dot(d,camera.forward.xyz)/32.0,1.0);
  o.normal=vec3f(dot(n,camera.right.xyz),dot(n,camera.up.xyz),dot(n,camera.forward.xyz));return o;
}
@fragment fn fragment(o:Out)->@location(0) vec4f {
  let n=normalize(o.normal);
  let key=max(dot(n,normalize(vec3f(-0.5,0.8,1.0))),0.0);
  let fill=max(dot(n,normalize(vec3f(0.8,0.0,0.4))),0.0);
  let rim=pow(1.0-max(n.z,0.0),3.0);
  let spec=pow(max(dot(n,normalize(vec3f(-0.3,0.45,1.0))),0.0),48.0);
  let color=camera.color.xyz*(0.24+key*0.65+fill*0.16)+vec3f(0.12,0.14,0.16)*rim+vec3f(0.12)*spec;
  return vec4f(pow(color,vec3f(1.0/2.2)),1.0);
}`;

export class Renderer {
  static async create(canvas, mesh, camera, quality = "balanced") {
    const rect = canvas.getBoundingClientRect();
    const pixels =
      quality === "economy" ? 600000 : quality === "detail" ? 2000000 : 1000000;
    const scale = Math.min(
      devicePixelRatio,
      quality === "economy" ? 1 : quality === "detail" ? 2 : 1.5,
      Math.sqrt(pixels / (rect.width * rect.height)),
    );
    canvas.width = Math.max(1, Math.round(rect.width * scale));
    canvas.height = Math.max(1, Math.round(rect.height * scale));
    const r = new Renderer();
    r.canvas = canvas;
    r.mesh = mesh;
    const bytes =
      (mesh.positions.length / 3) * 32 +
      Math.ceil(mesh.indices.length / 4) * 16 +
      80 +
      64 +
      256;
    if (bytes > 8 * 1024 * 1024)
      throw new Error("Mesh exceeds the render arena");
    r.core = new YawnCore(canvas, { arenaBytes: 8 * 1024 * 1024 });
    let timedOut = false;
    const timeout = setTimeout(() => {
      timedOut = true;
      r.dispose();
    }, 20000);
    try {
      await r.core.ready;
      [r.vertices, r.indices, r.camera, r.sample] =
        await r.core.createRowsBatch([
          {
            name: "sculptVertices",
            rows: mesh.positions.length / 3,
            stride: 32,
            format: "f32",
          },
          {
            name: "sculptIndices",
            rows: Math.ceil(mesh.indices.length / 4),
            stride: 16,
            format: "u32",
          },
          { name: "sculptCamera", rows: 1, stride: 80, format: "f32" },
          { name: "sculptSample", rows: 1, stride: 64, format: "i32" },
        ]);
      r.sample.view.fill(0);
      r.indices.view.set(mesh.indices);
      r.writeVertices(0, mesh.positions.length / 3);
      r.writeCamera(camera);
      const graph = {
        id: "sculpt",
        resources: {
          buffers: [
            {
              id: "vertices",
              array: "sculptVertices",
              usage: ["vertex"],
              sync: "manual",
            },
            {
              id: "indices",
              array: "sculptIndices",
              usage: ["index"],
              sync: "manual",
            },
            {
              id: "camera",
              array: "sculptCamera",
              usage: ["uniform"],
              sync: "manual",
            },
          ],
          textures: [
            {
              id: "depth",
              format: "depth24plus",
              size: ["canvas", "canvas"],
              usage: ["render"],
            },
          ],
        },
        pipelines: {
          render: [
            {
              id: "clay",
              code: shader,
              vertex: {
                buffers: [
                  {
                    arrayStride: 32,
                    attributes: [
                      { format: "float32x3", offset: 0, shaderLocation: 0 },
                      { format: "float32x3", offset: 16, shaderLocation: 1 },
                    ],
                  },
                ],
              },
              fragment: { targets: [{ format: "canvas" }] },
              primitive: {
                topology: "triangle-list",
                frontFace: "ccw",
                cullMode: "back",
                conservative: false,
              },
              depthStencil: {
                format: "depth24plus",
                depth_write_enabled: true,
                depth_compare: "less",
              },
            },
          ],
        },
        passes: [
          {
            id: "sculpt",
            type: "render",
            pipeline: "clay",
            bindings: [{ binding: 0, resource: "camera" }],
            color: [{ resource: "canvas", clear: [0.12, 0.14, 0.17, 1] }],
            depth: { resource: "depth" },
            vertexBuffers: [{ resource: "vertices" }],
            indexBuffer: { resource: "indices" },
            draw: { indices: mesh.indices.length, instances: 1 },
          },
        ],
      };
      await r.core.switchLoadout(
        await r.core.compileGraph(`(yawn-graph 1 ${wire(graph)})`),
      );
      await r.core.setFps(quality === "economy" ? 30 : 60);
      await r.core.play();
      return r;
    } catch (error) {
      r.dispose();
      if (timedOut) throw new Error("Renderer initialization timed out");
      throw error;
    } finally {
      clearTimeout(timeout);
    }
  }
  writeVertices(first, count) {
    const p = this.mesh.positions,
      n = this.mesh.normals,
      v = this.vertices.view;
    for (let i = first; i < first + count; i++) {
      const a = i * 3,
        b = i * 8;
      v[b] = p[a];
      v[b + 1] = p[a + 1];
      v[b + 2] = p[a + 2];
      v[b + 4] = n[a];
      v[b + 5] = n[a + 1];
      v[b + 6] = n[a + 2];
    }
  }
  writeCamera(camera) {
    const { right, up, forward } = cameraBasis(camera.yaw, camera.pitch);
    const aspect = this.canvas.width / this.canvas.height;
    this.camera.view.set([
      ...right,
      camera.zoom * aspect,
      ...up,
      camera.zoom,
      ...forward,
      0,
      ...camera.target,
      0,
      ...camera.color,
      0,
    ]);
  }
  // One acknowledged publication at a time: shared staging bytes are immutable in flight.
  async publish(engine, camera) {
    if (this.busy || this.disposed) return false;
    this.busy = true;
    const timeout = setTimeout(() => this.dispose(), 10000);
    try {
      let first = Infinity,
        last = -1;
      for (const v of engine.dirty) {
        first = Math.min(first, v);
        last = Math.max(last, v);
      }
      engine.dirty.clear();
      if (last >= first) {
        this.writeVertices(first, last - first + 1);
        await this.core.syncRows("sculptVertices", first, last - first + 1);
      }
      if (this.disposed) return false;
      this.writeCamera(camera);
      await this.core.syncRows("sculptCamera", 0, 1);
      return true;
    } finally {
      clearTimeout(timeout);
      this.busy = false;
    }
  }
  dispose() {
    this.disposed = true;
    this.processor?.dispose();
    this.core?.dispose();
  }
}