const assert = require("node:assert/strict");
const fs = require("node:fs");
const path = require("node:path");
const vm = require("node:vm");

const mainPath = process.argv[2]
  ? path.resolve(process.argv[2])
  : path.join(__dirname, "midctrl-homepage-optimized", "assets", "js", "main.js");
const source = fs.readFileSync(mainPath, "utf8");

const events = [];
const consoleErrors = [];
const windowListeners = new Map();
const documentListeners = new Map();
const canvasListeners = new Map();
const timers = new Map();
let nextTimerId = 1;
let rafQueue = [];
let rafTime = 0;
let nextObjectId = 1;
let reducedMotionChangeListener = null;
let documentHidden = true;
let documentReadyState = "loading";

function addListener(store, type, callback) {
  if (!store.has(type)) store.set(type, []);
  store.get(type).push(callback);
}

function emit(store, type, event = {}) {
  for (const callback of store.get(type) || []) callback(event);
}

function flushTimers() {
  const pending = [...timers.entries()];
  timers.clear();
  for (const [, callback] of pending) callback();
}

function flushAnimationFrames() {
  const pending = rafQueue;
  rafQueue = [];
  rafTime += 16.667;
  for (const callback of pending) callback(rafTime);
}

function makeObject(type) {
  return { type, id: nextObjectId++ };
}

const constants = {
  NO_ERROR: 0,
  FRAMEBUFFER_COMPLETE: 0x8cd5,
  MAX_TEXTURE_SIZE: 0x0d33,
  MAX_RENDERBUFFER_SIZE: 0x84e8,
  ALIASED_POINT_SIZE_RANGE: 0x846d,
  COMPILE_STATUS: 0x8b81,
  LINK_STATUS: 0x8b82,
  VERTEX_SHADER: 0x8b31,
  FRAGMENT_SHADER: 0x8b30,
  HIGH_FLOAT: 0x8df2,
  TEXTURE0: 0x84c0,
  TEXTURE1: 0x84c1,
};

const glTarget = {
  ...constants,
  failTexturePixelsAbove: Infinity,
  createFramebuffer() {
    events.push("createFramebuffer");
    return makeObject("framebuffer");
  },
  deleteFramebuffer() {
    events.push("deleteFramebuffer");
  },
  createTexture() {
    return makeObject("texture");
  },
  deleteTexture() {},
  createRenderbuffer() {
    return makeObject("renderbuffer");
  },
  deleteRenderbuffer() {},
  createShader() {
    return makeObject("shader");
  },
  createProgram() {
    return makeObject("program");
  },
  createBuffer() {
    return makeObject("buffer");
  },
  texImage2D(target, level, internalFormat, width, height) {
    if (width * height > this.failTexturePixelsAbove) {
      events.push("textureAllocationFailed");
      throw new Error("Synthetic texture allocation failure.");
    }
  },
  getParameter(parameter) {
    if (parameter === this.MAX_TEXTURE_SIZE || parameter === this.MAX_RENDERBUFFER_SIZE) return 16384;
    if (parameter === this.ALIASED_POINT_SIZE_RANGE) return [1, 64];
    return null;
  },
  getShaderPrecisionFormat() {
    return { precision: 23 };
  },
  getShaderParameter() {
    return true;
  },
  getProgramParameter() {
    return true;
  },
  getShaderInfoLog() {
    return "";
  },
  getProgramInfoLog() {
    return "";
  },
  getUniformLocation() {
    return makeObject("uniform");
  },
  getAttribLocation() {
    return 0;
  },
  checkFramebufferStatus() {
    return this.FRAMEBUFFER_COMPLETE;
  },
  getError() {
    return this.NO_ERROR;
  },
  isContextLost() {
    return false;
  },
  finish() {
    events.push("finish");
  },
};

let generatedConstant = 0x10000;
const gl = new Proxy(glTarget, {
  get(target, property) {
    if (property in target) return target[property];
    if (typeof property === "string" && /^[A-Z0-9_]+$/.test(property)) {
      target[property] = generatedConstant++;
      return target[property];
    }
    if (typeof property === "string") {
      target[property] = function noop() {};
      return target[property];
    }
    return undefined;
  },
});

const canvas = {
  width: 300,
  height: 150,
  hidden: false,
  getContext() {
    return gl;
  },
  addEventListener(type, callback) {
    addListener(canvasListeners, type, callback);
  },
};
gl.canvas = canvas;

const year = { textContent: "" };
const mediaQuery = {
  matches: false,
  addEventListener(type, callback) {
    if (type === "change") reducedMotionChangeListener = callback;
  },
  addListener(callback) {
    reducedMotionChangeListener = callback;
  },
};
const context = {
  console: {
    log() {},
    warn() {},
    error(...args) {
      consoleErrors.push(args.map(String).join(" "));
    },
  },
  document: {
    get hidden() {
      return documentHidden;
    },
    get visibilityState() {
      return documentHidden ? "hidden" : "visible";
    },
    get readyState() {
      return documentReadyState;
    },
    documentElement: { clientWidth: 1280, clientHeight: 720 },
    querySelector(selector) {
      if (selector === "#year") return year;
      return null;
    },
    getElementById(id) {
      return id === "sakura" ? canvas : null;
    },
    addEventListener(type, callback) {
      addListener(documentListeners, type, callback);
    },
  },
  navigator: { deviceMemory: 8 },
  innerWidth: 1280,
  innerHeight: 720,
  devicePixelRatio: 1,
  performance: { now: () => rafTime },
  matchMedia() {
    return mediaQuery;
  },
  addEventListener(type, callback) {
    addListener(windowListeners, type, callback);
  },
  setTimeout(callback) {
    const id = nextTimerId++;
    timers.set(id, callback);
    return id;
  },
  clearTimeout(id) {
    timers.delete(id);
  },
  requestAnimationFrame(callback) {
    rafQueue.push(callback);
    return rafQueue.length;
  },
  cancelAnimationFrame() {
    // Deliberately leave the callback queued to verify generation guards in
    // browsers where cancellation races with a frame already being dispatched.
    events.push("cancelAnimationFrame");
  },
  Date,
  Math,
  Number,
  Object,
  Array,
  Float32Array,
  Uint8Array,
  isFinite,
};
context.window = context;
context.globalThis = context;

vm.runInNewContext(source, context, { filename: "main.js" });

assert.equal(events.filter((event) => event === "createFramebuffer").length, 0, "WebGL must wait only for the DOM");
documentHidden = false;
documentReadyState = "interactive";
emit(documentListeners, "DOMContentLoaded");

assert.equal(consoleErrors.length, 0, "initialization must not log errors");
assert.deepEqual([canvas.width, canvas.height], [1280, 720]);
assert.equal(events.filter((event) => event === "createFramebuffer").length, 3);
assert.equal(rafQueue.length, 1, "a missed pre-DOM visibility transition must still start animation");

function resize(width, height, dpr, burstCount = 1) {
  context.innerWidth = width;
  context.innerHeight = height;
  context.devicePixelRatio = dpr;
  context.document.documentElement.clientWidth = width;
  context.document.documentElement.clientHeight = height;
  for (let i = 0; i < burstCount; i++) emit(windowListeners, "resize");
  assert.equal(timers.size, 1, "resize bursts must collapse to one timer");
  flushTimers();
  flushAnimationFrames();
}

events.length = 0;
resize(1366, 768, 1, 25);
assert.equal(events.filter((event) => event === "createFramebuffer").length, 3);
assert.equal(events.filter((event) => event === "deleteFramebuffer").length, 3);
assert.ok(events.indexOf("createFramebuffer") < events.indexOf("deleteFramebuffer"));

events.length = 0;
resize(3000, 1800, 2);
assert.ok(canvas.width * canvas.height <= 10000000, "normal pixel budget must be enforced");

events.length = 0;
resize(3200, 1800, 2);
assert.equal(events.filter((event) => event === "finish").length, 1);
assert.equal(events.filter((event) => event === "deleteFramebuffer").length, 3);
assert.equal(events.filter((event) => event === "createFramebuffer").length, 3);
assert.ok(events.indexOf("deleteFramebuffer") < events.indexOf("createFramebuffer"));

events.length = 0;
gl.failTexturePixelsAbove = 5000000;
resize(3600, 2000, 2);
assert.ok(events.filter((event) => event === "textureAllocationFailed").length >= 2);
assert.ok(canvas.width * canvas.height <= 5000000, "failed allocations must fall back to a smaller target");
assert.equal(consoleErrors.length, 0, "successful fallback must not log a terminal error");

events.length = 0;
gl.failTexturePixelsAbove = Infinity;
let contextLossPrevented = false;

documentHidden = true;
emit(windowListeners, "pagehide", { persisted: true });
assert.equal(events.filter((event) => event === "cancelAnimationFrame").length, 1);
assert.equal(rafQueue.length, 1, "the mock retains the stale frame after pagehide");
documentHidden = false;
emit(windowListeners, "pageshow", { persisted: true });
assert.equal(rafQueue.length, 2, "pageshow must queue a replacement frame");
emit(windowListeners, "pageshow", { persisted: true });
assert.equal(rafQueue.length, 3, "a repeated pageshow replaces the pending frame in the mock queue");
flushAnimationFrames();
assert.equal(rafQueue.length, 1, "only the newest pageshow loop may continue");

events.length = 0;
mediaQuery.matches = true;
reducedMotionChangeListener({ matches: true });
assert.equal(events.filter((event) => event === "cancelAnimationFrame").length, 1);
flushAnimationFrames();
assert.equal(rafQueue.length, 0, "reduced motion must leave no live animation callback");
mediaQuery.matches = false;
reducedMotionChangeListener({ matches: false });
assert.equal(rafQueue.length, 1, "animation must have one pending frame before context loss");

events.length = 0;
emit(canvasListeners, "webglcontextlost", {
  preventDefault() {
    contextLossPrevented = true;
  },
});
emit(canvasListeners, "webglcontextrestored");
assert.equal(contextLossPrevented, true);
assert.equal(events.filter((event) => event === "createFramebuffer").length, 3);
assert.equal(events.filter((event) => event === "cancelAnimationFrame").length, 1);
assert.equal(rafQueue.length, 2, "the mock keeps both the stale and restored callbacks queued");
flushAnimationFrames();
assert.equal(rafQueue.length, 1, "only the restored animation loop may schedule the next frame");
assert.equal(consoleErrors.length, 0, "context restoration must not log errors");

console.log("PASS: cold start, page recovery, Render Target resize, fallback, and context restoration");