import type { Page } from '@playwright/test';

export const environmentChunkPattern = /\/assets\/environment-[^/]+\.js(?:[?#].*)?$/u;

export interface SceneInstrumentationSnapshot {
  activeAnimationFrames: number;
  maximumCanvasCount: number;
  audioContextsConstructed: number;
  liveAudioContexts: number;
  routeLabelsDrawn: string[];
  clearColors: string[];
  unhandledRejections: string[];
}

type InstrumentedWindow = Window & {
  __portfolioJourneyInstrumentation?: SceneInstrumentationSnapshot & {
    animationFrameIds: Set<number>;
    audioContexts: AudioContext[];
  };
};

/**
 * Installs browser-owned observers before application code runs. The helper
 * patches platform boundaries only; no test API is compiled into the site.
 */
export async function installSceneInstrumentation(page: Page): Promise<void> {
  await page.addInitScript(() => {
    const instrumentedWindow = window as InstrumentedWindow;
    const state: NonNullable<InstrumentedWindow['__portfolioJourneyInstrumentation']> = {
      activeAnimationFrames: 0,
      maximumCanvasCount: 0,
      audioContextsConstructed: 0,
      liveAudioContexts: 0,
      routeLabelsDrawn: [],
      clearColors: [],
      unhandledRejections: [],
      animationFrameIds: new Set<number>(),
      audioContexts: [],
    };
    Object.defineProperty(instrumentedWindow, '__portfolioJourneyInstrumentation', {
      configurable: false,
      enumerable: false,
      value: state,
      writable: false,
    });

    const nativeRequestAnimationFrame = window.requestAnimationFrame.bind(window);
    const nativeCancelAnimationFrame = window.cancelAnimationFrame.bind(window);
    window.requestAnimationFrame = (callback: FrameRequestCallback): number => {
      let id = 0;
      id = nativeRequestAnimationFrame((now) => {
        state.animationFrameIds.delete(id);
        state.activeAnimationFrames = state.animationFrameIds.size;
        callback(now);
      });
      state.animationFrameIds.add(id);
      state.activeAnimationFrames = state.animationFrameIds.size;
      return id;
    };
    window.cancelAnimationFrame = (id: number): void => {
      state.animationFrameIds.delete(id);
      state.activeAnimationFrames = state.animationFrameIds.size;
      nativeCancelAnimationFrame(id);
    };

    const updateCanvasCount = (): void => {
      state.maximumCanvasCount = Math.max(
        state.maximumCanvasCount,
        document.querySelectorAll('.journey-canvas').length,
      );
    };
    document.addEventListener('DOMContentLoaded', () => {
      updateCanvasCount();
      new MutationObserver(updateCanvasCount).observe(document.documentElement, {
        childList: true,
        subtree: true,
      });
    }, { once: true });

    const nativeFillText = CanvasRenderingContext2D.prototype.fillText;
    const routeLabels = new Set([
      'Start',
      'Profile',
      'Experience',
      'Infrastructure',
      'Selected builds',
      'Additional work',
      'Toolkit',
      'Contact',
    ]);
    CanvasRenderingContext2D.prototype.fillText = function fillText(
      text: string,
      x: number,
      y: number,
      maxWidth?: number,
    ): void {
      if (routeLabels.has(text)) state.routeLabelsDrawn.push(text);
      if (maxWidth === undefined) nativeFillText.call(this, text, x, y);
      else nativeFillText.call(this, text, x, y, maxWidth);
    };

    const colorChannel = (value: number): string => Math.round(value * 255)
      .toString(16)
      .padStart(2, '0');
    const patchClearColor = (prototype: WebGLRenderingContext | WebGL2RenderingContext): void => {
      const nativeClearColor = prototype.clearColor;
      prototype.clearColor = function clearColor(red, green, blue, alpha): void {
        state.clearColors.push(`#${colorChannel(red)}${colorChannel(green)}${colorChannel(blue)}`);
        nativeClearColor.call(this, red, green, blue, alpha);
      };
    };
    if (typeof WebGLRenderingContext !== 'undefined') patchClearColor(WebGLRenderingContext.prototype);
    if (typeof WebGL2RenderingContext !== 'undefined') patchClearColor(WebGL2RenderingContext.prototype);

    const NativeAudioContext = window.AudioContext;
    if (NativeAudioContext) {
      class InstrumentedAudioContext extends NativeAudioContext {
        constructor(options?: AudioContextOptions) {
          super(options);
          state.audioContextsConstructed += 1;
          state.audioContexts.push(this);
          state.liveAudioContexts = state.audioContexts.filter((context) => context.state !== 'closed').length;
          this.addEventListener('statechange', () => {
            state.liveAudioContexts = state.audioContexts.filter((context) => context.state !== 'closed').length;
          });
        }
      }
      Object.defineProperty(window, 'AudioContext', {
        configurable: true,
        value: InstrumentedAudioContext,
      });
    }

    window.addEventListener('unhandledrejection', (event) => {
      const reason = event.reason;
      state.unhandledRejections.push(reason instanceof Error ? reason.message : String(reason));
    });
  });
}

export async function readSceneInstrumentation(page: Page): Promise<SceneInstrumentationSnapshot> {
  return page.evaluate(() => {
    const state = (window as InstrumentedWindow).__portfolioJourneyInstrumentation;
    if (!state) throw new Error('Scene instrumentation was not installed before navigation.');
    return {
      activeAnimationFrames: state.animationFrameIds.size,
      maximumCanvasCount: state.maximumCanvasCount,
      audioContextsConstructed: state.audioContextsConstructed,
      liveAudioContexts: state.audioContexts.filter((context) => context.state !== 'closed').length,
      routeLabelsDrawn: [...state.routeLabelsDrawn],
      clearColors: [...state.clearColors],
      unhandledRejections: [...state.unhandledRejections],
    };
  });
}

export async function waitForOneAnimationFrame(page: Page): Promise<void> {
  await page.evaluate(() => new Promise<void>((resolve) => {
    window.requestAnimationFrame(() => queueMicrotask(resolve));
  }));
}

export async function dispatchPersistedPageTransition(
  page: Page,
  type: 'pagehide' | 'pageshow',
): Promise<void> {
  await page.evaluate((eventType) => {
    window.dispatchEvent(new PageTransitionEvent(eventType, { persisted: true }));
  }, type);
}