SubMiner/src/window-trackers/macos-tracker.ts

/*
  subminer - Yomitan integration for mpv
  Copyright (C) 2024 sudacode

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

import { execFile } from 'child_process';
import * as path from 'path';
import * as fs from 'fs';
import * as os from 'os';
import { BaseWindowTracker } from './base-tracker';
import { createLogger } from '../logger';
import type { WindowGeometry } from '../types';

const log = createLogger('tracker').child('macos');

type MacOSTrackerRunnerResult = {
  stdout: string;
  stderr: string;
};

type MacOSTrackerDeps = {
  resolveHelper?: () => { helperPath: string; helperType: 'binary' | 'swift' } | null;
  runHelper?: (
    helperPath: string,
    helperType: 'binary' | 'swift',
    targetMpvSocketPath: string | null,
  ) => Promise<MacOSTrackerRunnerResult>;
  maxConsecutiveMisses?: number;
  trackingLossGraceMs?: number;
  now?: () => number;
};

export interface MacOSHelperWindowState {
  geometry: WindowGeometry;
  focused: boolean;
}

function runHelperWithExecFile(
  helperPath: string,
  helperType: 'binary' | 'swift',
  targetMpvSocketPath: string | null,
): Promise<MacOSTrackerRunnerResult> {
  return new Promise((resolve, reject) => {
    const command = helperType === 'binary' ? helperPath : 'swift';
    const args = helperType === 'binary' ? [] : [helperPath];
    if (targetMpvSocketPath) {
      args.push(targetMpvSocketPath);
    }

    execFile(
      command,
      args,
      {
        encoding: 'utf-8',
        timeout: 1000,
        maxBuffer: 1024 * 1024,
      },
      (error, stdout, stderr) => {
        if (error) {
          reject(Object.assign(error, { stderr }));
          return;
        }
        resolve({
          stdout: stdout || '',
          stderr: stderr || '',
        });
      },
    );
  });
}

export function parseMacOSHelperOutput(result: string): MacOSHelperWindowState | null {
  const trimmed = result.trim();
  if (!trimmed || trimmed === 'not-found') {
    return null;
  }

  const parts = trimmed.split(',');
  if (parts.length !== 4 && parts.length !== 5) {
    return null;
  }

  const x = parseInt(parts[0]!, 10);
  const y = parseInt(parts[1]!, 10);
  const width = parseInt(parts[2]!, 10);
  const height = parseInt(parts[3]!, 10);
  if (
    !Number.isFinite(x) ||
    !Number.isFinite(y) ||
    !Number.isFinite(width) ||
    !Number.isFinite(height) ||
    width <= 0 ||
    height <= 0
  ) {
    return null;
  }

  const focusedRaw = parts[4]?.trim().toLowerCase();
  const focused = focusedRaw === undefined ? true : focusedRaw === '1' || focusedRaw === 'true';

  return {
    geometry: {
      x,
      y,
      width,
      height,
    },
    focused,
  };
}

export class MacOSWindowTracker extends BaseWindowTracker {
  private pollInterval: ReturnType<typeof setInterval> | null = null;
  private pollInFlight = false;
  private helperPath: string | null = null;
  private helperType: 'binary' | 'swift' | null = null;
  private lastExecErrorFingerprint: string | null = null;
  private lastExecErrorLoggedAtMs = 0;
  private readonly targetMpvSocketPath: string | null;
  private readonly runHelper: (
    helperPath: string,
    helperType: 'binary' | 'swift',
    targetMpvSocketPath: string | null,
  ) => Promise<MacOSTrackerRunnerResult>;
  private readonly maxConsecutiveMisses: number;
  private readonly trackingLossGraceMs: number;
  private readonly now: () => number;
  private consecutiveMisses = 0;
  private trackingLossStartedAtMs: number | null = null;

  constructor(targetMpvSocketPath?: string, deps: MacOSTrackerDeps = {}) {
    super();
    this.targetMpvSocketPath = targetMpvSocketPath?.trim() || null;
    this.runHelper = deps.runHelper ?? runHelperWithExecFile;
    this.maxConsecutiveMisses = Math.max(1, Math.floor(deps.maxConsecutiveMisses ?? 2));
    this.trackingLossGraceMs = Math.max(0, Math.floor(deps.trackingLossGraceMs ?? 1_500));
    this.now = deps.now ?? (() => Date.now());
    const resolvedHelper = deps.resolveHelper?.() ?? null;
    if (resolvedHelper) {
      this.helperPath = resolvedHelper.helperPath;
      this.helperType = resolvedHelper.helperType;
    } else {
      this.detectHelper();
    }
  }

  private materializeAsarHelper(sourcePath: string, helperType: 'binary' | 'swift'): string | null {
    if (!sourcePath.includes('.asar')) {
      return sourcePath;
    }

    const fileName =
      helperType === 'binary' ? 'get-mpv-window-macos' : 'get-mpv-window-macos.swift';
    const targetDir = path.join(os.tmpdir(), 'subminer', 'helpers');
    const targetPath = path.join(targetDir, fileName);

    try {
      fs.mkdirSync(targetDir, { recursive: true });
      fs.copyFileSync(sourcePath, targetPath);
      fs.chmodSync(targetPath, 0o755);
      log.info(`Materialized macOS helper from asar: ${targetPath}`);
      return targetPath;
    } catch (error) {
      log.warn(`Failed to materialize helper from asar: ${sourcePath}`, error);
      return null;
    }
  }

  private tryUseHelper(candidatePath: string, helperType: 'binary' | 'swift'): boolean {
    if (!fs.existsSync(candidatePath)) {
      return false;
    }

    const resolvedPath = this.materializeAsarHelper(candidatePath, helperType);
    if (!resolvedPath) {
      return false;
    }

    this.helperPath = resolvedPath;
    this.helperType = helperType;
    log.info(`Using macOS helper (${helperType}): ${resolvedPath}`);
    return true;
  }

  private detectHelper(): void {
    const shouldFilterBySocket = this.targetMpvSocketPath !== null;

    // Fall back to Swift helper first when filtering by socket path to avoid
    // stale prebuilt binaries that don't support the new socket filter argument.
    const swiftPath = path.join(__dirname, '..', '..', 'scripts', 'get-mpv-window-macos.swift');
    if (shouldFilterBySocket && this.tryUseHelper(swiftPath, 'swift')) {
      return;
    }

    // Prefer resources path (outside asar) in packaged apps.
    const resourcesPath = process.resourcesPath;
    if (resourcesPath) {
      const resourcesBinaryPath = path.join(resourcesPath, 'scripts', 'get-mpv-window-macos');
      if (this.tryUseHelper(resourcesBinaryPath, 'binary')) {
        return;
      }
    }

    // Dist binary path (development / unpacked installs).
    const distBinaryPath = path.join(__dirname, '..', '..', 'scripts', 'get-mpv-window-macos');
    if (this.tryUseHelper(distBinaryPath, 'binary')) {
      return;
    }

    // Fall back to Swift script for development or if binary filtering is not
    // supported in the current environment.
    if (this.tryUseHelper(swiftPath, 'swift')) {
      return;
    }

    log.warn('macOS window tracking helper not found');
  }

  private maybeLogExecError(err: Error, stderr: string): void {
    const now = Date.now();
    const fingerprint = `${err.message}|${stderr.trim()}`;
    const shouldLog =
      this.lastExecErrorFingerprint !== fingerprint || now - this.lastExecErrorLoggedAtMs >= 5000;
    if (!shouldLog) {
      return;
    }
    this.lastExecErrorFingerprint = fingerprint;
    this.lastExecErrorLoggedAtMs = now;
    log.warn('macOS helper execution failed', {
      helperPath: this.helperPath,
      helperType: this.helperType,
      error: err.message,
      stderr: stderr.trim(),
    });
  }

  start(): void {
    this.pollInterval = setInterval(() => this.pollGeometry(), 250);
    this.pollGeometry();
  }

  stop(): void {
    if (this.pollInterval) {
      clearInterval(this.pollInterval);
      this.pollInterval = null;
    }
  }

  private resetTrackingLossState(): void {
    this.consecutiveMisses = 0;
    this.trackingLossStartedAtMs = null;
  }

  private shouldDropTracking(): boolean {
    if (!this.isTracking()) {
      return true;
    }
    if (this.trackingLossGraceMs === 0) {
      return this.consecutiveMisses >= this.maxConsecutiveMisses;
    }
    if (this.trackingLossStartedAtMs === null) {
      this.trackingLossStartedAtMs = this.now();
      return false;
    }
    return this.now() - this.trackingLossStartedAtMs > this.trackingLossGraceMs;
  }

  private registerTrackingMiss(): void {
    this.consecutiveMisses += 1;
    if (this.shouldDropTracking()) {
      this.updateGeometry(null);
      this.resetTrackingLossState();
    }
  }

  private pollGeometry(): void {
    if (this.pollInFlight || !this.helperPath || !this.helperType) {
      return;
    }

    this.pollInFlight = true;
    void this.runHelper(this.helperPath, this.helperType, this.targetMpvSocketPath)
      .then(({ stdout }) => {
        const parsed = parseMacOSHelperOutput(stdout || '');
        if (parsed) {
          this.resetTrackingLossState();
          this.updateFocus(parsed.focused);
          this.updateGeometry(parsed.geometry);
          return;
        }

        this.registerTrackingMiss();
      })
      .catch((error: unknown) => {
        const err = error instanceof Error ? error : new Error(String(error));
        const stderr =
          typeof error === 'object' &&
          error !== null &&
          'stderr' in error &&
          typeof (error as { stderr?: unknown }).stderr === 'string'
            ? (error as { stderr: string }).stderr
            : '';
        this.maybeLogExecError(err, stderr);
        this.registerTrackingMiss();
      })
      .finally(() => {
        this.pollInFlight = false;
      });
  }
}