Fix opencv4nodejs dependency issues with electron

fix.js

/**
 * This script takes care of resolving and packaging dependencies of opencv
 * For some reason they are not found in the opencv-build folder, but in /usr/shared...
 * MacOS provided ways to tell libraries where to find dependencies, so what we do here is to
 * 1. iterate all opencv libraries
 * 2. for each of them check for dependencies in /usr/...
 * 3. copy each of those dependencies to our opencv-build/../dependencies dir
 * 4. tell the opencv libraries to look in the opencv-build/../dependencies dir instead of in /usr/...
 * 5. go through all the libraries in opencv-build/../dependencies and check for even more dependencies, take care of them the same way (see steps 1-4)
 * 6. again: go through all the libraries in opencv-build/../dependencies and check for even more dependencies, take care of them the same way (see steps 1-4)
 * 7. again: go through all the libraries in opencv-build/../dependencies and check for even more dependencies, take care of them the same way (see steps 1-4)
 * At this point I am still not sure if I really need all these dependencies (the sum up to 85Mb), but this way I got rid of my errors
 *
 * Huge thanks to Jakob Schindegger, who provided me with insights on how osx libraries are working and a great starting point here: https://github.com/fakob/MoviePrint_v004/blob/master/scripts/ffmpeg.js
 */
import path from 'path'
const shell = require('shelljs')

// good article about rpath, otool, ...: https://medium.com/@donblas/fun-with-rpath-otool-and-install-name-tool-e3e41ae86172
// https://wincent.com/wiki/@executable_path,_@load_path_and_@rpath
// cross platform variables
const projectRoot = shell.pwd().stdout
const opencvLibDir = path.resolve(projectRoot, 'node_modules/opencv-build/opencv/build/lib/')
const dependencyDir = 'dependencies'
const outerDependencyDir = opencvLibDir + '/' + dependencyDir

console.log('projectRoot: ' + projectRoot)
console.log('outerDependencyDir: ' + outerDependencyDir)
console.log('opencvLibDir: ' + opencvLibDir)

shell.mkdir('-p', outerDependencyDir)

if (process.platform === 'darwin') {
  function fixDeps(dirPath, dependencyDirName) {
    // Copying ffmpeg_version=3.4.2 into dist folder and change library linking if necessary
    console.info('checking all openCv dylib files in given directory...')
    const dylibs = shell.ls(dirPath)
    const allDeps = []
    dylibs
      .filter(file => {
        return -1 != file.indexOf('dylib')
      })
      .forEach(dylibFilename => {
        const dylib = dirPath + '/' + dylibFilename
        console.log(`checking outer dependencies of file ${dylib}`)
        const outerDeps = shell
          .exec(`otool -l ${dylib} | grep 'name /usr'`)
          .stdout.split('\n')
          .filter(dep => {
            return dep != ''
          })

        if (outerDeps.length > 0) {
          //shell.exec(`install_name_tool -add_rpath @loader_path/${dependencyDirName}`);
        }
        outerDeps.forEach(depLine => {
          var regex = /name (.+?(?=\ \(offset))/g // transform "name /usr/lib/libc++.1.dylib (offset 24)" -> "/usr/lib/libc++.1.dylib"
          var depfilePath = regex.exec(depLine)[1] // "/usr/lib/libc++.1.dylib"
          var depfileName = depfilePath.replace(/^.*[\\\/]/, '')

          if (!allDeps.find(e => e == depfilePath)) {
            // if not added already -> add it
            allDeps.push(depfilePath)
            console.log(`    copying outer dependency ${depfilePath} to ${outerDependencyDir}`)
            shell.cp('-n', depfilePath, outerDependencyDir)
          }
          shell.chmod('-v', '666', dylib)
          const fixCommand = `install_name_tool -change ${depfilePath} @loader_path/${dependencyDirName}/${depfileName} ${dylib}`
          console.log('    fix with command: ' + fixCommand)
          shell.exec(fixCommand)
        })

        console.log(`\n\n`)
      })
    console.info('All outer dependencies:')
    console.log(allDeps)
    return allDeps
  }

  fixDeps(opencvLibDir, dependencyDir)
  fixDeps(outerDependencyDir, '')
  fixDeps(outerDependencyDir, '')
  fixDeps(outerDependencyDir, '')
} else if (process.platform === 'win32') {
  // variables
  console.error('missing implementation here!')
  // See https://github.com/fakob/MoviePrint_v004/blob/master/scripts/ffmpeg.js
  /*const ffmpegSourceDir = path.resolve(process.env.HOME || process.env.USERPROFILE, 'scoop\\apps\\ffmpeg\\');
  console.log(ffmpegSourceDir);

  // copy files
  shell.cp('-n', path.resolve(ffmpegSourceDir, '3.4.2\\bin\\*'), outerDependencyDir);*/
}