find the libgs path on macOS.

Author: NickNaso

binding.gyp

@@ -93,7 +93,7 @@
             "GS4JS_LIB%": "<!(echo $GS4JS_LIB)",
             "conditions": [
               ['"<!(echo $GS4JS_HOME)" == ""', {
-                "GS4JS_HOME%": "/usr/local/lib"
+                "GS4JS_HOME%": "<!(node macOS-lib-path-finder.js)"
               }],
               ['"<!(echo $GS4JS_LIB)" == ""', {
                 "GS4JS_LIB%": "libgs.dylib"

macOS-lib-path-finder.js

@@ -0,0 +1,65 @@
+'use strict'
+
+const { promisify } = require('util')
+const exec = promisify(require('child_process').exec)
+const {stat} = require('fs').promises
+const path = require('path')
+
+
+const LIBRARY = 'libgs.dylib'
+const SYSTEM_PATH = '/usr/local/lib'
+
+const isLibraryExists = async (libraryPath) => {
+    try {
+        await stat(libraryPath)
+        return true
+    } catch (err) {
+        return false
+    }
+}
+
+const isInstalled = async (command) => {
+    try {
+        await exec(`which ${command}`)
+        return true
+    } catch (err) {
+        return false
+    }
+
+}
+
+
+async function main() {
+    try {
+        let isGSExists = false
+        isGSExists = await isLibraryExists(path.join(SYSTEM_PATH, LIBRARY))
+        if (isGSExists) {
+            process.stdout.write(SYSTEM_PATH)
+            return
+        } else {
+            if (!await isInstalled('brew')) {
+                return 1
+            }
+            if (!await isInstalled('gs')) {
+                return 1
+            }
+            const cellarPath = (await exec('brew --cellar')).stdout
+            const gsVersion = (await exec('gs --version')).stdout
+            const gsLibraryPath = path.join(cellarPath.trim(), 'ghostscript', gsVersion.trim(), 'lib')
+            isGSExists = await isLibraryExists(path.join(gsLibraryPath, LIBRARY))
+
+            if (isGSExists) {
+                process.stdout.write(gsLibraryPath)
+                return
+            } else {
+                return 1
+            }
+        }
+    } catch (err) {
+        process.emitWarning(err)
+        return 1
+    }
+    
+}
+
+main()