fetch and archive flutter-sources.jar for using in Android Studio / IntelliJ

flutter-sources.jar.sc

// This script will fetch java source files for <flutter.sdk>/bin/cache/artifacts/engine/android-arm/flutter.jar
//  and pack into ~/flutter-sources.jar

// Run this script by [amm](http://ammonite.io/#ScalaScripts):
// + install amm:
// sudo sh -c '(echo "#!/usr/bin/env sh" && curl -L https://github.com/lihaoyi/Ammonite/releases/download/1.6.4/2.12-1.6.4) > /usr/local/bin/amm && chmod +x /usr/local/bin/amm'
// + run:
// amm flutter-sources.jar.sc

// Then you can Choose Sources for the flutter classes in IntelliJ/ Android Studio
// When flutter upgrade, you should re-run: amm flutter-sources.jar.sc

import java.io.Closeable
import java.net.URL
import java.nio.file.{Files, Paths}
import java.util.Properties

import scala.io.{BufferedSource, Source}

def use[A, B <: Closeable](r : B)(f : B => A) : A = try f(r) finally r.close()
def useFile[A](path: String)(f: BufferedSource => A): A = use(Source.fromFile(path, "UTF-8"))(f)

def parseProps(path: String): Properties = {
  val props = new Properties()
  useFile(path) { s =>
    props.load(s.reader())
  }
  props
}

def getSdkPath(): String = {
  def findFromProps(dir: String): String = {
    val p = s"$dir/local.properties"
    if (Files.notExists(Paths.get(p)))
      return null
    parseProps(p).getProperty("flutter.sdk")
  }

  var r = System.getenv("FLUTTER_ROOT")
  if (r != null) return r

  r = findFromProps(".")
  if (r != null) return r

  r = findFromProps("..")
  if (r != null) return r
  throw new RuntimeException(
    """Can't found flutter sdk path!
      |You can define FLUTTER_ROOT or run this script from a folder that has local.properties
      |with `flutter.sdk` property""".stripMargin)
}

val sdkPathStr = getSdkPath()
val engineVersion = useFile(s"$sdkPathStr/bin/internal/engine.version"){_.getLines().next()}
def githubUrl(path: String) =
  s"https://raw.githubusercontent.com/flutter/engine/$engineVersion/shell/platform/android/$path"

def getFlutterSourcePaths() = {
  val text = use(Source.fromURL(githubUrl("BUILD.gn")))(_.mkString)
  val i = text.indexOf("java_files = [") + "java_files = [".length
  val j = text.indexOf("]", i)

  // "io/flutter/app/FlutterActivity.java",
  // "io/flutter/app/FlutterActivityDelegate.java",
  // ...
  text.
    substring(i, j).
    split('\n').
    map(_.
      trim().
      drop(1). //remove `"`
      dropRight(2) //remove `",`
    ).
    filter(_.nonEmpty)
}

import $ivy.`org.zeroturnaround:zt-zip:1.13`
import org.zeroturnaround.zip._
import java.io.File
import java.util.zip.ZipEntry

class StreamSource(path: String) extends ZipEntrySource {
  def getEntry = new ZipEntry(path)
  def getInputStream = {
    println(s"get $path..")
    new URL(githubUrl(path)).openStream()
  }
  def getPath = path
}

val javaPaths = getFlutterSourcePaths()
val entries: Array[ZipEntrySource] = javaPaths.map(new StreamSource(_))
ZipUtil.pack(entries, new File(System.getProperty("user.home"), "flutter-sources.jar"))