ipa2epub.scala

// ipa2epub.scala
//  usage: scala ipa2epub.scala src.ipa [dst.epub]
//  TODO: error handling
import java.io.{ File, FileInputStream, FileOutputStream, BufferedInputStream }
import java.util.zip.{ ZipFile, ZipEntry, ZipOutputStream, CRC32 }
import scala.util.matching.Regex

val TopDir = "Payload"

def die(message: String) {
  println(message)
  exit(1)
}

def unzip(path: String): Option[String] = {
  var result: Option[String] = None
  val regex = new Regex("^" + TopDir + "/.+\\.app/book/")
  val zip = new ZipFile(path)
  val files = zip.entries
  while (files.hasMoreElements) {
    val file = files.nextElement
    val name = file.getName
    val base = regex.findPrefixOf(name) 
    if (base != None) {
      if (file.isDirectory)
	new File(name).mkdirs
      else {
	val in = new BufferedInputStream(zip.getInputStream(file))
	val out = new FileOutputStream(name)
	val buf = new Array[Byte](1024)
	var len = in.read(buf)
	while (len != -1) {
	  out.write(buf, 0, len)
	  len = in.read(buf)
	}
	in.close
	out.close
      }
      result = base;
    }
  }
  zip.close
  result
}

def zip(path: String, base: String): Option[String] = {
  var result: Option[String] = None
  val file = new File(path)
  val out = new ZipOutputStream(new FileOutputStream(file))
  if (archive(out, base, new File(base + "mimetype"), false))
    if (archive(out, base, new File(base + "META-INF"), true))
      if (archive(out, base, new File(base + "OEBPS"), true))
	result = Some(file.getPath)

  out.close
  result
}

def archive(out: ZipOutputStream, base: String, path: File, deflate: Boolean): Boolean = {
  val result = path.exists
  if (result) {
    if (path.isDirectory)
      path.listFiles.foreach(file => archive(out, base, file, deflate))
    else {
      val len = path.length.toInt
      val buf = new Array[Byte](len)
      val in = new BufferedInputStream(new FileInputStream(path))
      in.read(buf, 0, len)
      in.close

      val file = new ZipEntry(("^" + base).r.replaceFirstIn(path.getPath, ""))
      if (deflate == false) {
	// MUST: setCrc before putNextEntry
	val crc = new CRC32()
	crc.update(buf)

	file.setMethod(ZipEntry.STORED)
	file.setSize(len)
	file.setCrc(crc.getValue)
      }

      out.putNextEntry(file)
      out.write(buf, 0, len)
      out.closeEntry
    }
  }
  result
}

def clean(path: File) {
  if (path.isDirectory)
    path.listFiles.foreach(clean)
  path.delete
}

// main
val src = if (args.length > 0) args(0) else null
if (src == null || new File(src).exists == false) die("usage: scala ipa2epub.scala src.ipa [dst.epub]")
val dst = if (args.length > 1) args(1) else "\\w+$".r.replaceFirstIn(new File(src).getName, "epub")
val base = unzip(src)
if (base == None) die("No book found in the archive") 
val top = new File(TopDir)
if (zip(dst, base.get) == None) die("No contents found in the archive")
clean(top)