package cbt

import java.io._
import java.lang.reflect.InvocationTargetException
import java.net._
import java.nio.charset.StandardCharsets
import java.nio.file._
import java.nio.file.attribute.FileTime
import javax.tools._
import java.security._
import java.util.{Set=>_,Map=>_,List=>_,_}
import javax.xml.bind.annotation.adapters.HexBinaryAdapter

// CLI interop
case class ExitCode(integer: Int)
object ExitCode{
  val Success = ExitCode(0)
  val Failure = ExitCode(1)
}

object CatchTrappedExitCode{
  def unapply(e: Throwable): Option[ExitCode] = {
    Option(e) flatMap {
      case i: InvocationTargetException => unapply(i.getTargetException)
      case e if TrapSecurityManager.isTrappedExit(e) => Some( ExitCode(TrapSecurityManager.exitCode(e)) )
      case _ => None
    }
  }
}

class BaseLib{
  def realpath(name: File) = new File(java.nio.file.Paths.get(name.getAbsolutePath).normalize.toString)
}

class Stage1Lib( val logger: Logger ) extends BaseLib{
  lib =>
  implicit val implicitLogger: Logger = logger

  def libMajorVersion(libFullVersion: String) = libFullVersion.split("\\.").take(2).mkString(".")

  // ========== file system / net ==========

  def array2hex(padTo: Int, array: Array[Byte]): String = {
    val hex = new java.math.BigInteger(1, array).toString(16)
    ("0" * (padTo-hex.size)) ++ hex
  }
  def md5( bytes: Array[Byte] ): String = array2hex(32, MessageDigest.getInstance("MD5").digest(bytes)).toLowerCase
  def sha1( bytes: Array[Byte] ): String = array2hex(40, MessageDigest.getInstance("SHA-1").digest(bytes)).toLowerCase

  def red(string: String) = scala.Console.RED++string++scala.Console.RESET
  def blue(string: String) = scala.Console.BLUE++string++scala.Console.RESET
  def green(string: String) = scala.Console.GREEN++string++scala.Console.RESET

  def write(file: File, content: String, options: OpenOption*): File = Stage0Lib.write(file, content, options:_*)

  def download(url: URL, target: File, sha1: Option[String]): Boolean = {
    if( target.exists ){
      logger.resolver(green("found ") ++ url.string)
      true
    } else {
      val incomplete = ( target ++ ".incomplete" ).toPath;
      val connection = Stage0Lib.openConnectionConsideringProxy(url)
      if(connection.getResponseCode != HttpURLConnection.HTTP_OK){
        logger.resolver(blue("not found: ") ++ url.string)
        false
      } else {
        System.err.println(blue("downloading ") ++ url.string)
        logger.resolver(blue("to ") ++ target.string)
        target.getParentFile.mkdirs
        val stream = connection.getInputStream
        try{
          Files.copy(stream, incomplete, StandardCopyOption.REPLACE_EXISTING)
        } finally {
          stream.close()
        }
        sha1.foreach{
          hash =>
            val expected = hash.toLowerCase
            val actual = this.sha1(Files.readAllBytes(incomplete))
            assert( expected == actual, s"$expected == $actual" )
            logger.resolver( green("verified") ++ " checksum for " ++ target.string)
        }
        Files.move(incomplete, target.toPath, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.ATOMIC_MOVE);
        true
      }
    }
  }

  def listFilesRecursive(f: File): Seq[File] = {
    f +: (
      if( f.isDirectory ) f.listFiles.flatMap(listFilesRecursive).toVector else Seq[File]()
    )
  }

  // ========== compilation / execution ==========

  def runMain( cls: String, args: Seq[String], classLoader: ClassLoader, fakeInstance: Boolean = false ): ExitCode = {
    import java.lang.reflect.Modifier
    logger.lib(s"Running $cls.main($args) with classLoader: " ++ classLoader.toString)
    trapExitCode{
      val c = classLoader.loadClass(cls)
      val m = c.getMethod( "main", classOf[Array[String]] )
      val instance = 
        if(!fakeInstance) null else c.newInstance
      assert(
        fakeInstance || (m.getModifiers & java.lang.reflect.Modifier.STATIC) > 0,
        "Cannot run non-static method " ++ cls+".main"
      )
      m.invoke( instance, args.toArray.asInstanceOf[AnyRef] )
      ExitCode.Success
    }
  }

  /** shows an interactive dialogue in the shell asking the user to pick one of many choices */
  def pickOne[T]( msg: String, choices: Seq[T] )( show: T => String ): Option[T] = {
    if(choices.size == 0) None else if(choices.size == 1) Some(choices.head) else {
      Option(System.console).map{
        console =>
        val indexedChoices: Map[Int, T] = choices.zipWithIndex.toMap.mapValues(_+1).map(_.swap)
        System.err.println(
          indexedChoices.map{ case (index,choice) => s"[${index}] "++show(choice)}.mkString("\n")
        )
        val range = s"1 - ${indexedChoices.size}"
        System.err.println()
        System.err.println( msg ++ " [" ++ range ++ "] " )
        val answer = console.readLine()
        val choice = try{
          Some(Integer.parseInt(answer))
        }catch{
          case e:java.lang.NumberFormatException => None
        }

        choice.flatMap(indexedChoices.get).orElse{
          System.err.println("Not in range "++range)
          None
        }
      }.getOrElse{
        System.err.println("System.console() == null. Use `cbt direct <task>` or see https://github.com/cvogt/cbt/issues/236")
        None
      }
    }
  }

  /** interactively pick one main class */
  def runClass( mainClasses: Seq[Class[_]] ): Option[Class[_]] = {
    pickOne( "Which one do you want to run?", mainClasses )( _.toString )
  }

  def mainClasses( targetDirectory: File, classLoader : ClassLoader ): Seq[Class[_]] = {
    val arrayClass = classOf[Array[String]]
    val unitClass = classOf[Unit]

    listFilesRecursive(targetDirectory)
      .filter(_.isFile)
      .map(_.getPath)
      .collect{
        // no $ to avoid inner classes
        case path if !path.contains("$") && path.endsWith(".class") =>
          classLoader.loadClass(
            path
              .stripSuffix(".class")
              .stripPrefix(targetDirectory.getPath)
              .stripPrefix(File.separator) // 1 for the slash
              .replace(File.separator, ".")
          )
      }.filter(
        _.getDeclaredMethods().exists( m =>
          m.getName == "main"
            && m.getParameterTypes.toList == List(arrayClass)
            && m.getReturnType == unitClass
        )
      )
  }

  implicit class ClassLoaderExtensions(classLoader: ClassLoader){
    def canLoad(className: String) = {
      try{
        classLoader.loadClass(className)
        true
      } catch {
        case e: ClassNotFoundException => false
      }
    }
  }

  def needsUpdate( sourceFiles: Seq[File], statusFile: File ) = {
    val lastCompile = statusFile.lastModified
    sourceFiles.filter(_.lastModified > lastCompile).nonEmpty
  }

  def compile(
    cbtHasChanged: Boolean,
    needsRecompile: Boolean,
    files: Seq[File],
    compileTarget: File,
    statusFile: File,
    dependencies: Seq[Dependency],
    mavenCache: File,
    scalacOptions: Seq[String] = Seq(),
    classLoaderCache: ClassLoaderCache,
    zincVersion: String,
    scalaVersion: String
  )(
    implicit transientCache: java.util.Map[AnyRef, AnyRef]
  ): Option[File] = {
    val classpath = Dependencies(dependencies).classpath
    val cp = classpath.string
    if(classpath.files.isEmpty)
      throw new Exception("Trying to compile with empty classpath. Source files: " ++ files.toString)

    if( files.isEmpty ){
      None
    }else{
      if( needsRecompile ){
        def Resolver(urls: URL*) = MavenResolver(cbtHasChanged, mavenCache, urls: _*)
        val zinc = Resolver(mavenCentral).bindOne(MavenDependency("com.typesafe.zinc","zinc", zincVersion))
        val zincDeps = zinc.transitiveDependencies
        
        val sbtInterface =
          zincDeps
            .collect{ case d @
              BoundMavenDependency(
                _, _, MavenDependency( "com.typesafe.sbt", "sbt-interface", _, Classifier.none), _
              ) => d
            }
            .headOption
            .getOrElse( throw new Exception(s"cannot find sbt-interface in zinc $zincVersion dependencies: "++zincDeps.toString) )
            .jar

        val compilerInterface =
          zincDeps
            .collect{ case d @
              BoundMavenDependency(
                _, _, MavenDependency( "com.typesafe.sbt", "compiler-interface", _, Classifier.sources), _
              ) => d
            }
            .headOption
            .getOrElse( throw new Exception(s"cannot find compiler-interface in zinc $zincVersion dependencies: "++zincDeps.toString) )
            .jar

        val scalaLibrary = Resolver(mavenCentral).bindOne(MavenDependency("org.scala-lang","scala-library",scalaVersion)).jar
        val scalaReflect = Resolver(mavenCentral).bindOne(MavenDependency("org.scala-lang","scala-reflect",scalaVersion)).jar
        val scalaCompiler = Resolver(mavenCentral).bindOne(MavenDependency("org.scala-lang","scala-compiler",scalaVersion)).jar

        val start = System.currentTimeMillis

        val _class = "com.typesafe.zinc.Main"
        val dualArgs =
          Seq(
            "-scala-compiler", scalaCompiler.toString,
            "-scala-library", scalaLibrary.toString,
            "-sbt-interface", sbtInterface.toString,
            "-compiler-interface", compilerInterface.toString,
            "-scala-extra", scalaReflect.toString,
            "-d", compileTarget.toString
          )
        val singleArgs = scalacOptions.map( "-S" ++ _ )

        val code =
          redirectOutToErr{
            System.err.println("Compiling to " ++ compileTarget.toString)
            try{
              lib.runMain(
                _class,
                dualArgs ++ singleArgs ++ Seq(
                  "-cp", cp // let's put cp last. It so long
                ) ++ files.map(_.toString),
                zinc.classLoader(classLoaderCache)
              )
            } catch {
              case e: Exception =>
              System.err.println(red("The Scala compiler crashed. Try running it by hand:"))
              System.out.println(s"""
  java -cp \\
  ${zinc.classpath.strings.mkString(":\\\n")} \\
  \\
  ${_class} \\
  \\
  ${dualArgs.grouped(2).map(_.mkString(" ")).mkString(" \\\n")} \\
  \\
  ${singleArgs.mkString(" \\\n")} \\
  \\
  -cp \\
  ${classpath.strings.mkString(":\\\n")} \\
  \\
  ${files.sorted.mkString(" \\\n")}
  """
              )

              redirectOutToErr( e.printStackTrace )
              ExitCode.Failure
            }
          }

        if(code == ExitCode.Success){
          // write version and when last compilation started so we can trigger
          // recompile if cbt version changed or newer source files are seen
          write(statusFile, "")//cbtVersion.getBytes)
          Files.setLastModifiedTime(statusFile.toPath, FileTime.fromMillis(start) )
        } else {
          System.exit(code.integer) // FIXME: let's find a better solution for error handling. Maybe a monad after all.
        }
      }
      Some( compileTarget )
    }
  }
  def redirectOutToErr[T](code: => T): T = {
    val ( out, err ) = try{
      // trying nailgun's System.our/err wrapper
      val field = System.out.getClass.getDeclaredField("streams")
      assert(System.out.getClass.getName == "com.martiansoftware.nailgun.ThreadLocalPrintStream")
      assert(System.err.getClass.getName == "com.martiansoftware.nailgun.ThreadLocalPrintStream")
      field.setAccessible(true)
      val out = field.get(System.out).asInstanceOf[ThreadLocal[PrintStream]]
      val err = field.get(System.err).asInstanceOf[ThreadLocal[PrintStream]]
      ( out, err )
    } catch {
      case e: NoSuchFieldException =>
        // trying cbt's System.our/err wrapper
        val field = classOf[FilterOutputStream].getDeclaredField("out")
        field.setAccessible(true)
        val outStream = field.get(System.out)
        val errStream = field.get(System.err)
        assert(outStream.getClass.getName == "cbt.ThreadLocalOutputStream")
        assert(errStream.getClass.getName == "cbt.ThreadLocalOutputStream")
        val field2 = outStream.getClass.getDeclaredField("threadLocal")
        field2.setAccessible(true)
        val out = field2.get(outStream).asInstanceOf[ThreadLocal[PrintStream]]
        val err = field2.get(errStream).asInstanceOf[ThreadLocal[PrintStream]]
        ( out, err )
    }

    val oldOut: PrintStream = out.get
    out.set( err.get: PrintStream )
    val res = code
    out.set( oldOut )
    res
  }

  def trapExitCode( code: => ExitCode ): ExitCode = {
    val trapExitCodeBefore = TrapSecurityManager.trapExitCode().get
    try{
      TrapSecurityManager.trapExitCode().set(true)
      code
    } catch {
      case CatchTrappedExitCode(exitCode) =>
        logger.stage1(s"caught exit code $exitCode")
        exitCode
    } finally {
      TrapSecurityManager.trapExitCode().set(trapExitCodeBefore)
    }
  }

  def ScalaDependency(
    groupId: String, artifactId: String, version: String, classifier: Classifier = Classifier.none,
    scalaMajorVersion: String
  ) =
    MavenDependency(
      groupId, artifactId ++ "_" ++ scalaMajorVersion, version, classifier
    )

  def cacheOnDisk[T]
    ( cbtHasChanged: Boolean, cacheFile: File )
    ( deserialize: String => T )
    ( serialize: T => String )
    ( compute: => Seq[T] ) = {
    if(!cbtHasChanged && cacheFile.exists){
      import collection.JavaConversions._
      Files
        .readAllLines( cacheFile.toPath, StandardCharsets.UTF_8 )
        .toStream
        .map(deserialize)
    } else {
      val result = compute
      val string = result.map(serialize).mkString("\n")
      write(cacheFile, string)
      result
    }
  }

  def dependencyTreeRecursion(root: Dependency, indent: Int = 0): String = (
    ( " " * indent )
    ++ (if(root.needsUpdate) red(root.show) else root.show)
    ++ root.dependencies.map( d =>
      "\n" ++ dependencyTreeRecursion(d,indent + 1)
    ).mkString
  )

  def transitiveDependencies(dependency: Dependency): Seq[Dependency] = {
    def linearize(deps: Seq[Dependency]): Seq[Dependency] = {
      // Order is important here in order to generate the correct lineraized dependency order for EarlyDependencies
      // (and maybe this as well in case we want to get rid of MultiClassLoader)
      try{
        if(deps.isEmpty) deps else ( deps ++ linearize(deps.flatMap(_.dependencies)) )
      } catch{
        case e: Exception => throw new Exception(dependency.show, e)
      }
    }

    // FIXME: this is probably wrong too eager.
    // We should consider replacing versions during traversals already
    // not just replace after traversals, because that could mean we
    // pulled down dependencies current versions don't even rely
    // on anymore.

    val deps: Seq[Dependency] = linearize(dependency.dependencies).reverse.distinct.reverse
    val hasInfo: Seq[Dependency with ArtifactInfo] = deps.collect{ case d:Dependency with ArtifactInfo => d }
    val noInfo: Seq[Dependency]  = deps.filter{
      case _:Dependency with ArtifactInfo => false
      case _ => true
    }
    noInfo ++ BoundMavenDependency.updateOutdated( hasInfo ).reverse.distinct
  }


  def actual(current: Dependency, latest: Map[(String,String),Dependency]) = current match {
    case d: ArtifactInfo => latest((d.groupId,d.artifactId))
    case d => d
  }

  def classLoaderRecursion( dependency: Dependency, latest: Map[(String,String),Dependency], cache: ClassLoaderCache ): ClassLoader = {
    // FIXME: shouldn't we be using KeyLockedLazyCache instead of hashmap directly here?
    val d = dependency
    val dependencies = dependency.dependencies
    def dependencyClassLoader( latest: Map[(String,String),Dependency], cache: ClassLoaderCache ): ClassLoader = {
      if( dependency.dependencies.isEmpty ){
        // wrap for caching
        new cbt.URLClassLoader( ClassPath(), ClassLoader.getSystemClassLoader().getParent() )
      } else if( dependencies.size == 1 ){
        classLoaderRecursion( dependencies.head, latest, cache )
      } else{
        val cp = d.dependencyClasspath.string
        if( dependencies.exists(_.needsUpdate) && cache.cache.containsKey(cp) ){
          cache.cache.remove(cp)
        }
        def cl = new MultiClassLoader( dependencies.map( classLoaderRecursion(_, latest, cache) ) )
        if(d.isInstanceOf[BuildInterface])
          cl // Don't cache builds right now. We need to fix invalidation first.
        else
          cache.cache.get( cp, cl )
      }
    }

    val a = actual( dependency, latest )
    def cl = new cbt.URLClassLoader( a.exportedClasspath, dependencyClassLoader(latest, cache) )
    if(d.isInstanceOf[BuildInterface])
      cl
    else
      cache.cache.get( a.classpath.string, cl ).asInstanceOf[ClassLoader]
  }

}

import scala.reflect._
import scala.language.existentials
case class PerClassCache(cache: java.util.Map[AnyRef,AnyRef], moduleKey: String)(implicit logger: Logger){
  def apply[D <: Dependency: ClassTag](key: AnyRef): MethodCache[D] = new MethodCache[D](key)
  case class MethodCache[D <: Dependency: ClassTag](key: AnyRef){
    def memoize[T <: AnyRef](task: => T): T = {
      val fullKey = (classTag[D].runtimeClass, moduleKey, key)
      logger.transientCache("fetching key"+fullKey)
      if( cache.containsKey(fullKey) ){
        logger.transientCache("found    key"+fullKey)
        cache.get(fullKey).asInstanceOf[T]
      } else{
        val value = task
        logger.transientCache("put      key"+fullKey)
        cache.put( fullKey, value )
        value
      }
    }
  }
}