Dynamic Compilation and Interpretation

/**
 * Default compiler for dynamic Scala code compilation in Spark
 * Enables runtime compilation of Scala code within CDAP Spark applications
 */
class DefaultSparkCompiler extends SparkCompiler {
    /**
     * Compiles Scala code and returns the resulting class
     * @param code Scala source code to compile
     * @return Option containing the compiled class, or None if compilation fails
     * @throws CompilationException if compilation errors occur
     */
    def compile(code: String): Option[Class[_]]
    
    /**
     * Compiles Scala code with a specific class name
     * @param className Fully qualified name for the compiled class
     * @param code Scala source code to compile
     * @return Option containing the compiled class, or None if compilation fails
     * @throws CompilationException if compilation errors occur
     */
    def compileClass(className: String, code: String): Option[Class[_]]
    
    /**
     * Compiles multiple Scala source files
     * @param sources Map of class names to source code
     * @return Map of class names to compiled classes
     * @throws CompilationException if compilation errors occur
     */
    def compileClasses(sources: Map[String, String]): Map[String, Class[_]]
    
    /**
     * Sets the compiler class path
     * @param classpath Array of classpath entries
     */
    def setClassPath(classpath: Array[String]): Unit
    
    /**
     * Gets the current compiler settings
     * @return CompilerSettings containing current configuration
     */
    def getSettings: CompilerSettings
    
    /**
     * Validates Scala code syntax without compilation
     * @param code Scala source code to validate
     * @return ValidationResult containing validation status and errors
     */
    def validate(code: String): ValidationResult
}

/**
 * Default interpreter for dynamic Scala code execution in Spark
 * Provides REPL-like capabilities for interactive development
 */
class DefaultSparkInterpreter extends SparkInterpreter {
    /**
     * Interprets and executes Scala code
     * @param code Scala code to interpret and execute
     * @throws InterpretationException if interpretation or execution fails
     */
    def interpret(code: String): Unit
    
    /**
     * Interprets code and returns the result
     * @param code Scala expression to evaluate
     * @tparam T Expected return type
     * @return Result of the expression evaluation
     * @throws InterpretationException if interpretation fails
     */
    def interpretAndReturn[T](code: String): T
    
    /**
     * Binds a variable to the interpreter context
     * @param name Variable name
     * @param value Variable value
     * @tparam T Type of the value
     */
    def bind[T](name: String, value: T): Unit
    
    /**
     * Binds a variable with explicit type
     * @param name Variable name
     * @param tpe Type information
     * @param value Variable value
     */
    def bind(name: String, tpe: String, value: Any): Unit
    
    /**
     * Resets the interpreter state
     * Clears all bindings and compiled code
     */
    def reset(): Unit
    
    /**
     * Gets a bound variable value
     * @param name Variable name
     * @tparam T Expected type
     * @return Variable value
     * @throws NoSuchElementException if variable not found
     */
    def get[T](name: String): T
    
    /**
     * Checks if a variable is bound
     * @param name Variable name
     * @return true if variable exists in interpreter context
     */
    def isBound(name: String): Boolean
    
    /**
     * Gets all bound variable names
     * @return Set of bound variable names
     */
    def getBoundNames: Set[String]
}

/**
 * Interface for Spark compiler implementations
 * Defines the contract for dynamic Scala compilation
 */
trait SparkCompiler {
    /**
     * Compiles Scala source code
     * @param code Source code to compile
     * @return Option containing compiled class or None if compilation fails
     */
    def compile(code: String): Option[Class[_]]
    
    /**
     * Compiles code with specific class name
     * @param className Target class name
     * @param code Source code to compile
     * @return Option containing compiled class or None if compilation fails
     */
    def compileClass(className: String, code: String): Option[Class[_]]
    
    /**
     * Gets compiler configuration settings
     * @return Current compiler settings
     */
    def getSettings: CompilerSettings
}

/**
 * Interface for Spark interpreter implementations
 * Defines the contract for interactive Scala code execution
 */
trait SparkInterpreter {
    /**
     * Interprets and executes Scala code
     * @param code Code to interpret
     */
    def interpret(code: String): Unit
    
    /**
     * Binds a variable to interpreter context
     * @param name Variable name
     * @param value Variable value
     */
    def bind(name: String, value: Any): Unit
    
    /**
     * Resets interpreter state
     */
    def reset(): Unit
}

import co.cask.cdap.app.runtime.spark.dynamic.DefaultSparkCompiler

// Create compiler instance
val compiler = new DefaultSparkCompiler()

// Set up classpath
compiler.setClassPath(Array(
    "/path/to/spark-core.jar",
    "/path/to/cdap-api.jar"
))

// Compile simple class
val code = """
class DynamicTransform {
  def transform(input: String): String = {
    input.toUpperCase.reverse
  }
}
"""

compiler.compile(code) match {
    case Some(clazz) =>
        // Create instance and use
        val instance = clazz.newInstance()
        val method = clazz.getMethod("transform", classOf[String])
        val result = method.invoke(instance, "hello world")
        println(s"Result: $result") // Result: DLROW OLLEH
        
    case None =>
        println("Compilation failed")
}

// Compile with specific class name
val transformerCode = """
package com.example
class CustomTransformer(multiplier: Int) {
  def process(values: Array[Int]): Array[Int] = {
    values.map(_ * multiplier)
  }
}
"""

compiler.compileClass("com.example.CustomTransformer", transformerCode) match {
    case Some(clazz) =>
        val constructor = clazz.getConstructor(classOf[Int])
        val transformer = constructor.newInstance(Int.box(2))
        // Use transformer...
    case None =>
        println("Compilation failed")
}

import co.cask.cdap.app.runtime.spark.dynamic.DefaultSparkInterpreter

// Create interpreter instance
val interpreter = new DefaultSparkInterpreter()

// Bind variables
interpreter.bind("sparkContext", sparkContext)
interpreter.bind("inputData", Array(1, 2, 3, 4, 5))

// Execute code interactively
interpreter.interpret("val doubled = inputData.map(_ * 2)")
interpreter.interpret("println(s\"Doubled: ${doubled.mkString(', ')}\")")

// Get results back
val result = interpreter.interpretAndReturn[Array[Int]]("doubled")
println(s"Result array: ${result.mkString(", ")}")

// Check bindings
if (interpreter.isBound("doubled")) {
    val boundValue = interpreter.get[Array[Int]]("doubled")
    println(s"Bound value: ${boundValue.mkString(", ")}")
}

// Reset interpreter
interpreter.reset()

import org.apache.spark.SparkContext
import co.cask.cdap.app.runtime.spark.dynamic.{DefaultSparkCompiler, DefaultSparkInterpreter}

// Create Spark RDD processing with dynamic code
def processWithDynamicCode(sc: SparkContext, 
                          data: Array[String], 
                          transformCode: String): Array[String] = {
    
    val compiler = new DefaultSparkCompiler()
    
    // Compile transform function
    val wrapperCode = s"""
    class DynamicProcessor {
      def process(input: String): String = {
        $transformCode
      }
    }
    """
    
    compiler.compile(wrapperCode) match {
        case Some(clazz) =>
            // Create RDD and apply dynamic transformation
            val rdd = sc.parallelize(data)
            val transformedRDD = rdd.map { item =>
                val processor = clazz.newInstance()
                val method = clazz.getMethod("process", classOf[String])
                method.invoke(processor, item).asInstanceOf[String]
            }
            transformedRDD.collect()
            
        case None =>
            throw new RuntimeException("Failed to compile transformation code")
    }
}

// Usage
val inputData = Array("apple", "banana", "cherry")
val transformCode = "input.toUpperCase + \"_PROCESSED\""
val results = processWithDynamicCode(sparkContext, inputData, transformCode)
// Results: Array("APPLE_PROCESSED", "BANANA_PROCESSED", "CHERRY_PROCESSED")

import co.cask.cdap.app.runtime.spark.dynamic.DefaultSparkInterpreter

// Create development environment
class SparkREPL(sparkContext: SparkContext) {
    private val interpreter = new DefaultSparkInterpreter()
    
    // Initialize with common imports and bindings
    interpreter.interpret("import org.apache.spark.SparkContext")
    interpreter.interpret("import org.apache.spark.rdd.RDD")
    interpreter.bind("sc", sparkContext)
    
    def execute(code: String): Unit = {
        try {
            interpreter.interpret(code)
        } catch {
            case e: Exception => println(s"Error: ${e.getMessage}")
        }
    }
    
    def bindData(name: String, data: Any): Unit = {
        interpreter.bind(name, data)
    }
    
    def getResult[T](expression: String): T = {
        interpreter.interpretAndReturn[T](expression)
    }
}

// Usage
val repl = new SparkREPL(sparkContext)

// Bind data
repl.bindData("numbers", Array(1, 2, 3, 4, 5))

// Execute transformations
repl.execute("val rdd = sc.parallelize(numbers)")
repl.execute("val squares = rdd.map(x => x * x)")
repl.execute("val sum = squares.reduce(_ + _)")

// Get results
val finalSum = repl.getResult[Int]("sum")
println(s"Sum of squares: $finalSum") // Sum of squares: 55

/**
 * Compiler configuration settings
 */
case class CompilerSettings(
    /**
     * Classpath entries for compilation
     */
    classpath: Array[String],
    
    /**
     * Output directory for compiled classes
     */
    outputDirectory: String,
    
    /**
     * Scala compiler options
     */
    options: Map[String, String],
    
    /**
     * Maximum compilation time in milliseconds
     */
    maxCompilationTime: Long
)

/**
 * Result of code validation
 */
case class ValidationResult(
    /**
     * Whether the code is syntactically valid
     */
    isValid: Boolean,
    
    /**
     * Compilation errors if any
     */
    errors: List[CompilationError],
    
    /**
     * Compilation warnings if any
     */
    warnings: List[CompilationWarning]
)

/**
 * Compilation error information
 */
case class CompilationError(
    /**
     * Error message
     */
    message: String,
    
    /**
     * Line number where error occurred
     */
    line: Int,
    
    /**
     * Column number where error occurred
     */
    column: Int,
    
    /**
     * Severity level of the error
     */
    severity: ErrorSeverity
)

/**
 * Compilation warning information
 */
case class CompilationWarning(
    /**
     * Warning message
     */
    message: String,
    
    /**
     * Line number where warning occurred
     */
    line: Int,
    
    /**
     * Column number where warning occurred
     */
    column: Int
)

/**
 * Error severity levels
 */
sealed trait ErrorSeverity
object ErrorSeverity {
    case object Info extends ErrorSeverity
    case object Warning extends ErrorSeverity
    case object Error extends ErrorSeverity
    case object Fatal extends ErrorSeverity
}

/**
 * Exception thrown during compilation
 */
class CompilationException(message: String, cause: Throwable = null) extends Exception(message, cause)

/**
 * Exception thrown during interpretation
 */
class InterpretationException(message: String, cause: Throwable = null) extends Exception(message, cause)