Implicit Expression Conversions

package object api extends ImplicitExpressionConversions

import org.apache.flink.table.api._
// All implicit conversions are now available

implicit val UNBOUNDED_ROW: Expression
implicit val UNBOUNDED_RANGE: Expression
implicit val CURRENT_ROW: Expression
implicit val CURRENT_RANGE: Expression

// Use in over window definitions
table.window(Over.partitionBy($"userId").orderBy($"timestamp").preceding(UNBOUNDED_ROW))

/**
 * Creates an unresolved reference to a table's column
 * @param name Column name
 * @return Expression representing the field reference
 */
def $(name: String): Expression

/**
 * Synonym for $ method for cases where dollar sign would be inconvenient
 * @param name Column name  
 * @return Expression representing the field reference
 */
def col(name: String): Expression

implicit class FieldExpression(val sc: StringContext) {
  /**
   * Creates an unresolved reference to a table's column via string interpolation
   * @param args Interpolation arguments
   * @return Expression representing the field reference
   */
  def $(args: Any*): Expression
}

// String interpolation syntax
table.select($"key", $"value")

// Dynamic field names
val fieldName = "userId"
table.select($"$fieldName", $"amount")

implicit def symbol2FieldExpression(sym: Symbol): Expression

implicit class UnresolvedFieldExpression(s: Symbol) extends ImplicitExpressionOperations {
  def expr: Expression
}

// Using symbols for field references
table.select('name, 'age, 'email)
table.filter('age > 18)

// Numeric conversions
implicit def byte2Literal(b: Byte): Expression
implicit def short2Literal(s: Short): Expression  
implicit def int2Literal(i: Int): Expression
implicit def long2Literal(l: Long): Expression
implicit def float2Literal(f: Float): Expression
implicit def double2Literal(d: Double): Expression

// Java numeric types
implicit def byte2Literal(b: JByte): Expression
implicit def short2Literal(s: JShort): Expression
implicit def int2Literal(i: JInteger): Expression
implicit def long2Literal(l: JLong): Expression
implicit def float2Literal(f: JFloat): Expression
implicit def double2Literal(d: JDouble): Expression

// String and boolean
implicit def string2Literal(str: String): Expression
implicit def boolean2Literal(bool: Boolean): Expression
implicit def boolean2Literal(bool: JBoolean): Expression

// Decimal types
implicit def javaDec2Literal(javaDec: JBigDecimal): Expression
implicit def scalaDec2Literal(scalaDec: BigDecimal): Expression

// Date/time types
implicit def sqlDate2Literal(sqlDate: Date): Expression
implicit def sqlTime2Literal(sqlTime: Time): Expression
implicit def sqlTimestamp2Literal(sqlTimestamp: Timestamp): Expression
implicit def localDate2Literal(localDate: LocalDate): Expression
implicit def localTime2Literal(localTime: LocalTime): Expression
implicit def localDateTime2Literal(localDateTime: LocalDateTime): Expression

implicit def javaList2ArrayConstructor(jList: JList[_]): Expression
implicit def seq2ArrayConstructor(seq: Seq[_]): Expression
implicit def array2ArrayConstructor(array: Array[_]): Expression
implicit def javaMap2MapConstructor(map: JMap[_, _]): Expression
implicit def map2MapConstructor(map: Map[_, _]): Expression
implicit def row2RowConstructor(rowObject: Row): Expression

// Collections as expressions
val numbers = List(1, 2, 3, 4)
table.select($"id", lit(numbers) as "numbers")

val config = Map("timeout" -> 30, "retries" -> 3)  
table.select($"request", lit(config) as "config")

implicit def scalaRange2RangeExpression(range: Range.Inclusive): Expression

// Using ranges in column selection
table.select(withColumns(1 to 5))  // Select columns 1 through 5

implicit class LiteralLongExpression(l: Long) extends ImplicitExpressionOperations
implicit class LiteralIntExpression(i: Int) extends ImplicitExpressionOperations  
implicit class LiteralStringExpression(str: String) extends ImplicitExpressionOperations
implicit class LiteralBooleanExpression(bool: Boolean) extends ImplicitExpressionOperations
// ... additional literal wrapper classes for all primitive types

// Direct operations on literals
val result = table.select(
  $"price" * 1.2 as "priceWithTax",
  "Hello " + $"name" as "greeting",
  42 + $"bonus" as "total"
)

/**
 * Creates a SQL literal from a value with automatic type inference
 * @param v Value to convert to literal
 * @return Expression literal
 */
def lit(v: Any): Expression

/**
 * Creates a SQL literal with explicit DataType
 * @param v Value to convert to literal  
 * @param dataType Explicit data type
 * @return Expression literal
 */
def lit(v: Any, dataType: DataType): Expression

// Automatic type inference
table.select(lit(42), lit("hello"), lit(true))

// Explicit typing
table.select(
  lit(42, DataTypes.BIGINT()),
  lit("2021-01-01", DataTypes.DATE()),
  lit(null, DataTypes.STRING())
)

implicit class AnyWithOperations[T](e: T)(implicit toExpr: T => Expression) extends ImplicitExpressionOperations {
  def expr: Expression
}

implicit class WithOperations(e: Expression) extends ImplicitExpressionOperations {
  def expr: Expression
}

// Chain operations on any expression
val complexExpr = ($"amount" + 100) * 1.2 > $"threshold"
table.filter(complexExpr)