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Typed postgres boilerplate generation

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package typo.dsl

import scala.math.Ordering.Implicits.seqOrdering

/** Calculates aliases for all unique list of [[Path]]s in a select query. This is used to evaluate expressions from an [[SqlExpr]] when we have joined relations */
class RenderCtx(val alias: Map[List[Path], String]) extends AnyVal

object RenderCtx {
  val Empty = new RenderCtx(Map.empty)

  def from[F, R](s: SelectBuilderSql[F, R]): RenderCtx = {
    def findPathsAndTableNames(s: SelectBuilderSql[?, ?]): List[(List[Path], String)] =
      s match {
        case SelectBuilderSql.Relation(name, structure, _, _)      => List(structure._path -> name.filter(_.isLetterOrDigit))
        case x @ SelectBuilderSql.TableJoin(left, right, _, _)     => List(x.structure._path -> "join_cte") ++ findPathsAndTableNames(left) ++ findPathsAndTableNames(right)
        case x @ SelectBuilderSql.TableLeftJoin(left, right, _, _) => List(x.structure._path -> "left_join_cte") ++ findPathsAndTableNames(left) ++ findPathsAndTableNames(right)
      }

    val nameForPathsMap: Map[List[Path], String] =
      findPathsAndTableNames(s)
        .groupMap { case (_, name) => name } { case (path, _) => path }
        .flatMap { case (sameName, paths) =>
          paths.sorted.zipWithIndex.map { case (path, idx) => path -> s"$sameName$idx" }
        }

    new RenderCtx(nameForPathsMap)
  }
}