hhc-tsp/src/main/scala/util/Util.scala

package util

import model.Coord
import scala.math._
import scala.collection.mutable.ArrayBuffer
import scala.collection.mutable
import model.Customer
import scala.io.BufferedSource
import scala.reflect.ClassTag

object Util {
  private val r = 6471.00 // km

  def toRad(num: Double): Double = {
    val a = num * Pi / 180
    a
  }

  def getHaversineDistance(c1: Coord, c2: Coord): Double = {
    val x1 = c1.latitude - c2.latitude
    val x2 = c1.longitude - c2.longitude

    val dlat = toRad(x1)
    val dlon = toRad(x2)

    val a = pow(sin(dlat / 2), 2) +
      cos(toRad(c1.latitude)) *
        cos(toRad((c2.latitude))) *
        pow(sin(dlon / 2), 2)

    val c = 2 * atan2(sqrt(a), sqrt(1 - a))
    val d = r * c
    d
  }

  def getHaversineDistance(lat: Double, lon: Double): Double = {
    val x1 = lat
    val x2 = lon

    val dlat = toRad(x1)
    val dlon = toRad(x2)

    val a = pow(sin(dlat / 2), 2) +
      cos(toRad(x1)) *
        cos(toRad((0))) *
        pow(sin(dlon / 2), 2)

    val c = 2 * atan2(sqrt(a), sqrt(1 - a))
    val d = r * c
    d
  }

  def primTraverse(
      arr1: Array[Array[Int]],
      comp: Int,
      cond: (Int, Int) => Boolean,
      cb: (Int, Int, Array[Array[Int]], Array[Array[Int]]) => Array[Array[Int]]
  ): Unit = {
    val n = arr1.length
    val selected = Array.ofDim[Boolean](n)

    val arr2: Array[Array[Int]] = Array.ofDim(n, n)

    selected(0) = true

    // val mst: Array[Array[Int]] = Array.ofDim(5, 5)

    for (_ <- 0 until n - 1) {
      // var min = 999999
      var x = 0
      var y = 0
      for (i <- 0 until n) {
        if (selected(i) == true) {
          for (j <- 0 until n) {
            if (selected(j) == false && arr1(i)(j) != 0) {
              if (cond(comp, arr1(i)(j))) {
                x = i
                y = j
                cb(x, y, arr1, arr2)
              }
            }
          }

        }

      }
      // mst(x)(y) = mst(x)(y)
      selected(y) = true
    }
  }

  def mstUsingPrims[T: ClassTag](
      edges: Array[Array[T]]
  )(implicit num: Numeric[T]): Array[Array[T]] = {
    val n = edges.length
    val selected: ArrayBuffer[Boolean] = ArrayBuffer.fill(n)(false)

    selected(0) = true

    val mst: Array[Array[T]] = Array.ofDim[T](n, n)

    for (_ <- 0 until n - 1) {
      var min = 999999
      var x = 0
      var y = 0
      for (i <- 0 until n) {
        if (selected(i) == true) {
          for (j <- 0 until n) {
            if (selected(j) == false && edges(i)(j) != 0) {
              if (num.gt(num.fromInt(min), edges(i)(j))) {
                min = num.toInt(edges(i)(j))
                x = i
                y = j
              }
            }
          }
        }
      }
      // println(s"Edge selected $x - $y : ${edges(x)(y)}")
      mst(x)(y) = edges(x)(y)
      mst(y)(x) = edges(x)(y)

      selected(y) = true
    }
    mst
  }

  def findClusters[T](
      mst: Array[Array[T]],
      centroids: IndexedSeq[Int],
      removed: IndexedSeq[(Int, Int, T)]
  )(implicit num: Numeric[T]) =
    (
      centroids,
      centroids
        .map(d => {
          val y = DFS(d, mst)
          y(0) -> y
        })
        .toMap,
      removed
    )

  def makeAdjacencyList(
      mst: Array[Array[Int]],
      centroids: IndexedSeq[Int]
  ): ArrayBuffer[ArrayBuffer[Int]] = {
    val n = mst.length
    // val selected: ArrayBuffer[Boolean] = ArrayBuffer.fill(n)(false)
    val buf: ArrayBuffer[ArrayBuffer[Int]] =
      ArrayBuffer.fill(n)(ArrayBuffer.empty)
    // for (_ <- 0 until n -1) {

    // }
    for (i <- 0 until n) {
      for (j <- 0 until n) {
        if (mst(i)(j) != 0) {
          // println(s" $i $j = ${mst(i)(j)}")
          buf(i) += j
        }
      }
    }
    buf
  }

  def findCentroids[T](
      mst: Array[Array[T]]
  )(
      implicit ev: Numeric[T]
  ): (Array[Array[T]], IndexedSeq[Int], IndexedSeq[(Int, Int, T)]) = {
    val n = mst.length
    val centroids: mutable.Set[Int] = mutable.Set.empty
    val removed: ArrayBuffer[(Int, Int, T)] = ArrayBuffer.empty
    for (i <- 0 until n) {
      for (j <- 0 until n) {
        if (ev.gt(mst(i)(j), ev.fromInt(20)) && mst(i)(j) != 0) {
          // println(s" $i $j = ${mst(i)(j)}")
          centroids += i
          centroids += j
          removed.append((i, j, mst(i)(j)))
          mst(i)(j) = ev.zero
        }
      }
    }
    (mst, centroids.toIndexedSeq, removed.toIndexedSeq)
  }

  def DFS[T](
      start: Int,
      graph: Array[Array[T]]
  )(implicit num: Numeric[T]): ArrayBuffer[Int] = {
    val visited = Array.fill(graph.size)(false)
    val buf = ArrayBuffer[Int]()
    def loop(
        start: Int,
        graph: Array[Array[T]],
        visited: Array[Boolean]
    ): Unit = {
      visited(start) = true
      buf += start
      // print(s"$start ")

      for (i <- 0 until graph.size) {
        if (num.gt(graph(start)(i), num.fromInt(0)) && (!visited(i))) {
          loop(i, graph, visited);
        }
      }
    }

    loop(start, graph, visited)
    // println()
    buf
  }

  def DFS(
      start: Int,
      graph: Array[Array[Int]],
      num: Int,
      cond: (Int, Int) => Boolean
  ): ArrayBuffer[Int] = {
    val visited = Array.fill(graph.size)(false)
    val buf = ArrayBuffer[Int]()
    def loop(
        start: Int,
        graph: Array[Array[Int]],
        visited: Array[Boolean]
    ): Unit = {
      visited(start) = true
      buf += start
      // print(s"$start ")

      for (i <- 0 until graph.size) {
        if (graph(start)(i) > 0 && cond(graph(start)(i), num) && (!visited(i))) {
          loop(i, graph, visited);
        }
      }
    }

    loop(start, graph, visited)
    // println()
    buf
  }

  def groupClusters[T](
      centroids: IndexedSeq[Int],
      clusters: Map[Int, ArrayBuffer[Int]],
      removed: IndexedSeq[(Int, Int, T)]
  )(implicit num: Numeric[T]) =
    centroids
      .map(c => {
        val cluster = clusters(c)
        val lst = removed
          .filter(r => {
            c == r._1
          })
          .sortWith((x, y) => {
            num.lt(x._3, y._3)
          })
          .map(l => {
            (l._2, l._3)
          })
        c -> lst
      })
      .toMap

  def getCustomers(
      infile: BufferedSource
  ): String Either IndexedSeq[Customer] = {
    var customers: String Either IndexedSeq[Customer] = Right(IndexedSeq.empty)
    val it = infile.getLines
    @annotation.tailrec
    def loop(
        lst: IndexedSeq[Customer],
        iter: Iterator[String]
    ): String Either IndexedSeq[Customer] = {
      if (!iter.hasNext)
        return Right(lst)
      val line = iter.next
      val arr = line.split(",").map(_.trim)
      arr match {
        case Array(latitude, longitude, workLoad) => {
          val cust =
            Customer(
              Coord(latitude.toDouble, longitude.toDouble),
              workLoad.toFloat
            )
          loop(lst :+ cust, iter)
        }
        case _ =>
          Left(
            "Error reading customers from" +
              s" file - ${arr.mkString(", ")}"
          )
      }
    }
    try {
      customers = loop(IndexedSeq.empty, it)
    } catch {
      case e: NumberFormatException =>
        customers = Left(
          s"Expected number but received string ${e.getMessage()}"
        )
      case e: NullPointerException =>
        customers = Left("Input was null")
    }
    customers
  }

  def formAdjMatrix(customers: IndexedSeq[Customer]): Array[Array[Double]] = {
    val n = customers.length
    val edges: Array[Array[Double]] = Array.ofDim(n, n)
    for (i <- 0 until n) {
      for (j <- i until n) {
        val weight =
          getHaversineDistance(customers(i).location, customers(j).location)
        edges(i)(j) = weight
        edges(j)(i) = weight
      }
    }
    edges
  }

}