// Main Part 1 about a really dumb investment strategy

//===================================================

object M1 {

//two test portfolios

val blchip_portfolio = List("GOOG", "AAPL", "MSFT", "IBM", "FB", "AMZN", "BIDU")

val rstate_portfolio = List("PLD", "PSA", "AMT", "AIV", "AVB", "BXP", "CCI", 

                            "DLR", "EQIX", "EQR", "ESS", "EXR", "FRT", "HCP") 

import io.Source

import scala.util._

// ADD YOUR CODE BELOW

//======================

// (1) 

def get_january_data(symbol: String, year: Int) : List[String] = {

  Try(Source.fromFile(s"${symbol}.csv").getLines.toList.filter(_.startsWith(year.toString))).getOrElse(Nil)

}

// (2) 

def get_first_price(symbol: String, year: Int) : Option[Double] = {

  val list = get_january_data(symbol, year)

  if (list == Nil) None else {

    Some(list.head.split(",").toList(1).toDouble)

  }

}

// (3) 

def get_prices(portfolio: List[String], years: Range) : List[List[Option[Double]]] = {

  for (n <- years.toList) yield{

    for (m <- portfolio) yield{

      get_first_price(m, n)

    }

  }

}

// (4) 

def get_delta(price_old: Option[Double], price_new: Option[Double]) : Option[Double] = {

  if (price_old != None && price_new != None) Some((price_new.get - price_old.get) / price_old.get) else None

}

// (5) 

def get_deltas(data: List[List[Option[Double]]]) :  List[List[Option[Double]]] = {

  for (n <- data.tail) yield{

    for (m <- n) yield{

      get_delta(data(data.tail.indexOf(n))(n.indexOf(m)),m)

    }

  }

}

// (6) 

def yearly_yield(data: List[List[Option[Double]]], balance: Long, index: Int) : Long = {

  if(data.length == 0) balance else{

    val equal = balance / data(index).flatten.length

    val list = for(n <- data(index).flatten) yield n * equal

    (balance + list.sum).toLong

  }

}

// (7) 

def compound_yield(data: List[List[Option[Double]]], balance: Long, index: Int) : Long = {

  val deltas = get_deltas(data)

  if (deltas.length == 0) balance else{

      if(deltas.length - 1 == index) yearly_yield(deltas, balance, index) else compound_yield(data, yearly_yield(deltas, balance, index), index + 1)

  }

}

def investment(portfolio: List[String], years: Range, start_balance: Long) : Long = {

  val list = get_prices(portfolio, years)

  compound_yield(list, start_balance, 0)

}

//Test cases for the two portfolios given above

//println("Real data: " + investment(rstate_portfolio, 1978 to 2019, 100))

//println("Blue data: " + investment(blchip_portfolio, 1978 to 2019, 100))

}

// This template code is subject to copyright 

// by King's College London, 2022. Do not 

// make the template code public in any shape 

// or form, and do not exchange it with other 

// students under any circumstance.