// Advanvced Part 3 about Mr T. Drumb investing into stocks

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

//two test portfolios

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

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

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

import io.Source

import scala.util._

def get_yahoo_page(url: String): Option[List[String]] = {

  Try(Some(Source.fromURL(url)("ISO-8859-1").getLines.toList)).

    getOrElse { None }

}

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

  //println(s"download..${symbol} at ${year}")

  val year_string = year.toString

  val date_string = s"&a=0&b=1&c=${year_string}&d=1&e=1&f=${year_string}"

  val url = """http://ichart.yahoo.com/table.csv?s=""" + symbol + date_string

  val data = get_yahoo_page(url)

  data.map(_.last.split(",").toList(6).toDouble)

}

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

  for (year <- years.toList) yield

    for (symbol <- portfolio) yield get_first_price(symbol, year)

get_prices(List("GOOG", "AAPL"), 2010 to 2012)

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

  (price_old, price_new) match {

    case (Some(x), Some(y)) => Some((y - x) / x)

    case _ => None

  }

}

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

  for (i <- (0 until (data.length - 1)).toList) yield 

    for (j <- (0 until (data(0).length)).toList) yield get_delta(data(i)(j), data(i + 1)(j))

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

  val somes = data(year).flatten

  val somes_length = somes.length

  if (somes_length == 0) balance

  else {

    val portion: Double = balance / somes_length

    balance + (for (x <- somes) yield (x * portion)).sum.toLong

  }

}

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

  if (year >= data.length) balance else {

    val new_balance = yearly_yield(data, balance, year)

    compound_yield(data, new_balance, year + 1)

  }

}

val p = get_prices(List("GOOG", "AAPL"), 2010 to 2012)

val d = get_deltas(p)

yearly_yield(d, 100, 0)

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

  compound_yield(get_deltas(get_prices(portfolio, years)), start_balance, 0)

}

println("Real data: " + investment(rstate_portfolio, 1978 to 2016, 100))

println("Blue data: " + investment(blchip_portfolio, 1978 to 2016, 100))