// Part 2 about Buy-Low-Sell-High using Yahoo Financial Data

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

// (1) Complete the function that is given a list of floats

// and calculuates the indices for when to buy the commodity 

// and when to sell

def trade_times(xs: List[Double]): (Int, Int) = {

  val low = xs.min

  val low_index = xs.indexOf(low)

  val rest = xs.drop(low_index)

  val high = rest.max

  val high_index = rest.indexOf(high)

  (low_index, low_index + high_index)

}

val prices = List(28.0, 18.0, 20.0, 26.0, 24.0)

assert(trade_times(prices) == (1, 3), "the trade_times test fails")

// (2) Complete the ``get webpage'' function that takes a

// a stock symbol as argument and queries the Yahoo server

// at

//      http://ichart.yahoo.com/table.csv?s=<<insert stock symbol>>

// 

// This servive returns a CSV-list that needs to be separated into

// a list of strings.

import io.Source

import scala.util._

def get_yahoo_page(symbol: String): List[String] = {

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

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

    getOrElse { println(s"  Problem with: $url"); List() }

}

// (3) Complete the function that processes the CSV list

// extracting the dates and anjusted close prices. The

// prices need to be transformed into Doubles.

def process_page(symbol: String): List[(String, Double)] = {

  get_yahoo_page(symbol).drop(1).map(_.split(",").toList).map((xs) => (xs(0), xs(6).toDouble))

}

// (4) Complete the query_company function that obtains the

// processed CSV-list for a stock symbol. It should return

// the dates for when to buy and sell the stocks of that company.

def query_company(symbol: String): (String, String) = {

  val list = process_page(symbol).reverse

  val (tbuy, tsell) = trade_times(list.map(_._2))

  (list(tbuy)._1, list(tsell)._1)

}

//query_company("GOOG")

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

for (name <- indices) {

  val times = query_company(name)

  println(s"Buy ${name} on ${times._1} and sell on ${times._2}")

}

/*

scala trade.scala 2> /dev/null || echo "command1 borked it"

command1

if [ $? -ne 0 ]; then

    echo "command1 borked it"

fi

*/