my solution (gophercises#41)

* Add another student solution to Part 1.

* Refactor code.

* Refactor code.

* Part2: add timer.

* Remove unnecessary code.

students/mirekwalczak/problems.csv

@@ -0,0 +1,12 @@
+5+5,   10
+"1+1",2
+8+3,     11
+1+2,3
+   8+6,14
+3+1,4
+1+4,5
+5+1,6
+2+3,5
+3+3,6
+2+4,6
+5+2,7

students/mirekwalczak/quiz.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"bufio"
+	"encoding/csv"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+	"time"
+)
+
+// Quiz is structure for questions and answers
+type Quiz struct {
+	question, answer string
+}
+
+// Stat is struct for quiz statistics
+type Stat struct {
+	all, correct, incorrect int
+}
+
+func readCSV(file string) ([]Quiz, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	var quizes []Quiz
+	r := csv.NewReader(f)
+	for {
+		line, err := r.Read()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		quizes = append(quizes, Quiz{
+			strings.TrimSpace(line[0]),
+			strings.TrimSpace(line[1]),
+		})
+	}
+	return quizes, nil
+}
+
+func quiz(records []Quiz, timeout int) (*Stat, error) {
+	var stat Stat
+	reader := bufio.NewReader(os.Stdin)
+
+	timer := time.NewTimer(time.Second * time.Duration(timeout))
+	errs := make(chan error)
+
+	go func() {
+		for _, quiz := range records {
+			fmt.Print(quiz.question, ":")
+
+			ans, err := reader.ReadString('\n')
+			if err != nil {
+				errs <- err
+			}
+			stat.all++
+			if strings.TrimRight(ans, "\r\n") == quiz.answer {
+				stat.correct++
+			} else {
+				stat.incorrect++
+			}
+		}
+	}()
+
+	select {
+	case <-errs:
+		return nil, <-errs
+	case <-timer.C:
+		fmt.Println("\ntime's up!")
+	}
+
+	return &stat, nil
+}
+
+func main() {
+	f := flag.String("f", "problems.csv", "input file in csv format")
+	t := flag.Int("t", 30, "timeout for the quiz, in seconds")
+	flag.Parse()
+	recs, err := readCSV(*f)
+	if err != nil {
+		log.Fatal(err)
+	}
+	stat, err := quiz(recs, *t)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("\nQuestion answered: %v, Correct: %v, Incorrect: %v\n", stat.all, stat.correct, stat.incorrect)
+}