solve it (gophercises#12)

* solve it

* fix exit by first error

* change by solution

students/mielofon/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/mielofon/quiz.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"encoding/csv"
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+	"time"
+)
+
+type recordtype struct {
+	question string
+	answer   string
+}
+
+// ReadStringWithLimitTime - function read string from reader with time limit
+func ReadStringWithLimitTime(limit int) (string, error) {
+	timer := time.NewTimer(time.Duration(limit) * time.Second).C
+	doneChan := make(chan bool)
+	answer, err := "", error(nil)
+	go func() {
+		fmt.Scanf("%s\n", &answer)
+		doneChan <- true
+	}()
+	for {
+		select {
+		case <-timer:
+			return "", errors.New("Timer expired")
+		case <-doneChan:
+			return answer, err
+		}
+	}
+}
+
+// ParseLines  - parse lines from array of array of string to array of recordtype
+func ParseLines(lines [][]string) []recordtype {
+	ret := make([]recordtype, len(lines))
+	for i, line := range lines {
+		ret[i] = recordtype{
+			question: line[0],
+			answer:   strings.TrimSpace(line[1]),
+		}
+	}
+	return ret
+}
+
+func exit(msg string) {
+	fmt.Println(msg)
+	os.Exit(1)
+}
+
+func main() {
+
+	problemFileName := flag.String("csv", "./problems.csv", "a csv file in the format 'quastion,answer'")
+	limit := flag.Int("limit", 30, "the time limit for the quiz in seconds")
+	flag.Parse()
+
+	problemFile, err := os.Open(*problemFileName)
+	if err != nil {
+		exit(fmt.Sprintf("Failed to open the CSV file: %s\n", *problemFileName))
+	}
+
+	defer problemFile.Close() // close CSV file
+
+	readerProblem := csv.NewReader(problemFile)
+	lines, err := readerProblem.ReadAll()
+	if err != nil {
+		exit("Failed to parse the provided CSV file.")
+	}
+
+	problems := ParseLines(lines)
+
+	successAnswerCount := 0
+	for i, p := range problems {
+		fmt.Printf("Problem #%d: %s=", i+1, p.question)
+
+		answer, err := ReadStringWithLimitTime(*limit)
+		if err != nil {
+			println("Time expire!")
+			break
+		}
+		if strings.ToLower(strings.Trim(answer, "\n ")) == p.answer {
+			successAnswerCount++
+		}
+	}
+	println("You scored", successAnswerCount, "out of", len(problems))
+
+}