gpa.go

package main

import (
	"errors"
	"fmt"
)

type KeyValueSlice map[string]float64

func main() {
	CalculateGPA()
}

func CalculateGPA() {
	fmt.Println("CGPA Calculator v1.0")

	for i := 1; i < 4; i++ {

		// to store course grade and units
		datastore := make([]KeyValueSlice, 0)

		var numberOfCourses int
		fmt.Printf("How many courses do you offer? (Min. of 3): ")
		fmt.Scanln(&numberOfCourses)

		if numberOfCourses < 3 {
			fmt.Println("You should offer a minimum of three(53 courses!!!")
			return
		}

		for j := 0; j < numberOfCourses; j++ {
			var courseScore float64
			var courseUnit int

			fmt.Printf("Enter the score and unit of the course(e.g 49 5): ")
			fmt.Scanln(&courseScore, &courseUnit)

			if courseScore >= 70 && courseScore <= 100 {
				datastore = append(datastore, KeyValueSlice{"courseUnit": float64(courseUnit), "coursePoint": 5})
			} else if courseScore >= 60 && courseScore < 70 {
				datastore = append(datastore, KeyValueSlice{"courseUnit": float64(courseUnit), "coursePoint": 4})
			} else if courseScore >= 50 && courseScore < 60 {
				datastore = append(datastore, KeyValueSlice{"courseUnit": float64(courseUnit), "coursePoint": 3})
			} else if courseScore >= 45 && courseScore < 50 {
				datastore = append(datastore, KeyValueSlice{"courseUnit": float64(courseUnit), "coursePoint": 2})
			} else if courseScore >= 40 && courseScore < 45 {
				datastore = append(datastore, KeyValueSlice{"courseUnit": float64(courseUnit), "coursePoint": 1})
			} else {
				datastore = append(datastore, KeyValueSlice{"courseUnit": float64(courseUnit), "coursePoint": 0})
			}

		}
		studentGPA := sum(datastore, "") / sum(datastore, "courseUnit")
		fmt.Printf("\nStudent #%v offered %v course(s) and has a GPA of %.2f/5\n\n\n", i, numberOfCourses, studentGPA)
		datastore = nil
	}
}

func sum(sliceToSum []KeyValueSlice, keyToSum string) float64 {
	var _sum float64

	if keyToSum == "" {
		for _, item := range sliceToSum {
			_sum += item["courseUnit"] * item["coursePoint"]
		}
	} else if _, ok := sliceToSum[0][keyToSum]; ok {
		for _, item := range sliceToSum {
			_sum += item[keyToSum]
		}
	} else {
		panic(errors.New("invalid key provided"))
	}
	return _sum
}