package main

import (

    "fmt"

    "sort"

    "time"

)

type Track struct {

    Title  string

    Artist string

    Album  string

    Year   int

    Length time.Duration

}

type Tracks []Track

func ParseDurationTime(s string) time.Duration {

    d, err := time.ParseDuration(s)

    if err != nil {

        return ParseDurationTime("0s")

    } else {

        return d

    }

}

// {{{ implementation of Sort interface

// Len is the number of elements in the collection.

func (x Tracks) Len() int {

    return len(x)

}

// Less reports whether the element with

// index i should sort before the element with index j.

func (x Tracks) Less(i, j int) bool {

    return x[i].Year < x[j].Year

}

// Swap swaps the elements with indexes i and j.

func (x Tracks) Swap(i, j int) {

    x[i], x[j] = x[j], x[i]

}

// end implementation of Sort interface }}}

var tracks = Tracks{

    {Title: "C#", Artist: "Delu", Album: "Reading", Year: 2017, Length: ParseDurationTime("3m38s")},

    {Title: "Go", Artist: "Anderson", Album: "Reading", Year: 2018, Length: ParseDurationTime("3m38s")},

    {Title: "Java Bible", Artist: "Js", Album: "Reading", Year: 2016, Length: ParseDurationTime("3m38s")}}

//main function

func main() {

    sort.Sort(tracks)

    for key, value := range tracks {

        fmt.Printf("%v:%v \n", key, value)

    }

}