World Cup

四年一度的世界杯最近正在俄罗斯如火如荼的进行，昨天看了西班牙🇪🇸对葡萄牙🇵🇹的比赛，C罗真的是太帅了，帽子戏法，不过作为一个伪球迷-真程序员，准备写一点和世界杯有关的东西，想想用机器学习预测比赛结果好像并没有什么卵用，于是就写一个最简单的搬砖程序来提醒自己比赛时间吧。最终效果如下所示，典型的 MVC 。

Costa Rica                       0 - 0                           Serbia
------------------------------------------------------------------------
⚽  Will be played 4 hours from now


Germany                          0 - 0                           Mexico
------------------------------------------------------------------------
⚽  Will be played 7 hours from now


Brazil                           0 - 0                      Switzerland
------------------------------------------------------------------------
⚽  Will be played 10 hours from now

Model

比赛相关的数据可以从 http://worldcup.sfg.io/ 获取，我们使用结构体定义数据模型，注意结构体中的数据字段必须为大写，否则无法正确 Unmarshal，如果想要使结构体中的字段与 json 中的字段不同，可以额外增加 tag 来说明。

type match struct {
    Time     string `json:"time,omitempty"`
    DateTime string `json:"datetime,omitempty"`
    HomeTeam team   `json:"home_team,ommitempty"`
    AwayTeam team   `json:"away_team,omitempty"`
    Winner   string `json:"winner,omitempty"`
}

type team struct {
    Country string `json:"country,omitempty"`
    Code    string `json:"code,omitempty"`
    Goals   int    `json:"goals,omitempty"`
}

func fetch(endpoint) ([]match, error) {
    url := fmt.Sprintf("http://worldcup.sfg.io/%s", endpoint)
    res, err := http.Get(url)
    if err != nil {
        return nil, err
    }
    defer res.Body.Close()
    b, err := ioutil.ReadAll(res.Body)
    if err != nil {
        return nil, err
    }
    var matches []match
    err = json.Unmarshal(b, &matches)
    if err != nil {
        return nil, err
    }
    return matches, nil
}

View

因为我们的 layout 相对比较复杂，所以 View 部分代码也最多，但难度不大，就是繁琐，主要注意几点，彩色字体输出，不同情况下进度条的展示效果和各个字段所在的位置。

type status int

const (
    PAST status = iota
    NOW
    FUTURE
)

const ScreenWidth = 72

const (
    START = "\x1b[32m"
    END   = "\x1b[0m"
)

func colorize(s string) string {
    return START + s + END
}

func multiply(c rune, n int) string {
    var cs []rune
    for i := 0; i < n; i++ {
        cs = append(cs, c)
    }
    return string(cs)
}

func prettify(m match) string {

    t, _ := time.Parse(time.RFC3339, m.DateTime)
    diff := int(time.Now().Sub(t).Seconds())

    var status status
    switch {
    case diff > 60*90:
        status = PAST
    case diff < 0:
        status = FUTURE
    default:
        status = NOW
    }

    percentage := 0
    matchStatus := ""
    on := false

    switch status { 
    case PAST:
        percentage = 100
        var result string
        if m.Winner == "Draw" {
            result = "Draw"
        } else {
            result = fmt.Sprintf("%s won", m.Winner)
        }
        matchStatus = fmt.Sprintf("Played %s. %s", humanize.Time(t), result)
        on = true
    case NOW:
        percentage = int(diff / 60 / 90 * 100)
        matchStatus = fmt.Sprintf("Being played now: %s minutes gone", humanize.Time(t))
        on = true
    case FUTURE:
        percentage = 0
        matchStatus = fmt.Sprintf("Will be played %s", humanize.Time(t))
    }

    home := m.HomeTeam
    away := m.AwayTeam

    s, e := "", ""
    if on {
        s = start
        e = end
    }

    return fmt.Sprintf("    %s%-32s %d - %d %32s%s\n    %s\n    \u26BD  %s\n",
        s,home.Country,home.Goals,away.Goals,away.Country,e,
        progressBar(percentage),
        matchStatus,
    )
}

func progressBar(percentage int) string {
    var bar string

    switch percentage {
    case 0:
        bar = multiply('-', ScreenWidth)
    case 100:
        bar = colorize(multiply('-', ScreenWidth))
    default:
        completed := int(float64(ScreenWidth) / 100.0 * float64(percentage))
        bar = colorize(multiply('-', completed-1)+"o") + multiply('-', ScreenWidth-completed)
    }

    return bar
}

Controller

Controller 部分就是将 Model 部分和 view 部分代码整合在一起。

func main() {
    matches, err := fetch("matches/today")
    if err != nil {
        log.Fatal(err)
    }
    for i, match := range matches {
        if i == 0 {
            fmt.Println()
        }
        fmt.Println(prettify(match))
        if i != len(matches)-1 {
            fmt.Println()
        }
    }
}