You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: weedkay.go
    path of file: ./repos/when/rules/zh
    
    the code of the file until where you have to start completion: package zh

import (
	"regexp"
	"strings"
	"time"

	"github.com/olebedev/when/rules"
)

func Weekday(s rules.Strategy) rules.Rule {
	overwrite := s == rules.Override

	return &rules.F{
		RegExp: regexp.MustCompile("(?i)" +
			"(?:(本|这|下|上|这个|下个|上个|下下)\\s*)?" +
			"(?:(周|礼拜|星期)\\s*)" +
			"(1|2|3|4|5|6|天|一|二|三|四|五|六|日)" +
			"(?:\\W|$)",
		),

		Applier: func(m *rules.Match, c *rules.Context, o *rules.Options, ref time.Time) (bool, error) {
			_ 
    
func Weekday(s rules.Strategy) rules.Rule {
	overwrite := s == rules.Override

	return &rules.F{
		RegExp: regexp.MustCompile("(?i)" +
			"(?:(本|这|下|上|这个|下个|上个|下下)\\s*)?" +
			"(?:(周|礼拜|星期)\\s*)" +
			"(1|2|3|4|5|6|天|一|二|三|四|五|六|日)" +
			"(?:\\W|$)",
		),

		Applier: func(m *rules.Match, c *rules.Context, o *rules.Options, ref time.Time) (bool, error) {
			_ = overwrite

			if strings.TrimSpace(m.Captures[1]) == "" {
				return false, nil
			}

			day := strings.ToLower(strings.TrimSpace(m.Captures[2]))
			norm := strings.ToLower(strings.TrimSpace(m.Captures[0]))
			if norm == "" {
				norm = "本"
			}
			dayInt, ok := WEEKDAY_OFFSET[day]
			if !ok {
				return false, nil
			}

			if c.Duration != 0 && !overwrite {
				return false, nil
			}

			// Switch:
			switch {
			case strings.Contains(norm, "上"):
				diff := int(ref.Weekday()) - dayInt
				c.Duration = -time.Duration(7+diff) * 24 * time.Hour
			case strings.Contains(norm, "下下"):
				diff := dayInt - int(ref.Weekday())
				c.Duration = time.Duration(7+7+diff) * 24 * time.Hour
			case strings.Contains(norm, "下"):
				diff := dayInt - int(ref.Weekday())
				c.Duration = time.Duration(7+diff) * 24 * time.Hour
			case strings.Contains(norm, "本") || strings.Contains(norm, "这"):
				if int(ref.Weekday()) < dayInt {
					diff := dayInt - int(ref.Weekday())
					if diff > 0 {
						c.Duration = time.Duration(diff*24) * time.Hour
					} else if diff < 0 {
						c.Duration = time.Duration(7+diff) * 24 * time.Hour
					} else {
						c.Duration = 7 * 24 * time.Hour
					}
				} else if int(ref.Weekday()) > dayInt {
					diff := int(ref.Weekday()) - dayInt
					if diff > 0 {
						c.Duration = -time.Duration(diff*24) * time.Hour
					} else if diff < 0 {
						c.Duration = -time.Duration(7+diff) * 24 * time.Hour
					} else {
						c.Duration = -(7 * 24 * time.Hour)
					}
				}
			}

			return true, nil
		},
	}
}