From 74bd08dda0a8c079a6c33aae0f0e3a4d6cab67e9 Mon Sep 17 00:00:00 2001
From: ngharo <ngharo@gmail.com>
Date: Sun, 23 Feb 2020 15:10:50 -0600
Subject: Initial commit - hard coded test

---
 go.mod  |   3 ++
 main.go | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+)
 create mode 100644 go.mod
 create mode 100644 main.go

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..0a30bf6
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.ngha.ro/zackup_cleaner
+
+go 1.13
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..e100423
--- /dev/null
+++ b/main.go
@@ -0,0 +1,108 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"sort"
+	"strings"
+	"time"
+)
+
+type backup struct {
+	Name string
+	Time time.Time
+}
+
+var (
+	keep_yearly  = 1
+	keep_monthly = 6
+	keep_weekly  = 4
+	keep_daily   = 14
+
+	patterns = map[string]string{
+		"daily":   "2006-01-02",
+		"weekly":  "", // See special case in keepers()
+		"monthly": "2006-01",
+		"yearly":  "2006",
+	}
+)
+
+func enumerate_backups() []backup {
+	var backups []backup
+
+	files, err := ioutil.ReadDir("./test/data")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	for _, file := range files {
+		name := file.Name()
+		time, err := time.Parse(time.RFC3339, strings.Split(name, "@")[1])
+
+		if err != nil {
+			log.Fatalf("Failed to parse timestamp in %s\n", name)
+			continue
+		}
+
+		backups = append(backups, backup{name, time})
+	}
+
+	return backups
+}
+
+func keepers(backups []backup, rule string, keepCnt int) []backup {
+
+	var keep []backup
+	var last string
+
+	for _, backup := range backups {
+		var period string
+
+		// Special case because there is no support for "week number" in Time.Format
+		if rule == "weekly" {
+			year, week := backup.Time.Local().ISOWeek()
+			period = fmt.Sprintf("%d-%d", year, week)
+		} else {
+			period = backup.Time.Local().Format(patterns[rule])
+		}
+
+		// fmt.Printf("rule: %s, pattern: %s, t: %s, format: %s\n", rule, patterns[rule], backup.Time.Local(), period)
+
+		if period != last {
+			last = period
+			keep = append(keep, backup)
+
+			if len(keep) == keepCnt {
+				break
+			}
+		}
+	}
+
+	return keep
+}
+
+func main() {
+	backups := enumerate_backups()
+
+	sort.Slice(backups, func(i, j int) bool {
+		return backups[i].Time.After(backups[j].Time)
+	})
+
+	fmt.Println("==============  DAILY  ==============")
+	for _, kept := range keepers(backups, "daily", keep_daily) {
+		fmt.Printf("%s\n", kept.Name)
+	}
+	fmt.Println("============== WEEKLY  ==============")
+	for _, kept := range keepers(backups, "weekly", keep_weekly) {
+		fmt.Printf("%s\n", kept.Name)
+	}
+	fmt.Println("============== MONTHLY ==============")
+	for _, kept := range keepers(backups, "monthly", keep_monthly) {
+		fmt.Printf("%s\n", kept.Name)
+	}
+	fmt.Println("============== YEARLY  ==============")
+	for _, kept := range keepers(backups, "yearly", keep_yearly) {
+		fmt.Printf("%s\n", kept.Name)
+	}
+}
-- 
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