From 37fd41892efc55ade817c3869caa3133bbb2e40f Mon Sep 17 00:00:00 2001
From: Ted Unangst <tedu@tedunangst.com>
Date: Mon, 21 Oct 2019 02:28:35 -0400
Subject: [PATCH] make it possible for filters to expire

---
 hfcs.go         | 33 +++++++++++++++++++++++++++++++--
 honk.go         | 12 ++++++++++++
 views/hfcs.html |  5 +++++
 web.go          |  7 +++++--
 4 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/hfcs.go b/hfcs.go
index 50b4301..e21233d 100644
--- a/hfcs.go
+++ b/hfcs.go
@@ -43,6 +43,7 @@ type Filter struct {
 	Rewrite         string `json:",omitempty"`
 	re_rewrite      *regexp.Regexp
 	Replace         string `json:",omitempty"`
+	Expiration      time.Time
 }
 
 type filtType uint
@@ -65,7 +66,14 @@ func (ft filtType) String() string {
 
 type afiltermap map[filtType][]*Filter
 
-var filtcache = cache.New(cache.Options{Filler: func(userid int64) (afiltermap, bool) {
+var filtcache *cache.Cache
+
+func init() {
+	// resolve init loop
+	filtcache = cache.New(cache.Options{Filler: filtcachefiller})
+}
+
+func filtcachefiller(userid int64) (afiltermap, bool) {
 	rows, err := stmtGetFilters.Query(userid)
 	if err != nil {
 		log.Printf("error querying filters: %s", err)
@@ -73,6 +81,10 @@ var filtcache = cache.New(cache.Options{Filler: func(userid int64) (afiltermap,
 	}
 	defer rows.Close()
 
+	now := time.Now()
+
+	var expflush time.Time
+
 	filtmap := make(afiltermap)
 	for rows.Next() {
 		filt := new(Filter)
@@ -86,6 +98,14 @@ var filtcache = cache.New(cache.Options{Filler: func(userid int64) (afiltermap,
 			log.Printf("error scanning filter: %s", err)
 			continue
 		}
+		if !filt.Expiration.IsZero() {
+			if filt.Expiration.Before(now) {
+				continue
+			}
+			if expflush.IsZero() || filt.Expiration.Before(expflush) {
+				expflush = filt.Expiration
+			}
+		}
 		if filt.Text != "" {
 			filt.re_text, err = regexp.Compile("\\b(?i:" + filt.Text + ")\\b")
 			if err != nil {
@@ -127,8 +147,17 @@ var filtcache = cache.New(cache.Options{Filler: func(userid int64) (afiltermap,
 	sort.Slice(filtmap[filtAny], func(i, j int) bool {
 		return sorting[i].Name < sorting[j].Name
 	})
+	if !expflush.IsZero() {
+		dur := expflush.Sub(now)
+		go filtcacheclear(userid, dur)
+	}
 	return filtmap, true
-}})
+}
+
+func filtcacheclear(userid int64, dur time.Duration) {
+	time.Sleep(dur + time.Second)
+	filtcache.Clear(userid)
+}
 
 func getfilters(userid int64, scope filtType) []*Filter {
 	var filtmap afiltermap
diff --git a/honk.go b/honk.go
index b7be1ca..96f949e 100644
--- a/honk.go
+++ b/honk.go
@@ -20,6 +20,7 @@ import (
 	"html/template"
 	"log"
 	"os"
+	"strconv"
 	"strings"
 	"time"
 )
@@ -119,6 +120,17 @@ func (d Duration) String() string {
 	return s
 }
 
+func parseDuration(s string) time.Duration {
+	didx := strings.IndexByte(s, 'd')
+	if didx != -1 {
+		days, _ := strconv.ParseInt(s[:didx], 10, 0)
+		dur, _ := time.ParseDuration(s[didx:])
+		return dur + 24*time.Hour*time.Duration(days)
+	}
+	dur, _ := time.ParseDuration(s)
+	return dur
+}
+
 type Time struct {
 	StartTime time.Time
 	EndTime   time.Time
diff --git a/views/hfcs.html b/views/hfcs.html
index d840fad..1cfa721 100644
--- a/views/hfcs.html
+++ b/views/hfcs.html
@@ -36,6 +36,10 @@ Honk Filtering and Censorship System
 <p><label for="replace">replace:</label><br>
 <input tabindex=1 type="text" name="filtreplace" value="" autocomplete=off>
 <hr>
+<h3>expiration</h3>
+<p><label for="filtduration">duration:</label><br>
+<input tabindex=1 type="text" name="filtduration" value="" autocomplete=off>
+<hr>
 <p><button>impose your will</button>
 </form>
 </div>
@@ -49,6 +53,7 @@ Honk Filtering and Censorship System
 <p>Actions: {{ range .Actions }} {{ . }} {{ end }}
 {{ with .Rewrite }}<p>Rewrite: {{ . }}{{ end }}
 {{ with .Replace }}<p>Replace: {{ . }}{{ end }}
+{{ if not .Expiration.IsZero }}<p>Expiration: {{ .Expiration.Format "2006-01-02 03:04" }}{{ end }}
 <form action="/savehfcs" method="POST">
 <input type="hidden" name="CSRF" value="{{ $csrf }}">
 <input type="hidden" name="hfcsid" value="{{ .ID }}">
diff --git a/web.go b/web.go
index 79adeaf..7450c94 100644
--- a/web.go
+++ b/web.go
@@ -1217,8 +1217,8 @@ func submithonk(w http.ResponseWriter, r *http.Request) {
 			}
 		}
 		timeend := r.FormValue("timeend")
-		dur, err := time.ParseDuration(timeend)
-		if err == nil {
+		dur := parseDuration(timeend)
+		if dur != 0 {
 			t.Duration = Duration(dur)
 		}
 		if !t.StartTime.IsZero() {
@@ -1460,6 +1460,9 @@ func savehfcs(w http.ResponseWriter, r *http.Request) {
 	filt.Collapse = r.FormValue("docollapse") == "yes"
 	filt.Rewrite = strings.TrimSpace(r.FormValue("filtrewrite"))
 	filt.Replace = strings.TrimSpace(r.FormValue("filtreplace"))
+	if dur := parseDuration(r.FormValue("filtduration")); dur > 0 {
+		filt.Expiration = time.Now().UTC().Add(dur)
+	}
 
 	if filt.Actor == "" && filt.Text == "" {
 		log.Printf("blank filter")