Add subscription manager, fix corrupt read/write & short URI panic

More info on corrupt reads and writes:
https://github.com/makeworld-the-better-one/amfora/issues/61#issuecomment-735042805

The panic was occuring due to lines like:

    if u[:6] == "about:"

These would cause panics for URIs that were shorter than 6, like "docs/".
strings.HasPrefix was used instead to fix this.

NOTES.md

@@ -20,4 +20,4 @@
 - Bookmark keys aren't deleted, just set to `""`
   - Waiting on [this viper PR](https://github.com/spf13/viper/pull/519) to be merged
 - Help table cells aren't dynamically wrapped
-  - Filed [issue 29](https://gitlab.com/tslocum/cview/-/issues/29)
+  - Filed [issue 29](https://gitlab.com/tslocum/cview/-/issues/29)

README.md

@@ -165,8 +165,9 @@ Amfora ❤️ open source!
   - It uses [tcell](https://github.com/gdamore/tcell) for low level terminal operations
 - [Viper](https://github.com/spf13/viper) for configuration and TOFU storing
 - [go-gemini](https://github.com/makeworld-the-better-one/go-gemini), my forked and updated Gemini client/server library
-- My [progressbar fork](https://github.com/makeworld-the-better-one/progressbar)
+- My [progressbar fork](https://github.com/makeworld-the-better-one/progressbar) - pull request [here](https://github.com/schollz/progressbar/pull/69)
 - [go-humanize](https://github.com/dustin/go-humanize)
+- My [gofeed fork](https://github.com/makeworld-the-better-one/gofeed) - pull request [here](https://github.com/mmcdole/gofeed/pull/164)
 
 ## License
 This project is licensed under the GPL v3.0. See the [LICENSE](./LICENSE) file for details.

display/display.go

@@ -576,8 +576,11 @@ func Reload() {
 // URL loads and handles the provided URL for the current tab.
 // It should be an absolute URL.
 func URL(u string) {
-	if u[:6] == "about:" {
-		handleAbout(tabs[curTab], u)
+	t := tabs[curTab]
+	if strings.HasPrefix(u, "about:") {
+		if ok := handleAbout(t, u); ok {
+			t.addToHistory(u)
+		}
 		return
 	}
 
@@ -585,7 +588,7 @@ func URL(u string) {
 		// Assume it's a Gemini URL
 		u = "gemini://" + u
 	}
-	go goURL(tabs[curTab], u)
+	go goURL(t, u)
 }
 
 func NumTabs() int {

display/handlers.go

@@ -167,27 +167,34 @@ func handleFavicon(t *tab, host, old string) {
 // 'about:'. It will display errors if the URL is not recognized,
 // but not display anything if an 'about:' URL is not passed.
 //
+// It does not add the displayed page to history.
+//
 // It returns a bool indicating if the provided URL could be handled.
 func handleAbout(t *tab, u string) bool {
-	if u[:6] != "about:" {
+	if !strings.HasPrefix(u, "about:") {
 		return false
 	}
 
 	switch u {
 	case "about:bookmarks":
 		Bookmarks(t)
-		t.addToHistory("about:bookmarks")
 		return true
 	case "about:subscriptions":
 		Subscriptions(t)
-		t.addToHistory("about:subscriptions")
 		return true
 	case "about:newtab":
 		temp := newTabPage // Copy
 		setPage(t, &temp)
+		t.applyBottomBar()
 		return true
 	}
 
+	if u == "about:manage-subscriptions" || (len(u) > 27 && u[:27] == "about:manage-subscriptions?") {
+		ManageSubscriptions(t, u)
+		// Don't count remove command in history
+		return u == "about:manage-subscriptions"
+	}
+
 	Error("Error", "Not a valid 'about:' URL.")
 	return false
 }
@@ -244,7 +251,7 @@ func handleURL(t *tab, u string, numRedirects int) (string, bool) {
 
 	App.SetFocus(t.view)
 
-	if u[:6] == "about:" {
+	if strings.HasPrefix(u, "about:") {
 		return ret(u, handleAbout(t, u))
 	}
 

display/newtab.go

@@ -18,7 +18,7 @@ You can customize this page by creating a gemtext file called newtab.gmi, in Amf
 Happy browsing!
 
 => about:bookmarks Bookmarks
-=> about:subscriptions Feed and Page Tracking
+=> about:subscriptions Subscriptions
 
 => //gemini.circumlunar.space Project Gemini
 => https://github.com/makeworld-the-better-one/amfora Amfora homepage [HTTPS]

display/private.go

@@ -19,8 +19,10 @@ import (
 // Not when a URL is opened on a new tab for the first time.
 // It will handle setting the bottomBar.
 func followLink(t *tab, prev, next string) {
-	if next[:6] == "about:" {
-		handleAbout(t, next)
+	if strings.HasPrefix(next, "about:") {
+		if ok := handleAbout(t, next); ok {
+			t.addToHistory(next)
+		}
 		return
 	}
 

display/subscriptions.go

@@ -15,6 +15,7 @@ import (
 	"github.com/makeworld-the-better-one/amfora/renderer"
 	"github.com/makeworld-the-better-one/amfora/structs"
 	"github.com/makeworld-the-better-one/amfora/subscriptions"
+	"github.com/makeworld-the-better-one/go-gemini"
 	"github.com/mmcdole/gofeed"
 	"github.com/spf13/viper"
 )
@@ -28,7 +29,7 @@ func toLocalDay(t time.Time) time.Time {
 	return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
 }
 
-// Feeds displays the feeds page on the current tab.
+// Subscriptions displays the subscriptions page on the current tab.
 func Subscriptions(t *tab) {
 	logger.Log.Println("display.Subscriptions called")
 
@@ -43,9 +44,10 @@ func Subscriptions(t *tab) {
 
 	logger.Log.Println("started rendering subscriptions page")
 
-	subscriptionPageRaw := "# Subscriptions\n\n" +
+	rawPage := "# Subscriptions\n\n" +
 		"See the help (by pressing ?) for details on how to use this page.\n\n" +
-		"If you just opened Amfora then updates will appear incrementally. Reload the page to see them.\n"
+		"If you just opened Amfora then updates will appear incrementally. Reload the page to see them.\n\n" +
+		"=> about:manage-subscriptions Manage subscriptions\n"
 
 	// curDay represents what day of posts the loop is on.
 	// It only goes backwards in time.
@@ -67,21 +69,21 @@ func Subscriptions(t *tab) {
 		if pub.Before(curDay) {
 			// This post is on a new day, add a day header
 			curDay = pub
-			subscriptionPageRaw += fmt.Sprintf("\n## %s\n\n", curDay.Format("Jan 02, 2006"))
+			rawPage += fmt.Sprintf("\n## %s\n\n", curDay.Format("Jan 02, 2006"))
 		}
 		if entry.Title == "" || entry.Title == "/" {
 			// Just put author/title
 			// Mainly used for when you're tracking the root domain of a site
-			subscriptionPageRaw += fmt.Sprintf("=>%s %s\n", entry.URL, entry.Prefix)
+			rawPage += fmt.Sprintf("=>%s %s\n", entry.URL, entry.Prefix)
 		} else {
 			// Include title and dash
-			subscriptionPageRaw += fmt.Sprintf("=>%s %s - %s\n", entry.URL, entry.Prefix, entry.Title)
+			rawPage += fmt.Sprintf("=>%s %s - %s\n", entry.URL, entry.Prefix, entry.Title)
 		}
 	}
 
-	content, links := renderer.RenderGemini(subscriptionPageRaw, textWidth(), leftMargin(), false)
+	content, links := renderer.RenderGemini(rawPage, textWidth(), leftMargin(), false)
 	page := structs.Page{
-		Raw:       subscriptionPageRaw,
+		Raw:       rawPage,
 		Content:   content,
 		Links:     links,
 		URL:       "about:subscriptions",
@@ -97,6 +99,57 @@ func Subscriptions(t *tab) {
 	logger.Log.Println("done rendering subscriptions page")
 }
 
+// ManageSubscriptions displays the subscription managing page in
+// the current tab. `u` is the URL entered by the user.
+func ManageSubscriptions(t *tab, u string) {
+	if len(u) > 27 && u[:27] == "about:manage-subscriptions?" {
+		// There's a query string, aka a URL to unsubscribe from
+		manageSubscriptionQuery(t, u)
+		return
+	}
+
+	rawPage := "# Manage Subscriptions\n\n" +
+		"Below is list of URLs, both feeds and pages. Navigate to the link to unsubscribe from that feed or page.\n\n"
+
+	for _, u2 := range subscriptions.AllURLS() {
+		rawPage += fmt.Sprintf(
+			"=>%s %s\n",
+			"about:manage-subscriptions?"+gemini.QueryEscape(u2),
+			u2,
+		)
+	}
+
+	content, links := renderer.RenderGemini(rawPage, textWidth(), leftMargin(), false)
+	page := structs.Page{
+		Raw:       rawPage,
+		Content:   content,
+		Links:     links,
+		URL:       "about:manage-subscriptions",
+		Width:     termW,
+		Mediatype: structs.TextGemini,
+	}
+	go cache.AddPage(&page)
+	setPage(t, &page)
+	t.applyBottomBar()
+}
+
+func manageSubscriptionQuery(t *tab, u string) {
+	sub, err := gemini.QueryUnescape(u[27:])
+	if err != nil {
+		Error("URL Error", "Invalid query string: "+err.Error())
+		return
+	}
+
+	err = subscriptions.Remove(sub)
+	if err != nil {
+		ManageSubscriptions(t, "about:manage-subscriptions") // Reload
+		Error("Save Error", "Error saving the unsubscription to disk: "+err.Error())
+		return
+	}
+	ManageSubscriptions(t, "about:manage-subscriptions") // Reload
+	Info("Unsubscribed from " + sub)
+}
+
 // openSubscriptionModal displays the "Add subscription" modal
 // It returns whether the user wanted to subscribe to feed/page.
 // The subscribed arg specifies whether this feed/page is already

display/tab.go

@@ -146,9 +146,8 @@ func (t *tab) pageDown() {
 	t.view.ScrollTo(row+(termH/4)*3, col)
 }
 
-// hasContent returns true when the tab has a page that could be displayed.
-// The most likely situation where false would be returned is when the default
-// new tab content is being displayed.
+// hasContent returns false when the tab's page is malformed,
+// has no content or URL, or if it's an 'about:' page.
 func (t *tab) hasContent() bool {
 	if t.page == nil || t.view == nil {
 		return false

subscriptions/structs.go

@@ -73,8 +73,7 @@ type pageJSON struct {
 var data = jsonData{
 	feedMu: &sync.RWMutex{},
 	pageMu: &sync.RWMutex{},
-	Feeds:  make(map[string]*gofeed.Feed),
-	Pages:  make(map[string]*pageJSON),
+	// Maps are created in Init()
 }
 
 // PageEntry is a single item on a subscriptions page.

subscriptions/subscriptions.go

@@ -6,10 +6,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"mime"
 	"os"
 	"path"
 	"reflect"
+	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -42,20 +44,29 @@ func Init() error {
 	f, err := os.Open(config.SubscriptionPath)
 	if err == nil {
 		// File exists and could be opened
-		defer f.Close()
 
 		fi, err := f.Stat()
 		if err == nil && fi.Size() > 0 {
 			// File is not empty
-			dec := json.NewDecoder(f)
-			err = dec.Decode(&data)
-			if err != nil && err != io.EOF {
+
+			jsonBytes, err := ioutil.ReadAll(f)
+			f.Close()
+			if err != nil {
+				return fmt.Errorf("read subscriptions.json error: %w", err)
+			}
+			err = json.Unmarshal(jsonBytes, &data)
+			if err != nil {
 				return fmt.Errorf("subscriptions.json is corrupted: %w", err) //nolint:goerr113
 			}
 		}
+		f.Close()
 	} else if !os.IsNotExist(err) {
 		// There's an error opening the file, but it's not bc is doesn't exist
 		return fmt.Errorf("open subscriptions.json error: %w", err) //nolint:goerr113
+	} else {
+		// File does not exist, initialize maps
+		data.Feeds = make(map[string]*gofeed.Feed)
+		data.Pages = make(map[string]*pageJSON)
 	}
 
 	LastUpdated = time.Now()
@@ -130,26 +141,21 @@ func writeJSON() error {
 	writeMu.Lock()
 	defer writeMu.Unlock()
 
-	f, err := os.OpenFile(config.SubscriptionPath, os.O_WRONLY|os.O_CREATE, 0666)
+	data.Lock()
+	logger.Log.Println("subscriptions.writeJSON acquired data lock")
+	jsonBytes, err := json.MarshalIndent(&data, "", "  ")
+	data.Unlock()
 	if err != nil {
 		logger.Log.Println("subscriptions.writeJSON error", err)
 		return err
 	}
-	defer f.Close()
-	enc := json.NewEncoder(f)
-	enc.SetEscapeHTML(false)
-	enc.SetIndent("", "  ")
-
-	data.Lock()
-	logger.Log.Println("subscriptions.writeJSON acquired data lock")
-	err = enc.Encode(&data)
-	data.Unlock()
-
+	err = ioutil.WriteFile(config.SubscriptionPath, jsonBytes, 0666)
 	if err != nil {
 		logger.Log.Println("subscriptions.writeJSON error", err)
+		return err
 	}
 
-	return err
+	return nil
 }
 
 // AddFeed stores a feed.
@@ -363,3 +369,37 @@ func updateAll() {
 
 	wg.Wait()
 }
+
+// AllURLs returns all the subscribed-to URLS, sorted alphabetically.
+func AllURLS() []string {
+	data.RLock()
+	defer data.RUnlock()
+
+	urls := make([]string, len(data.Feeds)+len(data.Pages))
+	i := 0
+	for k := range data.Feeds {
+		urls[i] = k
+		i++
+	}
+	for k := range data.Pages {
+		urls[i] = k
+		i++
+	}
+
+	sort.Strings(urls)
+	return urls
+}
+
+// Remove removes a subscription from memory and from the disk.
+// The URL must be provided. It will do nothing if the URL is
+// not an actual subscription.
+//
+// It returns any errors that occured when saving to disk.
+func Remove(u string) error {
+	data.Lock()
+	// Just delete from both instead of using a loop to find it
+	delete(data.Feeds, u)
+	delete(data.Pages, u)
+	data.Unlock()
+	return writeJSON()
+}