Selected link and scroll position stays for non-cached pages

Fixes #122

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Syntax highlighting for preformatted text blocks with alt text (#252, #263, [wiki page](https://github.com/makeworld-the-better-one/amfora/wiki/Source-Code-Highlighting))
 - [Client certificates](https://github.com/makeworld-the-better-one/amfora/wiki/Client-Certificates) can be restricted to certain paths of a host (#115)
 - `header` config option in `[subscriptions]` to allow disabling the header text on the subscriptions page (#191)
+- Selected link and scroll position stays for non-cached pages (#122)
 
 ### Changed
 - Center text automatically, removing `left_margin` from the config (#233)

display/history.go

@@ -3,6 +3,18 @@ package display
 // applyHist is a history.go internal function, to load a URL in the history.
 func applyHist(t *tab) {
 	handleURL(t, t.history.urls[t.history.pos], 0) // Load that position in history
+
+	// Set page's scroll and link info from history cache, in case it didn't have it in the page already
+	// Like for non-cached pages like about: pages
+	// This fixes #122
+	pg := t.history.pageCache[t.history.pos]
+	p := t.page
+	p.Row = pg.row
+	p.Column = pg.column
+	p.Selected = pg.selected
+	p.SelectedID = pg.selectedID
+	p.Mode = pg.mode
+
 	t.applyAll()
 }
 
@@ -11,6 +23,10 @@ func histForward(t *tab) {
 		// Already on the most recent URL in the history
 		return
 	}
+
+	// Update page cache in history for #122
+	t.historyCachePage()
+
 	t.history.pos++
 	go applyHist(t)
 }
@@ -20,6 +36,10 @@ func histBack(t *tab) {
 		// First tab in history
 		return
 	}
+
+	// Update page cache in history for #122
+	t.historyCachePage()
+
 	t.history.pos--
 	go applyHist(t)
 }

display/private.go

@@ -137,6 +137,9 @@ func setPage(t *tab, p *structs.Page) {
 //
 // It should be called in a goroutine.
 func goURL(t *tab, u string) {
+	// Update page cache in history for #122
+	t.historyCachePage()
+
 	final, displayed := handleURL(t, u, 0)
 	if displayed {
 		t.addToHistory(final)

display/tab.go

@@ -20,9 +20,20 @@ const (
 	tabModeLoading
 )
 
+// tabHistoryPageCache is fields from the Page struct, cached here to solve #122
+// See structs/structs.go for an explanation of the fields.
+type tabHistoryPageCache struct {
+	row        int
+	column     int
+	selected   string
+	selectedID string
+	mode       structs.PageMode
+}
+
 type tabHistory struct {
-	urls []string
-	pos  int // Position: where in the list of URLs we are
+	urls      []string
+	pos       int // Position: where in the list of URLs we are
+	pageCache []*tabHistoryPageCache
 }
 
 // tab hold the information needed for each browser tab.
@@ -290,16 +301,37 @@ func makeNewTab() *tab {
 	return &t
 }
 
+// historyCachePage caches certain info about the current page in the tab's history,
+// see #122 for details.
+func (t *tab) historyCachePage() {
+	if t.page == nil || t.page.URL == "" || t.history.pageCache == nil || len(t.history.pageCache) == 0 {
+		return
+	}
+	t.history.pageCache[t.history.pos] = &tabHistoryPageCache{
+		row:        t.page.Row,
+		column:     t.page.Column,
+		selected:   t.page.Selected,
+		selectedID: t.page.SelectedID,
+		mode:       t.page.Mode,
+	}
+}
+
 // addToHistory adds the given URL to history.
 // It assumes the URL is currently being loaded and displayed on the page.
 func (t *tab) addToHistory(u string) {
 	if t.history.pos < len(t.history.urls)-1 {
 		// We're somewhere in the middle of the history instead, with URLs ahead and behind.
 		// The URLs ahead need to be removed so this new URL is the most recent item in the history
 		t.history.urls = t.history.urls[:t.history.pos+1]
+		// Same for page cache
+		t.history.pageCache = t.history.pageCache[:t.history.pos+1]
 	}
 	t.history.urls = append(t.history.urls, u)
 	t.history.pos++
+
+	// Cache page info for #122
+	t.history.pageCache = append(t.history.pageCache, &tabHistoryPageCache{}) // Add new spot
+	t.historyCachePage()                                                      // Fill it with data
 }
 
 // pageUp scrolls up 75% of the height of the terminal, like Bombadillo.

logger/logger.go

@@ -9,11 +9,11 @@ import (
 	"os"
 )
 
-var logger *log.Logger
+var Logger *log.Logger
 
 func GetLogger() (*log.Logger, error) {
-	if logger != nil {
-		return logger, nil
+	if Logger != nil {
+		return Logger, nil
 	}
 
 	var writer io.Writer
@@ -30,15 +30,15 @@ func GetLogger() (*log.Logger, error) {
 		writer = ioutil.Discard
 	}
 
-	logger = log.New(writer, "", log.LstdFlags)
+	Logger = log.New(writer, "", log.LstdFlags)
 
 	if !debugModeEnabled {
 		// Clear all flags to skip log output formatting step to increase
 		// performance somewhat if we're not logging anything
-		logger.SetFlags(0)
+		Logger.SetFlags(0)
 	}
 
-	logger.Println("Started logger")
+	Logger.Println("Started logger")
 
-	return logger, nil
+	return Logger, nil
 }