statusline: refactor to make it more customizable

Refactor statusline by clearly separating the rendering part from the
text display. Use printf-like format string for statusline
customization.

Document printf-like format string to customize the statusline.

Allow to completely mute the statusline (except for push notifications)
with a format specifier.

Provide a display mode with unicode icons for the status elements.

Implements: https://todo.sr.ht/~rjarry/aerc/34
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 73 insertions, 0 deletions

diff --git a/lib/statusline/texter.go b/lib/statusline/texter.go
new file mode 100644
index 00000000..d06b1982
--- /dev/null
+++ b/lib/statusline/texter.go
@@ -0,0 +1,73 @@
+package statusline
+
+import "strings"
+
+type Texter interface {
+	Connected() string
+	Disconnected() string
+	Passthrough() string
+	Sorting() string
+	Threading() string
+	FormatFilter(string) string
+	FormatSearch(string) string
+}
+
+type text struct{}
+
+func (t text) Connected() string {
+	return "Connected"
+}
+
+func (t text) Disconnected() string {
+	return "Disconnected"
+}
+
+func (t text) Passthrough() string {
+	return "passthrough"
+}
+
+func (t text) Sorting() string {
+	return "sorting"
+}
+
+func (t text) Threading() string {
+	return "threading"
+}
+
+func (t text) FormatFilter(s string) string {
+	return s
+}
+
+func (t text) FormatSearch(s string) string {
+	return s
+}
+
+type icon struct{}
+
+func (i icon) Connected() string {
+	return "✓"
+}
+
+func (i icon) Disconnected() string {
+	return "✘"
+}
+
+func (i icon) Passthrough() string {
+	return "➔"
+}
+
+func (i icon) Sorting() string {
+	return "⚙"
+}
+
+func (i icon) Threading() string {
+	return "🧵"
+}
+
+func (i icon) FormatFilter(s string) string {
+	return strings.ReplaceAll(s, "filter", "🔦")
+}
+
+func (i icon) FormatSearch(s string) string {
+	return strings.ReplaceAll(s, "search", "🔎")
+}