degesch: use formatting in the backlog

It's a rather crude solution to just pipe the raw terminfo strings
to less but hey, it works.

degesch.c

@@ -1642,10 +1642,6 @@ static struct config_schema g_config_behaviour[] =
 	  .type      = CONFIG_ITEM_BOOLEAN,
 	  .default_  = "off",
 	  .on_change = on_config_logging_change },
-	{ .name      = "backlog_helper",
-	  .comment   = "Shell command to display a buffer's history",
-	  .type      = CONFIG_ITEM_STRING,
-	  .default_  = "\"LESSSECURE=1 less -M -R +G\"" },
 	{ .name      = "save_on_quit",
 	  .comment   = "Save configuration before quitting",
 	  .type      = CONFIG_ITEM_BOOLEAN,
@@ -1656,6 +1652,18 @@ static struct config_schema g_config_behaviour[] =
 	  .default_  = "off",
 	  .on_change = on_config_debug_mode_change },
 
+	// We use -r here rather than -R because of GNU screen,
+	// which has an ^O in its string to reset formatting attributes
+
+	{ .name      = "backlog_helper",
+	  .comment   = "Shell command to display a buffer's history",
+	  .type      = CONFIG_ITEM_STRING,
+	  .default_  = "\"LESSSECURE=1 less -M -r +G\"" },
+	{ .name      = "backlog_helper_strip_formatting",
+	  .comment   = "Strip formatting from backlog helper input",
+	  .type      = CONFIG_ITEM_BOOLEAN,
+	  .default_  = "off" },
+
 	{ .name      = "reconnect_delay_growing",
 	  .comment   = "Growing factor for reconnect delay",
 	  .type      = CONFIG_ITEM_INTEGER,
@@ -2068,7 +2076,7 @@ enum
 struct attribute_printer
 {
 	struct app_context *ctx;            ///< Application context
-	terminal_printer_fn printer;        ///< Terminal printer
+	FILE *stream;                       ///< Output stream
 	bool dirty;                         ///< Attributes are set
 
 	int want;                           ///< Desired attributes
@@ -2076,21 +2084,33 @@ struct attribute_printer
 	int want_background;                ///< Desired background color
 };
 
+static void
+attribute_printer_tputs (struct attribute_printer *self, const char *attr)
+{
+	terminal_printer_fn printer = get_attribute_printer (self->stream);
+	if (printer)
+		tputs (attr, 1, printer);
+	else
+		// We shouldn't really do this but we need it to
+		// output formatting to the backlog
+		fputs (attr, self->stream);
+}
+
 static void
 attribute_printer_reset (struct attribute_printer *self)
 {
 	if (self->dirty)
-		tputs (self->ctx->attrs[ATTR_RESET], 1, self->printer);
+		attribute_printer_tputs (self, self->ctx->attrs[ATTR_RESET]);
 
 	self->dirty = false;
 }
 
 static void
 attribute_printer_init (struct attribute_printer *self,
-	struct app_context *ctx, terminal_printer_fn printer)
+	struct app_context *ctx, FILE *stream)
 {
 	self->ctx = ctx;
-	self->printer = printer;
+	self->stream = stream;
 	self->dirty = true;
 
 	self->want = 0;
@@ -2104,7 +2124,7 @@ attribute_printer_apply (struct attribute_printer *self, int attribute)
 	attribute_printer_reset (self);
 	if (attribute != ATTR_RESET)
 	{
-		tputs (self->ctx->attrs[attribute], 1, self->printer);
+		attribute_printer_tputs (self, self->ctx->attrs[attribute]);
 		self->dirty = true;
 	}
 }
@@ -2192,7 +2212,7 @@ attribute_printer_update (struct attribute_printer *self)
 	attribute_printer_reset (self);
 
 	if (attributes)
-		tputs (tparm (set_attributes,
+		attribute_printer_tputs (self, tparm (set_attributes,
 			0,   // standout
 			attributes & ATTRIBUTE_UNDERLINE,
 			attributes & ATTRIBUTE_INVERSE,
@@ -2201,15 +2221,14 @@ attribute_printer_update (struct attribute_printer *self)
 			attributes & ATTRIBUTE_BOLD,
 			0,   // blank
 			0,   // protect
-			0) // acs
+			0)); // acs
-			, 1, self->printer);
 	if (enter_italics_mode && (attributes & ATTRIBUTE_ITALIC))
-		tputs (enter_italics_mode, 1, self->printer);
+		attribute_printer_tputs (self, enter_italics_mode);
 
 	if (fg >= 0)
-		tputs (g_terminal.color_set_fg[fg], 1, self->printer);
+		attribute_printer_tputs (self, g_terminal.color_set_fg[fg]);
 	if (bg >= 0)
-		tputs (g_terminal.color_set_bg[bg], 1, self->printer);
+		attribute_printer_tputs (self, g_terminal.color_set_bg[bg]);
 
 	self->dirty = true;
 }
@@ -2677,10 +2696,9 @@ formatter_flush_text (struct app_context *ctx, const char *text, FILE *stream)
 }
 
 static void
-formatter_flush (struct formatter *self, FILE *stream)
+formatter_flush (struct formatter *self, FILE *stream, bool raw_attributes)
 {
-	terminal_printer_fn printer = get_attribute_printer (stream);
+	if (!raw_attributes && !get_attribute_printer (stream))
-	if (!printer)
 	{
 		LIST_FOR_EACH (struct formatter_item, iter, self->items)
 			if (iter->type == FORMATTER_ITEM_TEXT)
@@ -2689,7 +2707,7 @@ formatter_flush (struct formatter *self, FILE *stream)
 	}
 
 	struct attribute_printer state;
-	attribute_printer_init (&state, self->ctx, printer);
+	attribute_printer_init (&state, self->ctx, stream);
 	attribute_printer_reset (&state);
 
 	int attribute_ignore = 0;
@@ -2733,7 +2751,8 @@ buffer_update_time (struct app_context *ctx, time_t now)
 }
 
 static void
-buffer_line_flush (struct buffer_line *line, struct formatter *f, FILE *output)
+buffer_line_flush (struct buffer_line *line, struct formatter *f, FILE *output,
+	bool raw_attributes)
 {
 	int flags = line->flags;
 	if (flags & BUFFER_LINE_INDENT)  formatter_add (f, "    ");
@@ -2742,7 +2761,7 @@ buffer_line_flush (struct buffer_line *line, struct formatter *f, FILE *output)
 
 	formatter_add_from (f, line->formatter);
 	formatter_add (f, "\n");
-	formatter_flush (f, output);
+	formatter_flush (f, output, raw_attributes);
 	formatter_free (f);
 }
 
@@ -2775,12 +2794,32 @@ buffer_line_display (struct app_context *ctx,
 	}
 
 	input_hide (&ctx->input);
-	buffer_line_flush (line, &f, stdout);
+	buffer_line_flush (line, &f, stdout, false);
 	// Flush the trailing formatting reset item
 	fflush (stdout);
 	input_show (&ctx->input);
 }
 
+static void
+buffer_line_write_to_backlog (struct app_context *ctx,
+	struct buffer_line *line, FILE *log_file)
+{
+	struct formatter f;
+	formatter_init (&f, ctx, NULL);
+
+	struct tm current;
+	char buf[20];
+	if (!localtime_r (&line->when, &current))
+		print_error ("%s: %s", "localtime_r", strerror (errno));
+	else if (!strftime (buf, sizeof buf, "%F %T", &current))
+		print_error ("%s: %s", "strftime", "buffer too small");
+	else
+		formatter_add (&f, "#a#s#r ", ATTR_TIMESTAMP, buf);
+
+	buffer_line_flush (line, &f, log_file, !get_config_boolean
+		(ctx->config.root, "behaviour.backlog_helper_strip_formatting"));
+}
+
 static void
 buffer_line_write_to_log (struct app_context *ctx,
 	struct buffer_line *line, FILE *log_file)
@@ -2800,7 +2839,7 @@ buffer_line_write_to_log (struct app_context *ctx,
 	else
 		formatter_add (&f, "#s ", buf);
 
-	buffer_line_flush (line, &f, log_file);
+	buffer_line_flush (line, &f, log_file, false);
 }
 
 static void
@@ -3052,7 +3091,7 @@ buffer_print_read_marker (struct app_context *ctx)
 	struct formatter f;
 	formatter_init (&f, ctx, NULL);
 	formatter_add (&f, "#a-- -- -- ---\n", ATTR_READ_MARKER);
-	formatter_flush (&f, stdout);
+	formatter_flush (&f, stdout, false);
 	formatter_free (&f);
 }
 
@@ -8918,10 +8957,9 @@ display_backlog (struct app_context *ctx)
 	FILE *backlog = tmpfile ();
 	set_cloexec (fileno (backlog));
 
-	// TODO: retrieve the lines with formatting
 	for (struct buffer_line *line = ctx->current_buffer->lines;
 		line; line = line->next)
-		buffer_line_write_to_log (ctx, line, backlog);
+		buffer_line_write_to_backlog (ctx, line, backlog);
 
 	rewind (backlog);
 	suspend_terminal (ctx);