justify: handle the leading part when justifying a marked region

Unlike a regular paragraph, marked text may have different quotes and
more than two types of indentation.  Handle this by replacing deviant
quotes with the quote of the first line, and deviant indentation with
the indentation of the second line.

src/text.c

@@ -2023,6 +2023,17 @@ void do_justify(bool full_justify)
 	ssize_t was_top_lineno = 0;
 	size_t was_top_x = 0;
 	bool right_side_up = FALSE;
+
+	/* We need these to hold the leading part (quoting + indentation) of the
+	 * line where the marked text begins, whether or not that part is covered
+	 * by the mark. */
+	char *the_lead = NULL;
+	size_t lead_len = 0;
+
+	/* We need these to hold the leading part of the line after the line where
+	 * the marked text begins (if any). */
+	char *the_second_lead = NULL;
+	size_t second_lead_len = 0;
 #endif
 
 #ifndef NANO_TINY
@@ -2054,6 +2065,8 @@ void do_justify(bool full_justify)
 #ifndef NANO_TINY
 	/* If the mark is on, do as Pico: treat all marked text as one paragraph. */
 	if (openfile->mark) {
+		size_t quote_len;
+
 		mark_order((const filestruct **)&first_par_line, &top_x,
 						(const filestruct **)&last_par_line, &bot_x,
 						&right_side_up);
@@ -2064,6 +2077,28 @@ void do_justify(bool full_justify)
 
 		par_len = last_par_line->lineno - first_par_line->lineno +
 											(bot_x > 0 ? 1 : 0);
+
+		/* Copy the leading part that is to be used for the new paragraph. */
+		quote_len = quote_length(first_par_line->data);
+		lead_len = quote_len + indent_length(first_par_line->data + quote_len);
+		the_lead = mallocstrncpy(the_lead, first_par_line->data, lead_len + 1);
+		the_lead[lead_len] = '\0';
+
+		/* Copy the leading part that is to be used for the new paragraph after
+		 * its first line (if any): the quoting of the first line, plus the
+		 * indentation of the second line. */
+		if (first_par_line != last_par_line) {
+			size_t sample_quote_len = quote_length(first_par_line->next->data);
+			size_t sample_indent_len = indent_length(first_par_line->next->data +
+														sample_quote_len);
+
+			second_lead_len = quote_len + sample_indent_len;
+			the_second_lead = charalloc(second_lead_len + 1);
+			strncpy(the_second_lead, first_par_line->data, quote_len);
+			strncpy(the_second_lead + quote_len, first_par_line->next->data +
+					sample_quote_len, sample_indent_len);
+			the_second_lead[second_lead_len] = '\0';
+		}
 	} else
 #endif
 	{
@@ -2113,9 +2148,15 @@ void do_justify(bool full_justify)
 
 		/* Manually justify the marked region. */
 		concat_paragraph(&cutbuffer, par_len);
-		justify_format(cutbuffer, 0);
+		justify_format(cutbuffer, lead_len);
 		line = cutbuffer;
-		rewrap_paragraph(&line, "", 0);
+		if (the_second_lead != NULL) {
+			rewrap_paragraph(&line, the_second_lead, second_lead_len);
+			free(the_second_lead);
+		} else
+			rewrap_paragraph(&line, the_lead, lead_len);
+
+		free(the_lead);
 	} else
 #endif
 	{