Added check to prevent page down from looping endlessly

editor.c

@@ -5,8 +5,13 @@
 #include <string.h>
 #include <stdbool.h>
 #include <unistd.h>
+#include <sys/stat.h>
+
+#define ctrl(x) ((x) & 0x1f)
 
 int index_to_start = 0;
+WINDOW* mainwin;
+WINDOW* statusbar;
 
 typedef struct Buffer_struct Buffer;
 struct Buffer_struct {
@@ -58,13 +63,20 @@ void buffer_insert(char ch, Buffer* buffer) {
 	}
 }
 
-void buffer_delete(Buffer* buffer) {
+void buffer_delete_front(Buffer* buffer) {
 	if (buffer->start != buffer->text) {
 		buffer->start--;
 		buffer->gap_size++;
 	}
 }
 
+void buffer_delete_back(Buffer* buffer) {
+	if (buffer->end != buffer->text + buffer->size) {
+		buffer->end++;
+		buffer->gap_size++;
+	}
+}
+
 void buffer_right(Buffer* buffer) {
 	if (buffer->end != buffer->text + buffer->size) {
 		char c = *(buffer->end);
@@ -74,6 +86,12 @@ void buffer_right(Buffer* buffer) {
 	}
 }
 
+void right_key_handler(Buffer* buffer) {
+	if ((*(buffer->end) != '\n') || (getcury(mainwin) + 1 < getmaxy(mainwin))) {
+		buffer_right(buffer);
+	}
+}
+
 void buffer_left(Buffer* buffer) {
 	if (buffer->start != buffer->text) {
 		char c = *(buffer->start - 1);
@@ -84,7 +102,11 @@ void buffer_left(Buffer* buffer) {
 	}
 }
 
-
+void left_key_handler(Buffer* buffer) {
+	if ((getcurx(mainwin) > 0) || (getcury(mainwin) > 0)) {
+		buffer_left(buffer);
+	}
+}
 
 void scroll_page_down_handler(Buffer* buffer) {
 	while (*(buffer->text + index_to_start) != '\n') {
@@ -94,18 +116,18 @@ void scroll_page_down_handler(Buffer* buffer) {
 }
 
 void page_down_handler(Buffer* buffer) {
+	if ((getcury(mainwin) + 1) == getmaxy(mainwin)) {
+		scroll_page_down_handler(buffer);
+	}
+
 	buffer_right(buffer); /* I must advance the cursor at least 
 				once, so this hardcoded statement is fine. */
 
 
-	while (*(buffer->start - 1) != '\n') {
+	while ((*(buffer->start - 1) != '\n') && (buffer->end != (buffer->text + buffer->size))) {
 		buffer_right(buffer);
 	}
 
-	if ((getcury(stdscr) + 1) == getmaxy(stdscr)) {
-		scroll_page_down_handler(buffer);
-	}
-
 	/* You would think that I need to call 'buffer_right' once 
 	more, to advance the cursor onto the next line.	In fact, if 
 	you think about it, the place where the cursor (the rectangle) 
@@ -140,28 +162,67 @@ void page_up_handler(Buffer* buffer) {
 	}
 
 
-	if ((getcury(stdscr) == 0) && (index_to_start > 0)) {
+	if ((getcury(mainwin) == 0) && (index_to_start > 0)) {
 		scroll_page_up_handler(buffer);
 	}
 
 }
 
-void init_curses() {
-	initscr();
-	noecho();
-	keypad(stdscr,TRUE);
-	cbreak();
-//	scrollok(stdscr,TRUE);
+void keypress_handler(char key, Buffer* buffer) {
+	buffer_insert(key,buffer);
+	if ((getcury(mainwin) + 1) == getmaxy(mainwin)) {
+		scroll_page_down_handler(buffer);
+	}
 }
 
-void sigint_handler(int dummy) {
+int is_file(char* path) {
+	struct stat st;
+	if (stat(path, &st) < 0) {
+		return -1;
+	}
+	return S_ISREG(st.st_mode);
+}
+
+void save_text_helper(Buffer* buffer,char* filename) {
+	FILE* file = fopen(filename,"w");
+	int i = 0;
+	while (i < buffer->size) {
+		if ((buffer->start - buffer->text) == i) {  /* If we have encountered
+								the start of the gap */
+			i += buffer->gap_size;
+		}
+
+		if (i >= buffer->size) {
+			break;
+		}
+		fputc(*(buffer->text + i),file);
+		i++;
+	}
+}
+
+void init_curses() {
+	initscr();
+	mainwin = newwin(getmaxy(stdscr)-1,getmaxx(stdscr),0,0);
+
+	statusbar = newwin(1,getmaxx(stdscr),getmaxy(stdscr)-1,0);
+	wattrset(statusbar,A_REVERSE);
+	mvwhline(statusbar,0,0,' ',getmaxx(statusbar));
+	mvwprintw(statusbar,0,0,"Welcome to Editor!");
+	wrefresh(statusbar);
+
+	noecho();
+	keypad(stdscr,TRUE);
+	keypad(mainwin,TRUE);
+	raw();
+}
+
+void end_ncurses() {
 	endwin();
 	exit(130);
 }
 
 int main(int argc, char** argv) {
 
-	signal(SIGINT,sigint_handler);
 	Buffer* buffer = new_buffer(10);
 	FILE* logfile = fopen("logfile.txt","w");
 
@@ -175,23 +236,19 @@ int main(int argc, char** argv) {
 				num_of_chars++;
 			}
 	
-		} else {
-			printf("File does not exist.\n");
-			return -10;
-		}
-
 			while (num_of_chars > 0) {
 				buffer_left(buffer);
 				num_of_chars--;
 			}
 		}
+	}
 
 	init_curses();
 	int ch;
 
 	int y, x;
 	while (true) {
-		clear();
+		wclear(mainwin);
 
 		int i=index_to_start;
 		if ((buffer->start != buffer->text) || (buffer->gap_size != buffer->size)) {  /* We don't want to print the string, if the 
@@ -200,44 +257,52 @@ int main(int argc, char** argv) {
 	                while (i < buffer->size) {
 	                        if ((buffer->start - buffer->text) == i) {  /* If we have encountered 
 										the start of the gap */
-					getyx(stdscr,y,x);
+					getyx(mainwin,y,x);
 	                                i += buffer->gap_size;
 				}
 				if (i >= buffer->size) {
 					break;
 				}
-	                        addch(*(buffer->text + i));
-				i++;
 
-				fprintf(logfile,"At line %d of %d\n",getcury(stdscr),getmaxy(stdscr));
-				if (*(buffer->text + i) == '\n' && ((getcury(stdscr) + 1) == getmaxy(stdscr))) {
+				fprintf(logfile,"At line %d of %d\n",getcury(mainwin),getmaxy(mainwin));
+				if (*(buffer->text + i) == '\n' && ((getcury(mainwin) + 1) == getmaxy(mainwin))) {
 					fprintf(logfile,"Read newline\n");
 					break;
 				}
+
+	                        waddch(mainwin,*(buffer->text + i));
+				i++;
+
 	                }
 
-			move(y,x);
+			wmove(mainwin,y,x);
+
+			wrefresh(mainwin);
 
 		}
 
 
-		ch = getch();
+		ch = wgetch(mainwin);
 
 		switch(ch) {
 			case KEY_BACKSPACE:
-				buffer_delete(buffer);
+				buffer_delete_front(buffer);
+				break;
+
+			case KEY_DC:
+				buffer_delete_back(buffer);
 				break;
 
 			case KEY_LEFT:
-				buffer_left(buffer);
+				left_key_handler(buffer);
 				break;
 
 			case KEY_RIGHT:
-				buffer_right(buffer);
+				right_key_handler(buffer);
 				break;
 
 			case 10:  /* Enter key */
-				buffer_insert('\n',buffer);  /* Why handle this separately? 
+				keypress_handler('\n',buffer);  /* Why handle this separately? 
 								Because, by default, curses seems to send '\r\n', 
 								which is technically two characters. I should 
 								probably add some code to deal with this scenario 
@@ -253,13 +318,26 @@ int main(int argc, char** argv) {
 				page_up_handler(buffer);
 				break;
 
+			case ctrl(KEY_NPAGE):
+				abort();
+
+			case ctrl('s'):
+				if (argc == 2) {
+					save_text_helper(buffer,argv[1]);
+				} else if (argc == 1) {
+					save_text_helper(buffer,NULL);
+				}
+				break;
+
+			case ctrl('c'):
+				end_ncurses();
+				break;
+
 			default:
-				buffer_insert(ch,buffer);
+				keypress_handler(ch,buffer);
 
 		}
 
-		continue_while_loop:
-
 	}
 	endwin();
 }