From 7e76609326c853aefad981c948c24f9f14136e3b Mon Sep 17 00:00:00 2001
From: Aaron Fischer <aaron.fischer@marbis.net>
Date: Tue, 2 Oct 2018 10:30:17 +0200
Subject: [PATCH] Finish the text viewer

---
 kilo.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 87 insertions(+), 8 deletions(-)

diff --git a/kilo.c b/kilo.c
index 8666576..a3f872c 100644
--- a/kilo.c
+++ b/kilo.c
@@ -7,11 +7,13 @@
 #include <ctype.h>
 #include <errno.h>
 #include <stdio.h>
+#include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <termios.h>
+#include <time.h>
 #include <unistd.h>
 
 /*** defines ***/
@@ -45,12 +47,16 @@ typedef struct erow {
 
 struct editorConfig {
   int cx, cy;
+  int rx; // The x position in the rendered line (for tabs)
   int rowoff;
   int coloff;
   int screenrows;
   int screencols;
   int numrows;
   erow *row;
+  char *filename;
+  char statusmsg[80];
+  time_t statusmsg_time;
   struct termios orig_termios;
 };
 
@@ -175,6 +181,18 @@ int getWindowSize(int *rows, int *cols) {
 
 /*** row operations ***/
 
+int editorRowCxToRx(erow *row, int cx) {
+  int rx = 0;
+  int j;
+  for (j=0; j<cx; j++) {
+    if (row->chars[j] == '\t') {
+      rx += (KILO_TAB_STOP - 1) - (rx % KILO_TAB_STOP);
+    }
+    rx++;
+  }
+  return rx;
+}
+
 void editorUpdateRow(erow *row) {
   int tabs = 0;
   int j;
@@ -217,6 +235,9 @@ void editorAppendRow(char *s, size_t len) {
 /*** file i/o ***/
 
 void editorOpen(char *filename) {
+  free(E.filename);
+  E.filename = strdup(filename);
+
   FILE *fp = fopen(filename, "r");
   if (!fp) die("fopen");
 
@@ -256,17 +277,22 @@ void abFree(struct abuf *ab) {
 /*** output ***/
 
 void editorScroll() {
+  E.rx = E.cx;
+  if (E.cy < E.numrows) {
+    E.rx = editorRowCxToRx(&E.row[E.cy], E.cx);
+  }
+
   if (E.cy < E.rowoff) {
     E.rowoff = E.cy;
   }
   if (E.cy >= E.rowoff + E.screenrows) {
     E.rowoff = E.cy - E.screenrows + 1;
   }
-  if (E.cx < E.coloff) {
-    E.coloff = E.cx;
+  if (E.rx < E.coloff) {
+    E.coloff = E.rx;
   }
-  if (E.cx >= E.coloff + E.screencols) {
-    E.coloff = E.cx - E.screencols + 1;
+  if (E.rx >= E.coloff + E.screencols) {
+    E.coloff = E.rx - E.screencols + 1;
   }
 }
 
@@ -298,10 +324,38 @@ void editorDrawRows(struct abuf *ab) {
     }
 
     abAppend(ab, "\x1b[K", 3); // Erase one line
-    if (y < E.screenrows - 1) {
-      abAppend(ab, "\r\n", 2);
+    abAppend(ab, "\r\n", 2);
+  }
+}
+
+void editorDrawStatusBar(struct abuf *ab) {
+  abAppend(ab, "\x1b[7m", 4);
+  char status[80], rstatus[80];
+  int len = snprintf(status, sizeof(status), "%.20s - %d lines",
+      E.filename ? E.filename : "[No Name]", E.numrows);
+  int rlen = snprintf(rstatus, sizeof(rstatus), "%d/%d",
+      E.cy + 1, E.numrows);
+  if (len > E.screencols) len = E.screencols;
+  abAppend(ab, status, len);
+  while (len < E.screencols) {
+    if (E.screencols - len == rlen) {
+      abAppend(ab, rstatus, rlen);
+      break;
+    } else {
+      abAppend(ab, " ", 1);
+      len++;
     }
   }
+  abAppend(ab, "\x1b[m", 3);
+  abAppend(ab, "\r\n", 2);
+}
+
+void editorDrawMessageBar(struct abuf *ab) {
+  abAppend(ab, "\x1b[K", 3);
+  int msglen = strlen(E.statusmsg);
+  if (msglen > E.screencols) msglen = E.screencols;
+  if (msglen && time(NULL) - E.statusmsg_time < 5)
+    abAppend(ab, E.statusmsg, msglen);
 }
 
 void editorRefreshScreen() {
@@ -313,10 +367,12 @@ void editorRefreshScreen() {
   abAppend(&ab, "\x1b[H", 3); // CUP (cursor position)
 
   editorDrawRows(&ab);
+  editorDrawStatusBar(&ab);
+  editorDrawMessageBar(&ab);
 
   // Update cursor position
   char buf[32];
-  snprintf(buf, sizeof(buf), "\x1b[%d;%dH", (E.cy - E.rowoff) + 1, (E.cx - E.coloff) + 1);
+  snprintf(buf, sizeof(buf), "\x1b[%d;%dH", (E.cy - E.rowoff) + 1, (E.rx - E.coloff) + 1);
   abAppend(&ab, buf, strlen(buf));
 
   abAppend(&ab, "\x1b[?25h", 6); // Show cursor
@@ -325,6 +381,14 @@ void editorRefreshScreen() {
   abFree(&ab);
 }
 
+void editorSetStatusMessage(const char *fmt, ...) {
+  va_list ap;
+  va_start(ap, fmt);
+  vsnprintf(E.statusmsg, sizeof(E.statusmsg), fmt, ap);
+  va_end(ap);
+  E.statusmsg_time = time(NULL);
+}
+
 /*** input ***/
 
 void editorMoveCursor(int key) {
@@ -382,12 +446,20 @@ void editorProcessKeypress() {
       break;
 
     case END_KEY:
-      E.cx = E.screencols -1;
+      if (E.cy < E.numrows) {
+        E.cx = E.row[E.cy].size;
+      }
       break;
 
     case PAGE_UP:
     case PAGE_DOWN:
       {
+        if (c == PAGE_UP) {
+          E.cy = E.rowoff;
+        } else if (c == PAGE_DOWN) {
+          E.cy = E.rowoff + E.screenrows - 1;
+          if (E.cy > E.numrows) E.cy = E.numrows;
+        }
         int times = E.screenrows;
         while(times--)
           editorMoveCursor(c == PAGE_UP ? ARROW_UP : ARROW_DOWN);
@@ -408,13 +480,18 @@ void editorProcessKeypress() {
 void initEditor() {
   E.cx = 0;
   E.cy = 0;
+  E.rx = 0;
   E.rowoff = 0;
   E.coloff = 0;
   E.numrows = 0;
   E.row = NULL;
+  E.filename = NULL;
+  E.statusmsg[0] = '\0';
+  E.statusmsg_time = 0;
 
   if (getWindowSize(&E.screenrows, &E.screencols) == -1)
       die("getWindowSize");
+  E.screenrows -= 2;
 }
 
 int main(int argc, char *argv[]) {
@@ -424,6 +501,8 @@ int main(int argc, char *argv[]) {
     editorOpen(argv[1]);
   }
 
+  editorSetStatusMessage("HELP: Ctrl-Q = Quit");
+
   while (1) {
     editorRefreshScreen();
     editorProcessKeypress();