kilo.c

/* Includes */
#define _DEFAULT_SOURCE
#define _BSD_SOURCE
#define _GNU_SOURCE
#include <asm-generic/errno-base.h>
#include <asm-generic/ioctls.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.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 */
#define KILO_VERSION "0.0.1"
#define KILO_TAB_STOP 8
#define KILO_QUIT_TIMES 3

#define CTRL_KEY(k) ((k) & 0x1f)

enum editorKey {
  BACKSPACE = 127,
  ARROW_LEFT = 1000,
  ARROW_RIGHT,
  ARROW_UP,
  ARROW_DOWN,
  DEL_KEY,
  HOME_KEY,
  END_KEY,
  PAGE_UP,
  PAGE_DOWN
};

enum editorHighlight {
  HL_NORMAL = 0,
  HL_COMMENT,
  HL_MLCOMMENT,
  HL_KEYWORD1,
  HL_KEYWORD2,
  HL_STRING,
  HL_NUMBER,
  HL_MATCH
};

#define HL_HIGHLIGHT_NUMBERS (1<<0)
#define HL_HIGHLIGHT_STRINGS (1<<1)
/* Data */
struct editorSyntax {
  char *filetype;
  char **filematch;
  char **keywords;
  char *singleline_comment_start;
  char *multiline_comment_start;
  char *multiline_comment_end;
  int flags;
};

/* struct termios orig_termios; */
typedef struct {
  int idx;
  int size;
  int rsize;
  char *chars;
  char *render;
  unsigned char *hl;
  int hl_open_comment;
} erow;

struct editorConfig {
  int cx, cy;
  int rx;
  int rowoff;
  int coloff;
  int screenrows;
  int screencols;
  int numrows;
  erow *row;
  int dirty;
  char *filename;
  char statusmsg[80];
  time_t statusmsg_time;
  struct editorSyntax *syntax;
  struct termios orig_termios;
} E;

/* filetypes */
char *C_HL_extensions[] = {".c", ".h", ".cpp", NULL};

char *C_HL_keywords[] = {
  "switch", "if", "while", "for", "break", "continue", "return", "else",
  "struct", "union", "typedef", "static", "enum", "class", "case",

  "int|", "long|", "double|", "float|", "char|", "unsigned|", "signed|",
  "void|", NULL
};

char *Scheme_HL_extensions[] = {".scm", NULL};

char *Scheme_HL_keywords[] = {
  "access", "and", "begin", "bkpt", "case", "cond", "cons-stream", "declare", "default-object?", "define", "define-integrable", "define-macro", "define-structure", "define-syntax", "delay", "do", "fluid-let", "if", "in-package", "lambda", "let", "let*", "let-syntax", "letrec", "local-declare", "macro", "make-environment", "named-lambda", "or", "quasiquote", "quote", "scode-quote", "sequence", "set!", "the-environment", "unassigned?", "using-syntax", NULL
};

struct editorSyntax HLDB[] = {
  {
    "c",
    C_HL_extensions,
    C_HL_keywords,
    "//", "/*", "*/",
    HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRINGS
  },
  {
    "scheme",
    Scheme_HL_extensions,
    Scheme_HL_keywords,
    ";", "#|", "|#",
    HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRINGS
  },
};

#define HLDB_ENTRIES (sizeof(HLDB) / sizeof(HLDB[0]))

/* prototypes */
void editorSetStatusMessage(const char *fmt, ...);
void editorRefreshScreen();
char *editorPrompt(char *prompt, void (*callback) (char *, int));

/* Terminal */
void die(const char *s)
{
  write(STDOUT_FILENO, "\x1b[2J", 4);
  write(STDOUT_FILENO, "\x1b[H", 3);
  
  perror(s);
  exit(1);
}

void disableRawMode()
{
  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &E.orig_termios) == -1)
    die("tcsetattr");
}


void enableRawMode()
{
  if (tcgetattr(STDIN_FILENO, &E.orig_termios) == -1) die("tcgetattr");
  atexit(disableRawMode);

  struct termios raw = E.orig_termios;
  raw.c_iflag &= ~(IXON | ICRNL | BRKINT | ISTRIP | INPCK);
  raw.c_oflag &= ~(OPOST);
  raw.c_cflag |= (CS8);
  raw.c_lflag &= ~(ECHO | ICANON | ISIG | IEXTEN);
  raw.c_cc[VMIN] = 0;
  raw.c_cc[VTIME] = 1;

  if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) == -1) die("tcsetattr");
}

int editorReadKey()
{
  int nread;
  char c;
  while ((nread = read(STDIN_FILENO, &c, 1)) != 1) {
    if (nread == -1 && errno != EAGAIN) die("read");
  }

  if (c == '\x1b') {
    char seq[3];

    if (read(STDIN_FILENO, &seq[0], 1) != 1) return '\x1b';
    if (read(STDIN_FILENO, &seq[1], 1) != 1) return '\x1b';

    if (seq[0] == '[') {
      if (seq[1] >= '0' && seq[1] <= '9') {
	if (read(STDIN_FILENO, &seq[2], 1) != 1) return '\x1b';
	if (seq[2] == '~') {
	  switch (seq[1]) {
	  case '1': return HOME_KEY;
	  case '3': return DEL_KEY;
	  case '4': return END_KEY;
	  case '5': return PAGE_UP;
	  case '6': return PAGE_DOWN;
	  case '7': return HOME_KEY;
	  case '8': return END_KEY;
	  }
	}
      } else {
	switch (seq[1]) {
	case 'A': return ARROW_UP;
	case 'B': return ARROW_DOWN;
	case 'C': return ARROW_RIGHT;
	case 'D': return ARROW_LEFT;
	case 'H': return HOME_KEY;
	case 'F': return END_KEY;
	}
      }
    } else if (seq[0] == 'O') {
      switch (seq[1]) {
      case 'H': return HOME_KEY;
      case 'F': return END_KEY;
      }
    }
    return '\x1b';
  } else {
    return c;
  }
}

int getCursorPosition(int *rows, int *cols)
{
  char buf[32];
  unsigned int i = 0;
  
  if (write(STDOUT_FILENO, "\x1b[6n", 4) != 4) return -1;

  while (i < sizeof(buf) - 1) {
    if (read(STDIN_FILENO, &buf[i], 1) != 1) break;
    if (buf[i] == 'R') break;
    i++;
  }
  buf[i] = '\0';

  if (buf[0] != '\x1b' || buf[1] != '[') return -1;
  if (sscanf(&buf[2], "%d;%d", rows, cols) != 2) return -1;

  return 0;
}

int getWindowSize(int *rows, int *cols)
{
  struct winsize ws;

  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
    if (write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12) 
      return -1;
    return getCursorPosition(rows, cols);
  }
  else {
    *cols = ws.ws_col;
    *rows = ws.ws_row;
    return 0;
  }
}

/* syntax highlighting */
int is_separator(int c)
{
  return isspace(c) || c == '\0' || strchr(",.()+-/*=~%<>[];", c) != NULL;
}

void editorUpdateSyntax(erow *row)
{
  row->hl = realloc(row->hl, row->rsize);
  memset(row->hl, HL_NORMAL, row->rsize);

  if (E.syntax == NULL) return;

  char **keywords = E.syntax->keywords;

  char *scs = E.syntax->singleline_comment_start; /* singleline comment start */
  char *mcs = E.syntax->multiline_comment_start;
  char *mce = E.syntax->multiline_comment_end;
  
  int scs_len = scs ? strlen(scs) : 0;
  int mcs_len = mcs ? strlen(mcs) : 0;
  int mce_len = mce ? strlen(mce) : 0;
  
  int prev_sep = 1;
  int in_string = 0;
  int in_comment = (row->idx > 0 && E.row[row->idx - 1].hl_open_comment);
  
  int i = 0;
  while (i < row->rsize) {
    char c = row->render[i];
    unsigned char prev_hl = (i > 0) ? row->hl[i - 1] : HL_NORMAL;

    if (scs_len && !in_string && !in_comment) {
      if (!strncmp(&row->render[i], scs, scs_len)) {
	memset(&row->hl[i], HL_COMMENT, row->rsize - i);
	break;
      }
    }

    if (mcs_len && mce_len && !in_string) {
      if (in_comment) {
	row->hl[i] = HL_MLCOMMENT;
	if (!strncmp(&row->render[i], mce, mce_len)) {
	  memset(&row->hl[i], HL_MLCOMMENT, mce_len);
	  i += mce_len;
	  in_comment = 0;
	  prev_sep = 1;
	  continue;
	} else {
	  i++;
	  continue;
	}
      } else if (!strncmp(&row->render[i], mcs, mcs_len)) {
	memset(&row->hl[i], HL_MLCOMMENT, mcs_len);
	i += mcs_len;
	in_comment = 1;
	continue;
      }
    }
    if (E.syntax->flags & HL_HIGHLIGHT_STRINGS) {
      if (in_string) {
	row->hl[i++] = HL_STRING;
	if (c == '\\' && i + 1 < row->rsize) {
	  row->hl[i + 1] = HL_STRING;
	  i += 2;
	  continue;
	}
	if (c == in_string) in_string = 0;
	prev_sep = 1;
	continue;
      } else {
	if (c == '"' || c == '\'') {
	  in_string = c;
	  row->hl[i++] = HL_STRING;
	  continue;
	}
      }
    }

    if (E.syntax->flags & HL_HIGHLIGHT_NUMBERS) {
      if ((isdigit(c) && (prev_sep || prev_hl == HL_NUMBER)) ||
	  (c == '.' && prev_hl == HL_NUMBER)) {
	row->hl[i++] = HL_NUMBER;
	prev_sep = 0;
	continue;
      }
    }

    if (prev_sep) {
      int j;
      for (j = 0; keywords[j]; j++) {
	int klen = strlen(keywords[j]);
	int kw2 = keywords[j][klen - 1] == '|';
	if (kw2) klen--;

	if (!strncmp(&row->render[i], keywords[j], klen) &&
	    is_separator(row->render[i + klen])) {
	  memset(&row->hl[i], kw2 ? HL_KEYWORD2 : HL_KEYWORD1, klen);
	  i += klen;
	  break;
	}
      }
      if (keywords[j] != NULL) {
	prev_sep = 0;
	continue;
      }
    }
    prev_sep = is_separator(c);
    i++;
  }
  int changed = (row->hl_open_comment != in_comment);
  row->hl_open_comment = in_comment;
  if (changed && row->idx + 1 < E.numrows)
    editorUpdateSyntax(&E.row[row->idx + 1]);
}

int editorSyntaxToColor(int hl)
{
  switch (hl) {
  case HL_COMMENT:
  case HL_MLCOMMENT: return 36;
  case HL_KEYWORD1: return 33;
  case HL_KEYWORD2: return 32;
  case HL_STRING: return 35;
  case HL_NUMBER: return 31;
  case HL_MATCH: return 34;
  default: return 37;
  }
}

void editorSelectSyntaxHighlight()
{
  E.syntax = NULL;
  if (E.filename == NULL) return;

  char *ext = strrchr(E.filename, '.');

  for (unsigned int j = 0; j < HLDB_ENTRIES; j++) {
    struct editorSyntax *s = &HLDB[j];
    unsigned int i = 0;
    while (s->filematch[i]) {
      int is_ext = (s->filematch[i][0] == '.');
      if ((is_ext && ext && !strcmp(ext, s->filematch[i])) ||
	  (!is_ext && strstr(E.filename, s->filematch[i]))) {
	E.syntax = s;

	int filerow;
	for (filerow = 0; filerow < E.numrows; filerow++)
	  editorUpdateSyntax(&E.row[filerow]);
	return;
      }
      i++;
    }
  }
}

/* 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;
}

int editorRowRxToCx(erow *row, int rx)
{
  int cur_rx = 0;
  int cx;
  for (cx = 0; cx < row->size; cx++) {
    if (row->chars[cx] == '\t')
      cur_rx += (KILO_TAB_STOP - 1) - (cur_rx % KILO_TAB_STOP);
    cur_rx++;

    if (cur_rx > rx) return cx;
  }
  return cx;
}

void editorUpdateRow(erow *row)
{
  int tabs = 0;
  int j;
  for (j = 0; j < row->size; j++)
    if (row->chars[j] == '\t') tabs++;

  free(row->render);
  row->render = malloc(row->size + tabs * (KILO_TAB_STOP - 1) + 1);

  int idx = 0;
  for (j = 0; j < row->size; j++) {
    if (row->chars[j] == '\t') {
      row->render[idx++] = ' ';
      while (idx % KILO_TAB_STOP != 0) row->render[idx++] = ' ';
    } else
      row->render[idx++] = row->chars[j];
  }
  row->render[idx] = '\0';
  row->rsize = idx;

  editorUpdateSyntax(row);
}

void editorInsertRow(int at, char *s, size_t len)
{
  if (at < 0 || at > E.numrows) return;
  
  E.row = realloc(E.row, sizeof(erow) * (E.numrows + 1));
  memmove(&E.row[at + 1], &E.row[at], sizeof(erow) * (E.numrows - at));
  for (int j = at + 1; j <= E.numrows; j++) E.row[j].idx++;

  E.row[at].idx = at;
  
  E.row[at].size = len;
  E.row[at].chars = malloc(len + 1);
  memcpy(E.row[at].chars, s, len);
  E.row[at].chars[len] = '\0';

  E.row[at].rsize = 0;
  E.row[at].render = NULL;
  E.row[at].hl = NULL;
  E.row[at].hl_open_comment = 0;
  editorUpdateRow(&E.row[at]);

  E.numrows++;
  E.dirty++;
}

void editorFreeRow(erow *row)
{
  free(row->render);
  free(row->chars);
  free(row->hl);
}

void editorDelRow(int at)
{
  if (at < 0 || at >= E.numrows) return;
  editorFreeRow(&E.row[at]);
  memmove(&E.row[at], &E.row[at + 1], sizeof(erow) * (E.numrows - at - 1));
  for (int j = at; j < E.numrows - 1; j++) E.row[j].idx--;
  E.numrows--;
  E.dirty++;
}

void editorRowInsertChar(erow *row, int at, int c)
{
  if (at < 0 || at > row->size) at = row->size;
  row->chars = realloc(row->chars, row->size + 2);
  memmove(&row->chars[at + 1], &row->chars[at], row->size - at + 1);
  row->size++;
  row->chars[at] = c;
  editorUpdateRow(row);
  E.dirty++;
}

void editorRowAppendString(erow *row, char *s, size_t len)
{
  row->chars = realloc(row->chars, row->size + len + 1);
  memcpy(&row->chars[row->size], s, len);
  row->size += len;
  row->chars[row->size] = '\0';
  editorUpdateRow(row);
  E.dirty++;
}

void editorRowDelChar(erow *row, int at)
{
  if (at < 0 || at >= row->size) return;
  memmove(&row->chars[at], &row->chars[at + 1], row->size - at);
  row->size--;
  editorUpdateRow(row);
  E.dirty++;
}

/* editor operations */
void editorInsertChar(int c)
{
  if (E.cy == E.numrows)
    editorInsertRow(E.numrows, "", 0);
  editorRowInsertChar(&E.row[E.cy], E.cx, c);
  E.cx++;
}

void editorInsertNewline()
{
  if (E.cx == 0)
    editorInsertRow(E.cy, "", 0);
  else {
    erow *row = &E.row[E.cy];
    editorInsertRow(E.cy + 1, &row->chars[E.cx], row->size - E.cx);
    row = &E.row[E.cy];
    row->size = E.cx;
    row->chars[row->size] = '\0';
    editorUpdateRow(row);
  }
  E.cy++;
  E.cx = 0;
}

void editorDelChar()
{
  if (E.cy == E.numrows) return;
  if (E.cx == 0 && E.cy == 0) return;

  erow *row = &E.row[E.cy];
  if (E.cx > 0) {
    editorRowDelChar(row, E.cx - 1);
    E.cx--;
  } else {
    E.cx = E.row[E.cy - 1].size;
    editorRowAppendString(&E.row[E.cy - 1], row->chars, row->size);
    editorDelRow(E.cy);
    E.cy--;
  }
}

/* file i/o */
char *editorRowsToString(int *buflen)
{
  int totlen = 0;
  int j;
  for (j = 0; j < E.numrows; j++)
    totlen += E.row[j].size + 1;
  *buflen = totlen;

  char *buf = malloc(totlen);
  char *p = buf;
  for (j = 0; j < E.numrows; j++) {
    memcpy(p, E.row[j].chars, E.row[j].size);
    p += E.row[j].size;
    *p = '\n';
    p++;
  }
  return buf;
}

void editorOpen(char *filename)
{
  free(E.filename);
  E.filename = strdup(filename);

  editorSelectSyntaxHighlight();
  
  FILE *fp = fopen(filename, "r");
  if (!fp) die("fopen");

  char *line = NULL;
  size_t linecap = 0;
  ssize_t linelen;
  
  while ((linelen = getline(&line, &linecap, fp)) != -1) {
    while (linelen > 0 && (line[linelen - 1] == '\n' ||
			   line[linelen - 1] == '\r'))
      linelen--;
    editorInsertRow(E.numrows, line, linelen);
  }
  free(line);
  fclose(fp);
  E.dirty = 0;
}

void editorSave()
{
  if (E.filename == NULL) {
    E.filename = editorPrompt("Save as: %s (ESC to cancel).", NULL);
    if (E.filename == NULL) {
      editorSetStatusMessage("Save aborted.");
      return;
    }
    editorSelectSyntaxHighlight();
  }

  int len;
  char *buf = editorRowsToString(&len);

  int fd = open(E.filename, O_RDWR | O_CREAT, 0644);
  if (fd != -1) {
    if (ftruncate(fd, len) != -1) {
      if (write(fd, buf, len) == len) {
	close(fd);
	free(buf);
	E.dirty = 0;
	editorSetStatusMessage("%d bytes written to disk.", len);
	return;
      }
    }
    close(fd);
  }
  free(buf);
  editorSetStatusMessage("Can't save! I/O error: %s", strerror(errno));
}

/* find */
void editorFindCallback(char *query, int key)
{
  static int last_match = -1;
  static int direction = 1;

  static int saved_hl_line;
  static char *saved_hl = NULL;

  if (saved_hl) {
    memcpy(E.row[saved_hl_line].hl, saved_hl, E.row[saved_hl_line].rsize);
    free(saved_hl);
    saved_hl = NULL;
  }
  
  if (key == '\r' || key == '\x1b') {
    last_match = -1;
    direction = 1;
    return;
  } else if (key == ARROW_RIGHT || key == ARROW_DOWN){
    direction = 1;
  } else if (key == ARROW_LEFT || key == ARROW_UP) {
    direction = -1;
  } else {
    last_match = -1;
    direction = 1;
  }

  if (last_match == -1) direction = 1;
  int current_line = last_match;
  
  int i;
  for (i = 0; i < E.numrows; i++) {
    current_line += direction;
    if (current_line == -1) current_line = E.numrows - 1;
    else if (current_line == E.numrows) current_line = 0;
    erow *row = &E.row[current_line];
    char *match = strstr(row->render, query);
    if (match) {
      last_match = current_line;
      E.cy = current_line;
      E.cx = editorRowRxToCx(row, match - row->render);
      E.rowoff = E.numrows;

      saved_hl_line = current_line;
      saved_hl = malloc(row->rsize);
      memcpy(saved_hl, row->hl, row->rsize);

      memset(&row->hl[match - row->render], HL_MATCH, strlen(query));
      break;
    }
  }
}

void editorFind() {
  int saved_cx = E.cx;
  int saved_cy = E.cy;
  int saved_coloff = E.coloff;
  int saved_rowoff = E.rowoff;
  
  char *query = editorPrompt("Search: %s (Use ESC/Arrows/Enter)", editorFindCallback);
  if (query)
    free(query);
  else {
    E.cx = saved_cx;
    E.cy = saved_cy;
    E.coloff = saved_coloff;
    E.rowoff = saved_rowoff;
  }
}

/* append buffer */
struct abuf {
  char *b;
  int len;
};

#define ABUF_INIT {NULL, 0}

void abAppend(struct abuf *ab, const char *s, int len)
{
  char *new = realloc(ab->b, ab->len + len);

  if (new == NULL) return;
  memcpy(&new[ab->len], s, len);
  ab->b = new;
  ab->len += len;
}

void abFree(struct abuf *ab)
{
  free(ab->b);
}

/* output */
void editorScroll()
{
  E.rx = 0;
  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.rx < E.coloff)
    E.coloff = E.rx;
  if (E.rx >= E.coloff + E.screencols)
    E.coloff = E.rx - E.screencols + 1;
}

void editorDrawRows(struct abuf *ab)
{
  int y;
  for (y = 0; y < E.screenrows; y++) {
    int filerow = y + E.rowoff;
    if (filerow >= E.numrows) {
      if (E.numrows == 0 && y == E.screenrows / 3) {
	char welcome[80];
	int welcomelen = snprintf(welcome, sizeof(welcome),
				  "Kilo editor -- version %s", KILO_VERSION);
	if (welcomelen > E.screencols) welcomelen = E.screencols;
	int padding = (E.screencols - welcomelen) / 2;
	if (padding) {
	  abAppend(ab, "~", 1);
	  padding--;
	}
	while (padding--) abAppend(ab, " ", 1);
	abAppend(ab, welcome, welcomelen);
      } else {
	abAppend(ab, "~", 1);
      }
    } else {
      int len = E.row[filerow].rsize - E.coloff;
      if (len < 0) len = 0;
      if (len > E.screencols) len = E.screencols;
      char *c = &E.row[filerow].render[E.coloff];
      unsigned char *hl = &E.row[filerow].hl[E.coloff];
      int current_color = -1;
      int j;
      for (j = 0; j < len; j++) {
	if (iscntrl(c[j])) {
	  char sym = (c[j] <= 26) ? '@' + c[j] : '?';
	  abAppend(ab, "\x1b[7m", 4);
	  abAppend(ab, &sym, 1);
	  abAppend(ab, "\x1b[m", 3);
	  if (current_color != -1) {
	    char buf[16];
	    int clen = snprintf(buf, sizeof(buf), "\x1b[%dm", current_color);
	    abAppend(ab, buf, clen);
	  }
	}else if (hl[j] == HL_NORMAL) {
	  if (current_color != -1) {
	    abAppend(ab, "\x1b[39m", 5);
	    current_color = -1;
	  }
	  abAppend(ab, &c[j], 1);
	} else {
	  int color = editorSyntaxToColor(hl[j]);
	  if (color != current_color) {
	    current_color = color;
	    char buf[16];
	    int clen = snprintf(buf, sizeof(buf), "\x1b[%dm", color);
	    abAppend(ab, buf, clen);
	  }
	  abAppend(ab, &c[j], 1);
	}
      }
      abAppend(ab, "\x1b[39m", 5);
    }
    abAppend(ab, "\x1b[K", 3);
    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 %s",
		     E.filename ? E.filename : "[No Name]", E.numrows,
		     E.dirty ? "(modified)" : "");
  int rlen = snprintf(rstatus, sizeof(rstatus), "%s | %d/%d",
		      E.syntax ? E.syntax->filetype : "no ft", 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()
{
  editorScroll();
  struct abuf ab = ABUF_INIT;

  abAppend(&ab, "\x1b[?25l", 6);
  abAppend(&ab, "\x1b[H", 3);

  editorDrawRows(&ab);
  editorDrawStatusBar(&ab);
  editorDrawMessageBar(&ab);

  char buf[32];
  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);

  write(STDOUT_FILENO, ab.b, ab.len);
  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 */
char *editorPrompt(char *prompt, void (*callback) (char *, int))
{
  size_t bufsize = 128;
  char *buf = malloc(bufsize);

  size_t buflen = 0;
  buf[0] = '\0';

  while (1) {
    editorSetStatusMessage(prompt, buf);
    editorRefreshScreen();

    int c = editorReadKey();
    if (c == DEL_KEY || c == CTRL_KEY('h') || c == BACKSPACE) {
      if (buflen != 0) buf[--buflen] = '\0';
    } else if (c == '\x1b') {
      editorSetStatusMessage("");
      if (callback) callback(buf, c);
      free(buf);
      return NULL;
    } else if (c == '\r') {
      if (buflen != 0) {
	editorSetStatusMessage("");
	if (callback) callback(buf, c);
	return buf;
      }
    } else if (!iscntrl(c) && c < 128) {
      if (buflen == bufsize - 1) {
	bufsize *= 2;
	buf = realloc(buf, bufsize);
      }
      buf[buflen++] = c;
      buf[buflen] = '\0';
    }
    if (callback) callback(buf, c);
  }
}

void editorMoveCursor(int key)
{
  erow *row = (E.cy >= E.numrows) ? NULL : &E.row[E.cy];

  switch (key) {
  case ARROW_LEFT:
    if (E.cx != 0)
      E.cx--;
    else if (E.cy > 0) {
      E.cy--;
      E.cx = E.row[E.cy].size;
    }
    break;
  case ARROW_RIGHT:
    if (row && E.cx < row->size)
      E.cx++;
    else if (row && E.cx == row->size) {
      E.cy++;
      E.cx = 0;
    }
    break;
  case ARROW_UP:
    if (E.cy != 0)
      E.cy--;
    break;
  case ARROW_DOWN:
    if (E.cy < E.numrows)
      E.cy++;
    break;
  }

  row = (E.cy >= E.numrows) ? NULL : &E.row[E.cy];
  int rowlen = row ? row->size : 0;
  if (E.cx > rowlen)
    E.cx = rowlen;
}

void editorProcessKeypress()
{
  static int quit_times = KILO_QUIT_TIMES;
  
  int c = editorReadKey();

  switch (c) {
  case '\r':
    editorInsertNewline();
    break;

  case CTRL_KEY('q'):
    if (E.dirty && quit_times > 0) {
      editorSetStatusMessage("WARNING!!! File has unsaved changes. "
			     "Press Ctrl-Q %d more times to quit.", quit_times);
      quit_times--;
      return;
    }
    write(STDOUT_FILENO, "\x1b[2J", 4);
    write(STDOUT_FILENO, "\x1b[H", 3);
    exit(0);
    break;

  case CTRL_KEY('s'):
    editorSave();
    break;

  case HOME_KEY:
    E.cx = 0;
    break;
  case END_KEY:
    if (E.cy < E.numrows)
      E.cx = E.row[E.cy].size;
    break;

  case CTRL_KEY('f'):
    editorFind();
    break;

  case BACKSPACE:
  case CTRL_KEY('h'):
  case DEL_KEY:
    if (c == DEL_KEY) editorMoveCursor(ARROW_RIGHT);
    editorDelChar();
    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);
    }
    break;

  case ARROW_UP:
  case ARROW_DOWN:
  case ARROW_LEFT:
  case ARROW_RIGHT:
    editorMoveCursor(c);
    break;

  case CTRL_KEY('l'):
  case '\x1b':
    break;

  default:
    editorInsertChar(c);
    break;
  }
  quit_times = KILO_QUIT_TIMES;
}

/* Init */
void initEditor()
{
  E.cx = 0;
  E.cy = 0;
  E.rx = 0;
  E.rowoff = 0;
  E.coloff = 0;
  E.numrows = 0;
  E.row = NULL;
  E.dirty = 0;
  E.filename = NULL;
  E.statusmsg[0] = '\0';
  E.statusmsg_time = 0;
  E.syntax = NULL;

  if (getWindowSize(&E.screenrows, &E.screencols) == -1)
    die("getWindowSize");
  E.screenrows -= 2;
}

int main(int argc, char **argv)
{
  enableRawMode();
  initEditor();
  if (argc >= 2)
    editorOpen(argv[1]);

  editorSetStatusMessage("HELP: Ctrl-s = save | Ctrl-Q = quit | Ctrl-F = find");
  
  while (1) {
    editorRefreshScreen();
    editorProcessKeypress();
  }
  
  return 0;
}