tedit.c

#define _DEFAULT_SOURCE
#define _BSD_SOURCE
#define _GNU_SOURCE

#include <unistd.h>
#include <termios.h>
#include <stdlib.h>
#include <ctype.h>
#include <stdio.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <string.h>
#include <time.h>
#include <stdarg.h>
#include <fcntl.h>

/*** defines ***/

#define TEDIT_VERSION "0.0.1"
#define TAB_STOP 4
#define QUIT_TIMES 2

#define CTRL_KEY(k) ((k) & 0x1f)           // turns off bit 7, 6 and 5 of the char
#define HL_HIGHLIGHT_NUMBERS (1<<0)
#define HL_HIGHLIGHT_STRINGS (1<<1)

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
};

/*** data ***/

struct editorSyntax {
	char *filetype;
	char **filematch;
	char **keywords;
	char *singleline_comment_start;
	char *multiline_comment_start;
	char *multiline_comment_end;
	int flags;
};

// Stores row of text in editor
typedef struct erow {
 	int idx;   
	int size;
    int rsize;
    char *chars;
    char *render;
	unsigned char *hl;
	int hl_open_comment;
} erow;

// Keeps track of global editor state
struct editorConfig{
    // cx --> horizontal coordinate of cursor(columns) 
    // cy --> vertical coordinate of cursor(rows)
    int cx, cy;     
    int rx; 
    int screenrows;
    int screencols;
    int rowoff;
    int coloff;
    int numrows;
    int dirty;
    erow *row;
    char *filename;
    char statusmsg[80];
    time_t statusmsg_time;
    struct editorSyntax *syntax;
	struct termios orig_termios;
};


struct editorConfig E;   // global editor state object

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
};

struct editorSyntax HLDB[] = {
	{
		"c",
		C_HL_extensions,
		C_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));

/*** 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);
}

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


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 wbuf;
    if(ioctl(STDOUT_FILENO, TIOCGWINSZ, &wbuf) == -1 || wbuf.ws_col == 0){
        if(write(STDOUT_FILENO, "\x1b[999C\x1b[999B", 12) != 12)
            return -1;
        return getCursorPosition(rows, cols);
    }
    else{
        *cols = wbuf.ws_col;
        *rows = wbuf.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;
	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;
				i++;
				prev_sep = 1;
				continue;
			}else{
				if(c == '"' || c == '\'') {
					in_string = c;
					row->hl[i] = HL_STRING;
					i++;
					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;
				i++;
				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;     // cyan
		case HL_KEYWORD1: return 33;    // yellow
		case HL_KEYWORD2: return 32;    // green
		case HL_STRING: return 35;      // magenta
		case HL_NUMBER: return 31;      // red
		case HL_MATCH: return 34;       // blue
		default: return 37;             // white
	}
}

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

	char *ext = strchr(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++;
    	}
  	}
}

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

void enableRawMode(){
    if(tcgetattr(STDIN_FILENO, &E.orig_termios) == -1)
        die("tcgetsttr");
    atexit(disableRawMode);
    struct termios obj = E.orig_termios;
    obj.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
    obj.c_cflag |= (CS8);
    obj.c_oflag &= ~(OPOST);
    obj.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);

    // activate read with timeout: MIN == 0, TIME > 0
    // TIME  specifies the limit for a timer in tenths
    //  of a second.  The timer is started when read(2)
    //  is  called.   read(2)  returns  either  when at
    //  least one byte of data is  available,  or  when
    //  the  timer expires.  If the timer expires with‐
    //  out  any  input  becoming  available,   read(2)
    //  returns 0.  If data is already available at the
    //  time of the call to read(2), the  call  behaves
    //  as  though  the  data  was received immediately
    //  after the call.
    obj.c_cc[VMIN] = 0;
    obj.c_cc[VTIME] = 1;
    
    if(tcsetattr(STDIN_FILENO, TCSAFLUSH, &obj) == -1)
        die("tcsetattr");

}

/*** row operations ***/

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

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

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

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

    int index = 0;
    for(i = 0; i < row->size; i++) {
        if(row->chars[i] == '\t') {
            row->render[index++] = ' ';
            while(index % TAB_STOP != 0)
                row->render[index++] = ' ';
        } else {
            row->render[index++] = row->chars[i];
        }
    }
    row->render[index] = '\0';
    row->rsize = index;
		
	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 i;
    for( i = 0 ; i < E.numrows ; i++) {
        totlen += E.row[i].size + 1;
    }

    *buflen = totlen;

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

    return buf;
}

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));
}

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;
}

/*** 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 = last_match;
	int i;
    for(i = 0; i < E.numrows; i++){
		current += direction;
		if(current == -1)
			current = E.numrows - 1;
		else if(current == E.numrows)
			current = 0;

        erow *row = &E.row[current];
        char *match = strstr(row->render, query);
        if(match) {
			last_match = current;
            E.cy = current;
            E.cx = editorRowRxToCx(row, match - row->render);
            E.rowoff = E.numrows;
			
			saved_hl_line = current;
			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;
	}
}

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

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

		case CTRL_KEY('f'):
			editorFind();
			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_LEFT:
        case ARROW_DOWN:
        case ARROW_RIGHT:
            editorMoveCursor(c);
            break;
        
        case CTRL_KEY('l'):
        case '\x1b':
            break;

        default:
            editorInsertChar(c);
            break;
    }

    quit_times = QUIT_TIMES;
}

/*** 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), "Tedit Editor -- version %s", TEDIT_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);
}

/*** init ***/

void initEditor(){
    E.cx = 0;
    E.cy = 0;
    E.rx = 0;
    E.numrows = 0;
    E.row = NULL;
    E.rowoff = 0;
    E.coloff = 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-Q = quit | Ctrl-S = save | Ctrl-F = find");

    while(1){
        editorRefreshScreen();
        editorProcessKeypress();
    }
    return 0;
}