kadence.c

/*** includes ***/
// these defines are put in the includes part of the code 
// because this is actually gcc feature, including these defines
// defines the exact features one would like to use during compilation
#include <stdarg.h>
#include <time.h>
#define _DEFAULT_SOURCE
#define _BSD_SOURCE
#define _GNU_SOURCE
#include<sys/types.h>
#include <asm-generic/ioctls.h>
#include <errno.h>
#include <errno.h>
#include<unistd.h>
#include<time.h>
#include<errno.h>
#include<sys/ioctl.h>
#include<string.h>
#include<termios.h>
#include<stdio.h>
#include<stdlib.h>
// i can't make a vertical text editor cuz, the way buffer is printed out
// is always horizontal </3 :(
/*defines*/
#define KADENCE_VERSION "0.0.1"
#define KILO_TAB_STOP 8
#define CTRL_KEY(k) ((k) & 0x1f)

enum editorKey{
    ARROW_LEFT = 1000 ,
    ARROW_UP ,
    ARROW_RIGHT, 
    ARROW_DOWN,
    HOME_KEY,
    END_KEY,
    PAGE_UP,
    PAGE_DOWN,
    DEL_KEY
};
/*** data ***/
typedef struct erow{
    int size;
    int rsize;
    char *chars;
    char *render;
} erow;

struct editorConfig{
    int cx,cy;
    int rx;
    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;
};
struct editorConfig E;
/***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 loggingText(const char *format, const char *mode, ...){
    FILE *fptr;
    fptr = fopen("log.txt", mode);
    if (fptr == NULL){
        printf("Error!");
        exit(1);
    }
    va_list args;
    va_start(args, mode);

    vfprintf(fptr, format, args);
    va_end(args);
    fclose(fptr);
}
void enableRawMode(){
    if(tcgetattr(STDIN_FILENO, &E.orig_termios) == -1) die("tcgetattr"); 
    atexit(disableRawMode);
    
    struct termios raw = E.orig_termios;
    raw.c_lflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
    raw.c_lflag &= ~(ICRNL | IXON);
    raw.c_lflag &= ~(OPOST);
    raw.c_cflag |= (CS8);
    raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG); // this is a genius piece of code right here
    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 '2': return END_KEY;
                        case '3': return DEL_KEY;
                        case '5': return PAGE_UP;
                        case '6': return PAGE_DOWN;
                    }
                }
            }
            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;
            // here case ABCD represents up,down right left respectively due to escape sequence in VT100 terminals being coded
            // that way.
            }
        }
        }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 getWindowsSize(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;
    }
}
/*row operations */
int editorRowCxtoRx(erow *row, int cx){
    int rx = 0;
    int j = 0; // kya bhai C99 users ; ( 
    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;
    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] == '\n'){
            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; 
}
/*file input/output */
void editorAppendRow( char *s,size_t len){
    E.row = realloc(E.row, sizeof(erow)* (E.numrows+1));

    int at = E.numrows;
    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;
    editorUpdateRow(&E.row[at]);

    E.numrows++;
}
void editorRowInsertChar(erow *row, int at, int c){
    if(at < 0 || at > row->size) at = row->size; // idk why at < 0 was chosen
    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);
    loggingText("updated %c \n", "a", c );
}
/*editor operations*/

void editorInsertChar(int c){
   if(E.cy == E.numrows){
       editorAppendRow("", 0 );
   } 
   editorRowInsertChar(&E.row[E.cy], E.cx, 1);
   E.cx++;
}
void editorOpen(char *filename) {
  free(E.filename);
  E.filename = filename; // used to be strdup(filename)

  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--;
    editorAppendRow(line, linelen);
  }
  free(line);
  fclose(fp);
}
/*append buffer */
// this section creates functions to implement the functionality of dynamic strings to our program
// this is important because instead of using multiple write function which may cause flicker issue, we will use single write 
// on a string that we'll keep adding and mutating. we'll call this string a 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 */
// existence of a function named drawRows symmetrically implies existence of functionnamed DrawColumns, add it
// Make it a box boys 
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.cx;
    }
    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),
                    "Kadence editor -- versions %s",KADENCE_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].size - E.coloff;
            if(len < 0 ) len = 0;
            if(len > E.screencols) len  = E.screencols;
            abAppend(ab, &E.row[filerow].chars[E.coloff], len);
        }
        abAppend(ab, "\x1b[K", 3);
        abAppend(ab, "\r\n", 2); //  
    }
}
void editorDrawStatusBar(struct abuf *ab){
    abAppend(ab, "\x1b[7m", 4);
    char* string = "hi";
    char status[80], rstatus[80];
    // loggingText("%s","w", "start"); 
    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);
    // 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);
    int counter = 0;
    // loggingText("w", "start \n ");
    while(len < E.screencols){
        // loggingText("a", "enters the while counter = %d\n", counter++);
        if(E.screencols - len == rlen){
            abAppend(ab, rstatus, rlen);
            break;
        }else{
        abAppend(ab, " ", 1);
        len++;
        }
    }
    abAppend(ab,"\x1b[m", 3);
}
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) // checks if msglen is not 0 and if the time elapsed is less than 5 seconds
        abAppend(ab, E.statusmsg, msglen);
}
void editorRefreshScreen(){ 
    editorScroll();
    struct abuf ab = ABUF_INIT;
    abAppend(&ab, "\x1b[?25l", 6); // turning off the visibility of the cursor
    abAppend(&ab, "\x1b[H", 3);
    
    editorDrawRows(&ab);
    editorDrawStatusBar(&ab); // <- is present in the error stack!
    editorDrawMessageBar(&ab);

    abAppend(&ab, "\x1b[H", 3);
    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, "check", 30);/* it comes out to be 30 as there are 29 characters and last character is ending character so ek byte uski */
    abAppend(&ab, "\x1b[?25h", 6); // turning on the visibility of the cursor

    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 */
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_DOWN:
            if(E.cy  < E.numrows) E.cy++;
            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;
    }// one thing we haven't implemented yet is text based movement of cursor
     // jaise vim mei up down krne pe the cursor remember where it left the line(col)
     // waise abhi ni banaaya par kya krskte lets see
    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(){
    int c = editorReadKey();
    switch(c){
        case CTRL_KEY('c'):
            write(STDOUT_FILENO, "\x1b[2J", 4);
            write(STDOUT_FILENO, "\x1b[H", 3);
            exit(0);
            break;
        case HOME_KEY:
            E.cx = 0;
            break;
        case END_KEY: //for some reason it is not working : (
            if (E.cy < E.numrows)
                E.cx = E.row[E.cy].size;
            break;
        case PAGE_UP:
            //PAGE UP and PAGE DOWN both are handled in pagedown, using crazy ass ternary operator
        case PAGE_DOWN:
            {
                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;
        default:
            editorInsertChar(c);
            break;
    // clever part incoming------------
    // so instead of making home and key move one by one
    // to the edges of the terminal,
    // the author directly accessed the termios struct E 
    // to directly put the cursor to end or whatever, which is 
    // in my opinion sneakily smart.
    }
}
/*** init ***/
void initEditor(){
    E.cx = 0;
    E.cy = 0;
    E.rx = 0;
    E.coloff = 2;
    E.rowoff = 2;
    E.numrows = 0;
    E.row = NULL;
    E.filename = NULL;
    E.statusmsg[0] = '\0';
    E.statusmsg_time = 0;

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

}
int main(int argc, char *argv[]){
    enableRawMode();
    initEditor();
    loggingText("myself logger sir\n", "w");
    if (argc >= 2){
        editorOpen(argv[1]);
    }
    editorSetStatusMessage("HELP: Ctrl-C = quit");
    while(1){
        editorRefreshScreen();  // <--- this line must be present in the Error Stack 
        editorProcessKeypress();
    }
    return 0;
}
//