terminal.c

#include "terminal.h"

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <sys/ioctl.h>

#include "keys.h"
#include "config.h"

void die(char const *s)
{
    write(STDOUT_FILENO, "\x1b[2J", 4);
    write(STDOUT_FILENO, "\x1b[H", 3);

    perror(s);
    exit(EXIT_FAILURE);
}

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

void enableRawMode(void)
{
    if (tcgetattr(STDIN_FILENO, &E.original_termios) == -1) {
        die("tcgetattr");
    }

    atexit(disableRawMode);

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

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

int32_t readKey(void)
{
    int32_t 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 DELETE_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;
}

int32_t getCursorPosition(int32_t *rows, int32_t *cols)
{
    char buf[32];
    uint32_t i = 0u;
    
    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;
}
 
int16_t getWindowSize(int32_t *rows, int32_t *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;
    }
}