scribe.c

/*** includes ***/

#define _DEFAULT_SOURCE
#define _BSD_SOURCE
#define _GNU_SOURCE

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

/*** defines ***/
#define VERSION "0.0.1"
#define TAB_S 8
#define QUIT_UNSAVED 1
#define CTRL_KEY(k) ((k) & 0x1f)
#define ABUF_INIT {NULL, 0}
#define HL_HIGHLIGHT_NUMBERS (1 << 0)
#define HL_HIGHLIGHT_STRING (1 << 1)
// arrow keys
//  A stands for Arrow
#define A_UP 1000
#define A_DOWN 1001
#define A_LEFT 1002
#define A_RIGHT 1003

/*** data ***/

struct EditorSyntax
{
    char *filetype;
    char **filematch;
    char **keywords;
    char *singleline_comment_start;
    int flags;
};

enum EditorKeys
{
    BACKSPACE = 127,
    DEL = 8,
    INSERT = 'i',
    UP = 'k',
    DOWN = 'j',
    LEFT = 'h',
    RIGHT = 'l',
    H_KEY = 'a',
    E_KEY = 'd',
    P_UP = 'n',
    P_DOWN = 'm',
    ESC = 27
};

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

typedef struct
{
    int size;
    int rsize;
    char *chars;
    char *render;
    unsigned char *hl;
} erow;

struct EditorConfig
{
    int Cx, Cy; // cursor position Cx: Cursos horizontal position Cy: Cursor vertical position
    int Rx;
    int rowoff;
    int coloff;
    int S_rows;
    int S_cols;
    int numrows;
    erow *row;
    int dirty;
    char *filename;
    char statusmsg[80];
    time_t statusmsg_time;
    struct EditorSyntax *syntax;
    struct termios origin;
};

// using the editorconfig
struct EditorConfig E;

/*** filetypes ***/

// C
char *C_HL_extensions[] = {".c", ".h", NULL};
char *C_HL_keywords[] = {
    "switch", "if", "while", "for", "break", "continue", "return", "else",
    "struct", "union", "typedef", "static", "enum", "class", "case", "#define", "#include", "NULL"

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

// C++
char *CPP_HL_extensions[] = {".cpp", ".hpp", NULL};
char *CPP_HL_keywords[] = {
    "alignas", "alignof", "and", "and_eq", "asm", "atomic_cancel", "atomic_commit", "atomic_noexcept",
    "auto", "bitand", "bitor", "bool|", "break", "case", "catch", "char", "char8_t", "char16_t", "char32_t",
    "class", "compl", "concept", "const", "consteval", "constexpr", "constinit", "const_cast", "continue",
    "decltype", "default", "delete", "do", "double", "dynamic_cast", "else", "enum", "explicit", "export",
    "extern", "false", "float", "for|", "friend", "goto", "if|", "import", "inline", "int|", "long", "mutable",
    "namespace", "new", "noexcept", "not", "not_eq", "nullptr", "operator", "or", "or_eq", "private",
    "protected", "public", "register", "reinterpret_cast", "requires", "return|", "short", "signed",
    "sizeof", "static", "static_assert", "static_cast", "struct", "switch", "template", "this", "thread_local",
    "throw", "true", "try", "typedef", "typeid", "typename", "union", "unsigned", "using", "virtual", "void",
    "volatile", "wchar_t", "while", "xor", "xor_eq", NULL};

// Python
char *PY_HL_extensions[] = {".py", ".pyi", ".pyc", ".pyd", ".pyo", ".pyw", ".pyz", NULL};
char *PY_HL_keywords[] = {
    "False", "None|", "True|", "and", "as", "assert", "break", "class", "continue", "def|",
    "del", "elif", "else", "except", "finally", "for", "from", "global", "if", "import|",
    "in", "is", "lambda", "match", "meanwhile", "not", "or", "pass", "raise", "return|",
    "try", "while", "with", "yield", "abs", "all", "any", "ascii", "bin", "bool", "bytearray",
    "bytes", "callable", "chr", "classmethod", "compile", "complex", "copyright", "credits",
    "delattr", "dict", "dir", "divmod", "enumerate", "eval", "exit", "getattr", "globals",
    "hasattr", "hash", "help", "id", "input", "int", "isinstance", "issubclass", "iter",
    "len", "license", "list", "locals", "map", "max", "memoryview", "min", "next", "object",
    "oct", "open", "ord", "pow", "print", "property", "quit", "range", "repr", "reversed",
    "round", "set", "setattr", "slice", "sorted", "staticmethod", "str", "sum", "super",
    "tuple", "type", "vars", "zip", NULL};

struct EditorSyntax HLDB[] = {
    {"c",
     C_HL_extensions,
     C_HL_keywords,
     "//",
     HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRING},
    {"cpp",
     CPP_HL_extensions,
     CPP_HL_keywords,
     "//",
     HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRING},
    {"py",
     PY_HL_extensions,
     PY_HL_keywords,
     "#",
     HL_HIGHLIGHT_NUMBERS | HL_HIGHLIGHT_STRING},
};

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

// prototypes
char *EditorPrompt(char *prompt, void (*callback)(char *, int));

/*** funcs ***/

/*** terminal ***/

// void for error handaling (I think)
void errors(const char *s)
{
    write(STDOUT_FILENO, "\x1b[2J", 4);
    write(STDOUT_FILENO, "\x1b[H", 3);

    perror(s);
    exit(1);
}

// disable raw mode at end
void DisableRawMode()
{
    if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &E.origin) == -1)
    {
        errors("tcsetattr");
    }
}

// enable raw mode (disabling echo)
void EnableRawMode()
{
    if (tcgetattr(STDIN_FILENO, &E.origin) == -1)
        errors("tcgetattr");
    atexit(DisableRawMode); // disable raw mode at end

    struct termios raw = E.origin;

    // disableing stuff
    raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
    raw.c_oflag &= ~(OPOST);
    raw.c_cflag |= (CS8);
    raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);

    raw.c_cc[VMIN] = 0;

    raw.c_cc[VTIME] = 1;

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

int EditorReadKey()
{
    int nread;
    char c;
    while ((nread = read(STDIN_FILENO, &c, 1)) != 1)
    {
        if (nread == -1 && errno != EAGAIN)
            errors("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':
                    case '7':
                        return H_KEY;
                    case '4':
                    case '8':
                        return E_KEY;
                    case '5':
                        return P_UP;
                    case '6':
                        return P_DOWN;
                    }
                }
            }
            else
            {
                switch (seq[1])
                {
                case 'A':
                    return UP;
                case 'B':
                    return DOWN;
                case 'C':
                    return RIGHT;
                case 'D':
                    return LEFT;
                case 'H':
                    return H_KEY;
                case 'F':
                    return E_KEY;
                }
            }
        }
        else if (seq[0] == 'O')
        {
            switch (seq[1])
            {
            case 'H':
                return H_KEY;
            case 'F':
                return E_KEY;
            }
        }

        return '\x1b';
    }
    else
    {
        return c;
    }
}

int EditorReadInsertKey()
{
    int nread;
    char c;
    while ((nread = read(STDIN_FILENO, &c, 1)) != 1)
    {
        if (nread == -1 && errno != EAGAIN)
            errors("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 H_KEY;
                    case '4':
                        return E_KEY;
                    case '5':
                        return P_UP;
                    case '6':
                        return P_DOWN;
                    case '7':
                        return H_KEY;
                    case '8':
                        return E_KEY;
                    }
                }
            }
            else
            {
                switch (seq[1])
                {
                case 'A':
                    return A_UP;
                case 'B':
                    return A_DOWN;
                case 'C':
                    return A_LEFT;
                case 'D':
                    return A_RIGHT;
                }
            }
        }
        else if (seq[0] == 'O')
        {
            switch (seq[1])
            {
            case 'H':
                return H_KEY;
            case 'F':
                return E_KEY;
            }
        }

        return '\x1b';
    }
    else
    {
        return c;
    }
}

int GetCP(int *rows, int *cols)
{
    // decleration
    char buff[32];
    unsigned int i = 0;

    if (write(STDOUT_FILENO, "\x1b[6n", 4) != 4)
        return -1;

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

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

int GetWS(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 GetCP(rows, cols);
    }
    else
    {
        *cols = ws.ws_col;
        *rows = ws.ws_row;
    }
    return 0;
}

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

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);
}

/*** 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;
    int scs_len = scs ? strlen(scs) : 0;

    int prev_sep = 1;
    int in_string = 0;

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

        if (E.syntax->flags & HL_HIGHLIGHT_STRING)
        {
            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;
            }
            prev_sep = is_separator(c);
            i++;
        }

        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;
            }
        }
    }
}

int EditorSyntaxToColor(int hl)
{
    switch (hl)
    {
    case HL_COMMENT:
        return 36;
    case HL_KEYWORD1:
        return 35;
    case HL_KEYWORD2:
        return 31;
    case HL_STRING:
        return 33;
    case HL_NUMBER:
        return 32;
    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 += (TAB_S - 1) - (Rx % TAB_S);
        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_S - 1) - (cur_rx % TAB_S);
        cur_rx++;
        if (cur_rx > rx)
            return Cx;
    }
    return Cx;
}

void EditorUpdateRows(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 * (TAB_S - 1) + 1);

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

    EditorUpdateSyntax(row);
}

void EditorAppendRows(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));

    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;
    EditorUpdateRows(&E.row[at]);

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

void EditorRowInsert(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;
    EditorUpdateRows(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 += len] = '\0';
    EditorUpdateRows(row);
    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));
    E.numrows--;
    E.dirty++;
}

void EditorRowDelChar(erow *row, int at)
{
    if (at >= row->size || at < 0)
        return;

    memmove(&row->chars[at], &row->chars[at + 1], row->size - at);
    row->size--;
    row->chars = realloc(row->chars, row->size + 1);
    if (row->chars == NULL)
        exit(1);
    row->chars[row->size] = '\0';
}

/*** editor operations ***/

void EditorInsertChar(int c)
{
    if (E.Cy == E.numrows)
    {
        EditorAppendRows(E.numrows, " ", 0);
    }
    EditorRowInsert(&E.row[E.Cy], E.Cx, c);
    E.Cx++;
}

void EditorInsertNewLine()
{
    if (E.Cx == 0)
    {
        EditorAppendRows(E.Cy, "", 0);
    }
    else
    {
        erow *row = &E.row[E.Cy];
        EditorAppendRows(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';
        EditorUpdateRows(row);
    }
    E.Cy++;
    E.Cx = 0;
}

// Output Message

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);
}

/*** 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)
        errors("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--;
        }
        EditorAppendRows(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 | Save succsesful", len);
                return;
            }
        }
        close(fd);
    }

    free(buf);
    EditorSetStatusMessage("Error encountered while saving | Error: %s", strerror(errno));
}

/*** search ***/

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 == A_UP || key == A_DOWN)
    {
        direction = 1;
    }
    else if (key == A_LEFT || key == A_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()
{
    // old positions
    int old_Cx = E.Cx;
    int old_Cy = E.Cy;
    int old_coloff = E.coloff;
    int old_rowoff = E.rowoff;

    char *query = EditorPrompt("Search: %s (esc to cancel)", EditorFindCallback);

    if (query)
    {
        free(query);
    }
    else
    {
        E.Cx = old_Cx;
        E.Cy = old_Cy;
        E.coloff = old_coloff;
        E.rowoff = old_rowoff;
    }
}

/*** output ***/

void EditorDrawMessageBar(struct abuf *ab)
{
    abAppend(ab, "\x1b[K", 3);
    int msglen = strlen(E.statusmsg);
    if (msglen > E.S_cols)
        msglen = E.S_cols;
    if (msglen && time(NULL) - E.statusmsg_time < 5)
    {
        abAppend(ab, E.statusmsg, msglen);
    }
}

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.S_rows)
    {
        E.rowoff = E.Cy - E.S_rows + 1;
    }
    if (E.Rx < E.coloff)
    {
        E.coloff = E.Rx;
    }
    if (E.Rx >= E.coloff + E.S_cols)
    {
        E.coloff = E.Rx - E.S_cols + 1;
    }
}

// Tildes
void EditorDrawRows(struct abuf *ab)
{
    int y;
    for (y = 0; y < E.S_rows; y++)
    {
        int filerow = y + E.rowoff;

        if (filerow >= E.numrows)
        {
            if (E.numrows == 0 && y == E.S_rows / 3)
            {
                char welcome[100];
                int welcomelen = snprintf(welcome, sizeof(welcome),
                                          "Scribe -- version %s", VERSION);
                if (welcomelen > E.S_cols)
                    welcomelen = E.S_cols;
                int padding = (E.S_cols - 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.S_cols)
                len = E.S_cols;
            char *pC = &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 (hl[j] == HL_NORMAL)
                {
                    if (current_color != -1)
                    {
                        abAppend(ab, "\x1b[39m", 5);
                        current_color = -1;
                    }
                    abAppend(ab, &pC[j], 1);
                }
                else
                {
                    int color = EditorSyntaxToColor(hl[j]);
                    if (current_color == -1)
                    {
                        current_color = color;
                        char buff[16];
                        int clen = snprintf(buff, sizeof(buff), "\x1b[%dm", color);
                        abAppend(ab, buff, clen);
                    }
                    abAppend(ab, &pC[j], 1);
                }
            }
            if (current_color != -1)
            {
                abAppend(ab, "\x1b[39m", 5);
            }
        }

        // End the line
        abAppend(ab, "\x1b[K", 3);
        abAppend(ab, "\r\n", 2);
    }
}

void EditorDrawStatusLine(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.S_cols)
        len = E.S_cols;
    abAppend(ab, status, len);
    while (len < E.S_cols)
    {
        if (E.S_cols - len == rlen)
        {
            abAppend(ab, rstatus, rlen);
            break;
        }
        else
        {
            abAppend(ab, " ", 1);
            len++;
        }
    }
    abAppend(ab, "\x1b[m", 3);
    abAppend(ab, "\r\n", 2);
}

void EditorRefreshScreen()
{
    EditorScroll();

    struct abuf ab = ABUF_INIT;

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

    EditorDrawRows(&ab);
    EditorDrawStatusLine(&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 EditorRefreshChar()
{
    EditorRefreshScreen();
}

void EditorDelChar()
{
    if (E.Cy == E.numrows || (E.Cy == 0 && E.Cx == 0))
        return;

    erow *row = &E.row[E.Cy];
    if (E.Cx > 0)
    {
        EditorRowDelChar(row, E.Cx - 1);
        E.Cx--;
        EditorUpdateRows(row);
    }
    else if (E.Cx == 0 && E.Cy > 0)
    {
        E.Cx = E.row[E.Cy - 1].size;
        EditorRowAppendString(&E.row[E.Cy - 1], row->chars, row->size);
        EditorDelRow(E.Cy);
        E.Cy--;
    }

    E.dirty++;
    EditorRefreshChar();
}

/*** 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 || 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(char key)
{
    erow *row = (E.Cy >= E.numrows) ? NULL : &E.row[E.Cy];

    switch (key)
    {
    case LEFT:
        if (E.Cx != 0)
        {
            E.Cx--;
        }
        else if (E.Cy > 0)
        {
            E.Cy--;
            E.Cx = E.row[E.Cy].size;
        }
        break;
    case RIGHT:
        if (row && E.Cx < row->size)
        {
            E.Cx++;
        }
        else if (row && E.Cx == row->size)
        {
            E.Cy++;
            E.Cx = 0;
        }
        break;
    case UP:
        if (E.Cy != 0)
        {
            E.Cy--;
        }
        break;
    case 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 InsertMoveCursor(int key)
{
    erow *row = (E.Cy >= E.numrows) ? NULL : &E.row[E.Cy];

    switch (key)
    {
    case A_RIGHT:
        if (E.Cx != 0)
        {
            E.Cx--;
        }
        else if (E.Cy > 0)
        {
            E.Cy--;
            E.Cx = E.row[E.Cy].size;
        }

        break;
    case A_LEFT:
        if (row && E.Cx < row->size)
        {
            E.Cx++;
        }
        else if (row && E.Cx == row->size)
        {
            E.Cy++;
            E.Cx = 0;
        }
        break;
    case A_UP:
        if (E.Cy != 0)
        {
            E.Cy--;
        }
        break;
    case A_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;
        }
    }
}

/*** Insert mode ***/

void InsertMode(int c)
{
    EditorSetStatusMessage("-- INSERT MODE --");

    switch (c)
    {
    default:
        EditorInsertChar(c);
        break;

    case A_UP:
    case A_DOWN:
    case A_RIGHT:
    case A_LEFT:
        InsertMoveCursor(c);
        break;

    case '\r':
        EditorInsertNewLine();
        break;

    case BACKSPACE:
        EditorDelChar();
        EditorRefreshScreen();
        break;

    case ESC:
        break;

    case DEL:
        EditorMoveCursor(RIGHT);
        EditorDelChar();
        EditorRefreshScreen();
        break;
    }
    EditorRefreshScreen();
}

void EditorProcessKeypress()
{
    static int quit_times = QUIT_UNSAVED;

    char c = EditorReadKey();
    char i = c;

    switch (c)
    {
    case CTRL_KEY('q'):
        if (E.dirty && quit_times > 0)
        {
            EditorSetStatusMessage("WARNING!!! File has unsaved changes. "
                                   "Press Ctrl-Q %d more time to quit.",
                                   quit_times);
            quit_times--;
            return;
        }

        write(STDOUT_FILENO, "\x1b[2J", 4);
        write(STDOUT_FILENO, "\x1b[H", 3);

        exit(0);
        break;

    // save files
    case CTRL_KEY('s'):
        EditorSave();
        break;

    // Page keys
    case P_UP:
    case P_DOWN:
    {
        if (c == P_UP)
        {
            E.Cy = E.rowoff;
        }
        else if (c == P_DOWN)
        {
            E.Cy = E.rowoff + E.S_rows - 1;
            if (E.Cy > E.numrows)
                E.Cy = E.numrows;
        }

        int times = E.S_rows;
        while (times--)
        {
            EditorMoveCursor(c == P_UP ? UP : DOWN);
        }
        break;
    }

    // Home and End Keys
    case H_KEY:
        E.Cx = 0;
        break;

    case E_KEY:
        if (E.Cy < E.numrows)
        {
            E.Cx = E.row[E.Cy].size;
        }
        break;

    case '/':
        EditorFind();
        break;

    // basic movement
    case UP:
    case DOWN:
    case RIGHT:
    case LEFT:
        EditorMoveCursor(c);
        break;

    case CTRL_KEY('l'):
        break;

    // processing backspace key
    case BACKSPACE:
    case DEL:
        EditorDelChar();
        EditorRefreshScreen();
        break;

    case INSERT:
        while (i != ESC)
        {
            i = EditorReadInsertKey();
            InsertMode(i);
            EditorRefreshScreen();
        }
        EditorSetStatusMessage("-- Normal Mode --");
    }
    EditorRefreshScreen();
}

/*** 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 (GetWS(&E.S_rows, &E.S_cols) == -1)
        errors("GetWS");
    E.S_rows -= 2;
}

int main(int argc, char *argv[])
{
    EnableRawMode();
    InitEditor();
    if (argc >= 2)
    {
        EditorOpen(argv[1]);
    }

    EditorSetStatusMessage("Move around with h, j, k, l | Exit with Ctrl + Q | Save with Ctrl S");

    while (1)
    {
        EditorRefreshScreen();
        EditorProcessKeypress();
    }

    return 0;
}

// I am truly sorry for you having to read and see all of this code