editor.c

#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "./editor.h"
#include "./sv.h"

void editor_backspace(Editor *e)
{
    if (e->cursor > e->data.count) {
        e->cursor = e->data.count;
    }
    if (e->cursor == 0) return;

    memmove(
        &e->data.items[e->cursor - 1],
        &e->data.items[e->cursor],
        e->data.count - e->cursor
    );
    e->cursor -= 1;
    e->data.count -= 1;
    editor_recompute_lines(e);
}

void editor_delete(Editor *e)
{
    if (e->cursor >= e->data.count) return;
    memmove(
        &e->data.items[e->cursor],
        &e->data.items[e->cursor + 1],
        e->data.count - e->cursor - 1
    );
    e->data.count -= 1;
    editor_recompute_lines(e);
}

void editor_tab(Editor *e)
{
    for(int i = 0; i < 4; i++) {
        editor_insert_char(e, ' ');
    }
}

void editor_save_to_file(const Editor *editor, const char *file_path)
{
    FILE *f = fopen(file_path, "w");
    if (f == NULL) {
        fprintf(stdout, "ERROR: could not open file `%s`: %s\n",
                file_path, strerror(errno));
        exit(1);
    }

    fwrite(editor->data.items, 1, editor->data.count, f);
    fclose(f);
}

static size_t file_size(FILE *file)
{
    long saved = ftell(file);
    assert(saved >= 0);
    int err = fseek(file, 0, SEEK_END);
    assert(err == 0);
    long result = ftell(file);
    assert(result >= 0);
    err = fseek(file, saved, SEEK_SET);
    assert(err == 0);
    return result;
}

void editor_load_from_file(Editor *e, FILE *file)
{
    e->data.count = 0;

    size_t data_size = file_size(file);

    if (e->data.capacity < data_size) {
        e->data.capacity = data_size;
        e->data.items = realloc(e->data.items, e->data.capacity*sizeof(*e->data.items));
        assert(e->data.items != NULL && "Buy more RAM lol");
    }

    fread(e->data.items, data_size, 1, file);
    assert(!ferror(file));
    e->data.count = data_size;

    editor_recompute_lines(e);
}

size_t editor_cursor_row(const Editor *e)
{
    assert(e->lines.count > 0);
    for (size_t row = 0; row < e->lines.count; ++row) {
        Line line = e->lines.items[row];
        if (line.begin <= e->cursor && e->cursor <= line.end) {
            return row;
        }
    }
    return e->lines.count - 1;
}

void editor_move_line_up(Editor *e)
{
    size_t cursor_row = editor_cursor_row(e);
    size_t cursor_col = e->cursor - e->lines.items[cursor_row].begin;
    if (cursor_row > 0) {
        Line next_line = e->lines.items[cursor_row - 1];
        size_t next_line_size = next_line.end - next_line.begin;
        if (cursor_col > next_line_size) cursor_col = next_line_size;
        e->cursor = next_line.begin + cursor_col;
    }
}

void editor_move_line_down(Editor *e)
{
    size_t cursor_row = editor_cursor_row(e);
    size_t cursor_col = e->cursor - e->lines.items[cursor_row].begin;
    if (cursor_row < e->lines.count - 1) {
        Line next_line = e->lines.items[cursor_row + 1];
        size_t next_line_size = next_line.end - next_line.begin;
        if (cursor_col > next_line_size) cursor_col = next_line_size;
        e->cursor = next_line.begin + cursor_col;
    }
}

void editor_move_char_left(Editor *e)
{
    if (e->cursor > 0) e->cursor -= 1;
}

void editor_move_char_right(Editor *e)
{
    if (e->cursor < e->data.count) e->cursor += 1;
}

void editor_insert_char(Editor *e, char x)
{
    if (e->cursor > e->data.count) {
        e->cursor = e->data.count;
    }

    da_append(&e->data, '\0');
    memmove(
        &e->data.items[e->cursor + 1],
        &e->data.items[e->cursor],
        e->data.count - e->cursor - 1
    );
    e->data.items[e->cursor] = x;
    e->cursor += 1;

    editor_recompute_lines(e);
}

void editor_recompute_lines(Editor *e)
{
    e->lines.count = 0;

    Line line;
    line.begin = 0;

    for (size_t i = 0; i < e->data.count; ++i) {
        if (e->data.items[i] == '\n') {
            line.end = i;
            da_append(&e->lines, line);
            line.begin = i + 1;
        }
    }

    line.end = e->data.count;
    da_append(&e->lines, line);
}