use term;

export type vga_text = struct {
	term: term::term,
	address: *[*]u16,
	pos: (size, size),
	dim: (size, size),
	colors: (term::color, term::color)
};

const vga_text_term: term::vtable = term::vtable {
	setpos = &setpos,
	getpos = &getpos,
	setcolors = &setcolors,
	getcolors = &getcolors,
	putchar = &putchar,
	getdim = &getdim
};

export fn attach(address: uintptr, xsize: size, ysize: size) vga_text = {
	return vga_text {
		term = &vga_text_term,
		address = address: *[*]u16,
		dim = (xsize, ysize),
		pos = (0, 0),
		colors = (term::color::LMAGENTA, term::color::BLACK)
	};
};

fn setpos(ctrl: *term::term, pos: (size, size)) void = {
	let ctrl = ctrl: *vga_text;

	ctrl.pos = pos;
};

fn getpos(ctrl: *term::term) (size, size) = {
	let ctrl = ctrl: *vga_text;

	return ctrl.pos;
};

fn setcolors(ctrl: *term::term, colors: (term::color, term::color)) void = {
	let ctrl = ctrl: *vga_text;

	ctrl.colors = colors;
};

fn getcolors(ctrl: *term::term) (term::color, term::color) = {
	let ctrl = ctrl: *vga_text;

	return ctrl.colors;
};

fn putchar(ctrl: *term::term, c: u8) void = {
	let ctrl = ctrl: *vga_text;

	let attr: u16 = term_color_map(ctrl.colors.1) << 4 | term_color_map(ctrl.colors.0);
	ctrl.address[ctrl.pos.1 * ctrl.dim.0 + ctrl.pos.0] = attr << 8 | c;
};

fn getdim(ctrl: *term::term) (size, size) = {
	let ctrl = ctrl: *vga_text;

	return ctrl.dim;
};

fn term_color_map(col: term::color) u8 = {
	switch (col) {
	case term::color::BLACK => return 0x0;
	case term::color::BLUE => return 0x1;
	case term::color::GREEN => return 0x2;
	case term::color::CYAN => return 0x3;
	case term::color::RED => return 0x4;
	case term::color::MAGENTA => return 0x5;
	case term::color::BROWN => return 0x6;
	case term::color::LGRAY => return 0x7;
	case term::color::DGRAY => return 0x8;
	case term::color::LBLUE => return 0x9;
	case term::color::LGREEN => return 0xa;
	case term::color::LCYAN => return 0xb;
	case term::color::LRED => return 0xc;
	case term::color::LMAGENTA => return 0xd;
	case term::color::YELLOW => return 0xe;
	case term::color::WHITE => return 0xf;
	};
};