package codetable

import "errors"

var (
	ErrOutOfBounds = errors.New("Coordinates out of bounds")
)

const (
	CodeSpaceRowCount           = 16
	ControlCodeSpaceColumnCount = 2
	GraphicCodeSpaceColumnCount = 6
)

type CodeSpace interface {
	Get(int, int) (byte, error)
	ID() string
	Columns() int
}

type controlRow [ControlCodeSpaceColumnCount]byte
type controlTable [CodeSpaceRowCount]controlRow

type ControlCodeSpace struct {
	table controlTable
	id    string
}

func (t ControlCodeSpace) Get(col, row int) (byte, error) {
	colOffset := t.table[0][0] & 0xF0
	if col < int(colOffset) || col > int(colOffset+CodeSpaceRowCount) || row < 0 || row > 16 {
		return 0, ErrOutOfBounds
	}
	return t.table[col][row], nil
}

func (t ControlCodeSpace) ID() string {
	return t.id
}

func (t ControlCodeSpace) Columns() int {
	return len(t.table[0])
}

type graphicRow [GraphicCodeSpaceColumnCount]byte
type graphicTable [CodeSpaceRowCount]graphicRow

type GraphicCodeSpace struct {
	table graphicTable
	id    string
}

func (t GraphicCodeSpace) ColumnOffset() int {
	return int(t.table[0][0] & 0xF0) // Get highest order nibble.
}

func (t GraphicCodeSpace) Get(row, col int) (byte, error) {
	colOffset := t.ColumnOffset()
	if col < colOffset || col > (colOffset+GraphicCodeSpaceColumnCount) || row < 0 || row > 16 {
		return 0, ErrOutOfBounds
	}
	return t.table[col][row], nil
}

func (t GraphicCodeSpace) ID() string {
	return t.id
}

func (t GraphicCodeSpace) Columns() int {
	return len(t.table[0])
}