package stone

// Color represents all the different colors a cell can be.
type Color uint8

const (
	ColorBackground  Color = 0x0
	ColorSelection   Color = 0x1
	ColorForeground  Color = 0x2
	ColorApplication Color = 0x3
)

// Style contains styling information about cells. These properties can be or'd
// together to combine them.
type Style uint8

const (
	StyleNormal     Style = iota
	StyleBold       Style = iota >> 1
	StyleItalic
	StyleBoldItalic Style = StyleBold | StyleItalic
)

// Cell is a grid-aligned rune in a buffer with associated styling and color
// informaiton.
type Cell struct {
	color   Color
	style   Style
	content rune
}

// Color returns the cell's color.
func (cell Cell) Color (color Color) {
	color = cell.color
	return
}

// Style returns the styling information associated with the cell
func (cell Cell) Style (style Style) {
	style = cell.style
	return
}

// Rune returns the rune in the cell
func (cell Cell) Rune () (content rune) {
	content = cell.content
	return
}

// Buffer is a basic grid of cells.
type Buffer struct {
	content []Cell
	width  int
	height int
	Dot struct {
		X int
		Y int
	}
}

func (buffer *Buffer) isOutOfBounds (x, y int) (outOfBounds bool) {
	outOfBounds =
		x < 0 ||
		y < 0 ||
		x >= buffer.width ||
		y >= buffer.height
	return
}

// Size returns the width and height of the buffer.
func (buffer *Buffer) Size () (width, height int) {
	width  = buffer.width
	height = buffer.height
	return
}

// SetSize sets the width and height of the buffer. This clears all data in the
// buffer. If the width or height is negative, this method does nothing.
func (buffer *Buffer) SetSize (width, height int) {
	if width < 0 || height < 0 { return }
	buffer.width   = width
	buffer.height  = height
	buffer.content = make([]Cell, width * height)
}

// Cell returns the cell at the specified x and y coordinates. If the
// coordinates are out of bounds, this method will return a blank cell.
func (buffer *Buffer) Cell (x, y int) (cell Cell) {
	if buffer.isOutOfBounds(x, y) { return }
	cell = buffer.content[x + y * buffer.width]
	return
}

// SetColor sets the color of the cell at the specified x and y coordinates.
func (buffer *Buffer) SetColor (x, y int, color Color) {
	if buffer.isOutOfBounds(x, y) { return }
	buffer.content[x + y * buffer.width].color = color
}

// SetStyle sets the style of the cell at the specified x and y coordinates.
func (buffer *Buffer) SetStyle (x, y int, style Style) {
	if buffer.isOutOfBounds(x, y) { return }
	buffer.content[x + y * buffer.width].style = style
}

// SetRune sets the rune of the cell at the specified x and y coordinates.
func (buffer *Buffer) SetRune (x, y int, content rune) {
	if buffer.isOutOfBounds(x, y) { return }
	buffer.content[x + y * buffer.width].content = content
}

// Write writes data stored in a byte slice to the buffer at the current dot
// position. This makes Buffer an io.Writer.
func (buffer *Buffer) Write (bytes []byte) (bytesWritten int, err error) {
	text := string(bytes)
	bytesWritten = len(bytes)
	
	for _, character := range text {
		buffer.SetRune(buffer.Dot.X, buffer.Dot.Y, character)
		buffer.Dot.X ++
		if buffer.Dot.X > buffer.width { break }
	}
	
	return
}

// ResetDot is a convenience method to reset the dot to the buffer origin point
// (0, 0).
func (buffer *Buffer) ResetDot () {
	buffer.Dot.X = 0
	buffer.Dot.Y = 0
}

// DamageBuffer is a special buffer that keeps track of damage information.
// Cells are dirty by default, are only clean when marked as clean, and become
// dirty again when they are altered in some way.
type DamageBuffer struct {
	Buffer
	clean []bool
}

// SetSize sets the width and height of the buffer. This clears all data in the
// buffer. If the width or height is negative, this method does nothing.
func (buffer *DamageBuffer) SetSize (width, height int) {
	if width < 0 || height < 0 { return }
	buffer.Buffer.SetSize(width, height)
	buffer.clean = make([]bool, width * height)
}

// SetColor sets the color of the cell at the specified x and y coordinates.
func (buffer *DamageBuffer) SetColor (x, y int, color Color) {
	if buffer.isOutOfBounds(x, y) { return }
	index := x + y * buffer.width
	buffer.clean[index] = buffer.content[index].color == color
	buffer.Buffer.SetColor(x, y, color)
}

// SetStyle sets the style of the cell at the specified x and y coordinates.
func (buffer *DamageBuffer) SetStyle (x, y int, style Style) {
	if buffer.isOutOfBounds(x, y) { return }
	index := x + y * buffer.width
	buffer.clean[index] = buffer.content[index].style == style
	buffer.Buffer.SetStyle(x, y, style)
}

// SetRune sets the rune of the cell at the specified x and y coordinates.
func (buffer *DamageBuffer) SetRune (x, y int, content rune) {
	if buffer.isOutOfBounds(x, y) { return }
	index := x + y * buffer.width
	buffer.clean[index] = buffer.content[index].content == content
	buffer.Buffer.SetRune(x, y, content)
}

// Write writes data stored in a byte slice to the buffer at the current dot
// position. This makes DamageBuffer an io.Writer.
func (buffer *DamageBuffer) Write (bytes []byte) (bytesWritten int, err error) {
	text := string(bytes)
	bytesWritten = len(bytes)
	
	for _, character := range text {
		buffer.SetRune(buffer.Dot.X, buffer.Dot.Y, character)
		buffer.Dot.X ++
		if buffer.Dot.X > buffer.width { break }
	}
	
	return
}

// Clean returns whether or not the cell at the specified x and y coordinates is
// clean.
func (buffer *DamageBuffer) Clean (x, y int) (clean bool) {
	if buffer.isOutOfBounds(x, y) { return }
	clean = buffer.clean[x + y * buffer.width]
	return
}

// MarkClean marks the cell at the specified x and y coordinates as clean.
func (buffer *DamageBuffer) MarkClean (x, y int) {
	if buffer.isOutOfBounds(x, y) { return }
	buffer.clean[x + y * buffer.width] = true
}