package elements

import "image"
import "image/color"
import "golang.org/x/image/font"
import "git.tebibyte.media/sashakoshka/tomo"
import "git.tebibyte.media/sashakoshka/tomo/input"
import "git.tebibyte.media/sashakoshka/tomo/artist/shapes"
import "git.tebibyte.media/sashakoshka/tomo/default/theme"
import "git.tebibyte.media/sashakoshka/tomo/default/config"
// import "git.tebibyte.media/sashakoshka/tomo/textdraw"
import "git.tebibyte.media/sashakoshka/tomo/elements/core"

type Cell struct {
	Rune       rune
	Style      tomo.FontStyle
	Background tomo.Color
	Foreground tomo.Color
}

type gridCell struct {
	Cell
	clean bool
}

func (cell *Cell) initColor () {
	cell.Background = tomo.ColorBackground
	cell.Foreground = tomo.ColorForeground
}

// Grid is an array of monospaced character cells. Each one has a foreground and
// background color.
type Grid struct {
	*core.Core
	*core.FocusableCore
	core core.CoreControl
	focusableControl core.FocusableCoreControl
	
	cells      []gridCell
	stride     int
	cellWidth  int
	cellHeight int

	cursor image.Point

	face   font.Face
	config config.Wrapped
	theme  theme.Wrapped
	colors [19]color.RGBA
	
	onResize func ()
}

func NewGrid () (element *Grid) {
	element = &Grid { }
	element.theme.Case = tomo.C("tomo", "grid")
	element.Core, element.core = core.NewCore(element, element.drawAllAndPush)
	element.FocusableCore,
	element.focusableControl = core.NewFocusableCore(element.core, element.drawAndPush)
	element.updateFontAndColors()
	element.updateMinimumSize()
	return
}

func (element *Grid) Size () (columns, rows int) {
	columns = element.stride
	if element.stride > 0 {
		rows = len(element.cells) / element.stride
	}
	return
}

func (element *Grid) At (point image.Point) Cell {
	if !element.inBounds(point) { return Cell { } }
	return element.cells[element.index(point)].Cell
}

func (element *Grid) Set (point image.Point, cell Cell) {
	if !element.inBounds(point) { return }
	element.cells[element.index(point)].Cell  = cell
	element.cells[element.index(point)].clean = false
}

func (element *Grid) Push () {
	element.drawAndPush()
}

func (element *Grid) OnResize (callback func ()) {
	element.onResize = callback
}

func (element *Grid) HandleMouseDown (x, y int, button input.Button) {
	
}

func (element *Grid) HandleMouseUp (x, y int, button input.Button) {
	
}

func (element *Grid) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
	// TODO we need to grab shift ctrl c for copying text
}

func (element *Grid) HandleKeyUp(key input.Key, modifiers input.Modifiers) { }

// SetTheme sets the element's theme.
func (element *Grid) SetTheme (new tomo.Theme) {
	if new == element.theme.Theme { return }
	element.theme.Theme = new
	element.updateFontAndColors()
	element.updateMinimumSize()
	element.drawAndPush()
}

// SetConfig sets the element's configuration.
func (element *Grid) SetConfig (new tomo.Config) {
	if new == element.config.Config { return }
	element.config.Config = new
	element.updateMinimumSize()
	element.drawAndPush()
}


// -------- private methods -------- //


func (element *Grid) inBounds (point image.Point) bool {
	if point.X < 0 { return false }
	if point.Y < 0 { return false }
	width, height := element.Size()
	if point.X >= width  { return false }
	if point.Y >= height { return false }
	return true
}

func (element *Grid) index (point image.Point) int {
	return point.X + element.stride * point.Y
}

func (element *Grid) alloc () bool {
	bounds := element.Bounds()
	width  := bounds.Dx() / element.cellWidth
	height := bounds.Dy() / element.cellHeight
	oldWidth, oldHeight := element.Size()
	if width == oldWidth && height == oldHeight { return false }

	oldCells  := element.cells
	heightLarger := height < oldHeight
	
	element.stride = width
	element.cells  = make([]gridCell, width * height)
	
	// TODO: attempt to wrap text?

	if heightLarger {
	for index := range element.cells[oldHeight * width:] {
		element.cells[index].initColor()
	}}

	commonHeight := height
	if heightLarger { commonHeight = oldHeight }
	for index := range element.cells[:commonHeight * width] {
		x := index % width
		if x < oldWidth {
			element.cells[index] = oldCells[x + index / oldWidth]
		} else {
			element.cells[index].initColor()
		}
	}

	if element.onResize != nil { element.onResize() }
	return true
}

func (element *Grid) updateFontAndColors () {
	element.face = element.theme.FontFace (
		tomo.FontStyleMonospace,
		tomo.FontSizeNormal)
	emSpace, _ := element.face.GlyphAdvance('M')
	metrics    := element.face.Metrics()
	element.cellWidth  = emSpace.Round()
	element.cellHeight = metrics.Height.Round()

	for index := range element.colors {
		element.colors[index] = element.theme.Color (
			tomo.Color(index),
			element.state())
	}
}

func (element *Grid) updateMinimumSize () {
	element.core.SetMinimumSize(element.cellWidth, element.cellHeight)
}

func (element *Grid) state () tomo.State {
	return tomo.State {
		Focused: element.Focused(),
	}
}

func (element *Grid) drawAndPush () {
	if element.core.HasImage () {
		element.core.DamageRegion(element.draw(element.alloc()))
	}
}

func (element *Grid) drawAllAndPush () {
	element.alloc()
	if element.core.HasImage () {
		element.core.DamageRegion(element.draw(true))
	}
}

func (element *Grid) corner (index int) image.Point {
	return image.Point {
		X: (index % element.stride) * element.cellWidth,
		Y: (index / element.stride) * element.cellHeight,
	}.Add(element.Bounds().Min)
}

func (element *Grid) bound (index int) image.Rectangle {
	corner := element.corner(index)
	return image.Rectangle {
		Min: corner,
		Max: image.Pt (
			corner.X + element.cellWidth,
			corner.Y + element.cellHeight),
	}
}

func (element *Grid) draw (force bool) image.Rectangle {
	bounds := element.Bounds()

	for index, cell := range element.cells {
	if force || !cell.clean {
		// TODO
		shapes.FillColorRectangle (
			element.core,
			element.colors[cell.Background],
			element.bound(index))
	}}

	return bounds // FIXME
}