package objects

import "time"
import "image"
import "git.tebibyte.media/tomo/tomo"
import "git.tebibyte.media/tomo/tomo/text"
import "git.tebibyte.media/tomo/tomo/input"
import "git.tebibyte.media/tomo/tomo/event"
import "git.tebibyte.media/tomo/objects/internal"

const textInputHistoryMaximum = 64
const textInputHistoryMaxAge  = time.Second / 4
var _ tomo.ContentObject = new(TextInput)

type textHistoryItem struct {
	text string
	dot  text.Dot
}

// TextInput is a single-line editable text box.
type TextInput struct {
	box       tomo.TextBox
	text      []rune
	multiline bool
	history   *internal.History[textHistoryItem]
	on struct {
		dotChange   event.FuncBroadcaster
		valueChange event.FuncBroadcaster
		confirm     event.FuncBroadcaster
	}
}

func newTextInput (text string, multiline bool) *TextInput {
	textInput := &TextInput {
		box:       tomo.NewTextBox(),
		text:      []rune(text),
		multiline: multiline,
		history:   internal.NewHistory[textHistoryItem] (
			textHistoryItem { text: text },
			textInputHistoryMaximum),
	}
	textInput.box.SetRole(tomo.R("objects", "TextInput"))
	textInput.box.SetTag("multiline", multiline)
	if multiline {
		textInput.box.SetAttr(tomo.AOverflow(false, true))
		textInput.box.SetAttr(tomo.AWrap(true))
		textInput.box.SetAttr(tomo.AAlign(tomo.AlignStart, tomo.AlignStart))
	} else {
		textInput.box.SetAttr(tomo.AOverflow(true, false))
		textInput.box.SetAttr(tomo.AAlign(tomo.AlignStart, tomo.AlignMiddle))
	}
	textInput.box.SetText(text)
	textInput.box.SetFocusable(true)
	textInput.box.SetSelectable(true)
	textInput.box.OnKeyDown(textInput.handleKeyDown)
	textInput.box.OnKeyUp(textInput.handleKeyUp)
	textInput.box.OnScroll(textInput.handleScroll)
	textInput.box.OnDotChange(textInput.handleDotChange)
	return textInput	
}

// NewTextInput creates a new text input containing the specified text.
func NewTextInput (text string) *TextInput {
	return newTextInput(text, false)
}

// NewMultilineTextInput creates a new multiline text input containing the
// specified text.
func NewMultilineTextInput (text string) *TextInput {
	return newTextInput(text, true)
}

// GetBox returns the underlying box.
func (this *TextInput) GetBox () tomo.Box {
	return this.box
}

// SetFocused sets whether or not this text input has keyboard focus. If set to
// true, this method will steal focus away from whichever object currently has
// focus.
func (this *TextInput) SetFocused (focused bool) {
	this.box.SetFocused(focused)
}

// Select sets the text cursor or selection.
func (this *TextInput) Select (dot text.Dot) {
	this.box.Select(dot)
	this.historySwapDot()
}

// Dot returns the text cursor or selection.
func (this *TextInput) Dot () text.Dot {
	return this.box.Dot()
}

// OnDotChange specifies a function to be called when the text cursor or
// selection changes.
func (this *TextInput) OnDotChange (callback func ()) event.Cookie {
	return this.on.dotChange.Connect(callback)
}

// SetAlign sets the X and Y alignment of the text input.
func (this *TextInput) SetAlign (x, y tomo.Align) {
	this.box.SetAttr(tomo.AAlign(x, y))
}

// ContentBounds returns the bounds of the inner content of the text input
// relative to the input's InnerBounds.
func (this *TextInput) ContentBounds () image.Rectangle {
	return this.box.ContentBounds()
}

// ScrollTo shifts the origin of the text input's content to the origin of the
// inputs's InnerBounds, offset by the given point.
func (this *TextInput) ScrollTo (position image.Point) {
	this.box.ScrollTo(position)
}

// OnContentBoundsChange specifies a function to be called when the text input's
// ContentBounds or InnerBounds changes.
func (this *TextInput) OnContentBoundsChange (callback func ()) event.Cookie {
	return this.box.OnContentBoundsChange(callback)
}

// SetValue sets the text content of the input.
func (this *TextInput) SetValue (text string) {
	this.text = []rune(text)
	this.box.SetText(text)
	this.logLargeAction()
}

// Value returns the text content of the input.
func (this *TextInput) Value () string {
	return string(this.text)
}

// OnConfirm specifies a function to be called when the user presses enter
// within the text input.
func (this *TextInput) OnConfirm (callback func ()) event.Cookie {
	return this.on.confirm.Connect(callback)
}

// OnValueChange specifies a function to be called when the user edits the input
// text.
func (this *TextInput) OnValueChange (callback func ()) event.Cookie {
	return this.on.valueChange.Connect(callback)
}

// Undo undoes the last action.
func (this *TextInput) Undo () {
	this.recoverHistoryItem(this.history.Undo())
}

// Redo redoes the last previously undone action.
func (this *TextInput) Redo () {
	this.recoverHistoryItem(this.history.Redo())
}

// Type types a character at the current dot position.
func (this *TextInput) Type (char rune) {
	dot := this.Dot()
	this.historySwapDot()
	this.text, dot = text.Type(this.text, dot, rune(char))
	this.Select(dot)
	this.box.SetText(string(this.text))
	this.logKeystroke()
}

func (this *TextInput) logKeystroke () {
	if this.Dot().Empty() {
		this.history.PushWeak (
			this.currentHistoryState(),
			textInputHistoryMaxAge)
	} else {
		this.logLargeAction()
	}
}

func (this *TextInput) logLargeAction () {
	this.history.Push(this.currentHistoryState())
}

func (this *TextInput) historySwapDot () {
	top := this.history.Top()
	top.dot = this.Dot()
	this.history.SwapSilently(top)
}

func (this *TextInput) currentHistoryState () textHistoryItem {
	return textHistoryItem {
		text: string(this.text),
		dot:  this.Dot(),
	}
}

func (this *TextInput) recoverHistoryItem (item textHistoryItem) {
	this.box.SetText(item.text)
	this.text = []rune(item.text)
	this.box.Select(item.dot)
}

// TODO: add things like alt+up/down to move lines

func (this *TextInput) handleKeyDown (key input.Key, numpad bool) bool {
	dot        := this.Dot()
	txt        := this.text
	modifiers  := this.box.Window().Modifiers()
	word       := modifiers.Control
	changed    := false

	defer func () {
		if changed {
			this.historySwapDot()
			this.text = txt
			this.box.SetText(string(txt))
			this.box.Select(dot)
			this.on.valueChange.Broadcast()
			this.on.dotChange.Broadcast()
			this.logKeystroke()
		}
	} ()

	typeRune := func () {
		txt, dot = text.Type(txt, dot, rune(key))
		changed = true
	}

	if this.multiline && !modifiers.Control {
		switch {
		case key == '\n', key == '\t':
			typeRune()
			return true
		}
	}

	switch {
	case isConfirmationKey(key):
		this.on.confirm.Broadcast()
		return true
	case key == input.KeyBackspace:
		txt, dot = text.Backspace(txt, dot, word)
		changed = true
		return true
	case key == input.KeyDelete:
		txt, dot = text.Delete(txt, dot, word)
		changed = true
		return true
	case key.Printable() && !modifiers.Control:
		typeRune()
		return true
	case key == 'z' || key == 'Z' && modifiers.Control:
		if modifiers.Shift {
			this.Redo()
		} else {
			this.Undo()
		}
		return true
	case key == 'y' && modifiers.Control:
		this.Redo()
		return true
	default:
		return false
	}
}

func (this *TextInput) handleKeyUp (key input.Key, numpad bool) bool {
	modifiers := this.box.Window().Modifiers()

	if this.multiline && !modifiers.Control {
		switch {
		case key == '\n', key == '\t':
			return true
		}
	}
	
	switch {
	case isConfirmationKey(key):
		return true
	case key == input.KeyBackspace:
		return true
	case key == input.KeyDelete:
		return true
	case key.Printable() && !modifiers.Control:
		return true
	case key == 'z' && modifiers.Control:
		return true
	case key == 'y' && modifiers.Control:
		return true
	default:
		return false
	}
}

func (this *TextInput) handleScroll (x, y float64) bool {
	if x == 0 { return false }
	this.ScrollTo(this.ContentBounds().Min.Sub(image.Pt(int(x), int(y))))
	return true
}

func (this *TextInput) handleDotChange () {
	this.historySwapDot()
	this.on.dotChange.Broadcast()
}