package ui

import (
	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
)

// InputType distinguishes the different supported kinds of input.
type InputType int

const (
	// Click represents a mouse click.
	Click InputType = iota + 1
	// Scroll represents a mouse wheel event.
	Scroll
	// Text represents any keyboard input.
	Text
	// Tap represents a short touch input.
	Tap
	// Pan represents a longer moving touch input.
	Pan
	// Pinch represents a moving multi touch input.
	Pinch
)

// InputEvent contains all information associated with an occurred user input.
type InputEvent struct {
	Kind InputType
	// X and Y coordinates the event occured.
	X, Y int
	// Ctx contains additional information for the event.
	Ctx any
}

// ClickCtx contains the pressed mouse button.
type ClickCtx struct {
	Btn ebiten.MouseButton
}

// DistanceCtx contains the input's distance.
// Scroll and Pan events contain a DistanceCtx.
type DistanceCtx struct {
	scrollX, scrollY int
}

// TextCtx contains the inputted runes.
type TextCtx struct {
	in []rune
}

// Input contains all occurred input events since the last call to ui.Update.
// The input events should be handled in reverse order to prevent modify during iteration errors.
var Input []InputEvent

// ConsumeInput removes the i-ths input from the quehe.
func ConsumeInput(i int) {
	if len(Input) == 1 {
		Input = []InputEvent{}
	} else {
		Input[i] = Input[len(Input)-1]
	}
}

// AppendInput appends an input event to the input queue.
func AppendInput(ev InputEvent) {
	Input = append(Input, ev)
}

// Update all ui singletons and collect all occurred input.
func Update() error {
	Input = []InputEvent{}
	if err := TouchManager.Update(); err != nil {
		return err
	}

	for _, tap := range TouchManager.taps {
		AppendInput(InputEvent{Tap, tap.x, tap.y, nil})
	}

	if TouchManager.pan != nil {
		pan := TouchManager.pan
		iX, iY := pan.Incremental()
		AppendInput(InputEvent{Pan, pan.originX, pan.originY, DistanceCtx{int(iX) / 10, int(iY) / 10}})

	}

	// TODO: handle pinching
	if TouchManager.pinch != nil {
	}

	// TODO: make hover detector a singleton

	x, y := ebiten.CursorPosition()
	scrollX, scrollY := ebiten.Wheel()
	if scrollX != 0 || scrollY != 0 {
		AppendInput(InputEvent{Scroll, x, y, DistanceCtx{int(scrollX), int(scrollY)}})
	}

	var in []rune
	in = ebiten.AppendInputChars(in)
	if len(in) > 0 {
		AppendInput(InputEvent{Text, x, y, TextCtx{in}})
	}

	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
		AppendInput(InputEvent{Click, x, y, ClickCtx{ebiten.MouseButtonLeft}})
	}

	return nil
}