package mouse

import (
	"git.vezzani.net/ben/games/common/elements/v1"
	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
)

type NopHandler struct{}

func (n NopHandler) HandleMouseEvent(s State) bool {
	return false
}

type ChildrenProvider interface {
	GetChildren() []elements.Element
}

type EventHandler interface {
	HandleMouseEvent(s State) bool
}

type State struct {
	X, Y                      int
	LeftDown, RightDown       bool
	LeftChanged, RightChanged bool
	LeftClicked, RightClicked bool
	Clicked                   bool
}

func Handler(e elements.Element) func() bool {
	newState := StateBuilder()
	ms := newState()
	return func() bool {
		ms = newState()
		return propagateMouse(e, ms)
	}
}

func propagateMouse(e elements.Element, ms State) bool {
	if p, ok := e.(ChildrenProvider); ok {
		for _, c := range p.GetChildren() {
			if propagateMouse(c, ms) {
				return true
			}
		}
	}

	if e, ok := e.(EventHandler); ok {
		return e.HandleMouseEvent(ms)
	}

	return false
}

func StateBuilder() func() State {
	prevState := State{}
	state := State{}
	return func() State {
		state = prevState
		state.X, state.Y = ebiten.CursorPosition()

		if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonLeft) {
			state.LeftDown = true
		}
		if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonRight) {
			state.RightDown = true
		}
		if inpututil.IsMouseButtonJustReleased(ebiten.MouseButtonLeft) {
			state.LeftDown = false
			if !state.RightDown {
				state.Clicked = true
			}
		}
		if inpututil.IsMouseButtonJustReleased(ebiten.MouseButtonRight) {
			state.RightDown = false
			if !state.LeftDown {
				state.Clicked = true
			}
		}

		state.Clicked = state.Clicked && !prevState.Clicked

		state.LeftChanged = state.LeftDown != prevState.LeftDown
		state.RightChanged = state.RightDown != prevState.RightDown
		state.LeftClicked = state.LeftChanged && state.LeftDown
		state.RightClicked = state.RightChanged && state.RightDown

		prevState = state
		return state
	}
}