package screens

import (
	"image/color"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
	"github.com/hajimehoshi/ebiten/v2/text/v2"
)

// An interface for managing FPS cap settings.
type FPSCapSetting interface {
	String() string
	Cycle()
}

// Displays and manages game settings like FPS monitor and FPS cap.
// This screen can be accessed from both the title screen and pause menu.
type SettingsScreen struct {
	selectedIndex   int
	fpsMonitorValue *bool
	fpsCapValue     FPSCapSetting
}

// Creates a new settings screen instance.
func NewSettingsScreen() *SettingsScreen {
	return &SettingsScreen{
		selectedIndex: 0,
	}
}

// Sets the FPS monitor toggle reference.
func (s *SettingsScreen) SetFPSMonitor(enabled *bool) {
	s.fpsMonitorValue = enabled
}

// Sets the FPS cap setting reference.
func (s *SettingsScreen) SetFPSCap(cap FPSCapSetting) {
	s.fpsCapValue = cap
}

// Processes settings screen input.
// Returns true if the user wants to go back.
func (s *SettingsScreen) Update() bool {
	if inpututil.IsKeyJustPressed(ebiten.KeyEscape) {
		return true
	}

	settingsCount := 2
	if inpututil.IsKeyJustPressed(ebiten.KeyArrowUp) || inpututil.IsKeyJustPressed(ebiten.KeyW) {
		s.selectedIndex--
		if s.selectedIndex < 0 {
			s.selectedIndex = 0
		}
	}
	if inpututil.IsKeyJustPressed(ebiten.KeyArrowDown) || inpututil.IsKeyJustPressed(ebiten.KeyS) {
		s.selectedIndex++
		if s.selectedIndex >= settingsCount {
			s.selectedIndex = settingsCount - 1
		}
	}

	if inpututil.IsKeyJustPressed(ebiten.KeyEnter) || inpututil.IsKeyJustPressed(ebiten.KeySpace) {
		if s.selectedIndex == 0 && s.fpsMonitorValue != nil {
			*s.fpsMonitorValue = !*s.fpsMonitorValue
		} else if s.selectedIndex == 1 && s.fpsCapValue != nil {
			s.fpsCapValue.Cycle()
		}
	}

	return false
}

// Renders the settings screen.
func (s *SettingsScreen) Draw(screen *ebiten.Image, screenWidth, screenHeight int, title string) {
	// Draw background
	screen.Fill(color.RGBA{R: 20, G: 20, B: 30, A: 255})

	// Draw title
	titleX := (screenWidth / 2) - (len(title) * 7 / 2)
	titleY := screenHeight/3 - 50
	s.drawText(screen, title, color.White, titleX, titleY)

	// Draw settings options
	startY := screenHeight/2 - 20
	leftMargin := screenWidth/2 - 120

	fpsMonitorText := "FPS Monitor: "
	if s.fpsMonitorValue != nil && *s.fpsMonitorValue {
		fpsMonitorText += "ON"
	} else {
		fpsMonitorText += "OFF"
	}

	if s.selectedIndex == 0 {
		indicatorX := leftMargin - 20
		s.drawText(screen, ">", color.RGBA{R: 255, G: 200, B: 0, A: 255}, indicatorX, startY)
		s.drawText(screen, fpsMonitorText, color.RGBA{R: 255, G: 255, B: 100, A: 255}, leftMargin, startY)
	} else {
		s.drawText(screen, fpsMonitorText, color.RGBA{R: 180, G: 180, B: 200, A: 255}, leftMargin, startY)
	}

	fpsCapText := "FPS Cap: "
	if s.fpsCapValue != nil {
		fpsCapText += s.fpsCapValue.String()
	} else {
		fpsCapText += "60 FPS"
	}

	capY := startY + 40
	if s.selectedIndex == 1 {
		indicatorX := leftMargin - 20
		s.drawText(screen, ">", color.RGBA{R: 255, G: 200, B: 0, A: 255}, indicatorX, capY)
		s.drawText(screen, fpsCapText, color.RGBA{R: 255, G: 255, B: 100, A: 255}, leftMargin, capY)
	} else {
		s.drawText(screen, fpsCapText, color.RGBA{R: 180, G: 180, B: 200, A: 255}, leftMargin, capY)
	}

	// Draw hint text
	hintText := "Enter/Space to toggle, ESC to go back"
	hintX := (screenWidth / 2) - (len(hintText) * 7 / 2)
	hintY := screenHeight - 50
	s.drawText(screen, hintText, color.RGBA{R: 120, G: 120, B: 150, A: 255}, hintX, hintY)
}

func (s *SettingsScreen) drawText(screen *ebiten.Image, txt string, clr color.Color, x, y int) {
	op := &text.DrawOptions{}
	op.GeoM.Translate(float64(x), float64(y)-basicFaceAscent)
	op.ColorScale.ScaleWithColor(clr)
	text.Draw(screen, txt, basicFace, op)
}

// Resets the settings screen to its initial state.
func (s *SettingsScreen) Reset() {
	s.selectedIndex = 0
}