package flutter

import (
	"fmt"
	"image"
	"os"
	"path/filepath"

	"github.com/go-flutter-desktop/go-flutter/internal/execpath"
)

type config struct {
	flutterAssetsPath string
	icuDataPath       string
	elfSnapshotpath   string
	vmArguments       []string

	windowIconProvider      func() ([]image.Image, error)
	windowInitialDimensions windowDimensions
	windowInitialLocation   windowLocation
	windowDimensionLimits   windowDimensionLimits
	windowMode              windowMode
	windowAlwaysOnTop       bool
	windowTransparent       bool

	backOnEscape bool

	forcePixelRatio float64
	scrollAmount    float64

	plugins []Plugin
}

type windowDimensions struct {
	width  int
	height int
}

type windowLocation struct {
	xpos int
	ypos int
}

type windowDimensionLimits struct {
	minWidth  int
	minHeight int
	maxWidth  int
	maxHeight int
}

// newApplicationConfig define the default configuration values for a new
// Application. These values may be changed at any time.
func newApplicationConfig() config {
	execPath, err := execpath.ExecPath()
	if err != nil {
		fmt.Printf("go-flutter: failed to resolve path for executable: %v", err)
		os.Exit(1)
	}
	return config{
		windowInitialDimensions: windowDimensions{
			width:  800,
			height: 600,
		},
		windowMode:        WindowModeDefault,
		windowAlwaysOnTop: false,
		windowTransparent: false,
		scrollAmount:      100.0,

		backOnEscape: true,

		// Sane configuration values for the engine.
		flutterAssetsPath: filepath.Join(filepath.Dir(execPath), "flutter_assets"),
		icuDataPath:       filepath.Join(filepath.Dir(execPath), "icudtl.dat"),
		// only required for AOT app.
		elfSnapshotpath: filepath.Join(filepath.Dir(execPath), "libapp.so"),
	}
}

// Option for Application
type Option func(*config)

// ProjectAssetsPath specify the flutter assets directory.
func ProjectAssetsPath(p string) Option {
	_, err := os.Stat(p)
	if err != nil {
		fmt.Printf("go-flutter: failed to stat flutter assets path: %v\n", err)
		os.Exit(1)
	}
	return func(c *config) {
		c.flutterAssetsPath = p
	}
}

// ApplicationELFSnapshotPath specify the path to the ELF AOT snapshot.
// only required by AOT.
func ApplicationELFSnapshotPath(p string) Option {
	_, err := os.Stat(p)
	if err != nil {
		fmt.Printf("go-flutter: failed to stat ELF snapshot path: %v\n", err)
		os.Exit(1)
	}
	return func(c *config) {
		c.elfSnapshotpath = p
	}
}

// ApplicationICUDataPath specify the path to the ICUData.
func ApplicationICUDataPath(p string) Option {
	_, err := os.Stat(p)
	if err != nil {
		fmt.Printf("go-flutter: failed to stat icu data path: %v\n", err)
		os.Exit(1)
	}
	return func(c *config) {
		c.icuDataPath = p
	}
}

// OptionVMArguments specify the arguments to the Dart VM.
func OptionVMArguments(a []string) Option {
	return func(c *config) {
		// First should be argument is argv[0]
		c.vmArguments = append([]string{""}, a...)
	}
}

// WindowInitialDimensions specify the startup's dimension of the window.
func WindowInitialDimensions(width, height int) Option {
	if width < 1 {
		fmt.Println("go-flutter: invalid initial value for width, must be 1 or greater.")
		os.Exit(1)
	}
	if height < 1 {
		fmt.Println("go-flutter: invalid initial value for height, must be 1 or greater.")
		os.Exit(1)
	}

	return func(c *config) {
		c.windowInitialDimensions.width = width
		c.windowInitialDimensions.height = height
	}
}

// WindowInitialLocation specify the startup's position of the window.
// Location, in screen coordinates, of the upper-left corner of the client area
// of the window.
func WindowInitialLocation(xpos, ypos int) Option {
	if xpos < 1 {
		fmt.Println("go-flutter: invalid initial value for xpos location, must be 1 or greater.")
		os.Exit(1)
	}
	if ypos < 1 {
		fmt.Println("go-flutter: invalid initial value for ypos location, must be 1 or greater.")
		os.Exit(1)
	}

	return func(c *config) {
		c.windowInitialLocation.xpos = xpos
		c.windowInitialLocation.ypos = ypos
	}
}

// WindowDimensionLimits specify the dimension limits of the window.
// Does not work when the window is fullscreen or not resizable.
func WindowDimensionLimits(minWidth, minHeight, maxWidth, maxHeight int) Option {
	if minWidth < 1 {
		fmt.Println("go-flutter: invalid initial value for minWidth, must be 1 or greater.")
		os.Exit(1)
	}
	if minHeight < 1 {
		fmt.Println("go-flutter: invalid initial value for minHeight, must be 1 or greater.")
		os.Exit(1)
	}
	if maxWidth < minWidth {
		fmt.Println("go-flutter: invalid initial value for maxWidth, must be greater or equal to minWidth.")
		os.Exit(1)
	}
	if maxHeight < minHeight {
		fmt.Println("go-flutter: invalid initial value for maxHeight, must be greater or equal to minHeight.")
		os.Exit(1)
	}

	return func(c *config) {
		c.windowDimensionLimits.minWidth = minWidth
		c.windowDimensionLimits.minHeight = minHeight
		c.windowDimensionLimits.maxWidth = maxWidth
		c.windowDimensionLimits.maxHeight = maxHeight
	}
}

// BackOnEscape controls the mapping of the escape key.
//
// If true, pops the current route when escape is pressed.
// If false, escape is delivered to the application.
func BackOnEscape(backOnEscape bool) Option {
	return func(c *config) {
		c.backOnEscape = backOnEscape
	}
}

// WindowIcon sets an icon provider func, which is called during window
// initialization. For tips on the kind of images to provide, see
// https://godoc.org/github.com/go-gl/glfw/v3.3/glfw#Window.SetIcon
func WindowIcon(iconProivder func() ([]image.Image, error)) Option {
	return func(c *config) {
		c.windowIconProvider = iconProivder
	}
}

// ForcePixelRatio forces the the scale factor for the screen. By default,
// go-flutter will calculate the correct pixel ratio for the user, based on
// their monitor DPI. Setting this option is not advised.
func ForcePixelRatio(ratio float64) Option {
	return func(c *config) {
		c.forcePixelRatio = ratio
	}
}

// WindowTransparentBackground sets the init window background to be transparent
func WindowTransparentBackground(enabled bool) Option {
	return func(c *config) {
		c.windowTransparent = enabled
	}
}

// WindowAlwaysOnTop sets the application window to be always on top of other windows
func WindowAlwaysOnTop(enabled bool) Option {
	return func(c *config) {
		c.windowAlwaysOnTop = enabled
	}
}

// AddPlugin adds a plugin to the flutter application.
func AddPlugin(p Plugin) Option {
	return func(c *config) {
		c.plugins = append(c.plugins, p)
	}
}

// VirtualKeyboardShow sets an func called when the flutter framework want to
// show the keyboard.
// This Option is interesting for people wanting to display the on-screen
// keyboard on TextField focus.
// It's up to the flutter developer to implement (or not) this function with
// the OS related call.
func VirtualKeyboardShow(showCallback func()) Option {
	return func(c *config) {
		// Reference the callback to the platform plugin (singleton) responsible
		// for textinput.
		defaultTextinputPlugin.virtualKeyboardShow = showCallback
	}
}

// VirtualKeyboardHide sets an func called when the flutter framework want to
// hide the keyboard.
func VirtualKeyboardHide(hideCallback func()) Option {
	return func(c *config) {
		// Reference the callback to the platform plugin (singleton) responsible
		// for textinput.
		defaultTextinputPlugin.virtualKeyboardHide = hideCallback
	}
}

// ScrollAmount sets the number of pixels to scroll with the mouse wheel
func ScrollAmount(amount float64) Option {
	return func(c *config) {
		c.scrollAmount = amount
	}
}