package main

import (
	_ "embed"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"slices"
	"strconv"
	"strings"

	"git.yetaga.in/alazyreader/why/filetypes"
	"github.com/disintegration/imaging"
	tk "modernc.org/tk9.0"
)

// this is a default image
//
//go:embed noise.png
var noise []byte

// this is the app icon
//
//go:embed icon.png
var icon []byte

//go:generate go run ./filetypes/cmd/gen.go
var validFileTypes = filetypes.Valid
var metaActive bool
var fileList *tk.ToplevelWidget
var lb *tk.ListboxWidget

var directoryState struct {
	currentDirectory string
	currentFile      string
	images           []string
}

func must[T any](t T, err error) T {
	if err != nil {
		panic(err)
	}
	return t
}

func isImage(entry os.DirEntry) bool {
	if entry.IsDir() {
		return false
	}
	ext := filepath.Ext(entry.Name())
	if ext == "" {
		return false
	}
	for _, ft := range validFileTypes {
		if slices.Contains(ft.MacExtensions, ext[1:]) {
			return true
		}
	}
	return false
}

func newFileInDirectory(img *tk.LabelWidget) func() {
	return func() {
		files := tk.GetOpenFile(tk.Filetypes(filetypes.GetTkTypes(validFileTypes)), tk.Multiple(false))
		if len(files) < 1 || files[0] == "" {
			log.Println("no file chosen")
			return
		}
		file := strings.Join(files, " ") // GetOpenFile returns an array split on spaces!
		openFileAndDirectory(img, file)
	}
}

func openFileAndDirectory(img *tk.LabelWidget, file string) {
	directoryState.currentFile = filepath.Base(file)
	directoryState.currentDirectory = filepath.Dir(file)
	dirfiles, err := os.ReadDir(directoryState.currentDirectory)
	if err != nil {
		log.Printf("could not open dir: %v", err)
		return
	}
	directoryState.images = []string{}
	for _, v := range dirfiles {
		if isImage(v) {
			directoryState.images = append(directoryState.images, v.Name())
		}
	}
	updateImage(file, img)
}

func newDirectory(img *tk.LabelWidget) func() {
	return func() {
		dir := tk.ChooseDirectory()
		if dir == "" {
			log.Println("no directory chosen")
			return
		}
		directoryState.currentDirectory = dir
		dirfiles, err := os.ReadDir(directoryState.currentDirectory)
		if err != nil {
			log.Println(err)
			return
		}
		directoryState.images = []string{}
		for _, v := range dirfiles {
			if isImage(v) {
				directoryState.images = append(directoryState.images, v.Name())
			}
		}
		updateImage(filepath.Join(directoryState.currentDirectory, directoryState.images[0]), img)
	}
}

func updateImage(file string, img *tk.LabelWidget) {
	i, err := imaging.Open(file, imaging.AutoOrientation(true))
	if err != nil {
		log.Printf("error opening image: %v", err)
		return
	}
	i = imaging.Fit(i,
		must(strconv.Atoi(tk.WinfoScreenWidth(tk.App))),
		must(strconv.Atoi(tk.WinfoScreenHeight(tk.App))),
		imaging.Linear,
	)
	repaint(img, filepath.Base(file), tk.Data(i))
	directoryState.currentFile = filepath.Base(file)
}

func repaint(img *tk.LabelWidget, name string, opt tk.Opt) {
	img.Configure(tk.Image(tk.NewPhoto(opt)))
	if name != "" {
		tk.App.WmTitle(fmt.Sprintf("why | %s", name))
	} else {
		tk.App.WmTitle("why")
	}
}

func main() {
	img := tk.Label()
	repaint(img, "", tk.Data(noise))

	tk.MacOpenDocument(func(e string) {
		openFileAndDirectory(img, e)
	})

	menubar := tk.Menu()
	fileMenu := menubar.Menu()
	fileMenu.AddCommand(tk.Lbl("Open File"), tk.Accelerator("Meta+O"), tk.Command(newFileInDirectory(img)))
	fileMenu.AddCommand(tk.Lbl("Open Directory"), tk.Command(newDirectory(img)))
	fileMenu.AddSeparator()
	checkbox := fileMenu.AddCheckbutton(tk.Lbl("Show Filelist"))
	bindVar := tk.Variable("FileList")
	fileMenu.EntryConfigure(checkbox, bindVar)
	menubar.AddCascade(tk.Lbl("File"), tk.Underline(0), tk.Mnu(fileMenu))
	tk.App.Configure(tk.Mnu(menubar))

	destroyFileList := func(destroy bool) {
		if destroy {
			tk.Destroy(fileList)
		}
		fileList = nil
		lb = nil
		bindVar.Set("0")
	}
	constructFileList := func() {
		fileList = tk.Toplevel()
		fileList.WmTitle("Files")
		lb = fileList.Listbox(tk.Height(0))
		for i := range directoryState.images {
			lb.Insert("end", directoryState.images[i])
			if i == slices.Index(directoryState.images, directoryState.currentFile) {
				lb.SelectionSet(i)
			}
		}
		tk.Pack(lb)
		tk.Bind(lb, "<<ListboxSelect>>", tk.Command(func() {
			selection := lb.Curselection()
			updateImage(filepath.Join(directoryState.currentDirectory, directoryState.images[selection[0]]), img)
		}))
		tk.Bind(fileList, "<Destroy>", tk.Command(func(e *tk.Event) {
			// list closed by user click on <x>
			destroyFileList(false)
		}))
		bindVar.Set("1")
	}

	tk.Bind(fileMenu, "<<MenuSelect>>", tk.Command(func() {
		if bindVar.Get() == "1" && fileList == nil {
			constructFileList()
		} else if bindVar.Get() == "0" && fileList != nil {
			destroyFileList(true)
		}
	}))

	// TODO: if someone presses the Meta key again after the openfile dialog box closes,
	// it triggers a _release_ event instead of a press event. The second time afterward, it works correctly.
	tk.Bind(tk.App, "<KeyPress>", tk.Command(func(e *tk.Event) {
		curr := slices.Index(directoryState.images, directoryState.currentFile)
		switch e.Keysym {
		case ".":
			log.Printf("state: %+v", directoryState)
		case "Meta_L", "Meta_R":
			metaActive = true
		case "o":
			if metaActive {
				newFileInDirectory(img)()
			}
		case "a":
			if metaActive {
				if fileList == nil {
					constructFileList()
				} else {
					// list closed by Meta-a
					destroyFileList(true)
				}
			}
		case "Up":
			if curr > 0 {
				updateImage(filepath.Join(directoryState.currentDirectory, directoryState.images[curr-1]), img)
				if lb != nil {
					lb.SelectionClear("0", "end")
					lb.SelectionSet(curr - 1)
				}
			}
		case "Down":
			if curr < len(directoryState.images)-1 && curr != -1 {
				updateImage(filepath.Join(directoryState.currentDirectory, directoryState.images[curr+1]), img)
				if lb != nil {
					lb.SelectionClear("0", "end")
					lb.SelectionSet(curr + 1)
				}
			}
		}
	}))
	tk.Bind(tk.App, "<KeyRelease>", tk.Command(func(e *tk.Event) {
		switch e.Keysym {
		case "Meta_L", "Meta_R":
			metaActive = false
		}
	}))
	// todo: resize image based on scroll events
	// tk.Bind(tk.App, "<TouchpadScroll>", tk.Command(func(e *tk.Event) {
	// 	log.Printf("%v, %v", int16(e.Delta>>16), int16(e.Delta&0xFFFF))
	// }))

	tk.Pack(img)
	tk.App.IconPhoto(tk.NewPhoto(tk.Data(icon)))
	tk.App.Wait()
}