package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"time"

	"github.com/chromedp/cdproto/input"
	"github.com/chromedp/cdproto/page"
	"github.com/chromedp/chromedp"
	"github.com/chromedp/chromedp/kb"
)

var (
	nItemsFlag = flag.Int("n", -1, "number of items to download. If negative, get them all.")
	devFlag    = flag.Bool("dev", false, "dev mode. we reuse the same session dir (/tmp/gphotos-cdp), so we don't have to auth at every run.")
	dlDirFlag  = flag.String("dldir", "", "where to (temporarily) write the downloads. defaults to $HOME/Downloads/gphotos-cdp.")
)

func main() {
	flag.Parse()
	if *nItemsFlag == 0 {
		return
	}
	s, err := NewSession()
	if err != nil {
		log.Fatal(err)
	}
	defer s.Shutdown()

	log.Printf("Session Dir: %v", s.profileDir)

	if err := s.cleanDlDir(); err != nil {
		log.Fatal(err)
	}

	ctx, cancel := s.NewContext()
	defer cancel()

	var outerBefore string

	// login phase
	if err := chromedp.Run(ctx,
		chromedp.ActionFunc(func(ctx context.Context) error {
			log.Printf("pre-navigate")
			return nil
		}),
		chromedp.Navigate("https://photos.google.com/"),
		// chromedp.Sleep(30000*time.Millisecond),
		chromedp.Sleep(5000*time.Millisecond),
		chromedp.ActionFunc(func(ctx context.Context) error {
			log.Printf("post-navigate")
			return nil
		}),
		chromedp.OuterHTML("html>body", &outerBefore),
		chromedp.ActionFunc(func(ctx context.Context) error {
			log.Printf("Source is %d bytes", len(outerBefore))
			return nil
		}),
	); err != nil {
		log.Fatal(err)
	}

	navEnd := func(ctx context.Context) error {
		keyEnd, ok := kb.Keys['\u0305']
		if !ok {
			return errors.New("no End key")
		}

		down := input.DispatchKeyEventParams{
			Key:  keyEnd.Key,
			Code: keyEnd.Code,
			// Some github issue says to remove NativeVirtualKeyCode, but it does not change anything.
			NativeVirtualKeyCode:  keyEnd.Native,
			WindowsVirtualKeyCode: keyEnd.Windows,
			Type:                  input.KeyDown,
		}
		if runtime.GOOS == "darwin" {
			down.NativeVirtualKeyCode = 0
		}
		up := down
		up.Type = input.KeyUp

		for _, ev := range []*input.DispatchKeyEventParams{&down, &up} {
			log.Printf("Event: %+v", *ev)
			if err := ev.Do(ctx); err != nil {
				return err
			}
		}
		time.Sleep(5 * time.Second)
		return nil
	}

	download := func(ctx context.Context) (string, error) {
		dir := s.dlDir
		keyD, ok := kb.Keys['D']
		if !ok {
			log.Fatal("NO D KEY")
		}

		down := input.DispatchKeyEventParams{
			Key:  keyD.Key,
			Code: keyD.Code,
			// Some github issue says to remove NativeVirtualKeyCode, but it does not change anything.
			NativeVirtualKeyCode:  keyD.Native,
			WindowsVirtualKeyCode: keyD.Windows,
			Type:                  input.KeyDown,
			Modifiers:             input.ModifierShift,
		}
		if runtime.GOOS == "darwin" {
			down.NativeVirtualKeyCode = 0
		}
		up := down
		up.Type = input.KeyUp

		for _, ev := range []*input.DispatchKeyEventParams{&down, &up} {
			log.Printf("Event: %+v", *ev)
			if err := ev.Do(ctx); err != nil {
				return "", err
			}
		}

		started := false
		endTimeout := time.Now().Add(30 * time.Second)
		startTimeout := time.Now().Add(5 * time.Second)
		tick := 500 * time.Millisecond
		for {
			time.Sleep(tick)
			if time.Now().After(endTimeout) {
				return "", fmt.Errorf("timeout while downloading in %q", dir)
			}

			if !started && time.Now().After(startTimeout) {
				return "", fmt.Errorf("downloading in %q took too long to start", dir)
			}
			entries, err := ioutil.ReadDir(dir)
			if err != nil {
				return "", err
			}
			var fileEntries []string
			for _, v := range entries {
				if v.IsDir() {
					continue
				}
				fileEntries = append(fileEntries, v.Name())
			}
			if len(fileEntries) < 1 {
				continue
			}
			if !started {
				if len(fileEntries) > 0 {
					started = true
				}
				continue
			}
			if len(fileEntries) > 1 {
				return "", fmt.Errorf("more than one file (%d) in download dir %q", len(fileEntries), dir)
			}
			if !strings.HasSuffix(fileEntries[0], ".crdownload") {
				// download is over
				return fileEntries[0], nil
			}
		}
	}

	mvDl := func(dlFile string) func(ctx context.Context) error {
		return func(ctx context.Context) error {
			dir, err := ioutil.TempDir(s.dlDir, "")
			if err != nil {
				return err
			}
			if err := os.Rename(filepath.Join(s.dlDir, dlFile), filepath.Join(dir, dlFile)); err != nil {
				return err
			}
			return nil
		}
	}

	dlAndMove := func(ctx context.Context) error {
		var err error
		dlFile, err := download(ctx)
		if err != nil {
			return err
		}
		return mvDl(dlFile)(ctx)
	}

	firstNav := func(ctx context.Context) error {
		chromedp.KeyEvent(kb.ArrowRight).Do(ctx)
		log.Printf("sent key")
		chromedp.Sleep(500 * time.Millisecond).Do(ctx)
		chromedp.KeyEvent("\n").Do(ctx)
		chromedp.Sleep(500 * time.Millisecond).Do(ctx)
		return nil
	}

	navRight := func(ctx context.Context) error {
		chromedp.KeyEvent(kb.ArrowRight).Do(ctx)
		log.Printf("sent key")
		chromedp.Sleep(5000 * time.Millisecond).Do(ctx)
		chromedp.WaitReady("body", chromedp.ByQuery)
		return nil
	}

	navRightN := func(N int) func(context.Context) error {
		n := 0
		return func(ctx context.Context) error {
			if N == 0 {
				return nil
			}
			for {
				if N > 0 && n >= N {
					break
				}
				if err := navRight(ctx); err != nil {
					return err
				}
				// TODO(mpl): deal with getting the very last photo to properly exit that loop when N < 0.
				if err := dlAndMove(ctx); err != nil {
					return err
				}
				n++
			}
			return nil
		}
	}

	if err := chromedp.Run(ctx,
		chromedp.ActionFunc(navEnd),
		page.SetDownloadBehavior(page.SetDownloadBehaviorBehaviorAllow).WithDownloadPath(s.dlDir),
		// TODO(mpl): add policy func over photo URL, which decides what we do with the downloaded file. default policy is storing it on disk.
		chromedp.Navigate("https://photos.google.com/"),
		chromedp.Sleep(5000*time.Millisecond),
		chromedp.WaitReady("body", chromedp.ByQuery),
		chromedp.ActionFunc(func(ctx context.Context) error {
			log.Printf("body is ready")
			return nil
		}),
		chromedp.KeyEvent(kb.End),
		chromedp.Sleep(10000*time.Millisecond),
		/*
			chromedp.ActionFunc(firstNav),
			chromedp.ActionFunc(dlAndMove),
			chromedp.ActionFunc(navRightN(*nItemsFlag-1)),
		*/
	); err != nil {
		log.Fatal(err)
	}
	fmt.Println("OK")

	// Next: keys
	// https://github.com/chromedp/chromedp/issues/400
	// https://godoc.org/github.com/chromedp/chromedp/kb

	_, _ = firstNav, navRightN

}

type Session struct {
	parentContext context.Context
	parentCancel  context.CancelFunc
	dlDir         string
	profileDir    string
}

func NewSession() (*Session, error) {
	var dir string
	if *devFlag {
		dir = filepath.Join(os.TempDir(), "gphotos-cdp")
		if err := os.MkdirAll(dir, 0700); err != nil {
			return nil, err
		}
	} else {
		var err error
		dir, err = ioutil.TempDir("", "gphotos-cdp")
		if err != nil {
			return nil, err
		}
	}
	dlDir := *dlDirFlag
	if dlDir == "" {
		dlDir = filepath.Join(os.Getenv("HOME"), "Downloads", "gphotos-cdp")
	}
	if err := os.MkdirAll(dlDir, 0700); err != nil {
		return nil, err
	}
	s := &Session{
		profileDir: dir,
		dlDir:      dlDir,
	}
	return s, nil
}

func (s *Session) NewContext() (context.Context, context.CancelFunc) {
	ctx, cancel := chromedp.NewExecAllocator(context.Background(),
		chromedp.NoFirstRun,
		chromedp.NoDefaultBrowserCheck,
		chromedp.UserDataDir(s.profileDir),

		chromedp.Flag("disable-background-networking", true),
		chromedp.Flag("enable-features", "NetworkService,NetworkServiceInProcess"),
		chromedp.Flag("disable-background-timer-throttling", true),
		chromedp.Flag("disable-backgrounding-occluded-windows", true),
		chromedp.Flag("disable-breakpad", true),
		chromedp.Flag("disable-client-side-phishing-detection", true),
		chromedp.Flag("disable-default-apps", true),
		chromedp.Flag("disable-dev-shm-usage", true),
		chromedp.Flag("disable-extensions", true),
		chromedp.Flag("disable-features", "site-per-process,TranslateUI,BlinkGenPropertyTrees"),
		chromedp.Flag("disable-hang-monitor", true),
		chromedp.Flag("disable-ipc-flooding-protection", true),
		chromedp.Flag("disable-popup-blocking", true),
		chromedp.Flag("disable-prompt-on-repost", true),
		chromedp.Flag("disable-renderer-backgrounding", true),
		chromedp.Flag("disable-sync", true),
		chromedp.Flag("force-color-profile", "srgb"),
		chromedp.Flag("metrics-recording-only", true),
		chromedp.Flag("safebrowsing-disable-auto-update", true),
		chromedp.Flag("enable-automation", true),
		chromedp.Flag("password-store", "basic"),
		chromedp.Flag("use-mock-keychain", true),
	)
	s.parentContext = ctx
	s.parentCancel = cancel
	ctx, cancel = chromedp.NewContext(s.parentContext)
	return ctx, cancel
}

func (s *Session) Shutdown() {
	s.parentCancel()
}

func (s *Session) cleanDlDir() error {
	if s.dlDir == "" {
		return nil
	}
	entries, err := ioutil.ReadDir(s.dlDir)
	if err != nil {
		return err
	}
	for _, v := range entries {
		if v.IsDir() {
			continue
		}
		if err := os.Remove(filepath.Join(s.dlDir, v.Name())); err != nil {
			return err
		}
	}
	return nil
}