package cmdline

import (
	"bytes"
	"flag"
	"fmt"
	"log"
	"os"
	"strings"

	"github.com/antchfx/htmlquery"
	"github.com/playwright-community/playwright-go"
	"golang.org/x/net/html"
)

var (
	printDebug bool
	outputFile string
	errorLog   *log.Logger
	mainLog    *log.Logger
)

func recurseNodes(top *html.Node, sb *strings.Builder) {
	if top.Type == html.ElementNode && top.Data == "span" {
		sb.WriteString(htmlquery.InnerText(top) + "\n")
	}
	for c := top.FirstChild; c != nil; c = c.NextSibling {
		recurseNodes(c, sb)
	}
}

func searchGoogle(song string) error {
	runOption := &playwright.RunOptions{
		SkipInstallBrowsers: true,
	}
	err := playwright.Install(runOption)
	if err != nil {
		return fmt.Errorf("could not install playwright dependencies: %v", err)
	}
	pw, err := playwright.Run()
	if err != nil {
		return fmt.Errorf("could not start playwright: %v", err)
	}
	defer func(pw *playwright.Playwright) error {
		err := pw.Stop()
		if err != nil {
			return fmt.Errorf("could not stop Playwright: %v", err)
		}
		return nil
	}(pw)

	option := playwright.BrowserTypeLaunchOptions{
		Channel:  playwright.String("chrome"),
		Headless: playwright.Bool(false),
	}
	browser, err := pw.Chromium.Launch(option)
	if err != nil {
		return fmt.Errorf("could not launch browser: %v", err)
	}

	defer func(browser playwright.Browser) error {
		err = browser.Close()
		if err != nil {
			return fmt.Errorf("could not close browser: %v", err)
		}
		return nil
	}(browser)
	page, err := browser.NewPage()
	if err != nil {
		return fmt.Errorf("could not create page: %v", err)
	}
	if _, err := page.Goto(fmt.Sprintf("https://www.google.com/search?q=%ss+lyrics", song),
		playwright.PageGotoOptions{
			WaitUntil: playwright.WaitUntilStateLoad,
		}); err != nil {
		return fmt.Errorf("could not goto: %v", err)
	}
	err = page.Locator("body").WaitFor(playwright.LocatorWaitForOptions{
		State: playwright.WaitForSelectorStateVisible,
	})
	if err != nil {
		return fmt.Errorf("could not wait for body: %v", err)
	}
	html, err := page.Locator("html").InnerHTML()
	if err != nil {
		return fmt.Errorf("could not get innerHtml: %v", err)
	}
	doc, err := htmlquery.Parse(bytes.NewReader([]byte(html)))
	if err != nil {
		return fmt.Errorf("could not parse the innerHtml: %v", err)
	}
	nodes, err := htmlquery.QueryAll(doc, "//div[@data-lyricid]/div")
	if err != nil {
		return fmt.Errorf("could not get the nodes: %v", err)
	}

	var sb strings.Builder
	for _, node := range nodes {
		recurseNodes(node, &sb)
	}
	if sb.Len() > 0 {
		if printDebug {
			mainLog.Println("Writing lyrics from Google...")
		}
		filename := fmt.Sprintf("%s_google.txt", outputFile)
		err = os.WriteFile(filename, []byte(sb.String()), os.ModePerm)
		if err != nil {
			return fmt.Errorf("could not write to %s: %v", filename, err)
		}
	} else {
		mainLog.Println("Lyrics cannot be found...")
	}

	return nil
}

// func searchGenius(song string, lg *log.Logger) {

// }

func Main() int {
	programName := os.Args[0]
	errorLog = log.New(os.Stderr, "", 0)
	mainLog = log.New(os.Stdout, "", 0)

	flags := flag.NewFlagSet(os.Args[0], flag.ExitOnError)
	flags.Usage = func() {
		out := flags.Output()
		fmt.Fprintf(out, "Usage: %v \n\n", programName)
		fmt.Fprint(out, "  This program is used to download lyrics for a song\n")
		fmt.Fprint(out, "  from the internet. The steps of operation are shown here: \n\n")
		fmt.Fprint(out, "  (a) It first opens a chrome window, searches for the lyrics \n")
		fmt.Fprint(out, "  , and copies the lyrics returned by Google Search to a \n")
		fmt.Fprint(out, "  file defined by you.\n\n")
		fmt.Fprint(out, "  (b) It then tries to get search for the same song using the \n")
		fmt.Fprint(out, "  Genius API. It then tries to compare the lyrics with the \n")
		fmt.Fprint(out, "  Genius one.\n\n")
		flags.PrintDefaults()
	}

	outputFlag := flags.String("output", "", "Optional. Lyrics filename")
	verboseFlag := flags.Bool("verbose", false, "Optional. Turn on debug. Default is false.")
	searchFlag := flags.String("search", "", "Required. Name of song to search. If the name of the song is not a single word, put in quotes\"\"")
	helpFlag := flags.Bool("help", false, "Optional. Print Usage")

	flags.Parse(os.Args[1:])

	if len(flags.Args()) > 1 {
		errorLog.Println("Error: too many command-line arguments")
		flags.Usage()
		return 1
	}

	allSetFlags := flagsSet(flags)

	if allSetFlags["help"] && (allSetFlags["output"] || allSetFlags["search"] || allSetFlags["verbose"]) {
		errorLog.Println("Error: if -help is set, -output, -search and -verbose must remain unset")
		flags.Usage()
		return 1
	}

	if *helpFlag {
		flags.Usage()
		return 0
	}

	songToSearch := *searchFlag

	if len(songToSearch) == 0 {
		errorLog.Println("Error: the song name must be provided for search")
		flags.Usage()
		return 1
	}

	if allSetFlags["output"] {
		outputFile = *outputFlag
	} else {
		mainLog.Printf("Using %s as the name of the file(s) for downloaded lyrics..\n", songToSearch)
		outputFile = fmt.Sprintf("%s_lyrics", songToSearch)
	}

	printDebug = *verboseFlag
	if printDebug {
		mainLog.Printf("Output flag: %s, Debug flag: %t, Search flag: %s\n", outputFile, printDebug, songToSearch)
	}

	err := searchGoogle(songToSearch)
	if err != nil {
		errorLog.Printf("Err: %+v", err)
		return 1
	}

	return 0
}

// flagsSet returns a set of all the flags what were actually set on the
// command line.
func flagsSet(flags *flag.FlagSet) map[string]bool {
	s := make(map[string]bool)
	flags.Visit(func(f *flag.Flag) {
		s[f.Name] = true
	})
	return s
}