// Copyright (C) 2020  Raziman

package main

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"strings"
	"time"

	"github.com/gdamore/tcell/v2"
	"github.com/rivo/tview"
	"github.com/spf13/viper"
	spin "github.com/tj/go-spin"
	"github.com/ztrue/tracerr"
)

// Playlist and mp3 files are represented with this struct
// if isAudioFile equals to false it is a directory
type AudioFile struct {
	name        string
	path        string
	isAudioFile bool
	length      time.Duration
	node        *tview.TreeNode
	parent      *tview.TreeNode
}

// Playlist struct represents playlist panel
// that shows the tree of the music directory
type Playlist struct {
	*tview.TreeView
	prevNode     *tview.TreeNode
	defaultTitle string
	// number of downloads
	download int
	done     chan struct{}
}

func (p *Playlist) help() []string {

	return []string{
		"j      down",
		"k      up",
		"h      close node",
		"a      create a playlist",
		"l      add song to queue",
		"L      add playlist to queue",
		"d      delete file from filesystem",
		"D      delete playlist from filesystem",
		"Y      download audio",
		"r      refresh",
		"R      rename",
		"/      find in playlist",
	}

}

// newPlaylist returns new instance of playlist and runs populate function
// on root music directory.
func newPlaylist(args Args) *Playlist {

	rootDir, err := filepath.Abs(expandTilde(viper.GetString("general.music_dir")))

	// if not default value was given
	if *args.music != "~/music" {
		rootDir = expandFilePath(*args.music)
	}

	if err != nil {
		log.Fatalf("Unable to find music directory: %e", err)
	}

	rootTextView := fmt.Sprintf("%s %s",
		viper.GetString("emoji.playlist"), path.Base(rootDir))

	root := tview.NewTreeNode(rootTextView).
		SetColor(gomu.colors.accent)

	tree := tview.NewTreeView().SetRoot(root)

	playlist := &Playlist{
		TreeView:     tree,
		defaultTitle: "─ Playlist ──┤ 0 downloads ├",
		done:         make(chan struct{}),
	}

	rootAudioFile := &AudioFile{
		name: path.Base(rootDir),
		node: root,
		path: rootDir,
	}

	root.SetReference(rootAudioFile)

	playlist.
		SetTitle(playlist.defaultTitle).
		SetBorder(true).
		SetTitleAlign(tview.AlignLeft).
		SetBorderPadding(0, 0, 1, 1)

	populate(root, rootDir)

	var firstChild *tview.TreeNode

	if len(root.GetChildren()) == 0 {
		firstChild = root
	} else {
		firstChild = root.GetChildren()[0]
	}

	playlist.setHighlight(firstChild)

	playlist.SetChangedFunc(func(node *tview.TreeNode) {
		playlist.setHighlight(node)
	})

	playlist.SetSelectedFunc(func(node *tview.TreeNode) {
		node.SetExpanded(!node.IsExpanded())
	})

	playlist.SetInputCapture(func(e *tcell.EventKey) *tcell.EventKey {

		cmds := map[rune]string{
			'a': "create_playlist",
			'D': "delete_playlist",
			'd': "delete_file",
			'Y': "download_audio",
			'l': "add_queue",
			'L': "bulk_add",
			'h': "close_node",
			'r': "refresh",
			'R': "rename",
			'/': "playlist_search",
		}

		for key, cmd := range cmds {
			if e.Rune() != key {
				continue
			}
			fn, err := gomu.command.getFn(cmd)
			if err != nil {
				logError(err)
				return e
			}
			fn()
		}

		// disable default key handler for space
		if e.Rune() == ' ' {
			return nil
		}

		return e
	})

	return playlist

}

// Returns the current file highlighted in the playlist
func (p Playlist) getCurrentFile() *AudioFile {
	node := p.GetCurrentNode()
	if node == nil {
		return nil
	}
	return node.GetReference().(*AudioFile)
}

// Deletes song from filesystem
func (p *Playlist) deleteSong(audioFile *AudioFile) (err error) {

	confirmationPopup(
		"Are you sure to delete this audio file?", func(_ int, buttonName string) {

			if buttonName == "no" || buttonName == "" {
				return
			}

			err := os.Remove(audioFile.path)

			if err != nil {

				defaultTimedPopup(" Error ", "Unable to delete "+audioFile.name)

				err = tracerr.Wrap(err)

			} else {

				defaultTimedPopup(" Success ",
					audioFile.name+"\nhas been deleted successfully")

				p.refresh()
			}

		})

	return nil
}

// Deletes playlist/dir from filesystem
func (p *Playlist) deletePlaylist(audioFile *AudioFile) (err error) {

	var selectedDir *AudioFile

	// gets the parent dir if current focused node is not a dir
	if audioFile.isAudioFile {
		selectedDir = audioFile.parent.GetReference().(*AudioFile)
	} else {
		selectedDir = audioFile
	}

	confirmationPopup("Are you sure to delete this directory?",
		func(_ int, buttonName string) {

			if buttonName == "no" || buttonName == "" {
				return
			}

			err := os.RemoveAll(selectedDir.path)

			if err != nil {

				defaultTimedPopup(
					" Error ",
					"Unable to delete dir "+selectedDir.name)

				err = tracerr.Wrap(err)

			} else {

				defaultTimedPopup(
					" Success ",
					selectedDir.name+"\nhas been deleted successfully")

				p.refresh()
			}

		})

	return nil
}

// Bulk add a playlist to queue
func (p *Playlist) addAllToQueue(root *tview.TreeNode) {

	var childrens []*tview.TreeNode
	childrens = root.GetChildren()

	// gets the parent if the highlighted item is a file
	if root.GetReference().(*AudioFile).isAudioFile {
		childrens = root.GetReference().(*AudioFile).parent.GetChildren()
	}

	for _, v := range childrens {
		currNode := v.GetReference().(*AudioFile)
		gomu.queue.enqueue(currNode)
	}

}

// Refreshes the playlist and read the whole root music dir
func (p *Playlist) refresh() {

	root := gomu.playlist.GetRoot()

	prevFileName := gomu.playlist.GetCurrentNode().GetText()

	root.ClearChildren()

	populate(root, root.GetReference().(*AudioFile).path)

	root.Walk(func(node, parent *tview.TreeNode) bool {

		// to preserve previously highlighted node
		if node.GetText() == prevFileName {
			p.setHighlight(node)
			return false
		}

		return true
	})

}

// Adds child while setting reference to audio file
func (p *Playlist) addSongToPlaylist(
	audioPath string, selPlaylist *tview.TreeNode,
) error {

	f, err := os.Open(audioPath)

	if err != nil {
		return tracerr.Wrap(err)
	}

	defer f.Close()

	songName := getName(audioPath)
	node := tview.NewTreeNode(songName)

	audioLength, err := getLength(audioPath)

	if err != nil {
		return tracerr.Wrap(err)
	}

	audioFile := &AudioFile{
		name:        songName,
		path:        audioPath,
		isAudioFile: true,
		length:      audioLength,
		node:        node,
		parent:      selPlaylist,
	}

	displayText := songName

	if viper.GetBool("general.emoji") {
		displayText = fmt.Sprintf("🎵 %s", songName)
	}

	node.SetReference(audioFile)
	node.SetText(displayText)

	selPlaylist.AddChild(node)

	return nil

}

// Gets all audio files walks from music root directory
func (p *Playlist) getAudioFiles() []*AudioFile {

	root := p.GetRoot()

	audioFiles := []*AudioFile{}

	root.Walk(func(node, _ *tview.TreeNode) bool {

		audioFile := node.GetReference().(*AudioFile)
		audioFiles = append(audioFiles, audioFile)

		return true
	})

	return audioFiles
}

// Creates a directory under selected node, returns error if playlist exists
func (p *Playlist) createPlaylist(name string) error {

	selectedNode := p.GetCurrentNode()

	parentNode := selectedNode.GetReference().(*AudioFile).parent

	// if the current node is the root
	// sets the parent to itself
	if parentNode == nil {
		parentNode = selectedNode
	}

	audioFile := parentNode.GetReference().(*AudioFile)

	err := os.Mkdir(path.Join(audioFile.path, name), 0744)

	if err != nil {
		return tracerr.Wrap(err)
	}

	p.refresh()

	return nil

}

// This is used to replace default behaviour of SetCurrentNode which
// adds color highlight attributes
func (p *Playlist) setHighlight(currNode *tview.TreeNode) {

	if p.prevNode != nil {
		p.prevNode.SetColor(gomu.colors.background)
	}
	currNode.SetColor(gomu.colors.accent)
	p.SetCurrentNode(currNode)

	if currNode.GetReference().(*AudioFile).isAudioFile {
		p.prevNode = currNode
	}

}

// Traverses the playlist and finds the AudioFile struct
// audioName must be hashed with sha1 first
func (p *Playlist) findAudioFile(audioName string) (*AudioFile, error) {

	root := p.GetRoot()

	var selNode *AudioFile

	root.Walk(func(node, _ *tview.TreeNode) bool {

		audioFile := node.GetReference().(*AudioFile)

		hashed := sha1Hex(getName(audioFile.name))

		if hashed == audioName {
			selNode = audioFile
			return false
		}

		return true
	})

	if selNode == nil {
		return nil, tracerr.New("no matching audio name")
	}

	return selNode, nil
}

// Highlight the selected node searched using fzf
func (p *Playlist) fuzzyFind() error {

	var result string
	var err error

	audioFiles := p.getAudioFiles()
	paths := make(map[string]*tview.TreeNode, len(audioFiles))
	input := make([]string, 0, len(audioFiles))

	for _, v := range audioFiles {
		rootDir := audioFiles[0].path + "/"
		// path relative to music directory
		shortPath := strings.TrimPrefix(v.path, rootDir)
		paths[shortPath] = v.node
		input = append(input, shortPath)
	}

	gomu.suspend()
	ok := gomu.app.Suspend(func() {
		res, e := fzfFind(input)
		if e != nil {
			err = tracerr.Wrap(e)
		}
		result = res
	})
	gomu.unsuspend()

	if err != nil {
		return tracerr.Wrap(err)
	}

	if !ok {
		return tracerr.New("App was not suspended")
	}

	if result == "" {
		return nil
	}

	if err != nil {
		return tracerr.Wrap(err)
	}

	var selNode *tview.TreeNode
	selNode, ok = paths[result]

	if ok {
		p.setHighlight(selNode)
	}

	return nil
}

func (p *Playlist) rename(newName string) error {

	currentNode := p.GetCurrentNode()
	audio := currentNode.GetReference().(*AudioFile)
	pathToFile, _ := filepath.Split(audio.path)
	var newPath string
	if audio.isAudioFile {
		newPath = pathToFile + newName + ".mp3"
	} else {
		newPath = pathToFile + newName
	}
	err := os.Rename(audio.path, newPath)
	if err != nil {
		return tracerr.Wrap(err)
	}

	return nil
}

// updateTitle creates a spinning motion on the title
// of the playlist panel when downloading.
func (p *Playlist) updateTitle() {

	if p.download == 0 {
		p.SetTitle(p.defaultTitle)
		return
	}

	// only one call can be made in one time
	if p.download > 1 {
		return
	}

	s := spin.New()

Download:
	for {

		if gomu.isSuspend {
			continue
		}

		select {
		case <-p.done:
			p.download -= 1
			if p.download == 0 {
				p.SetTitle(p.defaultTitle)
				break Download
			}
		case <-time.After(time.Millisecond * 100):

			r, g, b := gomu.colors.accent.RGB()
			hexColor := padHex(r, g, b)

			title := fmt.Sprintf("─ Playlist ──┤ %d downloads [green]%s[#%s] ├",
				p.download, s.Next(), hexColor)
			p.SetTitle(title)
			gomu.app.Draw()
		}
	}

}

// Takes a list of input and suspends tview
// returns empty string if cancelled
func fzfFind(input []string) (string, error) {

	var in strings.Builder
	var out strings.Builder

	for _, v := range input {
		in.WriteString(v + "\n")
	}

	cmd := exec.Command("fzf")
	cmd.Stdin = strings.NewReader(in.String())
	cmd.Stderr = os.Stderr
	cmd.Stdout = &out

	if err := cmd.Run(); cmd.ProcessState.ExitCode() == 130 {
		// exit code 130 is when we cancel FZF
		// not an error
		return "", nil
	} else if err != nil {
		return "", fmt.Errorf("failed to find a file: %s", err)
	}

	f := strings.TrimSpace(out.String())

	return f, nil
}

// Download audio from youtube audio and adds the song to the selected playlist
func ytdl(url string, selPlaylist *tview.TreeNode) error {

	// lookup if youtube-dl exists
	_, err := exec.LookPath("youtube-dl")

	if err != nil {
		defaultTimedPopup(" Error ", "youtube-dl is not in your $PATH")

		return tracerr.Wrap(err)
	}

	dir := viper.GetString("general.music_dir")

	selAudioFile := selPlaylist.GetReference().(*AudioFile)
	selPlaylistName := selAudioFile.name

	defaultTimedPopup(" Ytdl ", "Downloading")

	// specify the output path for ytdl
	outputDir := fmt.Sprintf(
		"%s/%s/%%(title)s.%%(ext)s",
		dir,
		selPlaylistName)

	args := []string{
		"--extract-audio",
		"--audio-format",
		"mp3",
		"--output",
		outputDir,
		url,
	}

	cmd := exec.Command("youtube-dl", args...)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr

	gomu.playlist.download++
	go gomu.playlist.updateTitle()

	// blocking
	err = cmd.Run()

	gomu.playlist.done <- struct{}{}

	if err != nil {
		defaultTimedPopup(" Error ", "Error running youtube-dl")
		return tracerr.Wrap(err)
	}

	playlistPath := path.Join(expandTilde(dir), selPlaylistName)
	audioPath := extractFilePath(stdout.Bytes(), playlistPath)

	err = appendFile(expandTilde(viper.GetString("general.history_path")), url+"\n")
	if err != nil {
		return tracerr.Wrap(err)
	}

	err = gomu.playlist.addSongToPlaylist(audioPath, selPlaylist)
	if err != nil {
		return tracerr.Wrap(err)
	}

	downloadFinishedMessage := fmt.Sprintf("Finished downloading\n%s",
		getName(audioPath))

	defaultTimedPopup(" Ytdl ", downloadFinishedMessage)

	return nil
}

// Add songs and their directories in Playlist panel
func populate(root *tview.TreeNode, rootPath string) error {

	files, err := ioutil.ReadDir(rootPath)

	if err != nil {
		return tracerr.Wrap(err)
	}

	for _, file := range files {

		path := filepath.Join(rootPath, file.Name())
		f, err := os.Open(path)

		if err != nil {
			continue
		}

		defer f.Close()

		songName := getName(file.Name())
		child := tview.NewTreeNode(songName)

		if !file.IsDir() {

			filetype, err := getFileContentType(f)

			if err != nil {
				continue
			}

			// skip if not mp3 file
			if filetype != "mpeg" {
				continue
			}

			audioLength, err := getLength(path)

			if err != nil {
				continue
			}

			audioFile := &AudioFile{
				name:        songName,
				path:        path,
				isAudioFile: true,
				length:      audioLength,
				node:        child,
				parent:      root,
			}

			displayText := songName
			if viper.GetBool("general.emoji") {
				displayText = fmt.Sprintf(" %s %s",
					viper.GetString("emoji.file"), songName)
			}

			child.SetReference(audioFile)
			child.SetText(displayText)
			root.AddChild(child)

		}

		if file.IsDir() {

			audioFile := &AudioFile{
				name:   songName,
				path:   path,
				node:   child,
				parent: root,
			}

			displayText := songName
			if viper.GetBool("general.emoji") {
				displayText = fmt.Sprintf(" %s %s",
					viper.GetString("emoji.playlist"), songName)
			}

			child.SetReference(audioFile)
			child.SetColor(gomu.colors.accent)
			child.SetText(displayText)
			root.AddChild(child)
			populate(child, path)

		}

	}

	return nil
}