// Package app manages main application server.
package app

import (
	"fmt"
	"html/template"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strings"

	rice "github.com/GeertJohan/go.rice"
	"github.com/dustin/go-humanize"
	"github.com/fsnotify/fsnotify"
	"github.com/gorilla/handlers"
	"github.com/gorilla/mux"
	"github.com/renstrom/shortuuid"
	"github.com/rylio/ytdl"
	log "github.com/sirupsen/logrus"
	"github.com/wybiral/tube/media"
	"github.com/wybiral/tube/utils"
)

//go:generate rice embed-go

// App represents main application.
type App struct {
	Config    *Config
	Library   *media.Library
	Store     Store
	Watcher   *fsnotify.Watcher
	Templates *templateStore
	Feed      []byte
	Listener  net.Listener
	Router    *mux.Router
}

// NewApp returns a new instance of App from Config.
func NewApp(cfg *Config) (*App, error) {
	if cfg == nil {
		cfg = DefaultConfig()
	}
	a := &App{
		Config: cfg,
	}
	// Setup Library
	a.Library = media.NewLibrary()
	// Setup Store
	store, err := NewBitcaskStore(cfg.Server.StorePath)
	if err != nil {
		err := fmt.Errorf("error opening store %s: %w", cfg.Server.StorePath, err)
		return nil, err
	}
	a.Store = store
	// Setup Watcher
	w, err := fsnotify.NewWatcher()
	if err != nil {
		return nil, err
	}
	a.Watcher = w
	// Setup Listener
	ln, err := newListener(cfg.Server)
	if err != nil {
		return nil, err
	}
	a.Listener = ln

	// Templates
	box := rice.MustFindBox("../templates")

	a.Templates = newTemplateStore("base")

	templateFuncs := map[string]interface{}{
		"bytes": func(size int64) string { return humanize.Bytes(uint64(size)) },
	}

	indexTemplate := template.New("index").Funcs(templateFuncs)
	template.Must(indexTemplate.Parse(box.MustString("index.html")))
	template.Must(indexTemplate.Parse(box.MustString("base.html")))
	a.Templates.Add("index", indexTemplate)

	uploadTemplate := template.New("upload").Funcs(templateFuncs)
	template.Must(uploadTemplate.Parse(box.MustString("upload.html")))
	template.Must(uploadTemplate.Parse(box.MustString("base.html")))
	a.Templates.Add("upload", uploadTemplate)

	importTemplate := template.New("import").Funcs(templateFuncs)
	template.Must(importTemplate.Parse(box.MustString("import.html")))
	template.Must(importTemplate.Parse(box.MustString("base.html")))
	a.Templates.Add("import", importTemplate)

	// Setup Router
	r := mux.NewRouter().StrictSlash(true)
	r.HandleFunc("/", a.indexHandler).Methods("GET", "OPTIONS")
	r.HandleFunc("/upload", a.uploadHandler).Methods("GET", "OPTIONS", "POST")
	r.HandleFunc("/import", a.importHandler).Methods("GET", "OPTIONS", "POST")
	r.HandleFunc("/v/{id}.mp4", a.videoHandler).Methods("GET")
	r.HandleFunc("/v/{prefix}/{id}.mp4", a.videoHandler).Methods("GET")
	r.HandleFunc("/t/{id}", a.thumbHandler).Methods("GET")
	r.HandleFunc("/t/{prefix}/{id}", a.thumbHandler).Methods("GET")
	r.HandleFunc("/v/{id}", a.pageHandler).Methods("GET")
	r.HandleFunc("/v/{prefix}/{id}", a.pageHandler).Methods("GET")
	r.HandleFunc("/feed.xml", a.rssHandler).Methods("GET")
	// Static file handler
	fsHandler := http.StripPrefix(
		"/static",
		http.FileServer(rice.MustFindBox("../static").HTTPBox()),
	)
	r.PathPrefix("/static/").Handler(fsHandler).Methods("GET")

	cors := handlers.CORS(
		handlers.AllowedHeaders([]string{
			"X-Requested-With",
			"Content-Type",
			"Authorization",
		}),
		handlers.AllowedMethods([]string{
			"GET",
			"POST",
			"PUT",
			"HEAD",
			"OPTIONS",
		}),
		handlers.AllowedOrigins([]string{"*"}),
		handlers.AllowCredentials(),
	)

	r.Use(cors)

	a.Router = r
	return a, nil
}

// Run imports the library and starts server.
func (a *App) Run() error {
	for _, pc := range a.Config.Library {
		p := &media.Path{
			Path:   pc.Path,
			Prefix: pc.Prefix,
		}
		err := a.Library.AddPath(p)
		if err != nil {
			return err
		}
		err = a.Library.Import(p)
		if err != nil {
			return err
		}
		a.Watcher.Add(p.Path)
	}
	buildFeed(a)
	go startWatcher(a)
	return http.Serve(a.Listener, a.Router)
}

func (a *App) render(name string, w http.ResponseWriter, ctx interface{}) {
	buf, err := a.Templates.Exec(name, ctx)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}

	_, err = buf.WriteTo(w)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}

// HTTP handler for /
func (a *App) indexHandler(w http.ResponseWriter, r *http.Request) {
	log.Printf("/")
	pl := a.Library.Playlist()
	if len(pl) > 0 {
		http.Redirect(w, r, fmt.Sprintf("/v/%s?%s", pl[0].ID, r.URL.RawQuery), 302)
	} else {
		ctx := &struct {
			Sort     string
			Playing  *media.Video
			Playlist media.Playlist
		}{
			Sort:     "",
			Playing:  &media.Video{ID: ""},
			Playlist: a.Library.Playlist(),
		}

		a.render("index", w, ctx)
	}
}

// HTTP handler for /upload
func (a *App) uploadHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method == "GET" {
		ctx := &struct{}{}
		a.render("upload", w, ctx)
	} else if r.Method == "POST" {
		// TODO: Move to a constant
		r.ParseMultipartForm((10 << 20) * 10) // 100MB

		file, handler, err := r.FormFile("video_file")
		if err != nil {
			err := fmt.Errorf("error processing form: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer file.Close()

		title := r.FormValue("video_title")
		description := r.FormValue("video_description")

		// TODO: Make collection user selectable from drop-down in Form
		// XXX: Assume we can put uploaded videos into the first collection (sorted) we find
		keys := make([]string, 0, len(a.Library.Paths))
		for k := range a.Library.Paths {
			keys = append(keys, k)
		}
		sort.Strings(keys)
		collection := keys[0]

		uf, err := ioutil.TempFile(
			a.Config.Server.UploadPath,
			fmt.Sprintf("tube-upload-*%s", filepath.Ext(handler.Filename)),
		)
		if err != nil {
			err := fmt.Errorf("error creating temporary file for uploading: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer os.Remove(uf.Name())

		_, err = io.Copy(uf, file)
		if err != nil {
			err := fmt.Errorf("error writing file: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		tf, err := ioutil.TempFile(
			a.Config.Server.UploadPath,
			fmt.Sprintf("tube-transcode-*.mp4"),
		)
		if err != nil {
			err := fmt.Errorf("error creating temporary file for transcoding: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		vf := filepath.Join(
			a.Library.Paths[collection].Path,
			fmt.Sprintf("%s.mp4", shortuuid.New()),
		)
		thumbFn1 := fmt.Sprintf("%s.jpg", strings.TrimSuffix(tf.Name(), filepath.Ext(tf.Name())))
		thumbFn2 := fmt.Sprintf("%s.jpg", strings.TrimSuffix(vf, filepath.Ext(vf)))

		// TODO: Use a proper Job Queue and make this async
		if err := utils.RunCmd(
			a.Config.Transcoder.Timeout,
			"ffmpeg",
			"-y",
			"-i", uf.Name(),
			"-vcodec", "h264",
			"-acodec", "aac",
			"-strict", "-2",
			"-loglevel", "quiet",
			"-metadata", fmt.Sprintf("title=%s", title),
			"-metadata", fmt.Sprintf("comment=%s", description),
			tf.Name(),
		); err != nil {
			err := fmt.Errorf("error transcoding video: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		if err := utils.RunCmd(
			a.Config.Thumbnailer.Timeout,
			"mt",
			"-b",
			"-s",
			"-n", "1",
			tf.Name(),
		); err != nil {
			err := fmt.Errorf("error generating thumbnail: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		if err := os.Rename(thumbFn1, thumbFn2); err != nil {
			err := fmt.Errorf("error renaming generated thumbnail: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		if err := os.Rename(tf.Name(), vf); err != nil {
			err := fmt.Errorf("error renaming transcoded video: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		fmt.Fprintf(w, "Video successfully uploaded!")
	} else {
		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
	}
}

// HTTP handler for /import
func (a *App) importHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method == "GET" {
		ctx := &struct{}{}
		a.render("import", w, ctx)
	} else if r.Method == "POST" {
		r.ParseMultipartForm(1024)

		url := r.FormValue("url")
		if url == "" {
			err := fmt.Errorf("error, no url supplied")
			log.Error(err)
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		// TODO: Make collection user selectable from drop-down in Form
		// XXX: Assume we can put uploaded videos into the first collection (sorted) we find
		keys := make([]string, 0, len(a.Library.Paths))
		for k := range a.Library.Paths {
			keys = append(keys, k)
		}
		sort.Strings(keys)
		collection := keys[0]

		vid, err := ytdl.GetVideoInfo(url)
		if err != nil {
			err := fmt.Errorf("error retriving video info for %s: %w", url, err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		uf, err := ioutil.TempFile(
			a.Config.Server.UploadPath,
			fmt.Sprintf("tube-import-*.mp4"),
		)
		if err != nil {
			err := fmt.Errorf("error creating temporary file for importing: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		defer os.Remove(uf.Name())

		err = vid.Download(vid.Formats[0], uf)
		if err != nil {
			err := fmt.Errorf("error downloading video %s: %w", url, err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		tf, err := ioutil.TempFile(
			a.Config.Server.UploadPath,
			fmt.Sprintf("tube-transcode-*.mp4"),
		)
		if err != nil {
			err := fmt.Errorf("error creating temporary file for transcoding: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		vf := filepath.Join(
			a.Library.Paths[collection].Path,
			fmt.Sprintf("%s.mp4", shortuuid.New()),
		)
		thumbFn1 := fmt.Sprintf("%s.jpg", strings.TrimSuffix(tf.Name(), filepath.Ext(tf.Name())))
		thumbFn2 := fmt.Sprintf("%s.jpg", strings.TrimSuffix(vf, filepath.Ext(vf)))

		thumbURL := vid.GetThumbnailURL(ytdl.ThumbnailQualityHigh)
		res, err := http.Get(thumbURL.String())
		if err != nil {
			err := fmt.Errorf("error downloading thumbnail: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		thumbData, err := ioutil.ReadAll(res.Body)
		res.Body.Close()
		if err != nil {
			err := fmt.Errorf("error reading thumbnail data: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		if err := ioutil.WriteFile(thumbFn1, thumbData, 0644); err != nil {
			err := fmt.Errorf("error writing thumbnail data: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		// TODO: Use a proper Job Queue and make this async
		if err := utils.RunCmd(
			a.Config.Transcoder.Timeout,
			"ffmpeg",
			"-y",
			"-i", uf.Name(),
			"-vcodec", "h264",
			"-acodec", "aac",
			"-strict", "-2",
			"-loglevel", "quiet",
			"-metadata", fmt.Sprintf("title=%s", vid.Title),
			"-metadata", fmt.Sprintf("comment=%s", vid.Description),
			tf.Name(),
		); err != nil {
			err := fmt.Errorf("error transcoding video: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		if err := os.Rename(thumbFn1, thumbFn2); err != nil {
			err := fmt.Errorf("error renaming generated thumbnail: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		if err := os.Rename(tf.Name(), vf); err != nil {
			err := fmt.Errorf("error renaming transcoded video: %w", err)
			log.Error(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		fmt.Fprintf(w, "Video successfully imported!")
	} else {
		http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
	}
}

// HTTP handler for /v/id
func (a *App) pageHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	prefix, ok := vars["prefix"]
	if ok {
		id = path.Join(prefix, id)
	}
	log.Printf("/v/%s", id)
	playing, ok := a.Library.Videos[id]
	if !ok {
		ctx := &struct {
			Playing  *media.Video
			Playlist media.Playlist
		}{
			Playing:  &media.Video{ID: ""},
			Playlist: a.Library.Playlist(),
		}
		a.render("upload", w, ctx)
		return
	}

	views, err := a.Store.GetViews(id)
	if err != nil {
		err := fmt.Errorf("error retrieving views for %s: %w", id, err)
		log.Warn(err)
	}

	playing.Views = views

	playlist := a.Library.Playlist()

	// TODO: Optimize this? Bitcask has no concept of MultiGet / MGET
	for _, video := range playlist {
		views, err := a.Store.GetViews(video.ID)
		if err != nil {
			err := fmt.Errorf("error retrieving views for %s: %w", video.ID, err)
			log.Warn(err)
		}
		video.Views = views
	}

	sort := strings.ToLower(r.URL.Query().Get("sort"))
	switch sort {
	case "views":
		media.By(media.SortByViews).Sort(playlist)
	case "", "timestamp":
		media.By(media.SortByTimestamp).Sort(playlist)
	default:
		// By default the playlist is sorted by Timestamp
		log.Warnf("invalid sort critiera: %s", sort)
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	ctx := &struct {
		Sort     string
		Playing  *media.Video
		Playlist media.Playlist
	}{
		Sort:     sort,
		Playing:  playing,
		Playlist: playlist,
	}
	a.render("index", w, ctx)
}

// HTTP handler for /v/id.mp4
func (a *App) videoHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	prefix, ok := vars["prefix"]
	if ok {
		id = path.Join(prefix, id)
	}
	log.Printf("/v/%s", id)
	m, ok := a.Library.Videos[id]
	if !ok {
		return
	}

	if err := a.Store.Migrate(prefix, id); err != nil {
		err := fmt.Errorf("error migrating store data: %w", err)
		log.Warn(err)
	}

	if err := a.Store.IncViews(id); err != nil {
		err := fmt.Errorf("error updating view for %s: %w", id, err)
		log.Warn(err)
	}

	title := m.Title
	disposition := "attachment; filename=\"" + title + ".mp4\""
	w.Header().Set("Content-Disposition", disposition)
	w.Header().Set("Content-Type", "video/mp4")
	http.ServeFile(w, r, m.Path)
}

// HTTP handler for /t/id
func (a *App) thumbHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	prefix, ok := vars["prefix"]
	if ok {
		id = path.Join(prefix, id)
	}
	log.Printf("/t/%s", id)
	m, ok := a.Library.Videos[id]
	if !ok {
		return
	}
	w.Header().Set("Cache-Control", "public, max-age=7776000")
	if m.ThumbType == "" {
		w.Header().Set("Content-Type", "image/jpeg")
		w.Write(rice.MustFindBox("../static").MustBytes("defaulticon.jpg"))
	} else {
		w.Header().Set("Content-Type", m.ThumbType)
		w.Write(m.Thumb)
	}
}

// HTTP handler for /feed.xml
func (a *App) rssHandler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Cache-Control", "public, max-age=7776000")
	w.Header().Set("Content-Type", "text/xml")
	w.Write(a.Feed)
}