package main

import (
	"archive/tar"
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"html/template"
	"io"
	"io/ioutil"
	"log"
	"math"
	"mime"
	"net"
	"net/http"
	"net/http/cookiejar"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"time"

	"git.narnian.us/lordwelch/gloader/bundled"

	"github.com/cavaliercoder/grab"
	"github.com/lordwelch/pathvalidate"
	"github.com/wI2L/jettison"

	"golang.org/x/net/publicsuffix"
)

var (
	DefaultMaxActiveDownloads = 4

	ErrUnsupportedScheme = errors.New("unsupported scheme")
)

type Priority int
type Status int

const (
	Highest Priority = iota
	High
	Medium
	Low
)

const (
	Queued Status = iota
	Complete
	Stopped
	Paused
	Downloading
	Error
	Canceled
)

type Downloader struct {
	DataDir            string
	DownloadDir        string
	CompleteDir        string
	InfoDir            string
	MaxActiveDownloads int
	Server             *http.Server
	Downloads          RequestQueue
	History            RequestQueue
	NewRequest         chan Request
	requestDone        chan *Request
	OnComplete         func(d *Downloader, r Request)
	OnAdd              func(d *Downloader, r Request)
	OnDelete           func(d *Downloader, r Request)
}

type Request struct {
	URL           string         `json:"url"`
	Cookies       []http.Cookie  `json:"cookies"`
	ForceDownload bool           `json:"forceDownload"`
	Status        Status         `json:"status"`
	Priority      Priority       `json:"priority"`
	FilePath      string         `json:"filepath"`
	Filename      string         `json:"filename"`
	Subdir        string         `json:"subdir"`
	TempPath      string         `json:"tempPath"`
	Response      *grab.Response `json:"-"`
	Error         string         `json:"error"`
	Err           error          `json:"-"`
	Completed     time.Time      `json:"completed"`
	Started       time.Time      `json:"started"`
	Jar           http.CookieJar `json:"-"`
	Progress      string         `json:"progress,omitempty"`
	grab          *grab.Client
}

type RequestQueue struct {
	Queue    []*Request
	URLSort  bool
	DateSort bool
}

func (p Priority) MarshalJSON() ([]byte, error) {
	var v string
	switch p {
	default:
		v = "Medium"
	case Medium:
		v = "Medium"
	case Low:
		v = "Low"
	case High:
		v = "High"
	case Highest:
		v = "Highest"
	}
	return json.Marshal(v)
}

func (p *Priority) UnmarshalJSON(b []byte) error {
	var (
		v int
		s string
	)
	if err := json.Unmarshal(b, &v); err == nil {
		*p = Priority(v)
		return nil
	}
	json.Unmarshal(b, &s)
	switch strings.ToLower(s) {
	default:
		*p = Medium
	case "medium":
		*p = Medium
	case "low":
		*p = Low
	case "high":
		*p = High
	case "highest":
		*p = Highest
	}
	return nil
}

func (s *Status) UnmarshalJSON(b []byte) error {
	var v string
	json.Unmarshal(b, &v)
	switch strings.ToLower(v) {
	default:
		*s = Queued
	case "queue", "queued":
		*s = Queued
	case "complete", "completed":
		*s = Complete
	case "stop", "stopped":
		*s = Stopped
	case "download", "downloading":
		*s = Downloading
	case "error":
		*s = Error
	case "cancel", "canceled":
		*s = Canceled
	}
	return nil
}

func (s Status) MarshalJSON() ([]byte, error) {
	return json.Marshal(s.String())
}

func (s Status) String() string {
	switch s {
	default:
		return "Queued"
	case Queued:
		return "Queued"
	case Complete:
		return "Complete"
	case Stopped:
		return "Stopped"
	case Downloading:
		return "Downloading"
	case Error:
		return "Error"
	case Canceled:
		return "Canceled"
	}
}

func (rq RequestQueue) Less(i, j int) bool {
	ii := 0
	jj := 0
	if rq.Queue[i].ForceDownload {
		ii = 1
	}
	if rq.Queue[j].ForceDownload {
		jj = 1
	}
	if ii < jj {
		return true
	}

	if rq.Queue[i].Priority < rq.Queue[j].Priority {
		return true
	}

	if rq.DateSort && rq.Queue[i].Completed.Before(rq.Queue[j].Completed) {
		return true
	}

	if rq.URLSort && rq.Queue[i].URL < rq.Queue[j].URL {
		return true
	}

	return false
}

func (rq RequestQueue) Len() int {
	return len(rq.Queue)
}

func (rq RequestQueue) Swap(i, j int) {
	rq.Queue[i], rq.Queue[j] = rq.Queue[j], rq.Queue[i]
}

func (rq *RequestQueue) Pop(i int) *Request {
	r := rq.Queue[i]
	copy(rq.Queue[i:], rq.Queue[i+1:])
	rq.Queue[len(rq.Queue)-1] = nil
	rq.Queue = rq.Queue[:len(rq.Queue)-1]
	return r
}

func (rq *RequestQueue) find(url string) *Request {
	for _, req := range rq.Queue {
		if req.URL == url {
			return req
		}
	}
	return nil
}

func (rq *RequestQueue) remove(url string) *Request {
	for i, req := range rq.Queue {
		if req.URL == url {
			copy(rq.Queue[i:], rq.Queue[i+1:])
			rq.Queue[len(rq.Queue)-1] = nil
			rq.Queue = rq.Queue[:len(rq.Queue)-1]
			return req
		}
	}
	return nil
}

func (rq *RequestQueue) updateStatus() {
	for _, req := range rq.Queue {
		if req.Response != nil {
			req.Progress = fmt.Sprintf("%.2f", math.Abs(req.Response.Progress()*100))
		}
	}
}

func (r *Request) setError(err error) {
	if err != nil {
		r.Status = Error
		r.Err = err
		r.Error = err.Error()
	} else {
		r.Status = Paused
		r.Err = nil
		r.Error = ""
	}
}

func (r Request) Delete() error {
	var err, ret error
	if r.Response != nil {
		err = r.Response.Cancel()
		if err != nil && err != context.Canceled {
			ret = err
		}
	}
	_ = os.Remove(r.TempPath)
	err = os.Remove(r.FilePath)
	if err != nil && err != os.ErrNotExist {
		ret = err
	}
	return ret
}

func newCookieJar() http.CookieJar {
	c, _ := cookiejar.New(&cookiejar.Options{PublicSuffixList: publicsuffix.List})
	return c
}

func (d *Downloader) Start(network, address string) {
	var (
		listener net.Listener
		mux      = http.NewServeMux()
		err      error
	)

	if d.NewRequest == nil {
		d.NewRequest = make(chan Request, 64)
	}

	if d.requestDone == nil {
		d.requestDone = make(chan *Request, 64)
	}

	if d.MaxActiveDownloads < 1 {
		d.MaxActiveDownloads = DefaultMaxActiveDownloads
	}

	if d.Server == nil {
		d.Server = &http.Server{
			Addr:         address,
			Handler:      mux,
			ReadTimeout:  2 * time.Minute,
			WriteTimeout: 2 * time.Minute,
		}
	}

	if d.DataDir == "" {
		d.DataDir = "/perm/gloader"
	}

	if d.DownloadDir == "" {
		d.DownloadDir = path.Join(d.DataDir, "Download")
	}

	if d.CompleteDir == "" {
		d.CompleteDir = path.Join(d.DataDir, "Complete")
	}

	log.Println(d.DataDir)
	log.Println(d.DownloadDir)
	log.Println(d.CompleteDir)
	_ = os.MkdirAll(d.DataDir, 0777)
	_ = os.MkdirAll(d.DownloadDir, 0777)
	_ = os.MkdirAll(d.CompleteDir, 0777)

	listener, err = net.Listen(network, address)
	if err != nil {
		panic(err)
	}
	log.Println("adding http handlers")

	d.initStatus(mux)
	mux.HandleFunc("/add", d.restAddDownload)
	mux.HandleFunc("/queued", d.restStatus(true))
	mux.HandleFunc("/completed", d.restStatus(false))
	mux.HandleFunc("/set", d.restSetDownloadStatus)
	mux.HandleFunc("/delete", d.restDelete)
	mux.Handle("/get/", http.StripPrefix("/get", http.HandlerFunc(d.get)))

	log.Println("starting main go routine")

	go d.download()

	log.Println("serving http server")
	_ = d.Server.Serve(listener)
}

func httpMethodNotAllowed(w http.ResponseWriter, method ...string) {
	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.Header().Add("Allow", strings.Join(method, ", "))
	w.WriteHeader(http.StatusMethodNotAllowed)
	fmt.Fprintf(w, "HTTP Error 405 – Method Not Allowed\nOnly %s method(s) is allowed\n", strings.Join(method, ", "))
	log.Printf("HTTP Error 405 – Method Not Allowed\nOnly %s method(s) is allowed\n", strings.Join(method, ", "))
}

func (d *Downloader) get(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet && r.Method != http.MethodPost {
		httpMethodNotAllowed(w, http.MethodPost, http.MethodGet)
		return
	}
	if r.Method == http.MethodGet {
		var file = filepath.Join(d.CompleteDir, strings.TrimLeft(filepath.Clean(r.URL.Path), "./"))
		http.ServeFile(w, r, file)
		return
	}
	if r.Method == http.MethodPost {
		var (
			downloads []struct {
				Subdir   string
				Filename string
			}
			filenames []string
			err       error
		)
		err = json.NewDecoder(r.Body).Decode(&downloads)
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}

		filenames = make([]string, 0, len(downloads))

		for _, name := range downloads {
			var (
				subdir   = strings.TrimLeft(filepath.Clean(name.Subdir), "./")
				filename = strings.TrimLeft(filepath.Clean(name.Filename), "./")
			)
			filenames = append(filenames, filepath.Join(d.CompleteDir, subdir, filename))
		}
		tarFiles(w, filenames...)
		return
	}
}
func tarFiles(w http.ResponseWriter, files ...string) {
	var (
		err  error
		size int64
	)

	size, err = DirSize(files...)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Header().Add("content-length", fmt.Sprintf("%v", size))
	w.Header().Add("content-disposition", fmt.Sprintf("attachment; filename=\"downloads_%v.tar\"", time.Now().Format("01-02-2006_15-04-05")))
	w.Header().Add("content-type", "application/x-tar")

	tw := tar.NewWriter(w)
	defer tw.Close()
	var tarLength int64
	for _, filename := range files {
		var (
			info os.FileInfo
			file io.ReadCloser
		)
		info, err = os.Stat(filename)
		if err != nil {
			break
		}
		err = tw.WriteHeader(&tar.Header{
			Name: info.Name(),
			Mode: 0777,
			Size: info.Size(),
		})
		if err != nil {
			break
		}
		file, err = os.OpenFile(filename, os.O_RDONLY, 0o666)
		if err != nil {
			break
		}
		var data int64
		data, err = io.Copy(tw, file)
		tarLength += data
		file.Close()
		if err != nil {
			break
		}
	}
}

func DirSize(files ...string) (int64, error) {
	var size int64
	var err error

	for _, filename := range files {
		var (
			info os.FileInfo
		)
		info, err = os.Stat(filename)
		if err != nil {
			break
		}
		size += info.Size() + 512
		remainder := size % 512
		if remainder > 0 {
			size += 512 - remainder
		}
	}
	size += 1024
	return size, err
}

func (d *Downloader) restDelete(w http.ResponseWriter, r *http.Request) {
	var (
		err       error
		downloads struct {
			Requests []struct {
				URL string
			}
			History bool
		}
		ret []*Request
	)
	if r.Method != http.MethodDelete {
		httpMethodNotAllowed(w, http.MethodDelete)
		return
	}
	err = json.NewDecoder(r.Body).Decode(&downloads)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	sort.Slice(downloads.Requests, func(i, j int) bool {
		return downloads.Requests[i].URL < downloads.Requests[j].URL
	})
	if downloads.History {
		for _, i := range downloads.Requests {
			ret = append(ret, d.History.remove(i.URL))
			ret[len(ret)-1].Delete()
			if d.OnDelete != nil {
				d.OnDelete(d, *ret[len(ret)-1])
			}
		}
	} else {
		for _, i := range downloads.Requests {
			ret = append(ret, d.Downloads.remove(i.URL))
			ret[len(ret)-1].Delete()
			if d.OnDelete != nil {
				d.OnDelete(d, *ret[len(ret)-1])
			}
		}
	}
	d.syncDownloads()

	v, err := jettison.MarshalOpts(ret, jettison.DenyList([]string{"cookies"}))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Header().Add("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(http.StatusOK)
	w.Write(v)
}

func (d *Downloader) restSetDownloadStatus(w http.ResponseWriter, r *http.Request) {
	var (
		err       error
		downloads []struct {
			URL      string
			Status   Status
			Priority Priority
		}
		req *Request
	)
	if r.Method != http.MethodPost {
		httpMethodNotAllowed(w, http.MethodPost)
		return
	}
	err = json.NewDecoder(r.Body).Decode(&downloads)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	for _, i := range downloads {
		req = d.Downloads.find(i.URL)
		req.Priority = i.Priority
		req.Status = i.Status
		req.Err = nil
		req.Error = ""
	}
	d.syncDownloads()
}

func (d *Downloader) restStatus(q bool) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		w.Header().Add("Access-Control-Allow-Origin", "*")
		w.Header().Add("Access-Control-Allow-Methods", "GET")
		w.Header().Add("Access-Control-Allow-Headers", "X-PINGOTHER, Content-Type")
		if r.Method == http.MethodOptions {
			w.Header().Add("Allow", "GET")
			w.WriteHeader(http.StatusNoContent)
			return
		}
		var queue = &d.History
		if q {
			d.Downloads.updateStatus()
			queue = &d.Downloads
		}

		if r.Method != http.MethodGet {
			httpMethodNotAllowed(w, http.MethodGet)
			return
		}
		queue.updateStatus()
		v, err := jettison.MarshalOpts(queue.Queue, jettison.DenyList([]string{"cookies"}))
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		w.Header().Add("Content-Type", "application/json; charset=utf-8")
		w.WriteHeader(http.StatusOK)
		w.Write(v)
	}
}

func (d *Downloader) restAddDownload(w http.ResponseWriter, r *http.Request) {
	var (
		requests []Request
		err      error
	)
	if r.Method != http.MethodPost {
		httpMethodNotAllowed(w, http.MethodPost)
		return
	}
	// TODO fail only on individual requests
	err = json.NewDecoder(r.Body).Decode(&requests)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	for _, req := range requests {
		req.TempPath = "" // not allowed via REST API
		req.FilePath = "" // not allowed via REST API
		if req.Status != Paused {
			req.Status = Queued
		}
		log.Println("adding request", req.URL)
		d.NewRequest <- req
	}
	w.WriteHeader(http.StatusOK)
}

func (d Downloader) getNameFromHEAD(r Request) string {
	var (
		err error
		re  *http.Response
		p   map[string]string
	)

	r.insertCookies()
	ht := &http.Client{
		Jar:     r.Jar,
		Timeout: 30 * time.Second,
		Transport: &http.Transport{
			Dial: (&net.Dialer{
				Timeout:   5 * time.Second,
				KeepAlive: 30 * time.Second,
			}).Dial,
			TLSHandshakeTimeout:   5 * time.Second,
			ResponseHeaderTimeout: 5 * time.Second,
			ExpectContinueTimeout: 1 * time.Second,
		},
	}
	re, err = ht.Head(r.URL)
	if err != nil {
		return ""
	}
	if re.StatusCode < 200 || re.StatusCode > 299 {
		return ""
	}
	re.Body.Close()
	_, p, err = mime.ParseMediaType(re.Header.Get("Content-Disposition"))
	if err == nil {
		if f, ok := p["filename"]; ok {
			return f
		}
	}
	return path.Base(re.Request.URL.Path)
}

// getFilename checks the provided filepath
// if not set uses the content-disposition from a head request
// if not set uses the basename of the url
// and sanitizes the filename using github.com/lordwelch/pathvalidate
func (d *Downloader) getFilename(r *Request) {
	log.Println("Determining filename")
	r.Filename = filepath.Clean(r.Filename)
	if r.Filename == "." {
		log.Println("filename is empty, testing head request")
		r.Filename = d.getNameFromHEAD(*r)
		log.Println("path from head request:", r.Filename)
		if r.Filename == "" {
			u, _ := url.Parse(r.URL)
			r.Filename, _ = url.PathUnescape(filepath.Base(u.Path))
		}
	}
	r.Filename, _ = pathvalidate.SanitizeFilename(r.Filename, '_')
	// r.Filename = filepath.Join(d.CompleteDir, r.Filename)

	// if filepath.IsAbs(r.Filename) { // should already exist
	// 	dir, file := filepath.Split(r.Filename)
	// 	// someone is trying to be sneaky (or someone changed the CompleteDir), change path to the correct dir
	// 	if dir != filepath.Clean(d.CompleteDir) {
	// 		r.Filename = filepath.Join(d.CompleteDir, file)
	// 	}
	// 	return
	// }
	log.Println("result path:", r.Filename)
}

func getNewFilename(dir, name string) string {
	var (
		err   error
		index = 1
	)
	log.Println("getfilename", dir, name)
	ext := filepath.Ext(name)
	base := strings.TrimSuffix(name, ext)
	log.Println("stat", filepath.Join(dir, name))
	_, err = os.Stat(filepath.Join(dir, name))
	for err == nil {
		name = strings.TrimRight(base+"."+strconv.Itoa(index)+ext, ".")
		log.Println("stat", filepath.Join(dir, name))
		_, err = os.Stat(filepath.Join(dir, name))
		index++
	}
	if os.IsNotExist(err) {
		return filepath.Join(dir, name)
	}
	panic(err) // other path error
}

func (d Downloader) getTempFilename(r *Request) {
	if r.TempPath == "" {
		f, err := ioutil.TempFile(d.DownloadDir, filepath.Base(r.Filename))
		if err != nil {
			log.Printf("request for %v failed: %v", r.URL, err)
		}
		r.TempPath = f.Name()
		f.Close()
	}
	os.MkdirAll(filepath.Dir(r.FilePath), 0o777)
	f, err := os.OpenFile(r.Filename, os.O_CREATE|os.O_EXCL, 0666)
	if err != nil {
		return
	}
	f.Close()
}

func (d Downloader) SearchDownloads(u string) int {
	for i, req := range d.Downloads.Queue {
		if req.URL == u {
			return i
		}
	}
	return -1
}

func (d Downloader) SearchHistory(u string) int {
	for i, req := range d.History.Queue {
		if req.URL == u {
			return i
		}
	}
	return -1
}

func (d Downloader) FindRequest(u string) *Request {
	if i := d.SearchDownloads(u); i >= 0 {
		return d.Downloads.Queue[i]
	}
	if i := d.SearchHistory(u); i >= 0 {
		return d.History.Queue[i]
	}
	return nil
}

func (d *Downloader) addRequest(r *Request) {
	log.Println("adding download for", r.URL)
	req := d.FindRequest(r.URL)
	d.getFilename(r)

	if req != nil { // url alread added
		log.Println("URL is already added", r.URL)
		return
		// if fi, err := os.Stat(r.Filepath); filepath.Base(req.Filepath) == filepath.Base(r.Filepath) || (err == nil && fi.Name() == filepath.Base(r.Filepath) && fi.Size() != 0) { // filepath has been found, should this check for multiple downloads of the same url or let the download name increment automatically
		// 	log.Println("file already exists", r.Filepath)
		// 	d.validate(*r) // TODO, should also check to see if it seems like it is similar, (check first k to see if it is the same file?? leave option to user)
		// 	return
		// }
	}
	r.FilePath = getNewFilename(d.CompleteDir, filepath.Join(r.Subdir, r.Filename))
	d.Downloads.Queue = append(d.Downloads.Queue, r)

	if len(d.getRunningDownloads()) < d.MaxActiveDownloads {
		d.startDownload(d.Downloads.Len() - 1)
	}
}

// func (d *Downloader) validate(r Request) {
// 	//TODO
// }

func (d *Downloader) startDownload(i int) {
	var (
		r   *Request
		req *grab.Request
		err error
	)
	r = d.Downloads.Queue[i]
	r.insertCookies()
	d.getTempFilename(r)
	log.Println("starting download for", r.URL, "to", r.TempPath)
	// d.Downloads.Queue = append(d.Downloads.Queue, r)
	if r.Response == nil || r.Response.Err() != nil {
		req, err = grab.NewRequest(r.TempPath, r.URL)
		if err != nil {
			r.setError(err)
			return
		}
	}
	r.Status = Downloading

	if r.grab == nil {
		r.grab = &grab.Client{
			HTTPClient: &http.Client{
				Jar: r.Jar,
				Transport: &http.Transport{
					Dial: (&net.Dialer{
						Timeout:   10 * time.Second,
						KeepAlive: 30 * time.Second,
					}).Dial,
					TLSHandshakeTimeout:   5 * time.Second,
					ResponseHeaderTimeout: 5 * time.Second,
					ExpectContinueTimeout: 1 * time.Second,
				},
			},
		}
	}

	r.Response = r.grab.Do(req)
	r.Started = time.Now()
	go func(r *Request) {
		log.Println("wait for download")
		log.Println(r.Response.IsComplete())
		r.Response.Wait()
		log.Println("download completed for", r.URL)
		d.requestDone <- r
	}(r)
}

func (d Downloader) getRunningDownloads() []*Request {
	var (
		running = make([]*Request, 0, d.MaxActiveDownloads)
	)
	for _, req := range d.Downloads.Queue {
		if req.Status == Downloading && req.Response != nil {
			running = append(running, req)
		}
	}
	return running
}

func (d *Downloader) syncDownloads() {
	if len(d.getRunningDownloads()) >= d.MaxActiveDownloads {
		return
	}
	sort.Stable(d.Downloads)
	var downloadsMaxed bool
	// Start new downloads
	for i, req := range d.Downloads.Queue {
		switch req.Status {
		case Queued:
			if !downloadsMaxed && d.MaxActiveDownloads >= len(d.getRunningDownloads()) {
				d.startDownload(i)
			}
		case Stopped:
			if req.Response != nil {
				var err = req.Response.Cancel()
				if err != nil && err != context.Canceled {
					req.setError(err)
				}
				req.Response = nil
			}
		case Downloading:
			if req.Response == nil {
				d.startDownload(i)
			}
		case Error:
			if req.Response != nil && req.Err == nil {
				var err = req.Response.Err()
				var err2 = req.Response.Cancel()
				if err != nil && err2 != context.Canceled {
					err = err2
				}
				req.setError(err)
			}
		case Canceled:
			if req.Response != nil {
				err := req.Response.Cancel()
				if err != nil && err != context.Canceled {
					req.setError(err)
				}
				req.Response = nil
			}
		}
	}

	// Clean completed/canceled downloads
	for i := 0; i < d.Downloads.Len(); i++ {
		if d.Downloads.Queue[i].Status == Complete || d.Downloads.Queue[i].Status == Canceled {
			d.History.Queue = append(d.History.Queue, d.Downloads.Pop(i))
			i--
		}
	}
	d.Downloads.updateStatus()
}

func (d *Downloader) requestCompleted(r *Request) {
	if r.Response.Err() == nil {
		log.Println("removing from downloads")
		d.Downloads.remove(r.URL)
		r.Status = Complete
		log.Println(r.TempPath, "!=", r.FilePath)
		if r.TempPath != r.FilePath {
			log.Println("renaming download to the completed dir")
			os.Rename(r.TempPath, r.FilePath)
		}
		d.History.Queue = append(d.History.Queue, r)
		r.Completed = time.Now()
	} else {
		r.setError(r.Response.Err())
		log.Println("fucking error:", r.Err)
	}
}

func (d *Downloader) download() {
	for {
		select {
		case <-time.After(10 * time.Second):
			d.syncDownloads()

		case r := <-d.NewRequest:
			r.Progress = "" // not allowed when adding
			d.addRequest(&r)
			if d.OnAdd != nil {
				d.OnAdd(d, r)
			}

		case r := <-d.requestDone:
			log.Println("finishing request for", r.URL)
			d.requestCompleted(r)
			if d.OnComplete != nil {
				d.OnComplete(d, *r)
			}
		}
	}
}

func (r *Request) insertCookies() {
	if r.Jar == nil {
		r.Jar = newCookieJar()
	}
	u, _ := url.Parse(r.URL)
	for i, v := range r.Cookies {
		r.Jar.SetCookies(&url.URL{
			Scheme: u.Scheme,
			Path:   v.Path,
			Host:   v.Domain,
		}, []*http.Cookie{&r.Cookies[i]})
	}
}

func (d *Downloader) initStatus(mux *http.ServeMux) {
	for _, fn := range []string{
		"bootstrap-table-auto-refresh.min.js",
		"bootstrap-table-sticky-header.css",
		"bootstrap-table-sticky-header.min.js",
		"bootstrap-table.min.css",
		"bootstrap-table.min.js",
		"bootstrap.min.css",
		"bootstrap.min.js",
		"fontawesome.css",
		"jquery-3.2.1.min.js",
		"popper.min.js",
		"fa-solid-900.woff2",
		"downloads.js",
		"favicon.ico",
	} {
		mux.Handle("/"+fn, bundled.HTTPHandlerFunc(fn))
	}
	mux.HandleFunc("/", d.httpQueue(false))
	mux.HandleFunc("/history", d.httpQueue(true))
}
func (d *Downloader) httpQueue(history bool) func(w http.ResponseWriter, r *http.Request) {
	commonTmpls := template.New("root")
	commonTmpls = template.Must(commonTmpls.New("header").Parse(bundled.Asset("header.tmpl")))
	commonTmpls = template.Must(commonTmpls.New("footer").Parse(bundled.Asset("footer.tmpl")))

	queueTmpl := template.Must(template.Must(commonTmpls.Clone()).New("queueTmpl").Parse(bundled.Asset("queue.tmpl")))
	return func(w http.ResponseWriter, r *http.Request) {
		var buf bytes.Buffer
		d.Downloads.updateStatus()
		if err := queueTmpl.Execute(&buf, struct {
			Queue     []*Request
			History   []*Request
			Hostname  string
			IsHistory bool
		}{
			Queue:     d.Downloads.Queue,
			History:   d.History.Queue,
			Hostname:  "gloader",
			IsHistory: history,
		}); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
		io.Copy(w, &buf)
	}
}