/*
The MIT License (MIT)

Copyright (c) 2014-2017 DutchCoders [https://github.com/dutchcoders/]

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package server

import (
	// _ "transfer.sh/app/handlers"
	// _ "transfer.sh/app/utils"

	"archive/tar"
	"archive/zip"
	"bytes"
	"compress/gzip"
	"encoding/json"
	"errors"
	"fmt"
	"html"
	html_template "html/template"
	"io"
	"io/ioutil"
	"log"
	"math/rand"
	"mime"
	"net/http"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	text_template "text/template"
	"time"

	"net"

	web "github.com/dutchcoders/transfer.sh-web"
	"github.com/gorilla/mux"
	"github.com/russross/blackfriday"
)

var (
	htmlTemplates = initHTMLTemplates()
	textTemplates = initTextTemplates()
)

func stripPrefix(path string) string {
	return strings.Replace(path, web.Prefix+"/", "", -1)
}

func initTextTemplates() *text_template.Template {
	templateMap := text_template.FuncMap{"format": formatNumber}

	// Templates with functions available to them
	var templates = text_template.New("").Funcs(templateMap)
	return templates
}

func initHTMLTemplates() *html_template.Template {
	templateMap := html_template.FuncMap{"format": formatNumber}

	// Templates with functions available to them
	var templates = html_template.New("").Funcs(templateMap)

	return templates
}

func healthHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Approaching Neutral Zone, all systems normal and functioning.")
}

/* The preview handler will show a preview of the content for browsers (accept type text/html), and referer is not transfer.sh */
func (s *Server) previewHandler(w http.ResponseWriter, r *http.Request) {

	vars := mux.Vars(r)

	token := vars["token"]
	filename := vars["filename"]

	contentType, contentLength, err := s.storage.Head(token, filename)
	if err != nil {
		http.Error(w, http.StatusText(404), 404)
		return
	}

	var templatePath string
	var content html_template.HTML

	switch {
	case strings.HasPrefix(contentType, "image/"):
		templatePath = "download.image.html"
	case strings.HasPrefix(contentType, "video/"):
		templatePath = "download.video.html"
	case strings.HasPrefix(contentType, "audio/"):
		templatePath = "download.audio.html"
	case strings.HasPrefix(contentType, "text/"):
		templatePath = "download.markdown.html"

		var reader io.ReadCloser
		if reader, _, _, err = s.storage.Get(token, filename); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		var data []byte
		if data, err = ioutil.ReadAll(reader); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		if strings.HasPrefix(contentType, "text/x-markdown") || strings.HasPrefix(contentType, "text/markdown") {
			output := blackfriday.MarkdownCommon(data)
			content = html_template.HTML(output)
		} else if strings.HasPrefix(contentType, "text/plain") {
			content = html_template.HTML(fmt.Sprintf("<pre>%s</pre>", html.EscapeString(string(data))))
		} else {
			templatePath = "download.sandbox.html"
		}

	default:
		templatePath = "download.html"
	}

	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	data := struct {
		ContentType   string
		Content       html_template.HTML
		Filename      string
		Url           string
		ContentLength uint64
	}{
		contentType,
		content,
		filename,
		r.URL.String(),
		contentLength,
	}

	if err := htmlTemplates.ExecuteTemplate(w, templatePath, data); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

}

// this handler will output html or text, depending on the
// support of the client (Accept header).

func (s *Server) viewHandler(w http.ResponseWriter, r *http.Request) {
	// vars := mux.Vars(r)

	if acceptsHTML(r.Header) {
		if err := htmlTemplates.ExecuteTemplate(w, "index.html", nil); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	} else {
		if err := textTemplates.ExecuteTemplate(w, "index.txt", nil); err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}
}

func (s *Server) notFoundHandler(w http.ResponseWriter, r *http.Request) {
	http.Error(w, http.StatusText(404), 404)
}

func sanitize(fileName string) string {
	return path.Clean(path.Base(fileName))
}

func (s *Server) postHandler(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseMultipartForm(_24K); nil != err {
		log.Printf("%s", err.Error())
		http.Error(w, "Error occurred copying to output stream", 500)
		return
	}

	token := Encode(10000000 + int64(rand.Intn(1000000000)))

	w.Header().Set("Content-Type", "text/plain")

	for _, fheaders := range r.MultipartForm.File {
		for _, fheader := range fheaders {
			filename := sanitize(fheader.Filename)
			contentType := fheader.Header.Get("Content-Type")

			if contentType == "" {
				contentType = mime.TypeByExtension(filepath.Ext(fheader.Filename))
			}

			var f io.Reader
			var err error

			if f, err = fheader.Open(); err != nil {
				log.Printf("%s", err.Error())
				http.Error(w, err.Error(), 500)
				return
			}

			var b bytes.Buffer

			n, err := io.CopyN(&b, f, _24K+1)
			if err != nil && err != io.EOF {
				log.Printf("%s", err.Error())
				http.Error(w, err.Error(), 500)
				return
			}

			var reader io.Reader

			if n > _24K {
				file, err := ioutil.TempFile(s.tempPath, "transfer-")
				if err != nil {
					log.Fatal(err)
				}
				defer file.Close()

				n, err = io.Copy(file, io.MultiReader(&b, f))
				if err != nil {
					os.Remove(file.Name())

					log.Printf("%s", err.Error())
					http.Error(w, err.Error(), 500)
					return
				}

				reader, err = os.Open(file.Name())
			} else {
				reader = bytes.NewReader(b.Bytes())
			}

			contentLength := n

			metadata := MetadataForRequest(contentType, r)

			buffer := &bytes.Buffer{}
			if err := json.NewEncoder(buffer).Encode(metadata); err != nil {
				log.Printf("%s", err.Error())
				http.Error(w, errors.New("Could not encode metadata").Error(), 500)
				return
			} else if err := s.storage.Put(token, fmt.Sprintf("%s.metadata", filename), buffer, "text/json", uint64(buffer.Len())); err != nil {
				log.Printf("%s", err.Error())
				http.Error(w, errors.New("Could not save metadata").Error(), 500)
				return
			}

			log.Printf("Uploading %s %s %d %s", token, filename, contentLength, contentType)

			if err = s.storage.Put(token, filename, reader, contentType, uint64(contentLength)); err != nil {
				log.Printf("Backend storage error: %s", err.Error())
				http.Error(w, err.Error(), 500)
				return

			}

			relativeURL, _ := url.Parse(path.Join(token, filename))
			fmt.Fprint(w, getURL(r).ResolveReference(relativeURL).String())
		}
	}
}

type Metadata struct {
	// ContentType is the original uploading content type
	ContentType string
	// Secret as knowledge to delete file
	// Secret string
	// Downloads is the actual number of downloads
	Downloads int
	// MaxDownloads contains the maximum numbers of downloads
	MaxDownloads int
	// MaxDate contains the max age of the file
	MaxDate time.Time
}

func MetadataForRequest(contentType string, r *http.Request) Metadata {
	metadata := Metadata{
		ContentType:  contentType,
		MaxDate:      time.Now().Add(time.Hour * 24 * 365 * 10),
		Downloads:    0,
		MaxDownloads: 99999999,
	}

	if v := r.Header.Get("Max-Downloads"); v == "" {
	} else if v, err := strconv.Atoi(v); err != nil {
	} else {
		metadata.MaxDownloads = v
	}

	if v := r.Header.Get("Max-Days"); v == "" {
	} else if v, err := strconv.Atoi(v); err != nil {
	} else {
		metadata.MaxDate = time.Now().Add(time.Hour * 24 * time.Duration(v))
	}

	return metadata
}

func (s *Server) putHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)

	filename := sanitize(vars["filename"])

	contentLength := r.ContentLength

	var reader io.Reader

	reader = r.Body

	if contentLength == -1 {
		// queue file to disk, because s3 needs content length
		var err error
		var f io.Reader

		f = reader

		var b bytes.Buffer

		n, err := io.CopyN(&b, f, _24K+1)
		if err != nil && err != io.EOF {
			log.Printf("Error putting new file: %s", err.Error())
			http.Error(w, err.Error(), 500)
			return
		}

		if n > _24K {
			file, err := ioutil.TempFile(s.tempPath, "transfer-")
			if err != nil {
				log.Printf("%s", err.Error())
				http.Error(w, err.Error(), 500)
				return
			}

			defer file.Close()

			n, err = io.Copy(file, io.MultiReader(&b, f))
			if err != nil {
				os.Remove(file.Name())
				log.Printf("%s", err.Error())
				http.Error(w, err.Error(), 500)
				return
			}

			reader, err = os.Open(file.Name())
		} else {
			reader = bytes.NewReader(b.Bytes())
		}

		contentLength = n
	}

	contentType := r.Header.Get("Content-Type")

	if contentType == "" {
		contentType = mime.TypeByExtension(filepath.Ext(vars["filename"]))
	}

	token := Encode(10000000 + int64(rand.Intn(1000000000)))

	metadata := MetadataForRequest(contentType, r)

	buffer := &bytes.Buffer{}
	if err := json.NewEncoder(buffer).Encode(metadata); err != nil {
		log.Printf("%s", err.Error())
		http.Error(w, errors.New("Could not encode metadata").Error(), 500)
		return
	} else if err := s.storage.Put(token, fmt.Sprintf("%s.metadata", filename), buffer, "text/json", uint64(buffer.Len())); err != nil {
		log.Printf("%s", err.Error())
		http.Error(w, errors.New("Could not save metadata").Error(), 500)
		return
	}

	log.Printf("Uploading %s %s %d %s", token, filename, contentLength, contentType)

	var err error

	if err = s.storage.Put(token, filename, reader, contentType, uint64(contentLength)); err != nil {
		log.Printf("Error putting new file: %s", err.Error())
		http.Error(w, errors.New("Could not save file").Error(), 500)
		return
	}

	// w.Statuscode = 200

	w.Header().Set("Content-Type", "text/plain")

	relativeURL, _ := url.Parse(path.Join(token, filename))

	fmt.Fprint(w, escapeFilename(r, relativeURL))
}

func escapeFilename(r *http.Request, u *url.URL) string {
	if u.RawQuery != "" {
		u.Path = fmt.Sprintf("%s?%s", u.Path, url.QueryEscape(u.RawQuery))
		u.RawQuery = ""
	}

	if u.Fragment != "" {
		u.Path = fmt.Sprintf("%s#%s", u.Path, u.Fragment)
		u.Fragment = ""
	}

	return getURL(r).ResolveReference(u).String()
}

func getURL(r *http.Request) *url.URL {
	u := *r.URL

	if r.TLS != nil {
		u.Scheme = "https"
	} else if proto := r.Header.Get("X-Forwarded-Proto"); proto != "" {
		u.Scheme = proto
	} else {
		u.Scheme = "http"
	}

	if u.Host != "" {
	} else if host, port, err := net.SplitHostPort(r.Host); err != nil {
		u.Host = r.Host
	} else {
		if port == "80" && u.Scheme == "http" {
			u.Host = host
		} else if port == "443" && u.Scheme == "https" {
			u.Host = host
		} else {
			u.Host = net.JoinHostPort(host, port)
		}
	}

	return &u
}

func (s *Server) Lock(token, filename string) error {
	key := path.Join(token, filename)

	if _, ok := s.locks[key]; !ok {
		s.locks[key] = &sync.Mutex{}
	}

	s.locks[key].Lock()

	return nil
}

func (s *Server) Unlock(token, filename string) error {
	key := path.Join(token, filename)
	s.locks[key].Unlock()

	return nil
}

func (s *Server) CheckMetadata(token, filename string) error {
	s.Lock(token, filename)
	defer s.Unlock(token, filename)

	var metadata Metadata

	r, _, _, err := s.storage.Get(token, fmt.Sprintf("%s.metadata", filename))
	if s.storage.IsNotExist(err) {
		return nil
	} else if err != nil {
		return err
	}

	defer r.Close()

	if err := json.NewDecoder(r).Decode(&metadata); err != nil {
		return err
	} else if metadata.Downloads >= metadata.MaxDownloads {
		return errors.New("MaxDownloads expired.")
	} else if time.Now().After(metadata.MaxDate) {
		return errors.New("MaxDate expired.")
	} else {
		// todo(nl5887): mutex?

		// update number of downloads
		metadata.Downloads++

		buffer := &bytes.Buffer{}
		if err := json.NewEncoder(buffer).Encode(metadata); err != nil {
			return errors.New("Could not encode metadata")
		} else if err := s.storage.Put(token, fmt.Sprintf("%s.metadata", filename), buffer, "text/json", uint64(buffer.Len())); err != nil {
			return errors.New("Could not save metadata")
		}
	}

	return nil
}

func (s *Server) zipHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)

	files := vars["files"]

	zipfilename := fmt.Sprintf("transfersh-%d.zip", uint16(time.Now().UnixNano()))

	w.Header().Set("Content-Type", "application/zip")
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", zipfilename))
	w.Header().Set("Connection", "close")

	zw := zip.NewWriter(w)

	for _, key := range strings.Split(files, ",") {
		if strings.HasPrefix(key, "/") {
			key = key[1:]
		}

		key = strings.Replace(key, "\\", "/", -1)

		token := strings.Split(key, "/")[0]
		filename := sanitize(strings.Split(key, "/")[1])

		if err := s.CheckMetadata(token, filename); err != nil {
			log.Printf("Error metadata: %s", err.Error())
			continue
		}

		reader, _, _, err := s.storage.Get(token, filename)

		if err != nil {
			if s.storage.IsNotExist(err) {
				http.Error(w, "File not found", 404)
				return
			} else {
				log.Printf("%s", err.Error())
				http.Error(w, "Could not retrieve file.", 500)
				return
			}
		}

		defer reader.Close()

		header := &zip.FileHeader{
			Name:         strings.Split(key, "/")[1],
			Method:       zip.Store,
			ModifiedTime: uint16(time.Now().UnixNano()),
			ModifiedDate: uint16(time.Now().UnixNano()),
		}

		fw, err := zw.CreateHeader(header)

		if err != nil {
			log.Printf("%s", err.Error())
			http.Error(w, "Internal server error.", 500)
			return
		}

		if _, err = io.Copy(fw, reader); err != nil {
			log.Printf("%s", err.Error())
			http.Error(w, "Internal server error.", 500)
			return
		}
	}

	if err := zw.Close(); err != nil {
		log.Printf("%s", err.Error())
		http.Error(w, "Internal server error.", 500)
		return
	}
}

func (s *Server) tarGzHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)

	files := vars["files"]

	tarfilename := fmt.Sprintf("transfersh-%d.tar.gz", uint16(time.Now().UnixNano()))

	w.Header().Set("Content-Type", "application/x-gzip")
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", tarfilename))
	w.Header().Set("Connection", "close")

	os := gzip.NewWriter(w)
	defer os.Close()

	zw := tar.NewWriter(os)
	defer zw.Close()

	for _, key := range strings.Split(files, ",") {
		if strings.HasPrefix(key, "/") {
			key = key[1:]
		}

		key = strings.Replace(key, "\\", "/", -1)

		token := strings.Split(key, "/")[0]
		filename := sanitize(strings.Split(key, "/")[1])

		if err := s.CheckMetadata(token, filename); err != nil {
			log.Printf("Error metadata: %s", err.Error())
			continue
		}

		reader, _, contentLength, err := s.storage.Get(token, filename)
		if err != nil {
			if s.storage.IsNotExist(err) {
				http.Error(w, "File not found", 404)
				return
			} else {
				log.Printf("%s", err.Error())
				http.Error(w, "Could not retrieve file.", 500)
				return
			}
		}

		defer reader.Close()

		header := &tar.Header{
			Name: strings.Split(key, "/")[1],
			Size: int64(contentLength),
		}

		err = zw.WriteHeader(header)
		if err != nil {
			log.Printf("%s", err.Error())
			http.Error(w, "Internal server error.", 500)
			return
		}

		if _, err = io.Copy(zw, reader); err != nil {
			log.Printf("%s", err.Error())
			http.Error(w, "Internal server error.", 500)
			return
		}
	}
}

func (s *Server) tarHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)

	files := vars["files"]

	tarfilename := fmt.Sprintf("transfersh-%d.tar", uint16(time.Now().UnixNano()))

	w.Header().Set("Content-Type", "application/x-tar")
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", tarfilename))
	w.Header().Set("Connection", "close")

	zw := tar.NewWriter(w)
	defer zw.Close()

	for _, key := range strings.Split(files, ",") {
		token := strings.Split(key, "/")[0]
		filename := strings.Split(key, "/")[1]

		if err := s.CheckMetadata(token, filename); err != nil {
			log.Printf("Error metadata: %s", err.Error())
			continue
		}

		reader, _, contentLength, err := s.storage.Get(token, filename)
		if err != nil {
			if s.storage.IsNotExist(err) {
				http.Error(w, "File not found", 404)
				return
			} else {
				log.Printf("%s", err.Error())
				http.Error(w, "Could not retrieve file.", 500)
				return
			}
		}

		defer reader.Close()

		header := &tar.Header{
			Name: strings.Split(key, "/")[1],
			Size: int64(contentLength),
		}

		err = zw.WriteHeader(header)
		if err != nil {
			log.Printf("%s", err.Error())
			http.Error(w, "Internal server error.", 500)
			return
		}

		if _, err = io.Copy(zw, reader); err != nil {
			log.Printf("%s", err.Error())
			http.Error(w, "Internal server error.", 500)
			return
		}
	}
}

func (s *Server) getHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)

	token := vars["token"]
	filename := vars["filename"]

	if err := s.CheckMetadata(token, filename); err != nil {
		log.Printf("Error metadata: %s", err.Error())
		http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
		return
	}

	reader, contentType, contentLength, err := s.storage.Get(token, filename)
	if s.storage.IsNotExist(err) {
		http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
		return
	} else if err != nil {
		log.Printf("%s", err.Error())
		http.Error(w, "Could not retrieve file.", 500)
		return
	}

	defer reader.Close()

	w.Header().Set("Content-Type", contentType)
	w.Header().Set("Content-Length", strconv.FormatUint(contentLength, 10))
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", filename))
	w.Header().Set("Connection", "close")

	if _, err = io.Copy(w, reader); err != nil {
		log.Printf("%s", err.Error())
		http.Error(w, "Error occurred copying to output stream", 500)
		return
	}
}

func (s *Server) RedirectHandler(h http.Handler) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if !s.forceHTTPs {
			// we don't want to enforce https
		} else if r.URL.Path == "/health.html" {
			// health check url won't redirect
		} else if strings.HasSuffix(ipAddrFromRemoteAddr(r.Host), ".onion") {
			// .onion addresses cannot get a valid certificate, so don't redirect
		} else if r.Header.Get("X-Forwarded-Proto") == "https" {
		} else if r.URL.Scheme == "https" {
		} else {
			u := getURL(r)
			u.Scheme = "https"

			http.Redirect(w, r, u.String(), http.StatusPermanentRedirect)
			return
		}

		h.ServeHTTP(w, r)
	}
}

// Create a log handler for every request it receives.
func LoveHandler(h http.Handler) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("x-made-with", "<3 by DutchCoders")
		w.Header().Set("x-served-by", "Proudly served by DutchCoders")
		w.Header().Set("Server", "Transfer.sh HTTP Server 1.0")
		h.ServeHTTP(w, r)
	}
}