package http

import (
	"crypto/sha256"
	"dwelling-upload/pkg/utils"
	"dwelling-upload/web"
	"encoding/base64"
	"encoding/hex"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"path"
	"strings"
	"time"

	"git.arav.su/Arav/httpr"
)

type UploadHandlers struct {
	logFile *log.Logger

	uploadDir     string
	uploadDirSize *int64

	hashSalt string

	keepForHours  int
	limitStorage  int64
	limitFileSize int64
}

func NewUploadHandlers(lFile *log.Logger, uploadDir string, uploadDirSize *int64,
	hashSalt string, keepForHours int, limStorage, limFileSz int64) *UploadHandlers {
	return &UploadHandlers{
		logFile:       lFile,
		uploadDir:     uploadDir,
		uploadDirSize: uploadDirSize,
		hashSalt:      hashSalt,
		keepForHours:  keepForHours,
		limitStorage:  limStorage,
		limitFileSize: limFileSz}
}

func (h *UploadHandlers) Index(w http.ResponseWriter, r *http.Request) {
	var storCapacity int64 = h.limitStorage << 20
	var fMaxSize int64 = h.limitFileSize << 20

	_, _, availStr := utils.ConvertFileSize(storCapacity - *h.uploadDirSize)
	_, _, fMaxSzStr := utils.ConvertFileSize(fMaxSize)

	web.Index(utils.MainSite(r.Host), h.keepForHours, fMaxSzStr, availStr, w)
}

func (h *UploadHandlers) Upload(w http.ResponseWriter, r *http.Request) {
	var fMaxSizeBytes int64 = h.limitFileSize << 20
	var storCapacity int64 = h.limitStorage << 20

	r.Body = http.MaxBytesReader(w, r.Body, fMaxSizeBytes)

	if err := r.ParseMultipartForm(fMaxSizeBytes); err != nil {
		log.Println("failed to parse upload form:", err)
		Error(w, r, http.StatusExpectationFailed, "Failed to parse upload form.")
		return
	}

	f, fHandler, err := r.FormFile("file")
	if err != nil {
		log.Println("failed to open incoming file:", err)
		Error(w, r, http.StatusInternalServerError, "Error reading an incoming file.")
		return
	}
	defer os.Remove(fHandler.Filename)
	defer f.Close()

	var leftSpace int64 = storCapacity - *h.uploadDirSize

	if leftSpace < fHandler.Size {
		log.Println("not enough space left in storage, only", leftSpace>>20, "MiB left")
		Error(w, r, http.StatusInternalServerError, "Not enough space left, sorry.")
		return
	}

	s256 := sha256.New()
	if _, err := io.Copy(s256, f); err != nil {
		log.Println("failed to compute a SHA-256 hash:", err)
		Error(w, r, http.StatusInternalServerError, "A hash for the file cannot be computed.")
		return
	}

	fHash := hex.EncodeToString(s256.Sum(nil))
	s256.Write([]byte(h.hashSalt))
	fSaltedHash := base64.RawURLEncoding.EncodeToString(s256.Sum(nil))

	f.Seek(0, io.SeekStart)

	fPath := path.Join(h.uploadDir, fSaltedHash)

	_, err = os.Stat(fPath)
	if os.IsNotExist(err) {
		fDst, err := os.Create(fPath)
		if err != nil {
			log.Println("failed to open file for writing", err)
			Error(w, r, http.StatusInternalServerError, "File cannot be written.")
			return
		}
		defer fDst.Close()

		// We initialy set a dst file size to occupy space equal to uploaded's size.
		// This is called a sparse file, if you need to know.
		// It allows us to have a relatively small buffer size for inotify watcher.
		// And it really affects that. I tested it.
		fDst.Seek(fHandler.Size-1, io.SeekStart)
		fDst.Write([]byte{0})
		fDst.Seek(0, io.SeekStart)

		if _, err = io.Copy(fDst, f); err != nil {
			log.Println("failed to copy uploaded file to destination:", err)
			Error(w, r, http.StatusInternalServerError, "Failed to copy uploaded file to the storage.")
			return
		}

		typ, _ := utils.NetworkType(r.Host)

		h.logFile.Printf("| up | %s | %s | %s | SHA256 %s | %s | %d | %s",
			r.Header.Get("X-Real-IP"), typ, fHandler.Filename, fHash, fSaltedHash, fHandler.Size, r.UserAgent())

		w.WriteHeader(http.StatusCreated)
	} else {
		os.Chtimes(fPath, time.Now(), time.Now())
		w.WriteHeader(http.StatusFound)
	}

	downloadURL := path.Join("/", fSaltedHash, fHandler.Filename)
	downloadURLParsed, _ := url.Parse(downloadURL)

	_, scheme := utils.NetworkType(r.Host)
	site := scheme + "://" + r.Host

	if strings.Contains(r.UserAgent(), "curl") || strings.Contains(r.UserAgent(), "Wget") {
		fmt.Fprintln(w, site+downloadURLParsed.String(), "will be kept for", h.keepForHours)
	} else {
		web.Uploaded(utils.MainSite(r.Host), site, downloadURLParsed.String(), h.keepForHours, w)
	}
}

func (h *UploadHandlers) Download(w http.ResponseWriter, r *http.Request) {
	saltedHash := httpr.Param(r, "hash")

	path := path.Join(h.uploadDir, saltedHash)

	stat, err := os.Stat(path)
	if os.IsNotExist(err) {
		Error(w, r, http.StatusNotFound, "")
		return
	}

	name := httpr.Param(r, "name")

	w.Header().Add("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", name))

	fd, err := os.Open(path)
	if err != nil {
		log.Println("failed to open file to read:", err)
		Error(w, r, http.StatusInternalServerError, "Failed to open file to read.")
		return
	}
	defer fd.Close()

	netTyp, _ := utils.NetworkType(r.Host)

	h.logFile.Printf("| dw | %s | %s | %s | %s | %s",
		r.Header.Get("X-Real-IP"), netTyp, name, saltedHash, r.UserAgent())

	http.ServeContent(w, r, path, stat.ModTime(), fd)
}

func (h *UploadHandlers) Delete(w http.ResponseWriter, r *http.Request) {
	var saltedHash string
	if r.Method == "DELETE" {
		saltedHash = httpr.Param(r, "hash")
	} else {
		r.ParseForm()
		saltedHash = r.FormValue("hash")
	}

	path := path.Join(h.uploadDir, saltedHash)

	if _, err := os.Stat(path); os.IsNotExist(err) {
		Error(w, r, http.StatusNotFound, "")
		return
	}

	if err := os.Remove(path); err != nil {
		log.Println("failed to remove a file:", err)
		Error(w, r, http.StatusInternalServerError, "Failed to remove a file.")
		return
	}

	netTyp, _ := utils.NetworkType(r.Host)

	h.logFile.Printf("| dt | %s | %s | %s | %s",
		r.Header.Get("X-Real-IP"), netTyp, saltedHash, r.UserAgent())

	if strings.Contains(r.UserAgent(), "curl") || strings.Contains(r.UserAgent(), "Wget") {
		fmt.Fprintln(w, "File was successfully deleted.")
	} else {
		web.Deleted(utils.MainSite(r.Host), w)
	}
}

func Error(w http.ResponseWriter, r *http.Request, code int, reason string) {
	if strings.Contains(r.UserAgent(), "curl") || strings.Contains(r.UserAgent(), "Wget") {
		http.Error(w, reason, code)
		return
	}

	w.WriteHeader(code)
	web.ErrorXXX(utils.MainSite(r.Host), code, reason, w)
}

func RobotsTxt(w http.ResponseWriter, r *http.Request) {
	data, _ := web.AssetsGetFile("robots.txt")
	w.Write(data)
}

func Favicon(w http.ResponseWriter, r *http.Request) {
	data, _ := web.AssetsGetFile("img/favicon.svg")
	w.Write(data)
}