/*
GoCheese -- Python private package repository and caching proxy
Copyright (C) 2019-2021 Sergey Matveev <stargrave@stargrave.org>
              2019-2021 Elena Balakhonova <balakhonova_e@riseup.net>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package main

import (
	"bufio"
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"path/filepath"
)

func serveUpload(w http.ResponseWriter, r *http.Request) {
	// Authentication
	username, password, ok := r.BasicAuth()
	if !ok {
		log.Println(r.RemoteAddr, "unauthenticated", username)
		http.Error(w, "unauthenticated", http.StatusUnauthorized)
		return
	}
	auther, ok := passwords[username]
	if !ok || !auther.Auth(password) {
		log.Println(r.RemoteAddr, "unauthenticated", username)
		http.Error(w, "unauthenticated", http.StatusUnauthorized)
		return
	}

	// Form parsing
	var err error
	if err = r.ParseMultipartForm(1 << 20); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	pkgNames, exists := r.MultipartForm.Value["name"]
	if !exists || len(pkgNames) != 1 {
		http.Error(w, "single name is expected in request", http.StatusBadRequest)
		return
	}
	pkgName := normalizationRe.ReplaceAllString(pkgNames[0], "-")
	dirPath := filepath.Join(*root, pkgName)
	var digestExpected []byte
	if digestExpectedHex, exists := r.MultipartForm.Value["sha256_digest"]; exists {
		digestExpected, err = hex.DecodeString(digestExpectedHex[0])
		if err != nil {
			http.Error(w, "bad sha256_digest: "+err.Error(), http.StatusBadRequest)
			return
		}
	}
	gpgSigsExpected := make(map[string]struct{})

	// Checking is it internal package
	if _, err = os.Stat(filepath.Join(dirPath, InternalFlag)); err != nil {
		log.Println(r.RemoteAddr, "non-internal package", pkgName)
		http.Error(w, "unknown internal package", http.StatusUnauthorized)
		return
	}

	for _, file := range r.MultipartForm.File["content"] {
		filename := file.Filename
		gpgSigsExpected[filename+GPGSigExt] = struct{}{}
		log.Println(r.RemoteAddr, "put", filename, "by", username)
		path := filepath.Join(dirPath, filename)
		if _, err = os.Stat(path); err == nil {
			log.Println(r.RemoteAddr, filename, "already exists")
			http.Error(w, "already exists", http.StatusBadRequest)
			return
		}
		if !mkdirForPkg(w, r, pkgName) {
			return
		}
		src, err := file.Open()
		defer src.Close()
		if err != nil {
			log.Println("error", r.RemoteAddr, filename, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		dst, err := TempFile(dirPath)
		if err != nil {
			log.Println("error", r.RemoteAddr, filename, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		dstBuf := bufio.NewWriter(dst)
		hasher := sha256.New()
		wr := io.MultiWriter(hasher, dst)
		if _, err = io.Copy(wr, src); err != nil {
			log.Println("error", r.RemoteAddr, filename, err)
			os.Remove(dst.Name())
			dst.Close()
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if err = dstBuf.Flush(); err != nil {
			log.Println("error", r.RemoteAddr, filename, err)
			os.Remove(dst.Name())
			dst.Close()
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if err = dst.Sync(); err != nil {
			log.Println("error", r.RemoteAddr, filename, err)
			os.Remove(dst.Name())
			dst.Close()
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		dst.Close()
		digest := hasher.Sum(nil)
		if digestExpected != nil {
			if bytes.Compare(digestExpected, digest) == 0 {
				log.Println(r.RemoteAddr, filename, "good checksum received")
			} else {
				log.Println(r.RemoteAddr, filename, "bad checksum received")
				http.Error(w, "bad checksum", http.StatusBadRequest)
				os.Remove(dst.Name())
				return
			}
		}
		if err = os.Rename(dst.Name(), path); err != nil {
			log.Println("error", r.RemoteAddr, path, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if err = DirSync(dirPath); err != nil {
			log.Println("error", r.RemoteAddr, dirPath, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if err = WriteFileSync(dirPath, path+"."+HashAlgoSHA256, digest); err != nil {
			log.Println("error", r.RemoteAddr, path+"."+HashAlgoSHA256, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}
	for _, file := range r.MultipartForm.File["gpg_signature"] {
		filename := file.Filename
		if _, exists := gpgSigsExpected[filename]; !exists {
			log.Println(r.RemoteAddr, filename, "unexpected GPG signature filename")
			http.Error(w, "unexpected GPG signature filename", http.StatusBadRequest)
			return
		}
		delete(gpgSigsExpected, filename)
		log.Println(r.RemoteAddr, "put", filename, "by", username)
		path := filepath.Join(dirPath, filename)
		if _, err = os.Stat(path); err == nil {
			log.Println(r.RemoteAddr, filename, "already exists")
			http.Error(w, "already exists", http.StatusBadRequest)
			return
		}
		src, err := file.Open()
		if err != nil {
			log.Println("error", r.RemoteAddr, filename, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		sig, err := ioutil.ReadAll(src)
		src.Close()
		if err != nil {
			log.Println("error", r.RemoteAddr, filename, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if err = WriteFileSync(dirPath, path, sig); err != nil {
			log.Println("error", r.RemoteAddr, path, err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
	}
}