package contented

import (
	"crypto/sha512"
	"encoding/hex"
	"io"
	"mime"
	"mime/multipart"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"
)

func (this *Server) handleUpload(src multipart.File, hdr *multipart.FileHeader, UploadIP string) (string, error) {

	// Get file length
	srcLen, err := src.Seek(0, io.SeekEnd)
	if err != nil {
		return "", err
	}

	_, err = src.Seek(0, io.SeekStart)
	if err != nil {
		return "", err
	}

	// Get file hash
	hasher := sha512.New512_256()
	_, err = io.CopyN(hasher, src, int64(srcLen))
	if err != nil {
		return "", err
	}

	_, err = src.Seek(0, io.SeekStart)
	if err != nil {
		return "", err
	}

	// Save file to disk
	fileID := hex.EncodeToString(hasher.Sum(nil))
	dest, err := os.OpenFile(filepath.Join(this.opts.DataDirectory, fileID), os.O_CREATE|os.O_WRONLY, 0600)
	if err != nil {
		if os.IsExist(err) {
			return fileID, nil // hash matches existing upload
		}

		return "", err
	}
	defer dest.Close()

	_, err = io.CopyN(dest, src, int64(srcLen))
	if err != nil {
		return "", err
	}

	// Determine mime type
	ctype := hdr.Header.Get("Content-Type")
	if ctype == "" {
		ctype = mime.TypeByExtension(path.Ext(hdr.Filename))
	}
	if ctype == "" {
		ctype = `application/octet-stream`
	}

	// Blacklisted mime-types
	ctype = strings.ToLower(ctype)
	if strings.HasPrefix(ctype, `text/html`) ||
		strings.HasPrefix(ctype, `application/javascript`) {
		ctype = `application/octet-stream`
	}

	// Persist metadata to DB
	m := Metadata{
		Filename:   hdr.Filename,
		UploadTime: time.Now(),
		UploadIP:   UploadIP,
		FileSize:   srcLen,
		MimeType:   ctype,
	}
	err = this.SetMetadata(fileID, m)
	if err != nil {
		return "", err
	}

	// Done
	return fileID, nil
}