package needle

import (
	"compress/gzip"
	"crypto/md5"
	"fmt"
	"hash"
	"io"
	"io/ioutil"
	"mime"
	"net/http"
	"path"
	"path/filepath"
	"strconv"
	"strings"

	"github.com/chrislusf/seaweedfs/weed/glog"
	"github.com/chrislusf/seaweedfs/weed/util"
)

type ParsedUpload struct {
	FileName         string
	Data             []byte
	MimeType         string
	PairMap          map[string]string
	IsGzipped        bool
	OriginalDataSize int
	ModifiedTime     uint64
	Ttl              *TTL
	IsChunkedFile    bool
	UncompressedData []byte
}

func ParseUpload(r *http.Request, sizeLimit int64) (pu *ParsedUpload, e error) {
	pu = &ParsedUpload{}
	pu.PairMap = make(map[string]string)
	for k, v := range r.Header {
		if len(v) > 0 && strings.HasPrefix(k, PairNamePrefix) {
			pu.PairMap[k] = v[0]
		}
	}

	if r.Method == "POST" {
		e = parseMultipart(r, sizeLimit, pu)
	} else {
		e = parsePut(r, sizeLimit, pu)
	}
	if e != nil {
		return
	}

	pu.ModifiedTime, _ = strconv.ParseUint(r.FormValue("ts"), 10, 64)
	pu.Ttl, _ = ReadTTL(r.FormValue("ttl"))

	pu.OriginalDataSize = len(pu.Data)
	pu.UncompressedData = pu.Data
	// println("received data", len(pu.Data), "isGzipped", pu.IsCompressed, "mime", pu.MimeType, "name", pu.FileName)
	if pu.MimeType == "" {
		pu.MimeType = http.DetectContentType(pu.Data)
		// println("detected mimetype to", pu.MimeType)
		if pu.MimeType == "application/octet-stream" {
			pu.MimeType = ""
		}
	}
	if pu.IsGzipped {
		if unzipped, e := util.DecompressData(pu.Data); e == nil {
			pu.OriginalDataSize = len(unzipped)
			pu.UncompressedData = unzipped
			// println("ungzipped data size", len(unzipped))
		}
	} else {
		ext := filepath.Base(pu.FileName)
		if shouldGzip, iAmSure := util.IsGzippableFileType(ext, pu.MimeType); pu.MimeType == "" && !iAmSure || shouldGzip && iAmSure {
			// println("ext", ext, "iAmSure", iAmSure, "shouldGzip", shouldGzip, "mimeType", pu.MimeType)
			if compressedData, err := util.GzipData(pu.Data); err == nil {
				if len(compressedData)*10 < len(pu.Data)*9 {
					pu.Data = compressedData
					pu.IsGzipped = true
				}
				// println("gzipped data size", len(compressedData))
			}
		}
	}
	return
}

func parsePut(r *http.Request, sizeLimit int64, pu *ParsedUpload) (e error) {
	pu.IsGzipped = r.Header.Get("Content-Encoding") == "gzip"
	pu.MimeType = r.Header.Get("Content-Type")
	pu.FileName = ""
	pu.Data, e = ioutil.ReadAll(io.LimitReader(r.Body, sizeLimit+1))
	if e == io.EOF || int64(pu.OriginalDataSize) == sizeLimit+1 {
		io.Copy(ioutil.Discard, r.Body)
	}
	r.Body.Close()
	return nil
}

type ChecksumReader struct {
	h hash.Hash
	r io.Reader
}

func (cr *ChecksumReader) Read(p []byte) (int, error) {
	n, err := cr.r.Read(p)
	if err == nil {
		cr.h.Write(p[:n])
	}
	return n, err
}

func (cr *ChecksumReader) Checksum() string {
	return fmt.Sprintf("%x", cr.h.Sum(nil))
}

func parseMultipart(r *http.Request, sizeLimit int64, pu *ParsedUpload) (e error) {
	defer func() {
		if e != nil && r.Body != nil {
			io.Copy(ioutil.Discard, r.Body)
			r.Body.Close()
		}
	}()
	form, fe := r.MultipartReader()
	if fe != nil {
		glog.V(0).Infoln("MultipartReader [ERROR]", fe)
		e = fe
		return
	}

	// first multi-part item
	part, fe := form.NextPart()
	if fe != nil {
		glog.V(0).Infoln("Reading Multi part [ERROR]", fe)
		e = fe
		return
	}

	pu.FileName = part.FileName()
	if pu.FileName != "" {
		pu.FileName = path.Base(pu.FileName)
	}

	reader := io.LimitReader(part, sizeLimit+1)
	if expectedChecksum := r.Header.Get("Content-MD5"); expectedChecksum != "" {
		if part.Header.Get("Content-Encoding") == "gzip" {
			gr, err := gzip.NewReader(reader)
			if err != nil {
				e = fmt.Errorf("Content-Encoding == gzip but content was not gzipped: %s", err)
				return
			}
			reader = gr
		}
		cr := &ChecksumReader{md5.New(), reader}
		pu.Data, e = ioutil.ReadAll(cr)
		if expectedChecksum != cr.Checksum() {
			e = fmt.Errorf("Content-MD5 did not match md5 of file data [%s] != [%s]", expectedChecksum, cr.Checksum())
			return
		}
	} else {
		pu.Data, e = ioutil.ReadAll(reader)
	}

	if e != nil {
		glog.V(0).Infoln("Reading Content [ERROR]", e)
		return
	}
	if len(pu.Data) == int(sizeLimit)+1 {
		e = fmt.Errorf("file over the limited %d bytes", sizeLimit)
		return
	}

	// if the filename is empty string, do a search on the other multi-part items
	for pu.FileName == "" {
		part2, fe := form.NextPart()
		if fe != nil {
			break // no more or on error, just safely break
		}

		fName := part2.FileName()

		// found the first <file type> multi-part has filename
		if fName != "" {
			data2, fe2 := ioutil.ReadAll(io.LimitReader(part2, sizeLimit+1))
			if fe2 != nil {
				glog.V(0).Infoln("Reading Content [ERROR]", fe2)
				e = fe2
				return
			}
			if len(data2) == int(sizeLimit)+1 {
				e = fmt.Errorf("file over the limited %d bytes", sizeLimit)
				return
			}

			// update
			pu.Data = data2
			pu.FileName = path.Base(fName)
			break
		}
	}

	pu.IsChunkedFile, _ = strconv.ParseBool(r.FormValue("cm"))

	if !pu.IsChunkedFile {

		dotIndex := strings.LastIndex(pu.FileName, ".")
		ext, mtype := "", ""
		if dotIndex > 0 {
			ext = strings.ToLower(pu.FileName[dotIndex:])
			mtype = mime.TypeByExtension(ext)
		}
		contentType := part.Header.Get("Content-Type")
		if contentType != "" && contentType != "application/octet-stream" && mtype != contentType {
			pu.MimeType = contentType // only return mime type if not deductable
			mtype = contentType
		}

		pu.IsGzipped = part.Header.Get("Content-Encoding") == "gzip"
	}

	return
}